Group 3 and Group 13 Metal Hydride Compounds

G oup 3 and G oup 13 Me al Hyd ide Compounds DISSERTATION zu E langung des akademischen G ades eines Dok o s de Na u wissenscha en (D . e . na .) im Fach Chemie de Fakul ä ü Biologie, Chemie und Geowissenscha en de Uni e si ä Bay eu h o geleg on Dipl. Chem. Tobias Baue gebo en in Regensbu g Bay eu h, 2013 G oup 3 and G oup 13 Me al Hyd ide Compounds DISSERTATION zu E langung des akademischen G ades eines Dok o s de Na u wissenscha en (D . e . na .) im Fach Chemie de Fakul ä ü Biologie, Chemie und Geowissenscha en de Uni e si ä Bay eu h o geleg on Dipl. Chem. Tobias Baue gebo en in Regensbu g Bay eu h, 2013 The ollowing wo k has been ca ied ou in he pe iod Sep embe 2009 o July 2013 a he Leh s uhl ü Ano ganische Chemie II o he Uni e si ä Bay eu h unde he supe ision o P o . D . Rhe Kempe. This hesis ul ills he equi emen s o he doc o al deg ee o he Falkul ä ü Biologie, Chemie und Geowissenscha en a he Uni e si ä Bay eu h. Thesis submi ed: 03/07/2013 Thesis accep ed: 10/07/2013 Scien i ic Colloquium: 31/10/2013 Cu en dean o acul y: P o . D . Rhe Kempe Examina ion Commi ee: Fi s e e ee: P o . D . R. Kempe Second e e ee: P o . D . R. Schobe Thi d e e ee: P o . D . A. Fe y Chai man: P o . D . A. G eine „Das Auße o den liche geschieh nich au gla em, gewöhnlichem Wege.“ Johann Wol gang on Goe he Alphabe ical lis o abb e ia ions alane aluminum hyd ide Ap aminopy idina e, aminopy idina o ligand ApH aminopy idine °C deg ee celsius Cp cyclopen adienyl ligand ELI-D elec on localizabili y indica o E e hyl Gu guanidina e, guanidina o ligand GuH guanidine NMR nuclea magne ic esonance spec oscopy h /THF e ahyd o u an PE 3 ie hylphosphine Ph phenyl py py idinyl PyAp dep o ona ed N-(2,6-diisop opylphenyl)-6-(py olidin-1-yl)py idin-2-amine QTAIM quan um heo y o a oms in molecules XRD single c ys al X- ay s uc u e analysis Table o Con en s 1 Summa y/Zusammen assung ............................................................. 1 1.1 Summa y .................................................................................................... 1 1.2 Zusammen assung .................................................................................... 4 2 In oduc ion ......................................................................................... 7 3 O e iew o Thesis Resul s .............................................................. 13 3.1 Synopsis ................................................................................................... 13 3.2 Indi idual Con ibu ion o Join Publica ions ....................................... 19 4 The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions ..................................................................................... 21 4.1 In oduc ion .............................................................................................. 22 4.2 Resul s and Discussion .......................................................................... 23 4.3 Conclusions ............................................................................................. 32 4.4 Expe imen al Sec ion .............................................................................. 32 4.5 Acknowledgmen s ................................................................................... 36 4.6 Re e ences ............................................................................................... 36 4.7 Suppo ing In o ma ion ........................................................................... 40 4.8 Re e ences ............................................................................................... 45 5 Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes ........................................................ 46 5.1 In oduc ion .............................................................................................. 46 5.2 Resul s and Discussion .......................................................................... 47 5.3 Conclusions ............................................................................................. 53 5.4 Expe imen al Sec ion .............................................................................. 54 5.5 Re e ences ............................................................................................... 56 6 Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand ............................... 58 6.1 In oduc ion .............................................................................................. 58 6.2 Resul s and Discussion .......................................................................... 59 6.3 Conclusions ............................................................................................. 65 6.4 Acknowledgmen s ................................................................................... 66 6.5 Expe imen al Sec ion .............................................................................. 66 6.6 Re e ences ............................................................................................... 67 7 Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds ............................................................................................. 69 7.1 In oduc ion .............................................................................................. 69 7.2 Resul s and Discussion .......................................................................... 70 7.3 Conclusions ............................................................................................. 75 7.4 Acknowledgmen s ................................................................................... 75 7.5 Re e ences ............................................................................................... 76 7.6 Suppo ing In o ma ion ........................................................................... 78 7.7 Gene al ..................................................................................................... 78 7.8 De ails o he X- ay c ys al s uc u e analyses ..................................... 79 7.9 Syn hesis and cha ac e iza ion o he clus e compounds ................. 80 7.10 Re e ences ............................................................................................... 81 8 Lis o Publica ions ........................................................................... 82 9 Acknowledgemen s / Danksagung ................................................... 85 9.1 Acknowledgmen s ................................................................................... 85 9.2 Danksagung ............................................................................................. 87 10 Decla a ion / E klä ung: .................................................................... 89 2. In oduc ion 7 2 In oduc ion Me al-ca bon and me al-hyd ogen bonds a e a he e y hea o coo dina ion chemis y. Molecula me al hyd ides, in gene al, a e a ascina ing class o compounds ega ding hei s uc u e, eac i i y and applica ions. They a e key in e media es in a ple ho a o selec i e s oichiome ic ans o ma ions and/o ca aly ic cycles. The i s well-de ined ansi ion me al hyd ides, (CO)4FeH2 and (CO)4CoH, we e p epa ed by Hiebe and co-wo ke s in 1931 and 1932, espec i ely.[1,2] These qui e uns able compounds emained as labo a o y cu iosi ies o o e 20 yea s. The nex miles one da es back o he yea 1955 wi h he disco e y o (C5H5)2ReH by Bi mingham and Wilkinson[3] and (C5H5)(CO)3MH (M = C , Mo, W) by Fische and co- wo ke s.[4] Two yea s la e , Cha , Duncanson, and Shaw p epa ed he excep ionally s able hyd ide compound ans-(PE 3)2ClP H.[5] Since hen, apid de elopmen in his ield ook place and by he yea 1965 o e 200 de i a i es we e epo ed in some 300 publica ions.[6] In 2001 he Nobel P ize in chemis y was awa ded join ly o Knowles, Nyo i and Sha pless o asymme ic ca alysis (Knowles and Nyo i o con ibu ions on asymme ic hyd ogena ion). This can be seen as one magic momen o me al hyd ide chemis y. Resea ch in e es in he main g oup me al hyd ides was documen ed alike.[7] The s-block me al hyd ides a e sal -like and he p-block me al hyd ides o m co alen ly bonded molecules compa able o he ones o med by he d- and -block me als. Especially aluminum hyd ides, i s p epa ed by S eche and Wibe g in 1942,[8] ecei ed much a en ion due o p omising applica ions as educing agen s in o ganic syn hesis[9] and o he educ ion o me al complexes[10]. Fu he mo e, alanes a e used in hyd oamina ion eac ions[11] and as p ecu so s o me al o ganic chemical apo deposi ion p ocesses.[12] A mo e con enien p epa a ion me hod was epo ed by Finhol , Bond, and Schlesinge in 1947.[13] Pionie ing wo k on amine complexes o alane da es back o he ea ly 1950s and he ea ly 1960s.[14,15] Since hen, much e o has been de o ed o ex end he ield o alane chemis y. T ansi ion me al σ-alane complexes[16] we e p epa ed due o p omising applica ions. Recen s udies on alanes ocus on applica ions as hyd ogen s o age ma e ials.[17,18] Mo eo e , a guanidina o ligand s abilized adduc o dialane (Al2H4) was epo ed o ea u e a di ec Al-Al bond.[19] Ano he p ominen and ich ield o me al hyd ides is ound o be he hyd ides o a e ea h me als (g oup 3 me als and lan hanoid me als [Ce-Lu]). These compounds o en agg ega e and build up polyhyd ide clus e s. Ra e ea h (poly)hyd ide compounds possess a ascina ing a ie y o unique s uc u al mo i s and chemical p ope ies. The ea ly wo k on lan hanoid hyd ides is e iewed by Bos and Gaye and co e s he pe iod om 1891 o 1966.[20] 2. In oduc ion 8 Since hen, i ook o e a decade un il he i s example o a molecula lan hanoid hyd ide was epo ed. Schumann and co-wo ke s p epa ed [(C5H5)2LuH( h )] ( h = e ahyd o u an) by hyd ogenolysis o he co esponding alkyl o a yl p ecu so in 1981.[21] F om he e on, esea ch in e es inc eased and an oddless numbe o cyclopen adienyl s abilized hyd ide and alkyl complexes o he a e ea hs became known.[22] Va ious applica ions and eac i i ies like hyd ogena ion eac ions,[23] hyd obo a ion eac ions,[24] hyd oamina ion eac ions,[25] hyd osilyla ion eac ions,[26] hyd ophosphina ion eac ions[27] and polyme iza ion p ocesses[28] o alkenes by cyclopen adienyl- ype a e ea h me al hyd ides and alkyls a e published. Hence, pe manen in e es in his ype o compounds a ose. Recen ly, a shi om cyclopen adienyl ligand sandwich- and hal -sandwich (poly)hyd ide complexes owa ds al e na i ely suppo ed hyd ide compounds has aken place.[29] Mainly, because o hei p omising new applica ions and eac i i ies. None heless, a e ea h me al hyd ide compounds suppo ed by ligands o he han Cp and i s de i a i es s ill lack in numbe . The mos used and impo an Cp al e na i es a e amido[30] (Scheme 1, igh ) and alkoxy ligands (Scheme 1, cen e ). They ha e p o en o be sui able o he s abiliza ion o elec on poo ansi ion, main g oup and a e ea h me al ions in di e en oxida ion s a es. Scheme 1. Commonly used ligand ypes o he s abiliza ion o me al hyd ides (R, R’ = a yl, alkyl o silyl, M = Main g oup, ansi ion o a e ea h me al). The aminopy idina o ligand, a subclass o he amido ligand amily, de i ed om dep o ona ed 2-aminopy idines, has been p ominen ly used in he enaissance o amido me al chemis y.[31] Two di e en binding modes a e known (Scheme 2) and many subs i u ion pa e ns o ine une he s e ic bulk o he ligand a e possible. S a ing om 2,6-dib omopy idine, i s ly a subs i u ed phenyl g oup is in oduced ia Kumada coupling and secondly, a de i a i e o aniline is in oduced ia Buchwald-Ha wig a yl amina ion. Scheme 2. Binding modes o aminopy idina o ligands (R, R' = a yl, alkyl o silyl, M = Main g oup, ansi ion o a e ea h me al, M' = ansi ion me al). 2. In oduc ion 9 [Ru(PhNpy)2)PPh3)2] was he i s example o a s ained η2-coo dina ed aminopy idina o ligand s abilized complex, desc ibed by Co on and co-wo ke s in 1984.[32] In 1991 Gamba o a and co-wo ke s epo ed on he i s anadium compound s abilized by an aminopy idina o ligand.[33] Kempe e al. p epa ed he i s co esponding g oup 3 me al complex in 1997.[34] Ano he subclass o he amido ligands a e guanidina o ligands de i ed om dep o ona ed guanidines, which a e compa able o he aminopy idina o ligands ega ding hei binding mode (Scheme 3). Thei subs i u ion pa e n is mo e a iable han o he aminopy idina o ligands, due o subs i u ion on he ni ogen a oms. Recen ly, his ligand class was comp ehensi ely e iewed by Jones.[35] Syn hesis o guanidina o ligands is achie ed ia a di ec app oach s a ing om subs i u ed ca bodiimides, which a e eac ed, wi h li hia ed seconda y amine de i a i es. The esul ing li hium complexes o he ligands can be used in sal me a hesis eac ions owa ds me al halides o can be hyd olyzed o a o d he p o ona ed ligands. These p o ona ed ligands can be used in alkane o amine elimina ion ou es. Lappe and co-wo ke s published he i s ansi ion me al guanidina o ligand s abilized complex in 1970.[36] Scheme 3. Binding modes o guanidina o ligands (R, R',R'', R''' = a yl, alkyl o silyl, M = Main g oup, ansi ion o a e ea h me al, M' = ansi ion me al). Fi s ly, his wo k was ocused on syn hesis and cha ac e iza ion o guanidina o ligand s abilized aluminum dime hyl complexes. These complexes we e examined ega ding he subs i uen s R'' and R'''. Dependency o he s e ic bulk owa ds he (M)N-C-N(M) angle was obse ed (Scheme 3, le , M = Al). Secondly, syn hesis and s uc u e o Ap and Gu ligand s abilized Al-H complexes was discussed. The eac ion o a s e ically bulky guanidine wi h li hium alana e was examined. A a e example o a σ-alane li hium complex was obse ed. Thi dly, a guanidina o ligand s abilized y ium dialkyl complex was syn hesized and cha ac e ized. I s abili y owa ds hyd ogenolysis using H2 was in es iga ed. The esul ing inuclea y ium polyhyd ide clus e compound possesses highly dynamic beha io o he hyd ides and he guanidina o ligands, as obse ed by a iable empe a u e 1H NMR spec oscopy. 2. In oduc ion 10 Fou hly, he i s examples o e na y a e ea h- ansi ion me al polyhyd ide clus e compounds we e shown. Clus e o ma ion p oceeded h ough C–H bond ac i a ion o he Cp ligands ha s abilize he ansi ion me al-con aining educ . Quan um chemical calcula ions o he elec onic s uc u e showed ionic W–H∙∙∙Lu in e ac ions and a co alen , pola Lu–Re bond. [1] W. Hiebe , F. Leu e , Na u wissenscha en 1931,19, 360–361. [2] W. Hiebe , F. Mühlbaue , E. A. Ehmann, Be ich e de deu schen chemischen Gesellscha (A and B Se ies) 1963, 65, 1090–1101. [3] G. Wilkinson, J. M. Bi mingham, J. Am. Chem. Soc. 1955, 77, 3421–3422. [4] E. O. Fische , W. Ha ne , H. O. S ahl, Z. Ano g. Allg. Chem. 1955, 282, 47–62. [5] J. Cha , L. A. Duncanson, B. L. Shaw, P oc. Chem. Soc. 1957, 343. [6] Fo selec ed e iew a icles on molecula ansi ion me al hyd ides, please see: a) J. Cha , Science 1968, 160, 723–729; b) H. D. Kaesz, R. B. Saillan , Chem. Re . 1972, 72, 231–281; c) A. J. Hoskin, D. W. S ephan, Coo d. Chem. Re . 2002, 233–234, 107– 129; d) G. S. McG ady, G. Guile a, Chem. Soc. Re . 2003, 32, 383–392. [7] Fo selec ed e iew a icles on main g oup me al hyd ides, please see: a) S. Ald idge, A. J. Downs, Chem. Re . 2001, 101, 3305–3365, b) S. K. Mandal, H. W. Roesky, Acc. Chem. Res. 2012, 45, 298–307. [8] O. S eche , E. Wibe g, Be ich e de deu schen chemischen Gesellscha (A and B Se ies) 1942, 75, 2003–2012. [9] J. Málek, M. Ce ný, Syn hesis 1972, 217–234. [10] B. M. Bulyche , Polyhed on 1990, 9, 387–408. [11] H. Haubens ock, E. L. Eliel, J. Am. Chem. Soc. 1962, 84, 2363–2368. [12] J. A. Jegie , W. L. Glad el e , Coo d. Chem. Re . 2000, 206–207, 631–650. [13] A. E. Finhol , A. C. Bond, H. I. Schlesinge , J. Am. Chem. Soc. 1947, 69, 1199–1203. [14] E. Wibe g, H. G a , R. Usón, Z. Ano g. Allg. Chem. 1953, 272, 221–232. [15] J. K. Ru , M. F. Haw ho ne, J. Am. Chem. Soc. 1960, 82, 2141–2144. [16] I. M. Riddles one, S. Edmonds, P. A. Kau man, J. U bano, J. I. Ba es, M. J. Kelly, A. L. Thompson, R. Taylo , S. Ald idge, J. Am. Chem. Soc. 2012, 134, 2551−2554. [17] a) L. Schlapbach, A. Zü el, Na u e 2001, 414, 353-358; b) E. Da id, J. Ma e . P oc. Technol. 2005, 162, 169–177; c) U. Ebe le, M. Felde ho , F. Schü h, Angew. Chem. 2009, 121, 6732–6757; Angew. Chem. In . Ed. 2009, 48, 6608–6630, d) S. F. Ma a , P og. Solid S a e Chem. 2010, 38, 1-37; e) S. F. Ma a , P og. Solid S a e Chem. 2012, 40, 31–40. [18] Fo ecen examples see: a) A. Zü el, Ma e . Today 2003, 24–33; b) M. La oche, J. Phys. Chem. Solids 2004, 65, 517–522; c) W. G ochala, P. P. Edwa ds, Chem. Re . 2. In oduc ion 11 2004, 104, 1283–1315; d) S. Ha de , J. Spielmann, J. In emann, H. Bandmann, Angew. Chem. 2011, 123, 4242–4246; Angew. Chem. In . Ed. 2011, 50, 4156–4160; e) P. Jochmann, J. P. Da in, T. P. Spaniol, L. Ma on, J. Okuda, Angew. Chem. 2012, 124, 4528–4531; Angew. Chem. In . Ed. 2012, 51, 4452–4455. [19] S. J. Bonhady, D. Collis, G. F enking, N. Holzmann, C. Jones, A. S asch, Na . Chem. 2010, 2, 865–869. [20] W. G. Bos, K. H. Gaye , J. Nuc. Ma . 1966, 18, 1–30. [21] H. Schumann, W. Gen he, J. O ganome . Chem. 1981, 213, C7–C9. [22] Fo selec ed e iew a icles on cyclopen adienyl lan hanoid hyd ides, please see: a) H. Schumann, J. A. Meese-Ma k sche el, L. Esse , Chem. Re . 1995, 95, 865–986; b) M. Eph i ikhine, Chem. Re . 1997, 97, 2193–2242. [23] a) W. J. E ans, I. Bloom, W. E. Hun e , J. L. A wood, J. Am. Chem. Soc. 1983, 105, 1401–1403; b) G. Jeske, H. Lauke, H. Maue mann, H. Schumann, T. J. Ma ks, J. Am. Chem. Soc. 1985, 107, 8091–8103; c) D. S e n, M. Saba , T.J. Ma ks, J. Am. Chem. Soc. 1990, 112, 9558–9575; d) V. P. Con icello, L. B a d, M. A. Gia dello, Y. Tsuji, M. Saba , C. L. S e n, T. J. Ma ks, J. Am. Chem. Soc. 1992, 114, 2761–2762. [24] a) K. N. Ha ison, T. J. Ma ks, J. Am. Chem. Soc. 1992, 114, 9220–9221; b) E. A. Bijpos , R. Ducha eau, J. H. Teuben, J. Mol. Ca al. 1995, 95,121–128; [25] a) P. W. Roesky, T. E. Mülle , Angew. Chem. 2003, 115, 2812–2814; Angew. Chem. In . Ed. 2003, 42, 2708–2710; b) S. Hong, T. J. Ma ks, Acc. Chem. Res. 2004, 37, 673–686; c) K. C. Hul zsch, Ad . Syn h. Ca al. 2005, 347, 367–391. [26] G. A. Molande , J. A. C. Rome o, Chem. Re . 2002, 102, 2161–2186. [27] a) M. R. Douglass, T. J. Ma ks, J. Am. Chem. Soc. 2000, 122, 1824–1825; b) A. Kawaoka, T. J. Ma ks, J. Am. Chem. Soc. 2004, 126, 12764–12765; c) A. Kawaoka, T. J. Ma ks, J. Am. Chem. Soc. 2005, 127, 6311–6324. [28] a) Z. Hou, Y. Waka suki, Coo d. Chem. Re . 2002, 231, 1–22; b) H. Yasuda, J. O ganome . Chem. 2002, 647, 128–138; c) Y. Nakayama, H. Yasuda, J. O ganome . Chem. 2004, 689, 4489–4498. [29] Fo selec ed e iew a icles on non-cyclopen adienyl lan hanoid hyd ides and hei applica ions, please see: a) M. Konkol, J. Okuda, Coo d. Chem. Re . 2008, 252, 1577– 1591; b) A. A. T i ono , Coo d. Chem. Re . 2010, 254, 1327–1347. [30] M. F. Lappe , P. P. Powe , A. R. Sange , R. C. S i as a a, Me al and Me alloid Amides, Ellis No wood L d., Chiches e , 1980. [31] R. Kempe, Angew. Chem. 2000, 112, 478–504; Angew. Chem. In . Ed. 2000, 39, 468– 493. [32] A. R. Chak a a y, F. A. Co on, E. S. Shamshoum, Ino g. Chim. Ac a 1984, 86, 5–11. 2. In oduc ion 12 [33] J. J. H. Edema, S. Gamba o a, A. Mee sma, A. L. Spek, N. Veldman, Ino g. Chem. 1991,30, 2062–2066. [34] R. Kempe, A. Spannenbe g, Z. K is alog . NCS 1997, 212, 487–489. [35] C. Jones, Coo d. Chem. Re . 2010, 254, 1273–1289. [36] G. Chand a, A. D. Jenkins, M. F. Lappe , R. C. S i as a a, J. Chem. Soc. 1970, 2550– 2558. 3. O e iew o Thesis Resul s 13 3 O e iew o Thesis Resul s This hesis comp ises ou publica ions, which a e p esen ed in chap e s 4 o 7. The indi idual con ibu ions o join publica ions a e poin ed ou in chap e 3.2. In he ollowing, he cen al heme o he hesis is summa ized. 3.1 Synopsis The main ask o his hesis was o inc ease he small numbe o s uc u ally ully cha ac e ized g oup 3 and g oup 13 me al hyd ide compounds. Fu he mo e, g oup 3 and g oup 13 me al alkyl compounds we e syn hesized (and cha ac e ized). These alkyl compounds we e syn hesized as p ecu so s and hei abili y o a o d hyd ide compounds was s udied. Suppo ing ligands o all complexes p esen ed he ein we e es ic ed o aminopy idina o, guanidina o and phenola o ligands. These ypes o ligands a e used o a e y sligh ex en in g oup 3 and g oup 13 me al hyd ide chemis y. Chap e 4 deals wi h new aluminum alkyl compounds s abilized by guanidina o ligands. Guanidina o ligand s abilized aluminum dialkyls we e syn hesized and s uc u ally cha ac e ized. S uc u al da a o hese compounds based on single c ys al X-Ray s uc u e analysis led o a concep o sho ening me al-me al bonds. Due o his ligand based concep he bes sui ed ligand yielding a s able C -C compound ea u ing he sho es me al-me al bond obse ed o da e was ound. In diguanidina o dich omium complexes he leng h o he quin uple bond can be in luenced by he subs i uen a he cen al ca bon a om o he used ligand. To ind he guanidina o ligand o ming he sho es C -C quin uple bonded complex, he dependency o he ele an N-C-N angle in he guanidina o ligand om he in oduced subs i uen was in es iga ed. Fine uning o he ligands s e ic bulk was essen ial. Guanidina o ligand s abilized aluminum dialkyls we e expec ed o be well sui ed o such a ligand ine- uning. The e ahed al coo dina ion a oided in e -ligand epulsion and he smoo h syn hesis ia alkane elimina ion om aluminum ialkyls allowed o an easy access. Fou di e en guanidina o ligand s abilized aluminium dialkyls we e syn hesized. These compounds we e isola ed in good yields (> 80 %). 3. O e iew o Thesis Resul s 14 Figu e 3.1. C ys al s uc u e o [(MPipGu)AlMe2] and [{(MPipGu)C }2]. S uc u al da a o he co esponding aluminum dialkyls showed p omising (Al)N-C-N(Al) angles o he guanidina o ligands bea ing a 2,6-dime hylpipe idine and a diisop opylamine backbone, espec i ely. The ound (Al)N-C-N(Al) angles we e 107.68(12)° (2,6- dime hylpipe idine) and 107.39(15)° (diisop opylamine). These wo po en ial ligands we e examined owa ds ul a sho me al-me al dis ances. Figu e 3.2.N-C-N angles o all s uc u ally in es iga ed Al complexes. The guanidina o ligand ca ying he 2,6-dime hylpipe idine backbone was ound o be he op imal ligand. The educ ion o i s ch omium(II) chlo ide a e-complex yielded a quin uply bonded bime allic complex wi h a C -C -dis ance o 1.7056 (12) Å. Mo eo e , hese guanidina o ligand s abilized aluminum dialkyls we e hough o as p ecu so s o aluminum hyd ide 3. O e iew o Thesis Resul s 15 compounds. T ans o ma ion o he alkyl compounds using H2 and phenylsilane did no a o d he co esponding hyd ide compounds. So, a di ec app oach o molecula alanes s abilized by N-ligands was ca ied ou . Chap e 5 deals wi h he syn hesis and s uc u e o a e aminopy idina o and guanidina o ligand s abilized aluminum hyd ide compounds. Only a small numbe o s uc u ally ully cha ac e ized amidina o, aminopy idina o and guanidina o ligand s abilized alanes a e known un il now. S a ing om AlH3, he di ec app oach o a o d N-ligand s abilized aluminum hyd ide compounds was s udied. The eac ion o he aminopy idine N-(2,6- diisop opylphenyl)-6-(py olidin-1-yl)py idin-2-amine (PyApH) and he guanidine N,N'-bis(2,6- diisop opylphenyl)pipe idine-1-ca boximidamide (PipGuH) wi h eshly p epa ed AlH3 was in es iga ed. Fo bo h N-ligands he o ma ion o a dime ic, double hyd ogen b idged aluminum dihyd ide complex was obse ed. In hese isos uc u al dime ic complexes, he aluminum cen e s a e i e-coo dina ed by wo N a oms ( om he N-ligands), wo µ2-b idging hyd ides and a e minal hyd ide. The aminopy idina o ligand s abilized compound is uns able and in amolecula ligand edis ibu ion eac ion leading o monome ic [(PyAp)2AlH] was obse ed e en a oom empe a u e. The o ma ion p oceeded (mos likely) ia AlH3 o ma ion and i s decomposi ion o Al and H2. The guanidina o ligand s abilized complex was ound o be mo e s able and no ligand ans e was obse ed up o 50°C. Fu he mo e, he eac ion o (2R,6S,Z)- N,N'-bis(2,6-diisop opylphenyl)-2,6-dime hylpipe idine-1-ca boximidamide (MPipGuH) wi h LiAlH4 was examined. A a e example o a σ-alane li hium complex, namely [(MPipGu)(H)2Al(µ- H)Li( h )3], was syn hesized in 81 % yield. Figu e 3.3. C ys al s uc u e o he σ-alane li hium complex [(MPipGu)(H)2Al(µ-H)Li( h )3]. In his compound, he aluminum cen e was i e-coo dina ed. The guanidina o ligand was bound in a N,N’-dihap o-chela ing mode. Two e minal hyd ides and one b idging hyd ide o a THF s abilized li hium a om accomplished he coo dina ion sphe e a ound he aluminum a om. This complex could be a sui able p ecu so o syn hesize o he (example gi en) σ-alane 3. O e iew o Thesis Resul s 16 ansi ion me al o σ-alane lan hanoid complexes. Based on he knowledge, ha he guanidina o ligand s abilized aluminum dialykls we e no able o unde go hyd ogenolysis o a o d he co esponding hyd ide compounds, examina ions o g oup 3 me als we e ca ied ou . Chap e 6 deals wi h he syn hesis and s uc u e o a inuclea y ium polyhyd ide compound s abilized by a guanidina o ligand. The syn hesis and s uc u al de e mina ion o he i s a e ea h“(LnH2)3“ polyhyd ide s abilized by a guanidina o ligand was achie ed. An y ium alkyl complex was hough o as a p omising s a ing ma e ial and i s beha io o hyd ogenolysis using H2 was examined. The eac ion o equimola amoun s o y ium ialkyl complex ([YR3( h )2]) (R = CH2Si(CH3)3, h = e ahyd o u an) wi h he guanidine N,N'-bis(2,6-diisop opylphenyl)pipe idine- 1-ca boximidamide (PipGuH) ga e he esul ing guanidina o ligand s abilized y ium dialkyl complex ([PipGu)YR2( h )]. This complex ea u es a N,N’-dihap o-guanidina o ligand, wo alkyl moie ies and one THF molecule coo dina ed o he Y a om. In con as o he aluminum dialkyl compounds, hyd ogenolysis o his p ecu so wi h H2 (2 ba ) yielded clean o ma ion o he co esponding guanidina o ligand s abilized inuclea y ium hexahyd ide clus e compound [{(PipGu)YH2}3( h )2]. Figu e 3.4. C ys al s uc u e o he clus e co e uni o [{(PipGu)YH2}3( h )2] (guanidina o ligands only shown as NCN moie ies o cla i y). The isola ed yield was 96 %. Single c ys al X-Ray s uc u e analysis e ealed a iangle de ined by he h ee y ium a oms. Each y ium a om ca ied a guanidina o ligand in he same N,N’-dihap o-chela ing mode like in he p ecu so dialkyl complex, as was e ealed by XRD analysis. Mo eo e , coo dina ed THF molecules o wo o he h ee y ium a oms we e ound. Highly dynamic beha iou o he hyd ido and he guanidina o ligands was obse ed by a iable empe a u e 1H NMR spec oscopy. Lan hanoid polyhyd ide clus e possess a ious, in e es ing s uc u al mo i s and, despi e cyclopen adienyl ligand based compounds, a e small in numbe . Mo eo e , a b oad a ie y o applica ions a e known. This ype o compound was hough o as 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 23 Scheme 1. The ole o he s abilizing ligand on he me al-me al dis ance in complexes ha ing a ( o mal) quin uple bond. The subs i uen s on op ( ed) al e he N-C-N angle (blue) and comp ess he me al-me al mul iple bond. We epo he e he esul s o a sys ema ic sea ch o he sho es me al-me al (quin uple) bond. The inally ob ained dis ance is 1.7056(12) Å. Fu he mo e, we poin ou a a ew limi a ions o he abo e in oduced ligand based me al-me al bond sho ening concep , he main one being he o ma ion o a di e en coo dina ion isome , an unsuppo ed C (I) dime wi h a signi ican ly lowe bond o de . Quin uple bonding has gained a lo o a en ion meanwhile. The di-me allic (ch omium o molybdenum) pla o m is well sui ed o ac i a e small molecules.[15] 4.2 Resul s and Discussion The hypo hesis we de eloped om he s a e o he a in making ul a-sho ch omium-ch omium quin uple bonds basically means he C -C dis ance is de e mined by he subs i uen R linked o he cen al ca bon a om o he guanidina o (o amidina o) ligand (Scheme 2). Scheme 2. Syn hesis o he Al-complexes 5-8. 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 24 In o de o ind he guanidina e ligand o ming he sho es C -C quin uple bond he dependence o he ele an N-C-N angle in he guanidina e ligand om he in oduced subs i uen R (Scheme 2) was in es iga ed. Aluminum dialkyls we e expec ed o be well sui ed o such a s udy. The e ahed al coo dina ion a oids in e e ence wi h he emaining ligands and he smoo h syn hesis ia alkane elimina ion om comme cially a ailable ialkyls allows o an easy access. The aluminum guanidina es 5-8 (Scheme 2, Figu e 1) we e syn hesized and cha ac e ized ia X- ay c ys al s uc u e analysis. We obse ed ha inc easing he s e ic demand on he back bone om pipi idine o diisop opylamine dec eases he NCN bond angle om 109.8(3) in 5 o 107.39(15) in 8 (Figu e 1).[16] Thus, he ligands 3 and 4 should gi e C complexes wi h e en sho e me al-me al bond dis ances han 2. The C -C complex s abilized by 2 is ea u ing he sho es me al-me al bond [1.7293 (12) Å] obse ed in a s able molecule ye .[13b] Figu e 1.Molecula s uc u e o 7 wi h he hyd ogen a oms omi ed o cla i y and he c ucial N-C-N angle o all s uc u ally in es iga ed Al complexes (R = 2,6-diisop opylphenyl).Selec ed bond leng hs [Å] and angles [°]: Al1- N2 1.9245(13), Al1-N1 1.9318(13), Al1-C1 1.958(2), Al1-C2 1.9609(19); N2-C5-N1 107.68(12), N2-Al1-N1 69.09(5), N2-Al1-C1 113.78(7), N1-Al1-C1 120.33(8), N2-Al1-C2 118.70(7), N1-Al1-C2 113.44(7), C1-Al1-C2 114.32(9). The eac ions o he li hium guanidina es, Li[(2,6-dime hylpipi idine)C(NA )2] and Li[(diisop opylamine)C(NA )2][17] made om 3 and 4, wi h C Cl2 in THF a o ded, a e emo al o he sol en and subsequen ex ac ion wi h e he , he co esponding C (II) a e- complexes 9 and 10, espec i ely as blue c ys alline ma e ials in good yields (Scheme 4). 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 25 Scheme 4. Syn hesis o 9 and 10. The 1H NMR spec a showed only b oad signals due o he p esence o pa amagne ic C (II) ions. Bo h complexes we e s uc u ally in es iga ed by X- ay c ys al s uc u e analysis. The obse ed s uc u al mo i has been ecen ly epo ed o dike imina e ligands.[18] The molecula s uc u e o 9 is shown in Figu e 2. I s magne ic momen s (μB) was de e mined o be 4.54. F om he ini ially selec ed guanidines 3 and 4, ligand p ecu so 4 ca ies he bulkies subs i uen and o he co esponding Al complex 8 he smalles N-C-N angle was obse ed (Figu e 1). Figu e 2. Molecula s uc u e o 9 [ORTEP ep esen a ion (on he 50 % p obabili y le el) o all non ca bon a oms); Hyd ogen a oms ha e been omi ed o cla i y. Selec ed bond leng hs [Å] and angles [°]: C1-N1 1.348(2), C1-N2 1.352(3), C1-N3 1.375(3), Li1-O1 1.936(4), Li1-O2 1.941(4), Li1-Cl1 2.347(4), Li1-Cl2 2.361(4), Li1-C 1 3.209(4), N1-C 1 2.0527(16), N2-C 1 2.0455(16), C 1-Cl2 2.3492(6), C 1-Cl1 2.3691(6); N1-C1-N2 109.73(16), N1-C1-N3 126.79(17), N2-C1-N3 123.48(17), N2-C 1-N1 65.19(6), N2-C 1-Cl2 99.46(5), N1-C 1-Cl2 164.62(5), N1-C 1-Cl1 101.51(5), Cl2-C 1-Cl1 93.86(2). 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 26 Thus, we became in e es ed o use 10, which is s abilized by dep o ona ed 4. The educ ion o 10 wi h KC8 and wo k up in hexane led o a monome ic C 0 complex (compound 11, Scheme 5), in which he cen al C a om is sandwiched be ween wo a ene uni s o wo guanidina e ligands (Figu e 3). Scheme 5. Syn hesis o he C complex 11. No only he η6-coo dina ion o he a ene uni is limi ed o he b idging C , bu he same a ene uni also coo dina es one K in he same ashion. Fu he mo e, he guanidina e ligands in 11 a e ac ing as an amide coo dina ing he K a om h ough N1. Figu e 3. Molecula s uc u e o 11; Hyd ogen a oms ha e been omi ed o cla i y. Selec ed bond leng hs [Å] and angles [°]:C5-N2 1.310(5), C5-N1 1.359(5), C5-N3 1.424(6), N1-K1 2.688(4), C 1–A cen oid 1.667, K1–A cen oid 2.798, O1-K1 2.682(4), O2-K1 2.748(4); N2-C5-N1 122.9(4), N2-C5-N3 117.3(4), N1-C5-N3 119.8(4), C5-N1-K1 129.6(3), O1-K1-N1 119.59(13), O1-K1-O2 82.70(13), N1-K1-O2 139.72(13). 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 27 The K a oms a e u he coo dina ed by wo h molecules. The cen al s uc u al mo i esembles he classic bis(benzene)ch omium s uc u e.[19] Since he educ ion o 10 leads o an o e - educed p oduc , we epea ed he eac ion mo e han i e imes also wi h a ied amoun o po assium g aphi e. The esul s we e simila . We ob ained 11 and le o e s a ing ma e ial (10) wi h lowe amoun s o he educing agen . F om hese s udies, we concluded ha he s e ic bulk o he subs i uen in he backbone o 5 is al eady oo la ge o s abilize a complex ha ing a quin uple bond and con inued wi h a emp s based on 4 (o he dichlo ide 9). Reduc ion o 9 wi h KC8 in THF esul ed in a sudden colo change om oyal blue o o ange ed (Scheme 6). A e wo k up, 12 was isola ed as pu ple needles a oom empe a u e. The c ys al s uc u e o 12 e eals a compound whe e he wo guanidina e ligands do no ac as b idging ligands. They coo dina e o each C a om in a chela ing ashion gi ing ise o an unsuppo ed C -C -bond. The C -C bond axis is collinea o he C2 axis o NCN moie y o he guanidina e ligand. A C -C bond leng h o 2.652(2) Å is obse ed o 12. Scheme 6. Syn hesis o 12 and 13. The molecula s uc u e o 12 is shown in Figu e 4. The conjuga ed NCN moie y shows e y simila C-N dis ances [C1-N2 1.360(7), C1-N3 1.363(7), C1-N1 1.374(7) Ǻ]. 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 28 Figu e 4. Molecula s uc u e o 12. Hyd ogen a oms ha e been omi ed o cla i y. Selec ed bond leng hs [Å] and angles [°]: C1-N1 1.360(7), C1-N3 1.363(7), C1-N2 1.374(7), N1-C 1 2.036(5), N2-C 1 2.045(5), C 1-C 1 2.652(2); N1-C1-N3 125.5(6), N1-C1-N2 108.9(5), N3-C1-N2 125.5(6), N1-C 1-N2 66.06(18), N1-C 1-C1 32.84(18). Unsuppo ed ch omium-ch omium bonds a e a e. Pionee ing wo k in his ega d was epo ed by he Gamba o a g oup.[20] They syn hesized N-ligand s abilized C (II) wi h a a he weak bond be ween he wo me al a oms. Dime s o C (I) such as hose obse ed he ein a e di icul o ob ain, because a a ie y o “side eac ions” ha e o be a oided. Complexes o C (I) become mononuclea i he s abilizing ligand is oo bulky.[11,21] A ene sandwich complexes can be o med i a oma ic sol en s a e used.[22] The p esence o dini ogen can lead o N2 complexes.[23] Fu he mo e, b idging o he a yl subs i uen s o he N-ligand has o be a oided.[24] X- ay c ys al s uc u e analysis, magne ic da a and elec onic s uc u al calcula ions ( ide in a), IR da a and eac ion wi h CCl4 (no o ma ion o CHCl3)[25] indica e ha no b idging hyd ides a e p esen in 12. In e es ingly, he second and hi d c op o c ys alliza ion du ing he syn hesis o 12 did no a o d needles bu o ange ed pla es. The X- ay s uc u al analysis e ealed a b idged homobime allic compound (13) wi h an excep ionally sho me al-me al dis ance o 1.7056 (12) Å (Figu e 5). A second c ys al ga e ise o a s uc u e wi h a C -C dis ance o 1.7061(9) Å. I is he sho es C -C dis ance as well as he sho es me al-me al bond epo ed o a s able compound ye . A dis ance app oaching 1.70 Å is in e es ing in a ew ega ds. Fo ins ance, he ch omium-ch omium bond leng h o ansien C 2 molecule which can be gene a ed by lase -e apo a ion o he me al and ia lash pho olysis o C (CO)6 is in he same dis ance ange.[26,27] This compound has a o mal sex uple bond. Fu he mo e, a simila dis ance as o he me al-me al bond in 13 was ound ecen ly o he longes alkane C-C bond[28] [1.704 (4) Å]. This essen ially means a me al-me al bond and a C-C bond o an alkane can be o simila leng h. The C -N 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 29 bond leng hs [1.992(4), 1.993(4), 2.008(4) and 2.011(4) Å] a e compa able o he ones in he al eady known quin uply bonded ch omium complexes bu sho e han C -N bond dis ances [2.036(5) and 2.045(5) Å] obse ed o 12.[7,9] The C-N bond dis ances [1.390(6) Ǻ] o he non-coo dina ing ni ogen a e sligh ly longe han he C-N bond dis ances o ch omium coo dina ed ni ogen a oms [1.346(6) and 1.336(6) Å]. Figu e 5. Molecula s uc u e o 13. Hyd ogen a oms and one hexane molecule ha e been omi ed o cla i y. Selec ed bond leng hs [Å] and angles [°]: C1-N2 1.345(6), C1-N1 1.363(6), C1-N3 1.390(6), C13-N5 1.336(6), C13-N4 1.346(6), C13-N6 1.390(6), N1-C 2 1.992(4), N2-C 1 1.993(4), N4-C 2 2.008(4), N5-C 1 2.011(4), C 1- C 2 1.7056(12); N2-C1-N1 112.1(4), N2-C1-N3 124.1(4), N1-C1-N3 123.8(4), C 2-C 1-N2 98.27(12), N2-C 1-N5 164.29(17), C 1-C 2-N1 97.26(12), N1-C 2-N4 165.17(17). In e es ingly, pa allel o ou in es iga ion he Jones g oup syn hesized and cha ac e ized an i on(I) high-spin complex based on 3 wi h a e y sho Fe-Fe bond [2.1270(7) Å] ha displays signi ican mul iple-bond cha ac e .[29] The oom empe a u e magne ic momen o 12 is µB 4.66 which is highe han he heo e ically expec ed alue o wo S = 2/2 ch omium cen e s ( heo e ical alue o µB = 4.00), bu lowe han he heo e ical alue o wo S = 3/2 ch omium cen e s ( heo e ical alue o µB =5.48). This is in good ag eemen wi h a C -C bond wi h an e ec i e bond o de o 1.25 ( ide in a), whe e wo o he i e elec ons a e in ol ed in me al-me al bond o ma ion. Upon cooling a con inuous dec ease o he magne ic momen down o µB 0.58 was obse ed. This beha io is bes explained wi h an i e omagne ic in e ac ions be ween he emaining unpai ed elec ons o he wo ch omium cen e s. The expe imen al da a we e i assuming wo an i e omagne ically coupled S = 3/2 cen e s wi h H = -JS1S2. The ob ained coupling cons an J = -62 (1) cm-1 (g = 2, TIP = 0.0013(1) cm3·mol-1) is indica i e o s ong 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 30 an i e omagne ic in e ac ions be ween he wo ch omium cen e s. The oom empe a u e magne ic momen o 13 is µB 2.27 which is indica i e o an S = 0 g ound s a e o he dinuclea ch omium complex wi h a pa amagne ic impu i y (Ch omium (I) wi h S = 5/2). This alue does no change signi ican ly upon cooling. The expe imen al da a o 13 we e i assuming an S = 0 g ound s a e and a empe a u e independen pa amagne ism TIP due o Zeeman pe u ba ion. The bes i o compound 13 was ound wi h a pa amagne ic impu i y PI = 5.0 % pe C (S = 5/2) and TIP = 787·10-6 cm3·mol-1. Impu i ies in his %- ange a e no unusual o he e y eac i e quin uple bonds.[8,15a] In addi ion, he ein, impu i ies o 12 may play a ole. Figu e 6.Ac i e o bi als o s uc u e 12 and hei occupa ion numbe s in he g ound s a e. Finally, mul icon igu a ional quan um chemical calcula ions using he CASSCF/CASPT2 me hod[30] we e pe o med o examine he elec onic s uc u e o hese wo coexis ing C 2-guanidina e compounds and in pa icula , he unique bonding o he unsuppo ed C 2 uni in 12 and compa ed i o he bonding in 13. Va ious dich omium sys ems, analogues o 13 a e known o ea u e a quin uple me al-me al bond, despi e he di e en ligands o oxida ion s a e o he C a om. The me al-me al bonding is quan i ied in e ms o e ec i e bond o de (EBO), de ined as (ηb - ηa)/(ηb + ηa), whe e ηb is he occupa ion numbe o he bonding na u al o bi al and ηa is he occupa ion numbe o he co esponding an ibonding na u al o bi al. The g ound s a e o 12 has a highly mul icon igu a ional single na u e, which is p ac ically degene a e (< 2 kcal/mol) wi h he iple and quin e s a es. Inspec ion o he na u al o bi al occupa ion numbe s (Figu e 6) indica es ha all he 3d o bi als, excep one /* pai , a e singly occupied, which gi es a mino con ibu ion o he C - 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 31 C bond: he EBO alue o he  bond is 0.11, and he co esponding  and  alues a e 0.16 and 0.04, espec i ely. One elec on om each C a om is in ol ed in C -N in e ac ion wi h he ligands ( hose o bi als a e no included in he comple e ac i e space). In e es ingly, he s onges bond in he C 2 uni is he  bond o med om he in e ac ion o he 4s o bi als, wi h an EBO o 0.94. This esul s in a o al bond o de o 1.25 and an elec onic con igu a ion (C -C )4s2(C -C )3d1(C -C )3d*1(C -C )3d1(C -C )3d*1(C -C )3d2(C -C )3d*2. Thus, he long 2.65 Å C -C bond in his unsuppo ed C (I) dime bea s a single 4s–4s in e ac ion wi h he 3d shells an i e omagne ically coupled in o a ne single s a e. Table 1. E ec i e bond o de o 12 and 13:, ,  con ibu ions and o al EBO alues. C 2- guanidina e compound[13b] is gi en o compa ison. EBO 12 13 C 2-guanidina e[31e]  1.05 0.84 0.83  0.16 1.66 1.62  0.04 1.43 1.35 To al bond o de 1.25 3.93 3.80 In con as o 12, he sho C -C bond in 13 is a o mal quin uple bond wi h he C 3d o bi als o ming he me al-me al mul iple bond, whe eas he pai o C 4s o bi als is di ec ly in ol ed in he C -N in e ac ion wi h he ligands. The N a oms in e ac wi h he same weigh wi h he C -C co e as indica ed by he shape o he C -N molecula o bi als (see Figu e 7). The o al EBO alue o 3.93 (see Table 1) is sligh ly la ge han he alue o 3.80[31e] compu ed o he C 2-guanidina e sys em[13b] which holds he p e ious eco d o he sho es C -C bond. Inspec ion o Table 1 indica es ha he sho ening (ca. 0.02 Å) o he me al- me al bond is accompanied by a sligh inc ease o he s eng h o one o he  bonds. Analogously o o he dich omium species,[31e,32] he closed-shell con igu a ion (C -C )3d2(C -C )3d4(C -C )3d4(C -N)4s2 domina es he mul ide e minan al wa e unc ion wi h a o al weigh o 70 %. 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 32 Figu e 7.Ac i e o bi als o s uc u e 13 and hei occupa ion numbe s in he g ound s a e. The 1H NMR o 13 shows well esol ed single signal se indica i e o a diamagne ic compound. Complex 12 is a he s able in solu ion and does no show any decomposi ion o con e sion o 13 as moni o ed by NMR spec oscopy using a C4D8O solu ion. 4.3 Conclusions In conclusion, we epo on a a ional app oach o he complex ha ing he sho es me al-me al bond. The key o isola e i , was a s e ically ailo made guanidina e ligand. The me al-me al dis ance obse ed is o he same leng h as he longes C-C bond in s able alkanes. The ligand-based quin uple bond sho ening concep has a ew limi a ions. Mos impo an ly, he o ma ion o coo dina ion isome s in which in e -ligand epulsion is minimized. I is assumable ha addi ional sho ening is di icul o accomplish since we eached he end o he s abili y gap. 4.4 Expe imen al Sec ion Gene al: All manipula ions we e pe o med wi h igo ous exclusion o oxygen and mois u e in Schlenk- ype glasswa e on a dual mani old Schlenk line o in N2 illed glo e box (mB aun 120-G) wi h a high-capaci y eci cula o (<0.1ppm O2). Sol en s we e d ied by dis illa ion om sodium wi e / benzophenone. Comme cial C Cl2 (Al a Aeso ) was used as ecei ed. Compounds 2, 3, 4 and 8 we e p epa ed acco ding o published li e a u e.[16,17a,33] Deu e a ed sol en s we e ob ained om Camb idge Iso ope Labo a o ies and we e degassed, d ied and dis illed p io o use. NMR spec a we e eco ded on Va ian 300 MHz and Va ian 400 MHz a 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 39 2009, 471, 1–10; e) G. La Macchia, G. Li Manni, T. K. Todo o a, M. B ynda, F. Aquilan e, B. O. Roos, L. Gaglia di, Ino g. Chem. 2010, 49, 5216–5222. [32] G. Li Manni, A. Dzubak, A. Mulla, D. W. B ogden, J. F. Be y, L. Gaglia di, Chem. Eu . J. 2012, 18, 1737–1749. [33] S. Ge, A. Mee sma, B. Hessen, O ganome allics 2008, 27, 3131–3135. [34] A. Al oma e, M. C. Bu la, M. Camalli, G. L. Casca ano, C. Giaco azzo, A. Guaglia di, A. G. G. Moli e ni, G. Polido i and R. Spagna, J. Appl. C ys . 1999, 32, 115–119. [35] SHELX97 P og ams o C ys al S uc u e Analysis (Release 97-2). G. M. Sheld ick, Ins i u ü Ano ganische Chemie de Uni e si ä , Tammans asse 4, D-3400 Gö ingen, Ge many, 1998. [36] L. J. Fa ugia, J. Appl. C ys . 1999, 32, 837–838. 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 40 4.7 Suppo ing In o ma ion X- ay c ys allog aphic da a including ables, de ails o he magne ic and compu a ional s udy Figu e S1. Molecula s uc u e o 5 [ORTEP ep esen a ion (on he 50 % p obabili y le el) o all non ca bon a oms]; Hyd ogen a oms ha e been omi ed o cla i y. Figu e S2. Molecula s uc u e o 6 [ORTEP ep esen a ion (on he 50 % p obabili y le el) o all non ca bon a oms]; Hyd ogen a oms ha e been omi ed o cla i y. Figu e S3. Molecula s uc u e o 10 [ORTEP ep esen a ion (on he 50 % p obabili y le el) o all non ca bon a oms]; Hyd ogen a oms ha e been omi ed o cla i y. 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 41 Table S1. C ys al da a o Al compounds 5, 6 and 7. compound 5 6 7 Empi ical o mula C32H50AlN3 C29H46AlN3 C34H54AlN3 Fo mula weigh 503.73 463.67 531.78 c ys al sys em Hexagonal Hexagonal Monoclinic space g oup P3(2)21 P3(2)21 P2(1)/c a [Å] 14.9090(7) 14.4200(6) 9.4030(5) b [Å] 14.9090(7) 14.4200(6) 31.9350(17) c [Å] 12.2510(6) 12.2130(5) 11.2800(6) α [deg]  [deg] 106.059(4) γ [deg] V, [Å3] 2358.30(19) 2199.29(16) 3255.0(3) c ys al size, [mm3] 0.41 x 0.36 x 0.35 0.34 × 0.33 × 0.29 0.67 x 0.55 x 0.48 calcd, [g cm-3] 1.064 1.050 1.085 µ, [mm-1] (Mo K) 0.087 0.089 0.088 T, [K] 133(2) 133(2) 133(2)  ange, [deg] 1.58- 25.69 1.63- 25.60 1.28- 25.80 no. o e lec ions unique 2991 2769 6171 no. o e lec ions obs. [I > 2 ( I )] 2394 2580 5293 no. o pa ame e s 187 157 343 wR2 (all da a ) 0.1083 0.0785 0.1226 R alue [I>2 (I)] 0.0463 0.0352 0.0477 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 42 Table S2. C ys al da a o C compounds 9, 10, 11, 12 and 13. compound 9 10 11 12 13 Empi ical o mula C40H64Cl2C LiN3O2 C39H64Cl2C LiN3O2 C78H128C K2N6O4 C64H96C 2N6 C70H108C 2N6 Fo mula weigh 748.78 736.77 1344.06 526.73 1137.62 c ys al sys em T iclinic Monoclinic Monoclinic T iclinic T iclinic space g oup P-1 C2/c P2(1)/n P-1 P-1 a [Å] 11.2860(6) 16.0290(5) 10.6720(6) 10.8060(8) 12.6160(5) b [Å] 13.7030(6) 16.4480(5) 18.8650(10) 10.9290(9) 15.1330(6) c [Å] 14.689(8) 16.8070(7) 20.0340(10) 15.8220(12) 19.4170(7) α [deg] 102.318(4) 90.514(6) 112.679(3)  [deg] 94.489(4) 108.140(3) 104.381(4) 70.900(6) 95.143(3) γ [deg] 107.100(4) 69.395(6) 98.334(3) V, [Å3] 2096.95(18) 4210.8(3) 3907.0(4) 1601.6(2) 3341.0(2) c ys al size, [mm3] 0.36 x 0.32 x 0.24 0.23 x 0.21 x 0.18 0.42 x 0.27 x 0.07 0.31 x 0.29 x 0.15 0.21 × 0.20 × 0.12 calcd, [g cm-3] 1.186 1.162 1.142 1.092 1.131 µ, [mm-1] (Mo K) 0.435 0.432 0.302 0.379 0.368 T, [K] 133(2) 133(2) 133(2) 193(2) 133(2)  ange, [deg] 1.44-25.67 1.82-25.67 1.51-25.67 2.49-25.66 1.15-25.69 no. o e lec ions unique 7899 3961 7380 6018 12613 no. o e lec ions obs. [I > 2 ( I )] 6333 2919 3630 1959 4306 no. o pa ame e s 442 219 424 335 694 wR2 (all da a ) 0.1120 0.1025 0.1781 0.1685 0.1419 R alue [I>2 (I)] 0.0418 0.0463 0.0794 0.0718 0.0611 Suscep ibili y measu emen s: Magne ic suscep ibili y measu emen s we e ca ied ou wi h a Quan um Design MPMS-XL SQUID magne ome e in he ange om 2 o 300 K a 2 T (12) and 0.5 T (13). The powde ed sample 12 was placed in a gela in capsule, ixed in a non- magne ic sample holde and measu ed in he RSO mode. The powde ed sample 13 was placed in a qua z glass holde , ixed in a non-magne ic sample holde and measu ed in he DC mode. The magne ic da a we e co ec ed o he diamagne ic con ibu ion o he sample holde and he qua z glass o gela in capsule, espec i ely. The mola suscep ibili y da a we e co ec ed using he Pascal cons an . The expe imen al da a o 13 we e i assuming an S = 0 g ound s a e and a empe a u e independen pa amagne ism TIP due o Zeeman pe u ba ion. The bes i o compound 13 was ound wi h a pa amagne ic impu i y PI = 5.0 % pe C (S = 5/2) and TIP = 787·10-6 cm3·mol-1. 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 43 Figu e S4. Tempe a u e dependence o he MT p oduc o 12. The solid line ep esen s he i wi h H = -JS1S2 (S = 3/2), J = -62 (1) cm-1 and TIP = 0.0013(1) cm3·mol-1 assuming g = 2. Figu e S5. A) Tempe a u e dependence o he mola suscep ibili y o 13 (open ci cles). The solid line ep oduces he bes i wi h he pa ame e s PI = 5.0 % pe C (S = 5/2) and TIP = 787·10-6 cm3·mol-1. B) Tempe a u e dependence o he MT p oduc o 13. 050 100 150 200 250 300 0 1 2 3 molT[cm3Kmol-1] T [K] 050 100 150 200 250 300 0.0 0.5 1.0 MT[cm3Kmol-1] T [K] a) b) 050 100 150 200 250 300 0,00 0,01 0,02 0,03 0,04 0,05 M[cm3mol-1] T [K] 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 44 Figu e S6. The empe a u e dependence o he mola magne ic suscep ibili y o 11. The open poin s a e he obse ed suscep ibili y, he black line ep oduces he bes i wi h he pa ame e s PI = 0.55 % (pe C , S = 3/2 and Weiss cons an θ = –1 K) and TIP = 26∙10-6 cm3∙mol-1. Compu a ional de ails: Quan um chemical calcula ions we e pe o med using he mul i- con igu a ional Comple e Ac i e Space SCF (CASSCF)[1] me hod, ollowed by second-o de pe u ba ion heo y (CASPT2).[2] Rela i is ic all elec on ANO-RCC basis se s wi h iple-ze a quali y (ANO-RCC-VTZP) we e used on ch omium and ni ogen[3] and minimal basis se s (ANO-RCC-MB) on ca bon and hyd ogen.[4] Scala ela i is ic e ec s we e included using he Douglas-K oll-Hess Hamil onian.[5] The compu a ional cos s a ising om he wo-elec on in eg als we e d as ically educed by employing he Cholesky decomposi ion (CD) echnique[6] combined wi h he Local Exchange (LK) sc eening.[9] In he CASSCF ea men , he comple e ac i e space con ains en elec ons in wel e ac i e o bi als (10/12). This space comp ises all 3d and 4s o bi als o ming he C -C bond, namely one 4s, one 3d, wo 3d and wo 3d bonding and he co esponding an ibonding o bi als. In he subsequen CASPT2 calcula ions, o bi als up o and including he 2p o C and 1s o C and N we e kep ozen. The F ozen Na u al O bi al app oach wi h 70% o he i ual o bi als aken in o accoun was applied o CASPT2 (FNO-CASPT2) o sa ing disk equi emen s and educing compu a ional cos s.[10] Ci symme y was imposed. The C -C bonding is quan i ied in e ms o e ec i e bond o de (EBO), de ined as (ηb - ηa)/(ηb+ηa), whe e ηb is he occupa ion numbe o he bonding na u al o bi al andηa is he occupa ion numbe o he co esponding an ibonding na u al o bi al. The CASSCF/CASPT2 app oach has p o en o be e y success ul in he s udies o me al-me al bonded compounds.[11,14] All calcula ions we e pe o med wi h he MOLCAS 7.4 package.[15] 4. The Ligand-Based Quin uple Bond-Sho ening Concep and Some o I s Limi a ions 45 4.8 Re e ences [1] B.O. Roos, P. R. Taylo , P. E. M. Siegbahn, Chem. Phys. 1980, 48, 157-173. [2] K. Ande sson, P.-A. Malmq is , B.O. Roos, J. Chem. Phys. 1992, 96, 1218-1226. [3] B. O. Roos, R. Lindh, P. A. Malmq is , V. Ve yazo , P. O. Widma k, J. Phys. Chem. A 2005, 108, 2851-2858. [4] P. O. Widma k, P. A. Malmq is , B. O.Roos, Theo . Chim. Ac a 1990, 77, 291-306. [5] B. A. Hess, Phys. Re . A 1986, 33, 3742-3748. [6] F. Aquilan e, P.A. Malmq is , T. B. Pede sen, A. Gosh and B. O. Roos, J. Chem. Theo y Comp. 2008, 4, 694-702. [7] F. Aquilan e, T. B. Pede sen, R. Lindh, B. O. Roos, A. S. de Me as, H. Koch, J. Chem. Phys. 2008, 129, 024113. [8] F. Aquilan e, L. Gaglia di, T. B. Pede sen, R.Lind , J. Chem. Phys. 2009, 130, 154107. [9] F. Aquilan e, T. B. Pede sen, R. Lindh, J. Chem. Phys. 2007, 126, 194106. [10] F. Aquilan e, T. K. Todo o a, L. Gaglia di, T. B. Pede sen, B. O. Roos, J. Chem. Phys. 2009, 131, 034113. [11] M. B ynda, L. Gaglia di, B. O. Roos, Chem. Phys. Le . 2009, 471, 1-10. [12] G. La Macchia, L. Gaglia di, P. P. Powe , M. B ynda, J. Am. Chem. Soc. 2008, 130, 5104-5114. [13] L. Gaglia di, B. O. Roos, Ino g. Chem. 2003, 42, 1599-1603. [14] B. O. Roos, A. Bo in, L. Gaglia di, Angew. Chem. In . Ed. 2007, 46, 1469-1472. [15] G. Ka ls öm, R. Lindh, P. A. Malmq is , B.O. Roos, U. Ryde, V. Ve yazo , P. O. Widma k, M. Cossi, B. Schimmelp ennig, P. Neog ady, L. Seijo, Compu . Ma e . Sci. 2003, 28, 222-239. 5. Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes 46 5 Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes Tobias Baue ,[a] Win ied P. K e schme ,[a] Muhammad Ha eez[a,b], and Rhe Kempe*[a] [a] T. Baue , D . W. P. K e schme , D . M. Ha eez, P o . D . R. Kempe, Leh s uhl Ano ganische Chemie II, Uni e si ä Bay eu h, Uni e si ä ss asse 30, NW I, 95440 Bay eu h (Ge many), Fax: (+49) 921552157, E-mail: kempe@uni-bay eu h.de [b] D . M. Ha eez, Depa men o Chemis y, Uni e si y o Azad Jammu and Kashmi , Muza a abad 13100, Azad Kashmi ,(Pakis an). To be submi ed. Keywo ds: Alanes•σ-alanes • N-ligands Abs ac : The eac ion o he aminopy idine N-(2,6-diisop opylphenyl)-6-(py olidin-1-yl)py idin- 2-amine (PyApH) and he guanidine N,N'-bis(2,6-diisop opylphenyl)pipe idine-1- ca boximidamide (PipGuH) wi h ( eshly p epa ed) AlH3 was in es iga ed. Fo bo h N-ligands he o ma ion o a dime ic, double hyd ogen b idged aluminum dihyd ide complex is obse ed. The aminopy idina e is uns able and an in amolecula ligand edis ibu ion eac ion leading o monome ic [(PyAp)2AlH] is obse ed. The o ma ion p oceeds (mos likely) ia AlH3 o ma ion and i s decomposi ion o Al and H2. The guanidina e was ound o be mo e s able and no ligand ans e was obse ed up o 50°C. Fu he mo e, he eac ion o (2R,6S,Z)-N,N'-bis(2,6- diisop opylphenyl)-2,6-dime hylpipe idine-1-ca boximidamide (MPipGuH) wi h LiAlH4 was examined. The σ-alane li hium complex [(MPipGu)(H)2Al(µ-H)Li( h )3] was o med in 81 % yield. I could be a sui able educ o syn hesize o he ( o ins ance) σ-alane ansi ion me al complexes. 5.1 In oduc ion Aluminum is he hi d mos abundan elemen and he mos abundan me al in he ea h`s c us . I `s hyd ide, alane, is p ominen ly used in o ganic syn hesis as educing agen .[1] Mo eo e , i can be used o educe me al complexes.[2] Fu he mo e, alanes ha e in e es ing applica ions in hyd oalumina ion eac ions[3], as p ecu so s in me al o ganic chemical apou 5. Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes 47 deposi ion,[4] and as hyd ogen s o age ma e ials.[5,6] In addi ion, ansi ion me al σ-alane complexes a e o g ea in e es .[7] No el alanes could ex en o imp o e hese po en ial applica ions. He ein we epo on syn hesis and s uc u e o aminopy idina o and guanidina o ligand s abilized Al-H complexes. All complexes p esen ed he ein we e cha ac e ized ia single c ys al X- ay s uc u e analysis (XRD). Un il now, only a small numbe o s uc u ally ully cha ac e ized amidina o and guanidina o ligand s abilized alanes a e known. Recen ly, a guanidina o ligand s abilized adduc o dialane (Al2H4) wi h an aluminum-aluminum bond was epo ed.[8] 5.2 Resul s and Discussion Aminopy idina o ligands (Ap, Scheme 1, le )[9,10,11] a e biden a e, monoanionic ligands ela ed o guanidina o ligands (Gu, Scheme 1, igh )[12]. Bo h ligand classes a e able o s abilize a b oad a ie y o me al ions.[12,13] N NR R' N RN N R' R'' R''' Scheme 1. Aminopy idina o ligands and he ela ed guanidina o ligands (R, R’, R’’, R’’’ = a yl, alkyl o silyl subs i uen s). As one can see, bo h ligand amilies can be ine- uned wi h ega d o hei elec on dona ing abili ies and he s e ic bulk ia he subs i uen s (R and R’ in he Ap sys em, R, R’, R’’ and R’’’ in he Gu sys em). Fi s ly, we s a ed wi h s udies on Ap ligand s abilized alanes. We did chose N-(2,6-diisop opylphenyl)-6-(py olidin-1-yl)py idin-2-amine (PyApH, 1a) due o i s elec on dona ing abili y.[14] T ea men o one equi alen o he aminopy idine 1a in oluene wi h one equi alen o in si u p epa ed AlH3 in a 1:2 mix u e o e he / oluene lead o he o ma ion o he dime ic aluminium hyd ide species [(PyApAlH2)2] 2a in 54% yield (Scheme 3). C ys als sui able o XRD analysis could be g own by s o age o a concen a ed oluene solu ion o 2a a -40°C. The molecula s uc u e o compound 2a is shown in Figu e 1.Expe imen al de ails o he XRD s udies can be ound in Table 1. NMR s udies o compound 2a e ealed, as expec ed, a single se o p o on esonances o he equi alen Ap ligands and a e y b oad single a  = 5.00 ppm o he ou aluminium hyd ides. This indica es luxional, dynamic beha iou in solu ion. 5. Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes 48 Scheme 3. Syn hesis o he dime ic compound 2a. Two double s a  = 5.07 and 5.19 ppm belonging o he a oma ic p o ons in he py idine ing (3 and 5 posi ion) a e qui e up ield o a oma ic p o ons. This can be explained by he inc eased elec on dona ing abili y o he PyAp ligand due o he py olidinyl moie y. Ano he con i ma ion o he inc eased elec on dona ing abili y o PyAp is ound in he c ys al s uc u e o 2a. The sum o all angles a ound N3 is 359.8°, indica ing a nea ly pe ec plana sp2 hyb idized N a om. The o sion angle by which N3 is shi ed ou o he plane is only 2.7°. Mo eo e , he dis ance be ween N3 and C5 is 1.3475(10) Å, lying be ween a N-Csp2 double bond (1.28 Å in a e age) and a N-Csp2 single bond (1.48 Å in a e age).[15] The amido N-Al dis ance o 1.8742(6) Å and he py idine N a om o Al dis ance o 2.0358(7) Å indica e ha he anionic cha ge o he Ap ligand is localized a he amido N a om. The aluminum cen e s a e i e-coo dina ed by wo N a oms ( om he Ap ligand), a e minal and wo b idging hyd ides. Figu e 1. Molecula s uc u e o compound 2a wi h 50% he mal ellipsoids. Ca bon a oms a e displayed as sphe es, Hyd ogen a oms, excep o he hyd ides, a e omi ed o cla i y. Selec ed bond leng hs [Å] and bond angles [°]:Al1– H1 1.479(9), Al1–H2 1.624(9), C5–N3 1.3475(10), C5–N2 1.3498(10), N1–Al1 1.8742(6), N2–Al1 2.0358(7), N1–C1– N2 107.53(6). 5. Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes 55 6.8 Hz, CH(CH3)2), 2.63 (m, 4H, CH2), 3.02 (m, 4H, CH2), 3.59 (sep ., 2H, CH(CH3)2), 3.65 (sep ., 2H, CH(CH3)2), 5.21 (d, 2H, JHH = 7.7 Hz, m-C5N1H3), 5.27 (d, 2H, JHH = 7.7 Hz, m- C5N1H3), 6.94 ( , JHH = 8.0 Hz, 2H, p- C5N1H3), 7.10-7.19 (m, 6H, a om. CH). 13C NMR (100 MHz, C6D6, 298 K): δ = 22.09, 24.65, 25.04, 25.17, 27.22, 28.41, 28.94, 45.13, 46.94, 91.85, 93.91, 123.27, 124.30, 125.66, 127.70, 140.27, 140.87, 146.67, 147.53, 154.86, 166.71. Syn hesis o [{(PipGu)Al(H)(µ-H)}2] (2b): To a eshly p epa ed solu ion o AlH3 in e he (15 mL, 2 mmol) was added a solu ion o PipGuH (895.4 mg, 2 mmol) in e he (10 mL). The eac ion mix u e was s i ed a 300 pm o e nigh . Concen a ion o he mix u e o app oxima ely 5 mL, ollowed by hea ing un il he sa u a ed solu ion s a ed o boil, ga e colo less c ys als sui able o X- ay s uc u e analysis upon s o age a ambien empe a u e. Yield: 0.828 g (87 %). C60H92Al2N6 (951.38): Calcd. C 75.75, H 9.75, N 8.83; ound. C 75.30, H 9.61, N 8.78; 1H NMR (300 MHz, C6D6, 298 K): δ = 0.83 (m, b ., 12H CH2), 1.29 (d, 24H, CH(CH3)2), 1.34 (d, 24H, CH(CH3)2), 2.73 (m, 8H, N(CH2)2), 3.68 (sep , 8H, CH(CH3)2), 4.83 (s, b , 4H Al-H), 7.07 – 7.11 (m, 12H, m-C5H3, p-C5H3). 13C NMR (100 MHz, C6D6, 298 K): δ = 23.23, 23.49, 24.78, 26.12, 28.47, 47.67, 105.19, 123.88, 139.12, 144.53, 163.67. Syn hesis o [(MPipGu)(H)2Al(µ-H)Li( h )3](4c): LiAlH4 (151.8 mg, 4 mmol) was dissol ed in e he (10 mL) a 0° C and MPipGuH (1.902 g, 4 mmol) in e he (10 mL) was added slowly. The eac ion mix u e was allowed o wa m o ambien empe a u e and was s i ed a 300 pm o e nigh . The sol en was emo ed unde educed p essu e and he c ude esidue was ex ac ed wi h THF. Concen a ion o he clea solu ion ga e colo less c ys als a e s o age a 10° C o e nigh . Yield: 2.359 g (81 %). C44H75AlLiN3O3 (728.01): Calcd. C 72.59, H 10.38, N 5.77; ound. C 72.92, H 10.82, N 6.55; 1H NMR (300 MHz, C6D6, 298 K): δ = 0.77 (d, 6H, JHH = 7.0 Hz, N{CH(CH3)}2),0.86-1.23 (m, 6H, CH2), 1.32 (m, b , 12H, THF), 1.37 (d, 12H, JHH = 6.8 Hz, CH(CH3)2), 1.41 (d, 12H, JHH = 6.8 Hz, CH(CH3)2), 3.43 (m, 12H, THF),3.6-4.3 (m, b , 3H. Al-H), 3.81 (sep ., 4H, CH(CH3)2), CH(CH3)2), 3.93 (sep ., 2H, NCH(CH3)), 7.02-7.19 (m, 6H, a om. CH). 13C NMR (100 MHz, C6D6, 298 K): δ = 13.65, 21.37, 23.31, 25.56, 26.94, 28.46, 29.78, 48.43, 123.72, 145.08, 163.40. 5. Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes 56 5.5 Re e ences [1] J. Málek and M. Ce ný, Syn hesis 1972, 217–234. [2] B. M. Bulyche , Polyhed on 1990, 9, 387–408. [3] H. Haubens ock, E. L. Eliel, J. Am. Chem. Soc. 1962, 84, 2363–2368. [4] J. A. Jegie , W. L. Glad el e , Coo d. Chem. Re . 2000, 206–207, 631–650. [5] a) L. Schlapbach, A. Zü el, Na u e 2001, 414, 353-358; b) E. Da id, J. Ma e . P oc. Technol. 2005, 162, 169–177; c) U. Ebe le, M. Felde ho , F. Schü h, Angew. Chem. 2009, 121, 6732–6757; Angew. Chem. In . Ed. 2009, 48, 6608–6630, d) S. F. Ma a , P og. Solid S a e Chem. 2010, 38, 1-37; e) S. F. Ma a , P og. Solid S a e Chem. 2012, 40, 31–40. [6] Fo ecen examples see: a) A. Zü el, Ma e . Today 2003, 24–33; b) M. La oche, J. Phys. Chem. Solids 2004, 65, 517–522; c) W. G ochala, P. P. Edwa ds, Chem. Re . 2004, 104, 1283–1315; d) L. Hou, Renew. Sus ain. Ene gy Re . 2005, 9, 395–408; e) L. Zhou, Y. Zhou, Y. Sun, In . J. Hyd ogen Ene gy, 2006, 31, 259–264; ) U. Ebe le, G. A nold, R. V. Helmhol , J. Powe Sou . 2006, 154, 456–460; g) B. Sakin una, F. Lama i- Da k im, M. Hi sche , In . J. Hyd ogen Ene gy 2007, 32, 1121–1140; h) B. Bogdano ić, U. Ebe le, M. Felde ho , F. Schü h, Sc ip a Ma . 2007, 56, 813–816; i) S. Ha de , J. Spielmann, J. In emann, H. Bandmann, Angew. Chem. 2011, 123, 4242–4246; Angew. Chem. In . Ed. 2011, 50, 4156–4160; h) P. Jochmann, J. P. Da in, T. P. Spaniol, L. Ma on, J. Okuda, Angew. Chem. 2012, 124, 4528–4531; Angew. Chem. In . Ed. 2012, 51, 4452–4455; j) J. In emann, J. Spielmann, P. Si sch, S. Ha de , Chem. Eu . J. 2013, DOI: 10.1002/chem.201300684 [7] I. M. Riddles one, S. Edmonds, P. A. Kau man, J. U bano, J. I. Ba es, M. J. Kelly, A. L. Thompson, R. Taylo , S. Ald idge, J. Am. Chem. Soc. 2012, 134, 2551−2554. [8] S. J. Bonhady, D. Collis, G. F enking, N. Holzmann, C. Jones, A. S asch, Na . Chem. 2010, 2, 865–869. [9] Fo e iew a icles on aminopy idina o ligands, see: a) R. Kempe, H. Noss, T. I gang, J. O ganome . Chem. 2002, 647, 12–20; b) R. Kempe, Eu . J. Ino g. Chem. 2003, 791– 803. [10] Fo discussions on ligand binding modes, see: S. Deeken, G. Mo z, R. Kempe, Z. Ano g. Allg. Chem. 2007, 633, 320–325. [11] Fo de ails on he syn hesis o aminopy idines ia Pd-ca alyzed a yl amina ion ou e, see: a) S. Wagaw, S. L. Buchwald, J. O g. Chem. 1996, 61, 7240–7241; b) T. Scha eina, G. Hilleb and, H. Fuh mann, R. Kempe, Eu . J. Ino g. Chem. 2001, 2421–2426. 5. Syn hesis and S uc u e o Aminopy idina o and Guanidina o Ligand S abilized Al-H Complexes 57 [12] Fo e iew a icles on guanidina o ligands and hei gene al applicabili y, see: a) F. T. Edelmann, Ad . O ganome . Chem. 2008, 57, 183-352; b) C. Jones, Coo d. Chem. Re . 2010, 254, 1273–1289. [13] Fo examples o he gene al applicabili y o Ap ligands, see: a) G. Gla z, G. Mo z, R. Kempe, Z. Ano g. Allg. Chem. 2008, 634, 2897–2902. G. Gla z, S. Demeshko, G. Mo z, R. Kempe, Eu . J. Ino g. Chem. 2009, 1385–1392. [14] a) M. Ha eez, W. P. K e schme , R. Kempe, Eu . J. Ino g. Chem. 2011, 5512–5522; b) M. Ha eez, W. P. K e schme , R. Kempe, Z. Ano g. Allg. Chem. 2012, 638, 324–330. [15] F. H. Allen, O. Kenna d, D. G. Wa son, L. B amme , A. G. O pen, J. Chem. Soc., Pe kin T ans. 2 1987, S1–S19. [16] M. L. Cole, C. Jones, P. C. Junk, M. Klo h, A. S asch, Chem. Eu . J. 2005, 11, 4482- 4491. [17] H.-J. Himmel, Ino g. Chem. 2007, 46, 6585-6593. [18] F. M. B owe , N. E. Ma zek, P. F. Reigle , H. W. Rinn, C. B. Robe s, D. L. Schmid , J. A. Sno e , K. Te ada, J. Am. Chem. Soc. 1976, 98, 2450–2453. [19] a) W. P. K e schme , B. Hessen, A. Noo , N. M. Sco , R. Kempe, J. O ganome . Chem. 2007, 692, 4569–4579; b) C. Dö ing, R. Kempe, Eu . J. Ino g. Chem. 2009, 412–418. [20] R. Ducha eau, A. Mee sma, J. H. Teuben, Chem. Commun. 1996, 223–224. [21] S. K. T. Pillai, W. P. K e schme , M. T ebbin, S. Fö s e , R. Kempe, Chem. Eu . J. 2012, 18, 13974–13978. [22] a) A. Heine, D. S alke, Angew. Chem. 1992, 104, 941–942; Angew. Chem. In . Ed. 1992, 31, 854–855; b) M. G. Ga dine , C. l. Ras on, Coo d. Chem. Re . 1997, 166, 1–34; c) H. Nö h, A. Schlegel, J. Knizek, I. K ossing, W. Ponikwa , T. Sei e , Chem. Eu . J. 1998, 4, 2191–2203. [23] A. Noo , T. Baue , T. K. Todo o a, B. Webe , L. Gaglia di, R. Kempe, Chem. Eu . J. 2013, 19, 9825–9832.. [24] G. Jin, C. Jones, P. C. Junk, K.-A. Lippe , R. P. Rose, A. S asch, New J. Chem. 2009, 33, 64–75. [25] A. Al oma e, M. C. Bu la, M. Camalli, G. L. Casca ano, C. Giaco azzo, A. Guaglia di, A. G. G. Moli e ni, G. Polido i, R. Spagna, J. Appl. C ys . 1999, 32, 115–119. [26] G. M. Sheld ick, Ac a C ys . 2008, A64, 112–122. [27] L. J. Fa ugia, J. Appl. C ys . 1999, 32, 837–838. 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 58 6 Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand Tobias Baue [a], and Rhe Kempe*[a] [a] T. Baue , P o . D . R. Kempe, Leh s uhl Ano ganische Chemie II, Uni e si ä Bay eu h, Uni e si ä ss asse 30, NW I, 95440 Bay eu h (Ge many), Fax: (+49) 921552157, E-Mail: kempe@uni-bay eu h.de To be submi ed. Keywo ds: Polyhyd ide Clus e Compounds • Ra e Ea hs • X-Ray Di ac ion • Hyd ide Ligands • N-Ligands 6.1 In oduc ion Polyhyd ide complexes o he a e ea h (RE) me als (g oup 3 me als and lan hanoid me als [Ce-Lu]) ha e ascina ed chemis s due o hei eac i i y and s uc u al mo i s. Fu he mo e, RE (poly)hyd ides a e among he mos eac i e compounds known.[1] Recen ly, he in e es in RE hyd ides has shi ed om monohyd ide L2LnH complexes[2] o dihyd ide LLnH2 complexes. The dihyd ide complexes end o agg ega e and a y in s uc u e anging om hexanuclea ,[1e,3a-c] pen anuclea ,[3c] e anuclea ,[3b-j,3o] inuclea [3b,3k-o] o dinuclea complexes.[3 ] The nuclea i y mainly dependen s om he s e ic bulk o he ancilla y ligand used. An inc ease in he s e ic demand o he ancilla y ligand seems o lead o a dec ease in nuclea i y. S uc u ally ully cha ac e ized ( us able de e mina ion o he posi ions o he hyd ogen a oms) lan hanide polyhyd ide complexes s ill lack in numbe . Un il now, mos ly s e ically demanding cyclopen adienyl de i a i es,[3d-h,3j] sco piona o [ is(py azolyl)hyd obo a e] ligands,[3a,b] e aazacycloamido[3l] and aminopy idina o ligands[3m,q] ha e been used o s abilize he “(LnH2)x” uni . He ein, we epo on syn hesis and s uc u e o he i s RE (LnH2)3 polyhyd ide s abilized by a guanidina o ligand. 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 59 6.2 Resul s and Discussion All complexes syn hesized we e cha ac e ized by NMR spec oscopy, elemen al analysis and single c ys al X- ay s uc u e analysis (XRD). Fi s , we syn hesized he guanidina e y ium dialkyl complex 1 (Scheme 1). The equimola eac ion o h s abilized y ium ialkyl (Y(CH2SiMe3)3 h 2) wi h he guanidine (Z)-N,N'-bis(2,6-diisop opylphenyl)pipe idine-1- ca boximidamide (PipGuH) in n-hexane a o ded clean o ma ion o he guanidina o ligand s abilized y ium dialkyl complex [PipGuY(CH2SiMe3)2 h ] 1 in 80 % yield (Scheme 1). NMR in es iga ion o compound 1 showed, as one would expec o a mononuclea complex, a single se o p o on esonances o he guanidina o ligand, one signal se o he wo alkyl moie ies and one signal se o he coo dina ed h . The YCH2 esonance (D6-benzene, ) o 1 is ound a δ = -0.26 ppm wi h a coupling cons an JYH = 3.0 Hz. This is in good compa ison o ela ed NMR s udies (D6-benzene, ) on guanidina o ligand s abilized y ium dialkyl [(A NC(NMe2)NA )Y(CH2SiMe3)2 h ][4] (δ = -0.31, JYH = 2.9 Hz), amidina o ligand s abilized y ium dialkyl [PhC-(NA )2]Y(CH2SiMe3)2 h ][5] (δ = -0.11, JYH = 3 Hz) and aminopy idina o ligand s abilized y ium dialkyl [(A )6-{(2,4,6- iisop opylphenyl) py idine-2-yl)amido}Y(CH2SiMe3)2 h ][6] (δ = -0.42 JYH = 3.0 Hz) (A = 2,6-diisop opylphenyl) complexes. Scheme 1. Syn hesis o 1. Single c ys als sui able o XRD analysis we e g own om a sa u a ed hexane/ oluene (1:1 a io) solu ion by slowly cooling o -40° C. The molecula s uc u e o compound 1 is depic ed in Figu e 1. Compound 1 c ys allizes in he monoclinic spaceg oup P2(1)/n and ea u es a N,N’-dihap o-guanidina o ligand, wo alkyl moie ies and one h molecule coo dina ed o he Y a om. The O a om o he h molecule occupies a posi ion oughly in he plane de ined by he cen al y ium a om and he wo ni ogen a oms o he guanidina o ligand. To minimize s e ic epulsion wi h he ligand 2,6-diisop opylphenyl g oups, he wo alkyl moie ies occupy posi ions abo e and below his plane. The bond leng hs om he cen al y ium a om o he ligand ni ogen a oms a e 2.349(2) and 2.335(2) Å. In compa ison o he ela ed complex epo ed by Hessen and co-wo ke s [(A NC(NMe2)NA )Y(CH2SiMe3)2 h ][4] 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 60 (A = 2,6-diisop opylphenyl) he ound C–Y bond dis ances o 2.378(3) and 2.391(3) Å in compound 1 a e sligh ly longe han he ones in he Hessen compound (2.374(4) and 2.384(4) Å). Figu e 1. Molecula s uc u e o compound 1. Ellipsoids a e d awn on he 50 % p obabili y le el. Ca bon a oms a e shown as sphe es and hyd ogen a oms a e omi ed o cla i y. Selec ed bond leng hs [Å] and angles [°]:C2–Y1 2.378(3), C3–Y1 2.391(3), C1–N1 1.346(4), C1–N2 1.350(4), C1–N3 1.366(4), N1–Y1 2.349(2), N2–Y1 2.335(2), O1–Y1 2.382(2), N1 C1 N2 111.9(3). Hyd ogenolysis o compound 1 a 0°C (2 ba H2 p essu e) a o ded clean o ma ion o he inuclea polyhyd ide complex [{(PipGu)YH2}3 h 2] (2, Scheme 2) as indica ed by he NMR s udies and XRD analysis. Scheme 2. Syn hesis o 2. 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 61 1H NMR in es iga ions o compound 2, in con as o he s udies o compound 1, ga e a he b oad esonance peaks o he h ee guanidina o ligands, he wo coo dina ed h molecules and a sha p qua e o he six hyd ides (JYH = 18.5 Hz). In solu ion, we ace a complex dynamic beha io . The h ee guanidina o ligands a e no equi alen which can be explained by he ac , ha wo o he h ee y ium cen e s ha e a coo dina ed h molecule and he e o e he o a ion in wo o he h ee ligands is hinde ed a oom empe a u e. All six hyd ides gi e ise o a single qua e a δ = 6.26 ppm due o coupling wi h he h ee y ium a oms. This shows ha he hyd ides, in solu ion, a e all equi alen and e y luxional in he ime scale o NMR spec oscopy and a e no dis inguishable like in he solid-s a e s uc u e. Repo s on o he inuclea y ium hexahyd ide complexes a e in ag eemen wi h ou inding.[3b,p,l] To ge a deepe insigh in o he dynamic beha io o compound 2 we ca ied ou a iable empe a u e 1H NMR s udies (Figu e 2). Upon hea ing o 100°C he h ee guanidina o ligands gi e ise o a single se o p o on esonances as can be seen in Figu e 2 B). This con i med ha he b oadening o he ligand signals a e due o hind ance in o a ion a oom empe a u e and/o an equilib ium in coo dina ion and decoo dina ion o h . The qua e a δ = 6.26 ppm shows peak b oadening down o -35°C. A his empe a u e, he hyd ides s a o become inequi alen and hei as skipping is hinde ed as seen in Figu e 2 C). Un o una ely, he limi ing spec a whe e he µ3- and µ2-hyd ides become dis inguishable could no be ob ained. 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 62 Figu e 2. A) 1H NMR spec um o 2 (D8- oluene, , 7.6 o 0.4 ppm). B) 1H high empe a u e NMR spec a o 2 (D8- oluene, 100°C, 7.6 o 0.4 ppm). C) 1H a iable low empe a u e NMR spec a o 2 (D8- oluene, -65 o 10°C, 6.50 o 5.95 ppm). A molecula s uc u e o compound 2 is depic ed in Figu e 3 and a mo e de ailed iew o he co e s uc u e wi h pe iphe al ligands educed is shown in Figu e 4. Selec ed in e a omic dis ances and bond leng hs a e summa ized in Table 1. De ails on he XRD analysis o compound 1 and 2 a e gi en in Table 2. 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 63 Figu e 3. Molecula s uc u e o compound 2. Ellipsoids a e d awn on he 50 % p obabili y le el. Ca bon a oms a e shown as sphe es and non hyd ide hyd ogen a oms a e omi ed o cla i y. Figu e 4. De ailed iew o he clus e co e wi h pe iphe al ligands d awn as NCN moie ies and h molecules as O a oms. 6. Syn hesis and S uc u e o a T inuclea Y ium Polyhyd ide Clus e S abilized by a Bulky Guanidina o Ligand 64 Table 1. Selec ed in e a omic dis ances and bond leng hs [Å] o compound 2. N–Y (a e age alue) 2.387 O–Y (a e age alue) 2.362 Y(1,2,3)–H5 2.22(4), 2.16(4), 2.12(4) Y(1,2,3)–H6 2.11(4), 2.11(4), 2.24(4) Y(1,2)–H1 2.20(4), 2.17(4) Y(2,3)–H2 2.09(4), 2.17(4) Y(1,3)–H3 2.14(4), 1.93(3) Y(1,3)–H4 2.01(4), 2.04(4) Y1–Y2 3.5457(6) Y1–Y3 3.1697(5) Y2–Y3 3.4293(6) Compound 2 c ys alizes in he monoclinic spaceg oup P2(1)/c wi h a n-hexane molecule pe asymme ic uni . Each Y a om in complex 2 bea s a guanidina o ligand in he same N,N’- dihap o mode like in he p ecu so complex 1 bu wi h longe Y-N dis ances due o highe coo dina ion numbe o he y ium a oms. The h ee y ium a oms de ine a iangle. Fou o he six hyd ide ligands b idge one o he h ee Y---Y edges in a µ2 mode, meaning one o he edges is b idged by wo µ2-hyd ides while he o he wo edges a e b idged by only one µ2-hyd ide. The las wo hyd ides a e capping he sides o he Y3 plane in a µ3 ashion. The Y---Y edge b idged by wo hyd ides is signi ican ly sho e han he wo o he edges (3.1697(5) Å in compa ison o 3.4293(6) and 3.5457(6) Å, espec i ely). This Y---Y dis ance is he second sho es e e epo ed, he sho es being 3.1648(7) Å epo ed by Hou and co-wo ke s.[3p] O he (YH2)3 clus e compounds ha e Y-H and Y---Y dis ances in he ange om 2.06(4) o 2.37(4) Å and 3.1648(7) o 3.6841(2) Å.[3b,p,l] 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 71 on epo o Sla e .[15] 1H NMR s udies a oom empe a u e showed single s in he hyd ide egion wi h a 2:1 a io o he six hyd ide ligands in compound 1 a  = –13.69 (4H, JWH = 83.3 Hz) and –13.27 ppm (2H, JWH = 104.1 Hz). These signals show an up ield shi in compa ison o he signal a –12.26 ppm o he educ [Cp2WH2]. The obse ed JWH coupling cons an o 83.3 Hz is g ea e han ha o [Cp2WH2] o 73.0 Hz. The same e ec was epo ed o he compa able compounds [Cp*2Y(µ-η1:η5-C5H4)(µ-H)2WCp] (JWH = 78.0 Hz, Cp* = pen ame hylcyclopen adienyl)[8a] and [(E 3P)2(H)I (µ-η1:η5-C5H4)H2WCp] wi h JWH coupling cons an s o 92.4 Hz and 95.2 Hz.[16] The second JWH coupling cons an o 104.1 Hz is e en g ea e and migh indica e ha he hyd ide ligands on he b idging ungs enocene moie y a e bound in a µ3- ashion by W3, Lu1 and Lu2. The C–H ac i a ed Cp ligands showed signals ha one would expec o a mi o symme ic C5H4 moie y wi h wo single s pe ac i a ed Cp ligand gi ing h ee se s o signals in a 2:1:1 a io. Figu e 1. ORTEP d awing o compound 1 wi h 50% he mal ellipsoids. Hyd ogen a oms ha e been omi ed o cla i y. Selec ed bond leng hs [Å]: Lu1–O1 2.107(11), Lu2–O2 2.081(10), Lu1–W2 3.1211(10), Lu2–W1 3.1155(9), Lu1–C1 2.485(14), Lu2–C1 2.558(14), Lu1–C28 2.554(14), Lu2–C28 2.493(15), Lu1–C63 2.366(17), Lu2–C23 2.315(17), Cpcen oid–W1 1.965, C5H4cen oid–W1 1.927, Cpcen oid–W2 1.954, C5H4cen oid–W2 1.935, C5H4cen oid–W3 1.932 (a e age alue). The selec i e clus e o ma ion ia C–H bond ac i a ion indica i e by he good isola ed yield o 1 inspi ed us o in es iga e he o ma ion o e na y polyhyd ide clus e s. We chose [Lu(OA )(Cp2Re)R( h )] as a p omising and a he eac i e educ (Scheme 2).[13c] Reac ing equimola amoun s o [Lu(OA )(Cp2Re)R( h )] wi h [Cp2WH2] in benzene a oom empe a u e lead o he o ma ion o he ime allic polyhyd ide clus e compound 2a in 48% yield (Scheme 2). To he bes o ou knowledge, compound 2a is he i s example o a RE-me al polyhyd ide clus e ea u ing h ee di e en me als as was e ealed by XRD and NMR s udies (Figu e 2). 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 72 Compound 2a is well soluble in a oma ic sol en s and shows no solubili y in alipha ic hyd oca bons. Scheme 2: Syn hesis o 2a and 2b. One o he lu e ium cen e s in 2a is i e coo dina e by one phenola o ligand, h ee C–H ac i a ed Cp ings, and a henium a om. The o he lu e ium cen e has he coo dina ion numbe en con aining a phenola o ligand, h ee C–H ac i a ed Cp ligands, and wo ungs en a oms each b idged by wo µ2-hyd ides. Figu e 2.ORTEP d awing o 2a wi h 50% he mal ellipsoids. Hyd ogen a oms ha e been omi ed o cla i y. Selec ed bond leng hs [Å]: Lu1–O1 2.109(5), Lu2–O2 2.082(5), Lu1–W1 3.1760(5), Lu1–W2 3.2033(5), Lu2–Re1 2.7986(5), Lu1–C10 2.434(8), Lu1–C15 2.608(8), Lu1–C30 2.543(9), Lu2–C10 2.464(7), Lu2–C15 2.440(8), Lu2–C30 2.430(8), Cpcen oid–W1 1.889, C5H4cen oid–W1 1.867, Cpcen oid–W2 1.984, C5H4cen oid–W2 1.918, Cpcen oid–Re1 1.869, C5H4cen oid–Re1 1.857. The Lu–Re bond dis ance is 2.7986(5) Å, which is way sho e han he sum o he co alen adii o henium and lu e ium (3.38 Å) based on Al a ez and co-wo ke s da a,[14] sho e 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 73 han he sum o he a omic adii in c ys als (3.1 Å) based on Sla e ,[15] and e en sho e han he bond leng hs in [Lu(Cp2Re)3] (2.8773(8), 2.8899(7) and 2.8913(8) Å)[13c] and in [Lu(OA )(ReCp2)R( h )] (2.8498(6) Å).[13e] The Lu–W bond leng hs a e 3.1760(5) and 3.2033(5) Å. As such, hey a e longe han in 1, bu s ill sho e han he sum o he co alen adii[14] and he sum o he a omic adii.[15] The hyd ide signals in he 1H NMR spec um o compound 2a a e shi ed up ield again o  = –13.61 ppm and show a JWH coupling cons an o 82.5 Hz which is in good ag eemen wi h he inding o compound 1 (JWH = 83.3 Hz). The e a e no u he hyd ide signals p esen indica ing a non hyd ide-b idged Lu–Re bond. Each o he phenola o ligands shows one se o signals a oom empe a u e. Finally, we became in e es ed in syn hesizing he molybdenum analogue o 2a. The equimola eac ion o [Cp2MoH2] wi h [Lu(OA )(Cp2Re)R( h )] in benzene ga e he isos uc u al he e omul ime allic polyhyd ide clus e 2b in 52% yield (Figu e 3 and Scheme 2). The Lu–Mo bond dis ances o 3.2025(12) and 3.1613(9) Å a e sho e han he sum o he co alen adii o 3.41 Å based on epo o Al a ez and co-wo ke s,[14] and in good ag eemen wi h he sum o he a omic adii o 3.2 Å based on epo o Sla e .[15] Again, an up ield shi o he single a  = – 10.25 ppm accoun ing o ou hyd ide p o ons can be seen in he 1H NMR spec um, eco ded a oom empe a u e, in compa ison o he single a  = –8.80 ppm o he hyd ides in [Cp2MoH2]. Figu e 3.ORTEP d awing o 2b wi h 50% he mal ellipsoids. Hyd ogen a oms ha e been omi ed o cla i y. Selec ed bond leng hs [Å]: Lu1–O1 2.111(7), Lu2–O2 2.074(7), Lu1–Mo1 3.2025(12), Lu1–Mo2 3.1613(9), Lu2–Re1 2.8058(6), Lu1–C5 2.412(10), Lu1–C11 2.608(13), Lu1–C28 2.591(12), Lu2–C5 2.484(10), Lu2–C11 2.403(12), Lu2– C28 2.426(11), Cpcen oid–Mo1 1.982, C5H4cen oid–Mo1 1.917, Cpcen oid–Mo2 1.965, C5H4cen oid–Mo2 1.888, Cpcen oid– Re1 1.879, C5H4cen oid–Re1 1.852. Quan um chemical calcula ions we e pe o med o loca e he missing hyd ide-a omic posi ions in compound 2a and o analyze hei ole in W–Lu bonding compa ed o Re–Lu 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 74 bonding in he clus e compounds 2. Fo ha pu pose, ull s uc u e op imiza ion has been in oked on a sligh ly simpli ied model s uc u e 2a’ (subs i u ing H o he e -bu yl g oups) o compound 2a. Fo he scala - ela i is ic (ZORA app oach)[17] calcula ions wi h he ADF[18] p og am sys em he DFT/BP86[19] me hod and in e nal Sla e - ype iple-ze a basis se s wi h wo se s o pola iza ion unc ions (“TZ2P”, wi h ozen small co e) ha e been employed. A e 100 op imiza ion cycles he –OPhen g oups we e ixed, and he emaining a om posi ions we e u he op imized. A g adien s o less han 0.3 mHa eeÅ–1, he p ocedu e was inished. The inal s uc u e, especially he inne me al pa , is e y simila o he one om expe imen al s uc u e de e mina ion. Figu e 4. Op imized s uc u e o model 2a’ wi h ELI-D/QTAIM basin in e sec ions. Hyd idic H a oms a e displayed as blue sphe es, in e sec ion o co esponding ELI-D basin yields a egion (deep blue) con ained in he QTAIM H a om, a egion ( ed) con ained in he W QTAIM a om, and a egion (ligh blue) con ained in Lu1 a om; in e sec ion o he ELI-D Lu-Re bond basins yields a egion ( ed) belonging o he Re a om, and a egion (ligh blue) belonging o he Lu2 a om; all basins a e c opped a densi y alues below 0.0001 e/Boh –3. I displays dis ances d(Lu1–W) o 3.13 and 3.14 Å ( s. 3.18 and 3.20 Å om expe imen al s uc u e de e mina ion), d(Lu2–Re1) = 2.81 Å ( s. 2.80 Å om expe imen ), and d(W–H) be ween 1.72 and 1.73 Å wi h angles H-W-H o 87.3° and 87.6°. Unde he same compu a ional condi ions a sepa a e s uc u e op imiza ion o he [Cp2WH2] molecule yields d(W–H) = 1.71 Å and angle H-W-H = 78.6°, which shows ha he dis ances W–H only ma ginally inc ease upon coo dina ion o Lu, whe eas he angle H-W-H no ably widens by 9°. Conce ning he elec onic s uc u e, a HOMO-LUMO gap o 1.5 eV is ound, in which he HOMO, HOMO-1 and HOMO-2 can be classi ied as nominal Re(5d) o bi als. As has been p e iously done,[9c, 13c,d,e] posi ion-space bonding analysis (p og am DG id[20]) by using he elec on densi y (QTAIM me hod)[21] and he elec on localizabili y indica o (ELI-D)[22] has been employed. The nega i e alues Qe (H) = –0.35 ±0.01 o he QTAIM e ec i e cha ges o he 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 75 ou W-H-Lu1 b idging H a oms was consis en wi h hei hyd idic cha ac e . These alues we e ound o be e y simila o he ones Qe (H) = –0.30 in he isola ed [Cp2WH2] molecule. Applying he me hod o ELI-D/QTAIM basin in e sec ion[23] yields ha W–H bonding is pola -co alen wi h 70% o he ELI-D basin in eg a ed cha ge densi y o each hyd idic H a om belongs o he co esponding QTAIM H a om and 26% o he QTAIM W a om (Figu e 4). Only a iny amoun o 3% is con ained in he QTAIM Lu1 a om. Taking in o accoun he posi i e e ec i e cha ge Qe (Lu1) = +1.9, his inding is o be in e p e ed as a e y ionic ype o bonding in e ac ion H–Lu1, which is consis en wi h he i ually unchanged dis ances d(W–H) compa ed o isola ed [Cp2WH2]. Conce ning di ec W–Lu1 bonding a co esponding ELI-D maximum was no displayed; howe e owing o he b idging H a oms, his would no be expec ed o occu . As a signa u e o W–Lu1 bonding, inside he quad ila e al W-H’-Lu1-H’’, a egion wi h nega i e alues o he Laplacian o ELI-D,[22c] which ex ends pe pendicula o he W–Lu1 in e connec ion line, can be ound. Such a egion does no occu in he isola ed molecule [Cp2WH2], bu is ound also o he Lu2–Re bonding si ua ion, in which ELI-D a ac o s addi ionally signi y he co alen bonding in e ac ion. In comple e analogy o p e ious cases o pola -co alen a e ea h- ansi ion me al bonding,[9c, 13,c,d,e] unsuppo ed Lu2–Re bonding is indica ed by co esponding ELI-D maxima wi h 1.30 elec ons in wo Lu2–Re bonding ELI-D basins (me ged in o one supe basin). The ELI-D/QTAIM in e sec ion p ocedu e showed ha 79% o he basin popula ion is con ained in he Re, and 16% in he Lu QTAIM a om, which is simila o p e ious cases. 7.3 Conclusions In conclusion, ansi ion me al dihyd ide complexes o he o mula [Cp2MH2] (M = Mo, W) eac wi h a e ea h me al bis- and monoalkyl complexes and unde go mul iple C–H bond ac i a ion s eps, leading o bina y and e na y RE-me al polyhyd ide clus e compounds. The e na y clus e s display pola ReLu bonds and W–H∙∙∙Lu in e ac ions, whe e he hyd ide a oms a e pola -co alen ly coo dina ed o W, and he in e ac ion wi h Lu is e y ionic. Addi ionally, a co alen di ec in e ac ion W–Lu is indica ed by ELI-D analysis. Conce ning he b oade s a egy o building highe agg ega ed e na y RE–TM polyhyd ide clus e s [Cp2MH2] ep esen s a p omising ansi ion me al building block. In he u u e wo k, we a e in e es ed in s udying he eac i i y o he clus e compounds in oduced he ein. 7.4 Acknowledgmen s Financial suppo by he Deu sche Fo schungsgemeinscha (DFG, KE 756/ 21-1, WA 956/3-1) is g a e ully acknowledged. 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 76 Suppo ing In o ma ion a ailable: Suppo ing in o ma ion o his a icle con ains de ailed in o ma ion on he syn hesis and cha ac e iza ion o he compounds desc ibed he ein, as well as c ys allog aphic de ails o he s uc u es de e mined by XRD. I is a ailable on he WWW unde h p://dx.doi.o g/10.1002/chem.201301290. 7.5 Re e ences [1] Fo some examples, see: a) R. M. Bullock, M. H. Voges, J. Am. Chem. Soc. 2000, 122, 12594–12595; b) R. Noyo i, Angew. Chem. 2002,114, 2108–2123; Angew. Chem. In . Ed. 2002, 41, 2008–2022; c) C. Deu sch, N. K ause, B. H. Lipshu z, Chem. Re . 2008, 108, 2916–2927; d). H. Nakazawa, M. I azaki, Top. O ganome . Chem. 2011, 33, 27–81. [2] a) L. Schlapbach, A. Zü el, Na u e 2001, 414, 353–358; b) E. Da id, J. Ma e . P oc. Technol. 2005, 162, 169–177; c) B. Sakin una, F. Lama i-Da k im, M. Hi sche , In . J. Hyd ogen Ene gy 2007, 32, 1121–1140; d) S. F. Ma a , P og. Solid S a e Chem. 2010, 38, 1–37; e) S. F. Ma a , P og. Solid S a e Chem. 2012, 40, 31–40. [3] NiMH ma e ials a e used in ba e ies o hyb id ca s, o example in he Toyo a P ius [4] T. Shima, Y. Luo, T. S ewa , R. Bau, G. J. McIn y e, S. A. Mason, Z. Hou, Na . Chem. 2011, 3, 814–820. [5] W. J. E ans, J. H. Meadows, T. P. Hanusa, J. Am. Chem. Soc. 1984, 106, 4454–4460. [6] The localiza ion o H a oms is a undamen al p oblem in polyhyd ide complexes o hea y a oms: G. G. Hla ky, R. H. C ab ee, Coo d. Chem. Re . 1985, 65, 1–48. [7] a) M. L. H. G een, A. K. Hughes, D. M. Michaelidou, P. Moun o d, J. Chem. Soc., Chem. Commun. 1993, 591–593; b) D. M. Michaelidou, M. L. H. G een, A. K. Hughes, P. Moun o d, A. N. Che nega, Polyhed on 1995, 14, 2663–2675. [8] a) N. R. Radu, P. K. Gan zel, T. D. Tilley, J. Chem. Soc., Chem. Commun. 1994, 1175- 1176; b) Y. Takenaka, Z. Hou, O ganome allics 2009, 28, 5196–5203; c) T. Shima, Z. Hou, Chem. Eu . J., 2013, 19, 3458–3466 [9] a) D. Al a ez, J ., K. G. Caul on, W. J. E ans, J. W. Zille , J. Am. Chem. Soc. 1990, 112, 5674–5676; b) D. Al a ez, J ., K. G. Caul on, W. J. E ans, J. W. Zille , Ino g. Chem. 1992, 31, 5500–5508; c) M. V. Bu o skii, O. L. Tok, F. R. Wagne , R. Kempe, Angew. Chem. 2008, 120, 6569–6572; Angew. Chem. In . Ed. 2008, 47, 6469–6472; d) T. Shima, Z. Hou, Chem. Le . 2008, 37, 298–299; e) T. Shima, Z. Hou, O ganome allics 2009, 28, 2244–2252. [10] A. P. Sobaczynski, T. Baue , R. Kempe, O ganome allics, 2013, 32, 1363–1369. [11] P. Cui, T. P. Spaniol, J. Okuda, O ganome allics, 2013, 32, 1176–1182. 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 77 [12] Fo ecen e iews see: a) D. Pa el, S. T. Liddle, Re . Ino g. Chem. 2012, 32, 1–22; b) B. Oelke s, M. V. Bu o skii, R. Kempe, Chem. Eu . J. 2012, 18, 13566–13579. [13] a) I. P. Bele skaya, A. Z. Voskoboyniko , E. B. Chuklano a, N. I. Ki illo a, A. K. Shes ako a, I. N. Pa shina, A. I. Guse , G. K.-I. Magomedo , J. Am. Chem. Soc. 1993, 115, 3156–3166; b) P. L. A nold, J. McMas e , S. T. Liddle, Chem. Commun. 2009, 818– 820; c) M. V. Bu o skii, C. Dö ing, V. Bezugly, F. R. Wagne , Y. G in, R. Kempe, Na . Chem. 2010, 2, 741–744; d) C. Dö ing, A.-M. Die el, M. V. Bu o skii, V. Bezugly, F. R. Wagne , R. Kempe, Chem. Eu . J. 2010, 16, 10679-10683; e) M. V. Bu o skii, O. L. Tok, V. Bezugly, F. R. Wagne , R. Kempe, Angew. Chem. 2011, 123, 7873–7840; Angew. Chem. In . Ed. 2011, 50, 7695-7698; ) M. P. Blake, N. Kal soyannis, P. Moun o d, J. Am. Chem. Soc. 2011, 133, 15358–15361. [14] B. Co de o, V. Gómez, A. E. Pla e o-P a s, M. Re és, J. Eche e ía, E. C emades, F. Ba agán, S. Al a ez, Dal on T ans. 2008, 2832–2838. [15] J. C. Sla e , J. Chem. Phys. 1964, 41, 3199–3204. [16] P. S. P egosin, A. Togni, L. M. Venanzi, Angew. Chem. 1981, 93, 684; Angew. Chem. In . Ed. 1981, 20, 668–669. [17] E. an Len he, A. E. Ehle s and E. J. Bae ends, J. Chem. Phys. 1999, 110, 8943–8953. [18] a) G. e Velde, F. M. Bickelhaup , S. J. A. an Gisbe gen, C. Fonseca Gue a, E. J. Bae ends, J. G. Snijde s and T. Ziegle , J. Compu . Chem. 2001, 22, 931–967; b) C. Fonseca Gue a, J.G. Snijde s, G. e Velde, E. J. Bae ends, Theo . Chem. Acc. 1998, 99, 391–403; c) ADF2012.01, SCM, Theo e ical Chemis y, V ije Uni e si ei , Ams e dam, The Ne he lands, h p://www.scm.com [19] a) A. D. Becke, Phys. Re . A 1988, 38, 3098-3100; b) J. P. Pe dew, Phys. Re . B 1986, 33, 8820-8824. [20] M. Kohou , p og am DG id, e sion 4.6, Radebeul, Ge many, 2012. [21] R. F. W. Bade , A oms in Molecules: A Quan um Theo y, Ox o d Uni e si y P ess, Ox o d, 1994. [22] a) M. Kohou , Fa aday Discuss. 2007, 135, 43–54; b) F. R. Wagne , V. Bezugly, M. Kohou , Yu. G in, Chem. Eu . J. 2007, 13, 5724–5741; c) F. R. Wagne , M. Kohou , Yu. G in, J. Phys. Chem. A 2008, 112, 9814–9828. [23] a) S. Raub, G. Jansen, Theo . Chem. Acc. 2001, 106, 223–232; b) G. Jansen, M. Schuba , B. Findeis, L. H. Gade, I. J. Scowen, M. McPa lin, J. Am. Chem. Soc. 1998, 120, 7239–7251. 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 78 7.6 Suppo ing In o ma ion 7.7 Gene al All manipula ions we e pe o med wi h igo ous exclusion o oxygen and mois u e in Schlenk- ype glasswa e on a dual mani old Schlenk line o in a N2 illed glo e box (mB aun 120-G) wi h a high-capaci y eci cula o (<0.1ppm O2). Sol en s we e d ied by dis illa ion om sodium wi e/benzophenone. Comme cial [Cp2WH2] (ABCR) was used as ecei ed. [Lu(OA )R2( h )2],[1] [Lu(OA )(ReCp2)R( h )],[1] [Cp2MoH2][2] and [Cp2ReH][3] we e p epa ed acco ding o published p ocedu es. Deu e a ed sol en s we e ob ained om Camb idge Iso ope Labo a o ies and we e degassed, d ied and dis illed p io o use. NMR spec a we e eco ded on Va ian Uni y 300 MHz and Va ian Uni y 400 MHz ins umen s a ambien empe a u e. The chemical shi s a e epo ed in ppm ela i e o he in e nal TMS o esidual sol en signals. Elemen al analyses (CHN) we e de e mined using a Va io EL III ins umen . X- ay c ys al s uc u e analyses we e pe o med by using a STOE-IPDS II equipped wi h an Ox o d C yos eam low- empe a u e uni . S uc u e solu ion and e inemen was accomplished using SIR97,[4] SHELXL97[5] and WinGX.[6] C ys allog aphic de ails a e summa ized in Table 1. CCDC-932376 ( o 1), -932377 ( o 2a), and -932378 ( o 2b) con ain he supplemen a y c ys allog aphic da a o his pape . These da a can be ob ained ee o cha ge om The Camb idge C ys allog aphic Da a Cen e ia www.ccdc.cam.ac.uk/da a_ eques /ci . 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 79 7.8 De ails o he X- ay c ys al s uc u e analyses Table 1: De ails o he X- ay c ys al s uc u e analyses. Compound 1 2a 2b C ys al sys em iclinic monoclinic monoclinic space g oup P-1 P21/c P21/c a [Å] 14.5190(7) 19.4320(5) 19.2850(5) b [Å] 14.5450(7) 18.5290(4) 18.1160(5) c [Å] 16.5350(8) 19.4310(5) 19.4870(5) α [˚] 86.651(4) 90.00 90.00  [˚] 68.746(4) 119.476(2) 117.975(2) γ [˚] 76.211(4) 90.00 90.00 V [Å3] 3159.0(3) 6090.7(3) 6012.6(3) Z 2 4 4 ρ (calcd.) [g cm-3] 1.950 2.026 1.859 µ [mm-1] 8.580 8.999 5.709 T [K] 133 133 133 2θ ange [˚] 2.64-50.39 2.41-50.06 2.39-53.91 Re lec ions unique 10601 10239 12771 Re l. obs . [I > 2σ(I)] 5588 7554 7715 Pa ame e s 709 706 640 R1, wR2 [I > 2σ(I)] 0.0506, 0.1134 0.0336, 0.0703 0.0555, 0.1348 R1, wR2 (all da a) 0.0935, 0.1217 0.0526, 0.0741 0.0929, 0.1474 7. Te na y Ra e-Ea h T ansi ion-Me al Polyhyd ide Clus e Compounds 80 7.9 Syn hesis and cha ac e iza ion o he clus e compounds Syn hesis o [C58H74Lu2O2W3] (1): [Cp2WH2](71 mg, 225 µmol) was dissol ed in benzene (1.5 mL) and added o a solu ion o [Lu(OA )R2( h )2] (105 mg, 150 µmol) in benzene (1.5 mL). The eac ion mix u e was kep a oom empe a u e o 24 hou s wi hou s i ing o o m a yellow c ys alline p ecipi a e. Yield: 0.096 g, 75%. Yellow p ism like c ys als sui able o X-Ray s uc u e analysis whe e g own a he laye in e ace by eezing and laye ing bo h educ benzene solu ions and le ing hem haw slowly. C58H74Lu2O2W2 (1704.66): Calcd. C 40.87, H 4.38; ound C 41.25, H 4.35; 1H NMR (400 MHz, [D6]benzene): δ = -13.69 (s, 4H, JWH = 83.3 Hz, W-H), -13.27 (s, 2H, JWH = 104.1 Hz, W-H), 1.66 (s, 36H, C(CH3)3), 4.13 (s, 4H, C5H4), 4.24 (s, 10H, C5H5), 4.36 (s, 4H, C5H4), 4.53 (s, 2H, C5H4), 4.64 (s, 2H, C5H4), 5.16 (s, 2H, C5H4), 5.54, (s, 2H, C5H4), 6.85 ( , 2H, JHH = 7.7 Hz, p-C14H21O), 7.38 (d, 4H, JHH = 7.7 Hz, m-C14H21O) ppm.Due o he poo solubili y o compound 1 meaning ul 13C NMR expe imen s we e no possible. Syn hesis o [C58H73Lu2O2ReW2] (2a): To [Cp2WH2] (31.6 mg, 100 µmol) in benzene (1 mL) was added [Lu(OA )(Cp2Re)R( h )] (85.6 mg, 100 µmol) in benzene (2 mL). The eac ion mix u e u ned om ligh yellow o o ange wi hin one hou . Concen a ion in acuum yielded yellow block-like c ys als a 10° C. Yield: 0.408 g, 48%.C58H73Lu2O2ReW2 (1706.02): Calcd. C 40.83, H 4.31; ound C 40.29, H 4.16; 1H NMR (400 MHz, [D6]benzene): δ = -13.61 (s, 4H, JWH = 82.5 Hz, W-H), 1.53 (s, 18H, C(CH3)3), 1.65 (s, 18H, C(CH3)3), 4.20 (s, 5H, (C5H5)Re), 4.24 (s, 10H, (C5H5)W), 4.40 (s, 2H, C5H4), 4.55 (s, 2H, C5H4), 4.83 (s, 2H, C5H4), 5.21 (s, 2H, C5H4), 6.83 ( , 1H, JHH = 8,0 Hz, p- C14H21O), 6.85 ( , 1H, JHH = 8.2 Hz, p-C14H21O), 7.29 (d, 2H, JHH = 7.7 Hz, m-C14H21O), 7.38 (d, 2H, JHH = 7.7 Hz, m-C14H21O);13C NMR (100 MHz, [D6]benzene): δ = 32.28 (C(CH3)3), 35.48 (C(CH3)3), 64.55 ((C5H5)Re), 71.62 ((C5H5)W), 73.73 (C5H4), 78.10 (C5H4), 117.67 (p-C14H21O), 125.63 (m-C14H21O), 137.90 (o-C14H21O), 163.16 (i-C14H21O) ppm. Syn hesis o [C58H73Lu2Mo2O2Re] (2b): To [Lu(OA )(Cp2Re)R( h )] (0.428 g, 500 µmol) in benzene (10 mL) was added [Cp2MoH2] (0.114 g, 500 µmol) in benzene (5 mL). The yellow solu ion u ned da k o ange o b own wi hin one hou . Concen a ion in acuum ga e yellow c ys als wi h a block shaped habi a 10° C. Yield: 0.198 g, 52%. C58H73Lu2Mo2O2Re (1530.22): Calcd. C 45.52, H 4.81; ound C 45.02, H 4.32;1H NMR (400 MHz, [D6]benzene): δ = -10.25 (s, 4H, Mo-H), 1.52 (s, 18H, C(CH3)3), 1.65 (s, 18H, C(CH3)3), 4.20 (s, 5H, (C5H5)Re), 4.24(s, 2H,C5H4), 4.36 (s, 10H, (C5H5)Mo), 4.53 (s, 9. Acknowledgemen s / Danksagung 87 9.2 Danksagung Mein au ich ige Dank gil meinem akademischen Leh e P o . D . Rhe Kempe ü die Möglichkei , dieses seh in e essan e Thema in seinem A bei sk eis zu bea bei en, die une müdliche Diskussionsbe ei scha und das s e e In e esse am Fo gang de A bei , so wie die gewäh e wissenscha liche F eihei bei de Bea bei ung des Themas. Wei e hin danke ich Ihm ü die exzellen en A bei sbedingungen und die Ein üh ung in die Rön gen- eink is alls uk u analyse. D . Win ied P. K e schme danke ich ü s e e Diskussionsbe ei scha , Mo i a ion, Un e s ü zung und ü das Ko ek u lesen meine Publika ionen. D . Ch is ian Dö ing danke ich he zlich ü die Ein üh ung in die Lan hanoidchemie und ü die gemeinsam e b ach e Zei im Labo und auße halb des Labo s. D . Awal Noo möch e ich au ich ig danken ü die Mo i a ion, Un e s ü zung und s e e Hil sbe ei scha in iele lei Hinsich . D . To s en I gang danke ich ielmals ü das Ko ek u lesen de Zusammen assung und de Einlei ung. Ein besonde es Dankeschön gil den on mi be eu en P ak ikan en Thomas Wi mann, Sab ina Sachau, And eas Ma k, Michael Vogel und F anziska Speckne ü ih e Hil e und A bei . He zlich bedanken möch e ich mich bei Wal e K emni z, Heidi Maisel, Simone O , Ma lis Schilling, Sand a Kelle und Anna-Ma ia Die el ü die Hil es ellungen und Un e s ü zung bei Ve wal ungsangelegenhei en und Zua bei en im Labo all ag. Bei meinen Labo kollegen D . Win ied K e schme , Ch is ian Hübne , Isabelle Hass und Anna- Ma ia-Die el möch e ich mich ü die gu e A bei sa mosphä e und Hil sbe ei scha bedanken. 9. Acknowledgemen s / Danksagung 88 Meinen A bei skollegen und dem gesam en A bei sk eis Kempe, D . Ch is ine Denne , Anna- Ma ia-Die el, Julia Ewe , Daniel Fo be g, Ma in F ied ich, Isabelle Haas, Muhammad Ha eez, Jus us He mannsdö e , Toni Hille, Ch is ian Hübne , D . To s en I gang, D . Win ied P. K e schme , Sonja Lippe , Geo g Lochne , S e an Michlik, D . Awal Noo , Johannes Obenau , D . Benjamin Oelke s, Simone O , Sa a ana Pillai, D . Sada Qayyum, Susanne Ruch, Sab ina Sachau, S e an Schwa z, Adam Sobaczynski, Emmanuel Sobgwi Tamne, The esa Winkle und Muhammad Zahee danke ich ganz besonde s ü die gu e A bei sa mosphä e und die schöne Zei auch absei s des Labo all ags. Des Wei e en bin ich ihnen seh dankba ü die Hil e und Un e s ü zung, die ich in iele lei Hinsich e ah en habe. Meine liebenden Familie, meinen Geschwis e n Debo ah Baue , Rebekka Baue , Manuel Baue , Do o hea Baue , Daniel Baue und Tama a Baciu danke ich aus ie s em He zen ü all die Au mun e ung wäh end de Zei meine P omo ion. Bei meinen El e n, besonde s bei meinem Va e Ul ich Baue , möch e ich mich ü die Hil e und Un e s ü zung in jegliche Hinsich au ich ig bedanken. Ich bin seh glücklich und s olz Teil diese ollen Familie zu sein. Zule z möch e ich mich bei B ina ü all ih e Liebe, ih Ve s ändnis, die Un e s ü zung, au mun e nden Wo e und ih en une schü e lichen Glauben und niemals endendes Ve auen in mich au ich ig und aus ie s em He zen bedanken. 10. Decla a ion / E klä ung 89 10 Decla a ion / E klä ung: I he eby decla e ha I ha e w i en his wo k by mysel and ha no o he sou ces han hose men ioned in his wo k ha e been used. This wo k has so a nei he been submi ed o he Facul y o Biology, Chemis y and Ea h Sciences a he Uni e si y o Bay eu h no o any o he scien i ic ins i u ion o he pu pose o a doc o al hesis. I ne e inally ailed a simila doc o al examina ion a any o he uni e si y. Hie mi e siche e ich an Eides s a , dass ich die o liegende A bei selbs s ändig und nu un e Ve wendung de angegebenen Hil smi el und Quellen ange e ig habe. Diese A bei wu de bishe wede an de Fakul ä ü Biologie, Chemie und Geowissenscha en de Uni e si ä Bay eu h noch eine ande en wissenscha lichen Ein ich ung zum Zwecke de P omo ion einge eich . Ich habe keine gleicha ige Dok o p ü ung an eine ande en uni e si ä en Hochschule endgül ig nich bes anden. Tobias Baue