1
FULL PAPER
DOI: 10.1002/chem.200((……))
In es iga ions on he Coupling o E hylene and Alkynes in TpMe2I Compounds:
Wa e as an E ec i e T apping Agen
Eleu e io Ál a ez,[a] Ma ga i a Paneque,*[a] C is ina M. Posadas,[a] Manuel L. Po eda,*[a] Nu ia
Rendón,[a] and Ku Me ei e [b]
Abs ac : The eac ion o he
bis(e hylene) complex TpMe2I (C2H4)2
(1) (TpMe2 = hyd o is(3,5-
dime hylpy azolyl)bo a e) wi h 2 equi .
o dime hyl ace ylenedica boxyla e,
MeO2CCCCO2Me (DMAD), in
CH2Cl2 a 25 ºC gi es he hyd ide-
alkenyl species
Tp
Me2
I H(C(R)=C(R)C(R)=C(R)CH=CH
2
)
(2, R = CO2Me) in high yield. A ca e ul
s udy o his sys em has es ablished he
ac i e ole o a numbe o in e media es
in ou e o 2. The i s o hese is he
I (I) complex TpMe2I (C2H4)(DMAD)
(4) o med by subs i u ion o one o he
e hylene ligands in 1 by a molecule o
DMAD. 4 eac s u he wi h ano he
equi alen o he alkyne wi h o ma ion
o he unsa u a ed
me allacyclopen adiene
“
Tp
Me2
I (C(R)=C(R)C(R)=C(R))
” which
can be apped by added wa e o gi e
adduc 7, o eac wi h he C2H4 p esen
in solu ion gene a ing complex 2. This
las s ep has been shown o p oceed by
inse ion o e hylene in o one o he
I —C bonds o he
me allacyclopen adiene and subsequen
-H elimina ion. Complex 1 eac s
sequen ially wi h 1 equi . o DMAD
and 1 equi . o me hyl p opiola e,
HCCCO2Me (MP), in he p esence o
wa e , wi h egioselec i e o ma ion o
he unsymme ical i idacyclopen adiene
Tp
Me2
I (C(R)=C(R)C(H)=C(R))(H
2
O)
(9). Complex 9 eac s wi h e hylene
gi ing a hyd ide-alkenyl complex 10,
ela ed o 2, in which he C2H4 has
inse ed egiospeci ically in o he I —
C(R) bond ha bea s he CH
unc ionali y. Hea ing CH2Cl2 solu ions
o ei he 2 o 10 allows he o ma ion o
he allyl species 3 o 11, espec i ely,
by simple s e eoselec i e mig a ion o
he hyd ide ligand in o he C alkenyl
ca bon and concomi an bond
eo ganiza ion o he esul ing o ganic
chain. All he compounds desc ibed
he ein ha e been cha ac e ized by
mic oanalysis, IR, and NMR
spec oscopy and o he case o 3, 7,
7·CO, 8·NCMe, 9, 9·NCMe and 10,
also by single c ys al X- ay di ac ion
s udies.
Keywo ds: C-C coupling ·
i idacyclopen adienes · C2H4
inse ion · C-H ac i a ion · wa e
complexes
In oduc ion
Me allacyclopen adienes[1] a e e y in e es ing o ganome allic
species which a e in ol ed, as in e media es, in a numbe o
impo an ca aly ic o s oichiome ic p ocesses media ed by
ansi ion me al complexes, as is he case o he cyclo ime iza ion
o alkynes ( o gi e benzene de i a i es),[2] alkynes-ni iles ( o he
syn hesis o py idines),[3] alkynes-ole ins ( o ma ion o
cyclohexadienes),[3,4] e c.[1h,5] In his con ibu ion, we epo on he
coupling o wo molecules o DMAD (dime hyl
ace ylenedica boxyla e, MeO2CC≡CCO2Me) in he TpMe2I sys em
(TpMe2 = hyd o is(3,5-dime hylpy azolyl)bo a e),[6] o gi e an
i idacyclopen adiene[7] which comple es he 18-elec on me al coun
by coo dina ion o a molecule o wa e . Subs i u ion and inse ion
eac ions o his complex ha e been in es iga ed, as well as he
syn hesis and eac i i y o a ela ed unsymme ical
i idacyclopen adiene ha esul s om he egioselec i e coupling o
DMAD and MP (MP = me hyl p opiola e, HC≡CCO2Me). Pa o
his wo k has been published in p elimina y o m.[8]
Resul s and Discussion
The addi ion o 2 equi . o DMAD o a solu ion o he
bis(e hylene) complex TpMe2I (C2H4)2 (1)[9] in CH2Cl2, a oom
empe a u e, p oduces immedia e consump ion o 1 and o ma ion
o a new compound, 2, as deduced om he NMR spec a o he
eac ion mix u e [Eq. (1)]. The eac ion is s e eospeci ic, and he
spec oscopic yield o his species is highe han 85%. The chela ing
[a] D . E. Ál a ez, D . M. Paneque, D . C. M. Posadas, P o . D . M. L.
Po eda, D . N. Rendón, Ins i u o de In es igaciones Químicas and
Depa amen o de Química Ino gánica
Consejo Supe io de In es igaciones Cien í icas (CSIC) and Uni e sidad
de Se illa
A . Amé ico Vespucio 49, Isla de la Ca uja, 41092 Se illa (Spain)
Fax: (+34)954460565
E-mail: [email protected]
[b] D . K. Me ei e
Depa men o Chemis y, Vienna Uni e si y o Technology,
Ge eidema k 9/164, A-1060 Vienna (Aus ia)
Suppo ing in o ma ion o his a icle is a ailable on he WWW unde
h p://www.chemeu j.o g/ o om he au ho .
2
hyd oca byl-alkene ligand in compound 2 o mally esul s om he
C—C coupling o wo molecules o DMAD and a inyl agmen ,
which de i es i sel om one o he e hylene ligands in 1.
B
NNN
NNN
I
H
[I ] = Tp
Me2
I =
CH
2
Cl
2,
25 °C
[I ]
R
RR
R
2
2DMAD
[I ]
1
DMAD = RR
(1)
H
-C
2
H
4
R=CO
2
Me
Al hough compound 2 is he majo p oduc in his eac ion,
a emp s o ob ain an analy ical and spec oscopically pu e sample
o i ailed, due o i s slow ans o ma ion in o a new allyl de i a i e
3 (see below). Ei he by c ys alliza ion o by column
ch oma og aphy, species 2 is always isola ed as a mix u e wi h 3.
Ne e heless, i su i es in solu ion long enough as o be p ope ly
cha ac e ized by spec oscopy, ei he in he mix u e wi h 3 o in he
c ude p oduc om he eac ion. The p esence o he hyd ide ligand
is shown by a high- ield esonance a -16.91 ppm in he 1H NMR
spec um, while he π-coo dina ed inyl moie y exhibi s he pa e n
o esonances expec ed o a ligand o his ype:[10] h ee mul iple s
cen e ed a 6.39, 3.63 and 3.07 ppm, wi h ans and cis 3JHH
coupling cons an s o 11.5 and 9.8 Hz, espec i ely (see
Expe imen al Sec ion o assignmen s). 13C NMR da a and a ull se
o wo-dimension expe imen s a e also in ag eemen wi h he
s uc u e p oposed and, in pa icula , he NOESY spec um con i ms
he coo dina ion o he ole in o he me al h ough he ace indica ed.
Complex 2 cleanly ans o ms in o he alkyl-allyl 3 when
solu ions o 2 a e wa med a 60 °C [Eq. (2)], and 3 is also ob ained,
in almos quan i a i e yield, when he eac ion depic ed in Eq. (1) is
pe o med in CH2Cl2 a 60 °C. The o ma ion o 3 is he nea esul
o he s e eospeci ic ans e o he hyd ide ligand o he α-ca bon
a om o he alkenyl end o he chela ing ligand in 2. Di e en
pa hways could in p inciple be en isaged o his ans o ma ion;
ne e heless, we p opose ha i akes place by di ec mig a ion o
he hyd ide o he alkenyl ca bon, wi h conce ed o s epwise bond
ea angemen along he chain. Compound 3 exhibi s 1H NMR
esonances due o he -coo dina ed allyl moie y[9] a 7.07 (CH),
4.09 and 2.94 (CH2) ppm, he co esponding C a oms p oducing
signals in he 13C NMR spec um a 91.2 (1JCH = 170 Hz) and 25.2
ppm (1JCH = 155 and 166 Hz) while he emaining allylic ca bon
appea s a 53.0 ppm. The I -bonded alkyl ca bon, I —
C(H)(CO2Me)R esona es a 12.0 ppm (1JCH = 135 Hz). This
compound has been addi ionally cha ac e ized by an X- ay
di ac ion s uc u e analysis (see below).
3
CH
2
Cl
2,
60 °C
[I ]
R
RR
R
2
H
[I ]
R
RR
R
H
(2)
R=CO
2
Me
The eac ion shown in Eq. (1) has been moni o ed by NMR, a
low empe a u e. When 2 equi . o DMAD a e added o a solu ion
o 1 in CD2Cl2 a -40 ºC, he 1
H NMR spec um eco ded
immedia ely a e mixing shows quan i a i e o ma ion o a new
compound, which has been cha ac e ized by NMR, a 0 ºC, as he
I (I) adduc TpMe2I (C2H4)(MeO2CCCCO2Me) (4) [Eq. (3)]. I s 1H
and 13C{1H} NMR spec a show local Cs symme y o he TpMe2
ligand and all he p o ons and bo h ca bon nuclei o he e hylene
ligand a e equi alen , gene a ing a single in each spec um (3.14
ppm o 1H and 51.1 ppm o 13C{1H}). The 11B{1H} NMR
spec um shows a single a 32.5 ppm, and his alue[11] compa es
well wi h he co esponding chemical shi eco ded o complex 1
(32.9 ppm), which has been shown p e iously o be a 18-e- species
wi h he TpMe2 ligand κ3 coo dina ed bo h in he solid s a e and in
solu ion.[9] Compound 4 is gene a ed by subs i u ion o one o he
e hylene ligands in 1 by a molecule o DMAD, a p ocess ha also
occu s when his de i a i e eac s wi h one equi alen o so Lewis
bases (CO and PR3; R3 = Me3, Me2Ph, E 3).[12] These eac ions ha e
been p oposed o occu by an associa i e mechanism, by means o a
change on he coo dina ion mode o he TpMe2 ligand, om κ3 o
κ2.[12,13]
CD
2
Cl
2,
-40 °C
2DMAD
[I ]
1
[I ]
4
R
R
(3)
R=CO
2
Me
Howe e , and unlike o he de i a i es o composi ion
TpMe2I (C2H4)(L) (L = CO, PR3)[12] and ela ed Tp species,[13,14]
which adop a igid igonal bipy amidal s uc u e wi h he, slowly
o a ing in he NMR ime scale, e hylene ligand occupying he
equa o ial posi ion, and hence gi ing ise o an AA’BB’ spin sys em
in he 1H NMR spec a, compound 4 is luxional, and i s e hylene
ligand seems o be as o a ing, e en a -40 ºC. This di e ence can
be a ibu ed o he ac ha he e hylene ligand is occupying an
axial posi ion in he igonal bipy amid (Fig. 1), whe e he π back
dona ion would be weake han when in he equa o ial place.[15] The
adop ion o his s uc u e is also suppo ed by a compa ison o he
13C NMR chemical shi o he e hylene ligand in he se ies o
compounds TpMe2I (C2H4)(L) (L = PMe3, CO, C2H4 and DMAD)
(see Table 1). Fo he case o L = C2H4, all he e hylene ca bon
a oms esona e a 26.2 ppm. As al eady epo ed, his compound is
luxional, and his signal ep esen s he a e age o he chemical
shi s co esponding o he axial and equa o ial posi ions, and hus,
he 13C{1H} NMR spec um eco ded o 1 in he solid s a e exhibi s
wo signals o he e hylene ligands, a 48 and 5 ppm (axial and
equa o ial, espec i ely).[9] P obably, he p e e ence o he DMAD
o he equa o ial posi ion in 4 is because i is a be e -accep o
han he e hylene ligand. Al hough i can no be deduced om he
da a a ailable, i is p oposed ha he DMAD ligand does no o a e
a ound he I —DMAD axis, due o i s s ong π-accep o cha ac e .
Finally on his espec , he ela ed Tp de i a i e
TpI (C2H4)(DMAD)[7c] has also been epo ed o be luxional, and
he au ho s sugges a s e eochemis y analogous o he one p oposed
he ein o 4.
3
I
N
N
N
NN
N
HB
CO
2
Me
CO
2
Me
Figu e 1. P oposed s uc u e o complex 4.
Table 1. Solu ion Chemical Shi s o he 13C Nuclei o he E hylene Ligands in
Compounds o Composi ion TpMe2I (C2H4)(L).
L PMe3 CO C2H4 DMAD
δ C2H4 (ppm) -8.1 0.6 26.2[a] 51.1
[a] 48 and 5 ppm in he solid s a e.
Compound 4 is s able up o 10 °C; abo e his empe a u e, and
unde he condi ions o Eq. (3), i e ol es o a mix u e o species.
Moni o ing he eac ion by 1H NMR a 20 ºC e eals he o ma ion
o 2 oge he wi h o he uniden i ied species, al hough hey
subsequen ly disappea , and inally 2 is p esen in ca. 90%
spec oscopic yield. As we we e unable o di ec ly cha ac e ize any
o he in e media e(s) species en ou e o 2, and in o de o ob ain
u he in o ma ion abou his sys em, we decided o seek al e na i e
ways o p epa e likely in e media es in he o ma ion o 2. In a
ecen p elimina y communica ion,[8a] we ha e epo ed ha he
i idacyclohep a iene 6, o be desc ibed in ull de ail elsewhe e, is
ob ained by he eac ion o he I -dime hylbu adiene de i a i e 5
wi h 3 equi . o DMAD in CH2Cl2 [Eq. (4)]. In e es ingly, he
p esence o a la ge excess o wa e (≥ 10 equi .) in he eac ion
mix u e p e en s he inco po a ion o he hi d equi alen o alkyne,
yielding he wa e s abilized[16] i idacyclopen adiene de i a i e 7
[Eq. (5)], ha ob iously has been o med by he coupling o wo
DMAD molecules in he me al coo dina ion sphe e.[7] As expec ed,
he wa e ligand p esen in 7 is labile, as demons a ed by he
subs i u ion eac ions ca ied ou wi h NCMe and CO, ha yield he
co esponding de i a i es 7·NCMe and 7·CO. Wi h excess o
DMAD, an inse ion eac ion in o one o he I —C bonds akes
place and compound 6 is o med (Scheme 1). All hese
me allacyclopen adienes ha e been ully cha ac e ized by
spec oscopy (see Expe imen al Sec ion) and in addi ion, he solid-
s a e s uc u es o 7 and 7·CO ha e been de e mined by X- ay
c ys allog aphy (see below).
[I ] [I ] R
RR
R
RR
H
2
O
CH
2
Cl
2,
60 °C
3DMAD(H
2
O)
6
5
(4)
R=CO
2
Me
[I ] [I ]
H
2
O
CH
2
Cl
2,
60 °C
3DMAD,10H
2
O
7
5
R
R
R
R
(5)
R=CO
2
Me
L, 60-90 ºC
[I ]
L
7·L(L = NCMe, CO)
R
R
R
R
R=CO
2
Me
[I ]
H
2
O
7
R
R
R
R
[I ] R
RR
R
RR
H
2
O
6
DMAD
C
6
H
12
100 ºC, 18 h
Scheme 1. Syn hesis o complex 7 and i s eac i i y wi h Lewis bases and DMAD.
Mo e in e es ing, in he p esen con ex , is he eac ion o 7 wi h
e hylene which, a 60 ºC, esul s in he clean o ma ion o he
al eady desc ibed compound 3 [Eq. (6)], suppo ing he
in e mediacy o an i idacyclopen adiene species in he o ma ion o
compound 2 (o 3) s a ing om 1 (o 4). Fu he mo e, i e hylene is
bubbled h ough a solu ion o 7 in CDCl3, and he mix u e kep a
oom empe a u e, NMR moni o ing shows he slow o ma ion o a
new species 8 (Scheme 2). Compound 8 is s able a oom
empe a u e and o ms me as able solu ions in chlo o o m om
whe e i e en ually p ecipi a es and, a e dissolu ion in ace one-d6,
could be app op ia ely cha ac e ized by NMR. The mo e
cha ac e is ic signals o his compound a e hose co esponding o
he wo adjacen CH2 g oups: mul iple s a 3.37, 2.90 (I CH2CH2)
and 2.71, 2.17 (I CH2CH2) ppm in he 1H NMR spec um and
esonances a 35.5 (I CH2CH2) and -2.6 (I CH2CH2) ppm in he
13C{1H} NMR spec um. P obably, compound 8 is o med ia
displacemen o wa e by a molecule o e hylene o gi e A (Scheme
2), ollowed by he inse ion o his ligand in o one o he equi alen
I —C bonds. I is wo h o men ion he acili y wi h which he
e hylene inse s in o he I —C bond o he p esumed in e media e A.
In he case o he ela ed, isolable, compound wi h he unsubs i u ed
Tp ligand,[7c] no inse ion was obse ed up o 110 ºC. This is in
ag eemen wi h he known dec eased eac i i y o he TpI
compounds, as compa ed wi h he ela ed TpMe2I ones, in ac i a ion
p ocesses. In he TpMe2I sys em we ha e obse ed cases in which
C2H4 easily inse s in o an I —C bond, o example in i s eac ion
wi h TpMe2I (C6H5)2(N2),[17] bu also ound complexes ha a e
un eac i e in his espec , as he i idacyclopen ene
T
p
Me2
I
(
CH
2
C
(
Me
)
=C
(
Me
)
CH
2
)
(
C
2
H
4
)
which, upon hea ing,
dissocia es he coo dina ed e hylene;[18] o he e y eac i e
TpMe2I (H)(CH=CH2)(C2H4), which has been shown o yield a C4
chain by he coupling o he wo C2 ligands, al hough by ollowing a
mechanis ic pa hway di e en om he inse ion o e hylene in o he
I —C bond.[9] The wa e ligand in 8 is also labile and he
co esponding adduc s 8·NCMe and 8·CO a e easily ob ained [Eq.
(7)]. These complexes ha e been ully cha ac e ized by
spec oscopy and, in addi ion, by an X- ay s udy ca ied ou wi h
8·NCMe (see below). Finally and as expec ed, hea ing solu ions o
compound 8 a 40 °C p omo es i s ans o ma ion in o he allyl
de i a i e 3 [Eq. (8)].
4
[I ]
H
2
O
7
R
R
R
R
CH
2
Cl
2,
60 °C
C
2
H
4
3
[I ]
R
RR
R
H
(6)
R = CO
2
Me
[I ]
H
2
O
7
R
R
R
R20 °C
C
2
H
4
[I ]
H
2
O
R
R
8
R
R
[I ] R
R
R
R
A
H
2
O
CDCl
3
R = CO
2
Me
Scheme 2. Fo ma ion o he alkyl-allyl de i a i e 3 and apping o an in e media e as
he wa e adduc 8.
8
L,20-60 ºC
[I ]
H
2
OR
R
R
R
8·L (L =NCMe, CO)
[I ]
LR
R
R
R
R=CO
2
Me
(7)
83
40 °C
d6-ace one
[I ]
H2OR
R
R
R
[I ]
R
RR
R
H
(8)
R = CO2Me
Compounds 7 o 8 we e no de ec ed du ing he cou se o he
ans o ma ion depic ed in Eq. (1), and his nega i e e idence is
p obably due o he absence o enough H2O in he eac ion mix u e.
In ac , i he eac ion is ca ied ou in he p esence o an excess o
H2O, compound 7 is o med in almos quan i a i e spec oscopic
yield [Eq. (9)] and, despi e o he p esence o he e ol ed e hylene
in he eac ion lask, compound 2 is no obse ed. The la ge
amoun o wa e s. e hylene compe es e ec i ely o he
coo dina ion o i idium, p e en ing he inco po a ion o he ole in.
CH
2
Cl
2,
25 °C
2 DMAD, 10 H
2
O
[I ]
1
[I ]
H
2
O
7
R
R
R
R
(9)
R = CO
2
Me
Conside ing all he obse a ions commen ed so a , he
mechanism depic ed in Scheme 3 can be p oposed o he o ma ion
o compounds 2 and 3, in which compounds 7 and 8 ha e also been
included. F om he expe imen al da a we canno say which o he
in e media es A o B (B is depic ed as an unsa u a ed 16-e- I (III)
species a he han as ha ing a 18-e- bis(ca bene) I (I) s uc u e[2c,7b])
is o med di ec ly om 4 (in bo h cases we p esume ha he second
molecule o DMAD en e s he coo dina ion sphe e in an associa i e
p ocess, as is he no m in subs i u ion eac ions o Tp’I (I) species).
I B is o med i s , hen he e is a compe ence o coo dina ion o
his in e media e, o he e ol ed e hylene ( o gi e A) and he wa e
p esen in he eac ion mix u e ( o gi e 7). On he con a y, i A is
he a o ed kine ic species, he coo dina ed e hylene would be
dissocia i ely exchanged by H2O unde he eac ion condi ions,
be o e C2H4 inse ion in o one o he I —C bonds o he
me allacycle akes place. The acili y wi h which his inse ion akes
place, and he obse a ion ha , unde ce ain condi ions, he
i idacyclohep a iene 6 is obse ed in his eac ion (see below), and
o he da a ob ained in ou labo a o y in sys ems ela ed o his one,
o be discussed elsewhe e, sugges he ini ial o ma ion o
in e media e B. Whiche e is he i s species o med, i is clea ha
i is he esul o he oxida i e coupling o wo molecules o DMAD
bonded simul aneously o i idium, and his p ocess is likely
go e ned by he high endency o he Tp’I (I) de i a i es o oxidize
o I (III), and mo e impo an ly by he mu ually cis disposi ion
adop ed by hese ligands in he pu po ed in e media e ha also
con ains a ac- ype TpMe2-I linkage. This is in ag eemen wi h he
expe imen al and heo e ical s udies ca ied ou wi h he sys em
[I (PR3)3(alkyne)2]+, which indica e ha he phosphines ha e o
occupy a ac disposi ion o he coupling o he wo alkynes o ake
place.[7b] Recen ly, i has been epo ed ha a bis(e hylene)i idium(I)
de i a i e s abilized by a me ipodal ni ogen dono ligand, eac s
wi h DMAD gi ing ise o a s able bis(alkyne)i idium(I) complex,
e en in he p esence o NCMe.[19]
[I ]
1 DMAD
[I ] R
R[I ] R
R
R
R
[I ]
H
2
O
R
R
R
R
DMAD
H
2
O
1
< 10 °C
47
> 10 °C
40 °C
C
2
H
4
-H
elim.
H-mig .
C
2
H
4
ins.
-C
2
H
4
[I ] R
R
R
R
-H
2
O
3
[I ]
R
RR
R
H
[I ] R
R
R
R
B
A
(?)
-C
2
H
4
DMAD
> 10 °C
(?)
[I ]
R
RR
R
2
H
C
[I ]
H
2
O
R
R
8
R
R
H
2
O
-H
2
O
R = CO
2
Me
Scheme 3. Mechanism p oposed o he o ma ion o complex 3 om he bis(e hylene)
de i a i e 1 and DMAD wi h inclusion o all he in e media e species isola ed.
5
In o de o comple e his s udy, some deu e a ion expe imen s
ha e been ca ied ou . Fi s , we ha e p epa ed, a low empe a u e,
complex 4 by addi ion o 1 o only one equi alen o DMAD, o add
a e wa ds an excess (≥ 6 equi .) o DMAD-d6. A e wa ming a
60 °C, compound 3-d6 is o med and he co esponding 1H NMR
spec um exhibi s esonances o he ou CO2Me g oups o
in ensi y hal o he obse ed in compound 3 [Eq. (10)]. This
indica es ha 4 does no in e change wi h ee DMAD, and also
e lec s he symme y o he in e media es A and B. Secondly, we
ha e ound ha wo equi alen CO2Me g oups p esen in 7 can be
selec i ely eplaced by CO2CD3 by a anses e i ica ion p ocess in
CD3OD, ca alyzed by acid. Al hough no con i med, i is highly
p obable, on s e ic g ounds, ha he deu e a ed posi ions a e hose
shown in Scheme 4. When 7-d6 is subjec ed o eac ion wi h C2H4,
no sc ambling o he labels is obse ed, as wo CO2Me esonances
a e absen in he 1H NMR spec a o compound 3-d6, p obably hose
shown in Scheme 4. This expe imen ules ou any in e con e sion
be ween he i idacyclopen adiene and a bis(alkyne)I (I) species [Eq.
(11)] and his is in acco d wi h he indings obse ed in a ela ed
sys em.[7a]
3-d
6
CD
2
Cl
2,
60 °C
>6 DMAD-d
6
[I ]
4
R
R
[I ]
R-d
1.5
R-d
1.5
R-d
1.5
R-d
1.5
H
(10)
R = CO
2
Me
[I ]
H2O
7
R
R
R
R
[I ]
H2O
7-d6
R
R-d3
R-d3
R
CD3OD
H+
3-d6
[I ]
R
R-d3
R-d3
R
H
C2H4
60 ºC
R = CO2Me
Scheme 4. Pa ial deu e a ion o complex 7 by a anses e i ica ion eac ion in CD3OD.
[I ]
H
2
O
7
R
R
R
R
(11)
[I ] R
R
R
R
D
R = CO
2
Me
Men ion has o be done o he di e en eac i i y obse ed when
he eac ion o compound 1 is ca ied ou , in solu ion a 60 ºC, wi h
3 equi . o DMAD, and whe e, unde he app op ia e condi ions, he
i idacyclohep a iene 6 is gene a ed. This esul is almos
independen on he sol en employed (C6H12, CH2Cl2 o CHCl3), bu
s ongly depends on he condi ions o he eac ion. Thus, i i is
ca ied ou in deu e a ed chlo o o m o dichlo ome hane (in
cyclohexane he s a ing ma e ial is no soluble enough), in a NMR
ube, compound 3 is o med in almos quan i a i e spec oscopic
yield (>90%). By con as , i he eac ion is pe o med, s a ing wi h
he same amoun o compound and sol en in a much bigge sealed
lask (hence wi h much bigge a mosphe e olume), bo h 3 and 6 a e
o med, in ca. 1:1 a io. This seems o indica e ha he
i idacyclopen adiene in e media e B o Scheme 3 is less eac i e
owa ds DMAD han owa ds e hylene (as men ioned be o e, he
H2O adduc 7 eac s wi h C2H4 a 25 ºC, while i s eac ion wi h
DMAD equi es much highe empe a u es), and his may be due o
he lesse endency o he I (III) in e media e (al eady elec on
de icien ) o bind he alkyne, less elec on-dona ing han e hylene.
A his poin i seems app op ia e o make ano he compa ison wi h
he ela ed sys em o he unsubs i u ed Tp ligand, TpI (C2H4)2-
DMAD (Scheme 5).[7c] In his case, he i s s ep is also he
o ma ion o he I (I) adduc Tp(C2H4)(DMAD), a compound ha is
s able a oom empe a u e, and ha when hea ed in ace oni ile o
o he sol en s like THF o ms an i idacyclopen -2-ene, by oxida i e
coupling o e hylene and DMAD. This coupling is no obse ed in
he case o he co esponding TpMe2 de i a i e 4, which, as al eady
men ioned, decomposes a >10 ºC in he p esence o 1 equi . o
C2H4 and 1 equi . o DMAD o gi e 2 (in he absence o DMAD 4
e ol es by a inylic C—H ac i a ion p ocess o be epo ed
elsewhe e). I DMAD is p esen , he Tp-i idacyclopen ene s uc u e
can be ans o med, unde app op ia e condi ions, in o an
i idacyclopen adiene analogous o ou p oposed in e media e A. As
al eady men ioned, his compound is e y s able and highly
eluc an o expe ience e hylene inse ion in o he I —C bonds o he
me allacycle, no ans o ma ion aking place e en a 100 ºC, his
ac highligh ing once mo e he highe eac i i y o he TpMe2
de i a i es in compa ison wi h he Tp ones.
I R
R
R
R
I
O
R
R
TpI R
R
THF
60 ºC
Tp
Tp DMAD
C
6
H
6
, 60 ºC
oluene-d
8
100 ºC, 13 h no eac ion
R = CO
2
Me
Scheme 5. Fo ma ion o an i idacyclopen -2-ene and an i idacyclopen adiene in he
sys em TpI -C2H4-DMAD.
We ha e also s udied he eac ion o compound
TpMe2I (C2H4)(DMAD) (4) wi h me hyl p opiola e (MP), a e minal
alkyne. In p inciple, a eac i i y simila o ha obse ed o DMAD
could be ad anced, al hough he asymme y o MP may gi e ise o
wo di e en coupled egioisome s. Also, he p esence o he
e minal C—H bond in MP could p omo e C—H ac i a ion
eac ions.[20,21] The sequen ial addi ion o 1, a low empe a u e, o 1
equi . o DMAD and 1 equi . o MP in he p esence o added wa e
(10 equi .), p oduces selec i ely, upon wa ming o oom
empe a u e, he i idacyclopen adiene 9 [Eq. (12)] in which he CH
o he MP occupies a  posi ion in he ing, as deduced by i s 1H
NMR chemical shi o 7.75 ppm (in his kind o I -complexes an
alkenyl CH in  posi ion would gi e a signal u he down ield,
e en a 10 ppm).[20] As expec ed, he wa e ligand in 9 is labile, and
he compounds 9·NCMe and 9·CO a e eadily syn hesized by i s

6
eac ion wi h an excess o L [Eq. (13)]. The new
i idacyclopen adienes ha e been ully cha ac e ized by
mic oanalysis and spec oscopy (IR, 1H and 13C NMR s udies) and
in addi ion, he solid-s a e s uc u e o 9 and 9·NCMe ha e been
de e mined by X- ay c ys allog aphy (see below).
[I ]
H2O
9
R
H
R
R
1 DMAD
[I ]
1
[I ]
4
R
R
THF
-20 °C
1 MP, >10 H2O
THF25 °C
(12)
-20 ºC
R = CO2Me
[I ]
H
2
O
9
R
H
R
R
[I ]
L
9·L (L=NCMe, CO)
R
H
R
R
L, 25 ºC
R=CO
2
Me
(13)
Complex 9 eac s wi h e hylene, a oom empe a u e, wi h he
egio- and s e eoselec i e o ma ion o he hyd ido-ole in de i a i e
10 (Scheme 6). In his case, he o ma ion o his kind o species
seems o be e y a o able, since he pu po ed in e media e
i idacyclohexadiene ela ed o 8 has no been obse ed, e en in he
p esence o excess o added wa e . Sequen ial addi ion o DMAD
and MP o compound 1, in he absence o wa e , a low empe a u e,
ollowed by s i ing a 25 ºC o 15 min, also yields complex 10, in
almos quan i a i e yield. Unlike 2, 10 is e y s able, can be
p ope ly pu i ied, and i has been comple ely cha ac e ized,
including an X- ay s uc u e de e mina ion (see below), which
i mly es ablishes ha he inse ion o he e hylene has aken place
egioselec i ely in o he I —C bond o 9 adjacen o he C—H
unc ionali y. In acco d wi h he high s abili y o his de i a i e,
isome iza ion o he co esponding allyl de i a i e 11 equi es qui e
o cing condi ions [Eq (15)]. The NMR da a ob ained o his
compound a e in ag eemen wi h he s uc u e depic ed, bu he
compound expe iences some kind o luxional p ocess, p obably
con o ma ional in o igin, which is esponsible o he b oadening o
some o he esonances, in bo h 1H and 13C{1H} NMR spec a (see
Expe imen al Sec ion).
11
[I ]
R
RH
R
H
[I ]
H
2
O
9
R
H
R
R
[I ]
R
RH
R
10
H
C
2
H
4
CH
2
Cl
2
25 °C
CH
2
Cl
2
80 °C
24 h
R = CO
2
Me
Scheme 6. Consecu i e o ma ion o complexes 10 and 11 om he
i idacyclopen adiene 9 and C2H4.
X-Ray di ac ion s udies
Table 2 p esen s c ys al da a and da a collec ion de ails o all
compounds analyzed in his sec ion.
Complex 3: Figu e 2 shows an ORTEP iew o a molecule o 3
while Table 3 gi es selec ed bond leng hs and angles. The sp3
ca bon a om bonded o i idium o ms an i idium-ca bon bond wi h a
leng h o 2.12 Å, a alue ypical o an I —C single bond.[22] The η3-
allyl—I in e ac ion is cha ac e ized by I —C bond dis ances o I —
C(1), 2.16; I —C(2), 2.10 and I —C(3), 2.18 Å and he C(1)—
C(2)—C(3) angle o 121.4º is clea ly in acco d wi h almos pu e sp2
hyb idiza ion a he C(2) ca bon.
INSERT TABLE 2 HERE
Figu e 2. X- ay s uc u e o complex 3 ( he mal ellipsoids d awn a he 50% p obabili y
le el).
Table 3. Selec ed bond leng hs [Å] and angles [º] o complex 3
I —N(6) 2.214(2) I —C(2) 2.098(2)
I —C(3) 2.181(2) C(5)—C(6) 1.507(3)
I —C(1) 2.164(2) C(3)—C(4) 1.482(3)
I —N(2) 2.139(2) C(2)—C(3) 1.442(3)
I —C(6) 2.118(2) C(1)—C(2) 1.411(3)
I —N(4) 2.106(2) C(4)—C(5) 1.366(3)
N(2)—I —N(6) 87.61(7) C(1)—C(2)—C(3) 121.4(2)
N(4)—I —N(2) 90.68(7) C(2)—C(3)—C(4) 116.4(2)
N(4)—I —N(6) 80.62(7) C(5)—C(4)—C(3) 118.5(2)
C(6)—I —C(1) 87.48(9) C(4)—C(5)—C(6) 117.4(2)
C(6)—I —C(3) 79.86(8) C(5)—C(6)—I 110.06(15)
C(1)—I —C(3) 69.86(9) C(2)—C(3)—I 67.21(12)
7
Complexes 7 and 7·CO: In Figu es 3 and 4, he molecula
s uc u es o complexes 7 and 7·CO a e ep esen ed, while Table 4
collec s selec ed bond leng hs and angles. The i s compound
c ys allized wi h ca. 1.25 molecules o addi ional wa e which o m
hyd ogen bonds wi h he I —OH2 moie y. The i idacyclopen adiene
uni s in 7 and 7·CO a e almos plana , cha ac e ized by C—I —C
bi e angles o 79.3 and 78.6º, espec i ely, and all he I —C bond
dis ances all be ween 2.00 and 2.06 Å as expec ed o sp2
ca bons.[22] In e es ingly, o complex 7 he I —N(py azolyl) bond
ans wi h espec o he ha d wa e ligand is sho e (2.03 Å) han
he o he wo (2.16 Å a .) bu his e ec is a he diminished in
7·CO.
Figu e 3. X-Ray s uc u e o complex 7 ( he mal ellipsoids d awn a he 50%
p obabili y le el).
Figu e 4. X-Ray s uc u e o complex 7·CO ( he mal ellipsoids d awn a he 20%
p obabili y le el.
Table 4. Selec ed Bond Leng hs (Å) and Angles (deg) o Complexes 7 and 7·CO.
7 7·CO
I —N(12) 2.171(5) 2.151(3)
I —N(22) 2.157(5) 2.128(3)
I —N(32) 2.035(4) 2.111(3)
I —C(42) 2.001(6) 2.055(4)
I —C(52) 2.037(6) 2.067(4)
I —L 2.091(3) 1.852(4)
C(42)—C(43) 1.368(8) 1.358(6)
C(43)—C(53) 1.463(9) 1.463(5)
C(52)—C(53) 1.375(8) 1.355(6)
C(42)—I —C(52) 79.3(2) 78.64(16)
C(42)—I —L 90.19(19) 85.45(17)
C(52)—I —L 87.72(18) 84.99(17)
Complex 8·NCMe: Figu e 5 shows an ORTEP iew o his
compound and Table 5 collec s selec ed bond leng hs and angles.
The I —C(alkenyl) dis ance (2.02 Å) compa es well wi h hose
commen ed o he i idacyclopen adienes 7 and 7·CO while he
co esponding I —CH2 is longe a 2.09 Å. In u n, his la e bond is
sligh ly sho e han he I —C(alkyl) p esen in complex 3 which
suppo s a CO2Me subs i uen . O he h ee I —N(py azolyl) bonds,
he one ans wi h espec o he NCMe is sho e (2.05 Å) han he
o he wo (2.16 Å a .), and in ha way he ace oni ile beha es like
he H2O ligand, ano he ha d dono , in 7.
8
Figu e 5. X-Ray s uc u e o complex 8·NCMe ( he mal ellipsoids d awn a he 20%
p obabili y le el.
Table 5. Selec ed bond leng hs [Å] and angles [º] o complex 8·NCMe
I —N(12) 2.164(4) C(41)—C(42) 1.545(6)
I —N(22) 2.157(4) C(42)—C(52) 1.496(6)
I —N(32) 2.049(3) C(53)—C(62) 1.477(6)
I —C(41) 2.091(4) C(52)—C(53) 1.368(6)
I —C(63) 2.025(4) C(62)—C(63) 1.354(6)
I —N(71) 1.976(3) N(71)—C(72) 1.133(5)
N(22)—I —N(12) 84.47(13) C(62)—C(63)—I 127.6(3)
N(32)—I —N(12) 88.30(13) C(42)—C(41)—I 117.3(3)
N(32)—I —N(22) 89.85(16) C(52)—C(42)—C(41) 110.6(4)
C(63)—I —C(41) 94.02(17) C(53)—C(52)—C(42) 121.8(4)
N(71)—I —C(41) 92.68(18) C(52)—C(53)—C(62) 122.4(4)
N(71)—I —C(63) 90.91(16) C(63)—C(62)—C(53) 124.4(4)
Complex 9: The s uc u e o his complex is shown in Figu e 6,
while selec ed bond leng hs and angles a e collec ed in Table 6.
Once again he i idacyclopen adiene ing is almos plana and he
I —N(py azolyl) bond ans o he H2O is sho e (2.04 Å) han he
o he wo (2.15 Å a .). As commen ed in sec ion Resul s, he I —
C(alkenyl) bond ha suppo s he CH unc ionali y is mo e eac i e
agains C2H4 inse ion han he o he simila one p esen in his
molecule. F om he co esponding bond dis ances, 2.04 s. 2.02 Å, i
may be concluded ha he i s bond is sligh ly weake han he
second and his may be he eason o he di e en eac i i y.
Howe e , we ha e ound ha me hyl p opiola e inse s in o he ing
o 9 wi h he opposi e egioselec i i y.[23]
Figu e 6. X-Ray s uc u e o complex 9 ( he mal ellipsoids d awn a he 40%
p obabili y le el).
Table 6. Selec ed Bond Leng hs (Å) and Angles (deg) o complex 9.
I —N(1) 2.142(3) I —O(1) 2.103(2)
I —N(3) 2.041(3) C(16)—C(17) 1.363(5)
I —N(5) 2.155(3) C(17)—C(18) 1.464(4)
I —C(16) 2.021(3) C(18)—C(19) 1.357(4)
I —C(19) 2.039(3)
C(16)-I (1)-C(19) 79.45(12) C(16)-I (1)-N(1) 177.72(11)
C(16)-I (1)-N(3) 93.49(11) C(19)-I (1)-N(1) 99.04(11)
C(19)-I (1)-N(3) 96.87(11) O(1)-I (1)-N(1) 89.46(10)
C(16)-I (1)-O(1) 88.74(11) C(16)-I (1)-N(5) 97.52(12)
C(19)-I (1)-O(1) 86.28(11) C(19)-I (1)-N(5) 172.68(11)
N(3)-I (1)-O(1) 176.43(10) O(1)-I (1)-N(5) 86.99(10)
9
Complex 9·NCMe: An ORTEP iew o his molecule is shown
in Figu e 7 and selec ed bond leng h and angles a e collec ed in
Table 7. These a e e y simila o hose ound in 9 and will no be
commen ed wi h he excep ion o he wo I —C(alkenyl) bond
dis ances. In e es ingly, and in compa ison wi h 9, o he ca bon
ha suppo s he CH g oup he I —C dis ance is much longe (2.03
Å) han he o he one (1.97 Å).
Figu e 7. X-Ray s uc u e o complex 9·NCMe ( he mal ellipsoids d awn a he 30%
p obabili y le el).
Table 7. Selec ed bond leng hs [Å] and angles [º] o complex 9·NCMe
I —N(22) 2.158(5) I —N(61) 1.991(5)
I —N(12) 2.157(5) C(41)—C(53) 1.410(9)
I —N(32) 2.044(4) C(52)—C(53) 1.364(8)
I —C(42) 2.033(5) C(41)—C(42) 1.351(8)
I —C(52) 1.974(7) N(61)—C(62) 1.144(7)
N(12)-I -N(22) 82.98(17) C(52)-I -C(42) 77.1(2)
N(32)-I -N(12) 89.91(17) C(53)-C(52)-I 118.6(5)
N(32)-I -N(22) 88.38(18) C(41)-C(42)-I 114.6(4)
N(61)-I -C(42) 87.8(2) C(42)-C(41)-C(53) 115.8(6)
C(52)-I -N(61) 87.3(2) C(52)-C(53)-C(41) 111.5(6)
Complex 10: The molecula s uc u e o his compound is
shown in Figu e 8, while selec ed bond leng h and angles a e
collec ed in Table 8. The I —C(41) bond dis ance a 2.02 Å is in he
expec ed ange o an I —C(alkenyl) species while, o he ole in
bonded o I , he C(45)—C(46) sepa a ion o 1.49 Å is much close
o he co esponding o a single C—C bond (1.54 Å) han o a
double one (1.34 Å), and his p obably e lec s a qui e s ong I -
ole in bond.
Figu e 8. X-Ray s uc u e o complex 10 ( he mal ellipsoids d awn a he 40%
p obabili y le el).
Table 8. Selec ed Bond Leng hs (Å) and Angles (deg) o complex 10
I —N(12) 2.193(2) I —H(1I) 1.600
I —C(45) 2.180(3) C(44)—C(45) 1.495(4)
I —N(22) 2.162(2) C(42)—C(43) 1.460(4)
I —C(46) 2.138(3) C(45)—C(46) 1.391(5)
I —N(32) 2.090(2) C(41)—C(42) 1.363(4)
I —C(41) 2.015(3) C(43)—C(44) 1.343(4)
N(22)-I -N(12) 87.79(9) C(46)-I (1)-C(45) 37.56(13)
N(32)-I -N(12) 88.19(9) C(42)-C(41)-I 129.1(2)
N(32)-I -N(22) 82.82(9) C(44)-(45)-I 116.8(2)
C(41)-I -H(1I) 94.7(14) C(41)-C(42)-C(43) 123.4(3)
C(41)-I -C(46) 92.93(13) C(44)-C(43)-C(42) 127.1(3)
C(41)-I -C(45) 90.64(12) C(43)-C(44)-C(45) 126.0(3)
C(45)-I -H(1H) 69.5(10) C(46)-C(45)-C(44) 123.0(3)