Bis[μ-4-(ethylammoniomethyl)-3,5-dimethylpyrazolato-κ2N1:N2]bis[(η4-1,5-cyclooctadiene)rhodium(I)] dichloride dichloromethane methanol solvate

Bis[l-4-(ethylammoniomethyl)-3,5dimethylpyrazolato-j 2 N 1 :N 2 ]bis[(g 4 - 1,5-cyclooctadiene)rhodium(I)] dichloride dichloromethane methanol solvate Glo Ária Esquius, a Josefina Pons, a Ramo ÂnYa Ân Äez, a Josep Ros, a Xavier Solans b * and Merce ÁFont-Bardia b a Departament de Quõ Âmica, Universitat Auto Ánoma de Barcelona, E-08193 Bellaterra, Spain, and b Departament de Cristallografia, Mineralogia i Dipo Ásits Minerals, Universitat de Barcelona, Martõ Âi Franque Âs s/n, E-08028 Barcelona, Spain Correspondence e-mail: [email protected] Received 29 October 2001 Accepted 20 November 2001 Online 31 January 2002 In the title compound, [Rh 2 (C 8 H 15 N 3 ) 2 (C 8 H 12 ) 2 ]Cl 2 CH 2 - Cl 2 CH 3 OH, the dinuclear Rh I complex has C 2 symmetry and the two pyrazolato ligands act as -bridges. The coordination of each Rh I cation is completed by one cyclooctadiene (COD) ligand. It is shown that the average RhÐC(COD) distance is linearly dependent on the RhÐ N(pyrazole) distance in this type of compound, and this is ascribed to the steric hindrance produced by the packing. Comment Research into the coordination chemistry of pyrazole-derived ligands has progressed rapidly over the last two decades. Mukherjee (2000) published an extensive review, completing those presented by La Monica & Ardizzoia (1997) and Tro®menko (1972, 1986, 1993). Only four structures of dinuclear rhodium(I) complexes with pyrazole bridges and cyclooctadiene ligands (cod) (Louie et al., 1984; Cano et al., 1997; Esquius et al., 2000) are present in the Cambridge Structural Database (CSD, release of November 2001; Allen & Kennard, 1993). A feature of these compounds is the variation of the RhÐC and RhÐN bond distances without a clear reason. In order to increase understanding of this distance variation, the title compound, (I), was prepared, which is similar to those previously published by Esquius et al. (2000). The molecular structure of (I) is shown in Fig. 1 and selected geometric details are given in Table 1. The structure of (I) consists of discrete molecules separated by van der Waals interactions and weak hydrogen bonds (Table 2). The methanol molecules were located as disordered, and atom O1 seems to form a hydrogen bond with a Cl ÿ anion [O1Cl1 i 3.118 (4) A Ê; symmetry code (i) 1 2ÿx,1 2ÿy,1ÿz]. Each Rh atom is linked to four C atoms of a cyclooctadiene ligand and two N atoms of two different pyrazole units. The pyrazole acts as a -N,N0-bridge between two Rh atoms. The Acta Cryst. (2002). C58, m133±m134 DOI: 10.1107/S0108270101020017 #2002 International Union of Crystallography m133 metal-organic compounds Acta Crystallographica Section C Crystal Structure Communications ISSN 0108-2701 Figure 1 A view of the molecular structure of (I) showing 50% probability displacement ellipsoids and the atom-numbering scheme. The H atoms, the Cl ÿ anions and the dichloromethane and methanol solvent molecules have been omitted for clarity. Figure 2 A graph of average RhÐC versus average RhÐN bond lengths in -pyrazole-[Rh(COD)] 2 units. metal-organic compounds m134 Glo Ária Esquius et al. [Rh 2 (C 8 H 15 N 3 ) 2 (C 8 H 12 ) 2 ]Cl 2 CH 2 Cl 2 CH 4 OActa Cryst. (2002). C58, m133±m134 RhÐN1ÐN2ÐRh i torsion angle is 2.43 (19). The planarity of this moiety is similar to that observed when the pyrazole lacks a bulky substituent in position 4 (Louie et al., 1984; Esquius et al., 2000). The dihedral angle between the Rh/N1/ N2/Rh i and pyrazole planes is 20.17 (10). The ethylammoniomethyl moiety is planar and twisted by 87.0 (2)with respect to the pyrazole plane. If the average RhÐC(COD) and RhÐN(pyrazole) lengths are compared, it is observed that <RhÐC> increases when <RhÐN> increases (Fig. 2), while the NÐN and CÐC lengths remain practically constant [average values in the ®ve structures are 1.360 (7) and 1.375 (12) A Ê, respectively]. This suggests that the bond lengths involving the Rh atom are more affected by the steric hindrance of the packing than by electronic effects. This is corroborated by the two electronically more similar pyrazole ligands, 3,5-dimethyl-4-[N-(isopropyl)- aminomethyl]pyrazolyl and 3,5-dimethyl-4-(ethylammonium)methylpyrazolate, presenting the upper and lower limiting values. Experimental To prepare (I), [RhCl(COD)] 2 (0.08 g, 0.16 mmol) dissolved in CH 2 Cl 2 (5 ml) was added to a solution of 3,5-dimethyl-4-(ethylamino)methylpyrazole (0.08 g, 0.32 mmol) in CH 2 Cl 2 (5 ml) and the mixture stirred for 15 h. The solvent was evaporated to dryness in vacuo and the residue was washed with Et 2 O and dissolved in a minimum amount of CH 2 Cl 2 . The title complex was precipitated by adding hexane to the solution. A yellow±orange solid was ®ltered off and dried in vacuo. Crystals of (I) were obtained by evaporation of a methanol solution. Crystal data [Rh 2 (C 8 H 15 N 3 ) 2 (C 8 H 12 ) 2 ]Cl 2 - CH 2 Cl 2 CH 4 O M r = 916.52 Monoclinic, C2=c a= 12.587 (3) A Ê b= 25.762 (9) A Ê c= 13.240 (13) A Ê = 108.24 (3) V= 4078 (4) A Ê 3 Z=4 D x = 1.492 Mg m ÿ3 Mo Kradiation Cell parameters from 25 re¯ections = 12±21 = 1.11 mm ÿ1 T= 293 (2) K Prism, yellow±orange 0.2 0.1 0.1 mm Data collection Enraf±Nonius CAD-4 diffractometer !/2scans 6120 measured re¯ections 5860 independent re¯ections 4234 re¯ections with I>2(I) R int = 0.061  max =30  h=ÿ17 !16 k=0!36 l=0!18 3 standard re¯ections frequency: 120 min intensity decay: none Re®nement Re®nement on F 2 R[F 2 >2(F 2 )] = 0.028 wR(F 2 ) = 0.079 S= 0.98 5860 re¯ections 222 parameters H atoms: see below w= 1/[ 2 (F o 2 ) + (0.0406P) 2 ] where P=(F o 2 +2F c 2 )/3 (/) max = 0.001  max = 0.58 e A Ê ÿ3  min =ÿ0.35 e A Ê ÿ3 Methanol atoms O1 and C19 were located from a difference Fourier synthesis. Their occupancy factor of 0.5 was assigned according to the peak heights. The molar ratio with respect to the remaining formula was con®rmed by elemental analysis. The H atoms on N15 were re®ned freely. The positions of 27 H atoms were geometrically computed (CÐH = 0.93±0.97 A Ê) and re®ned using a riding model, with U iso (H) = 1.2U eq (C). Dichloromethane H atoms were located from a difference Fourier synthesis, while methanol H atoms were not located. Data collection: CAD-4/PC (Kretschmar, 1996); cell re®nement: CAD-4/PC; data reduction: CFEO (Solans, 1978); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP3.2 (Brueggemann & Schmid, 1990); software used to prepare material for publication: PLATON (Spek, 1990). Supplementary data for this paper are available from the IUCr electronic archives (Reference: OB1049). Services for accessing these data are described at the back of the journal. References Allen, F. H. & Kennard, O. (1993). Chem. Des. Autom. News,8, 1, 31±37. Brueggemann, R. & Schmid, G. (1990). ORTEP3.2. PC version. University of Ulm, Germany. Cano, M., Heras, J. V., Maeso, M., Alvaro, M., Ferna Ândez, R., Pinilla, E., Campo, J. A. & Monge, A. (1997). J. Organomet. Chem. 534, 159±166. Esquius, G., Pons, J., Ya Ân Äez, R., Ros, J., Solans, X. & Font-Bardia, M. (2000). J. Organomet. Chem. 605, 226±233. Kretschmar, M. (1996). CAD-4/PC. Version 2.0. PC version of CAD-4 Software (Version 5.0). University of Tu Èbingen, Germany. La Monica, G. & Ardizzoia, G. A. (1997). Prog. Inorg. Chem. 46, 151±213. Louie, B. M., Rettig, S. J., Storr, A. & Trotter, J. (1984). Can. J. Chem. 62, 1057± 1062. Mukherjee, R. (2000). Coord. Chem. Rev. 203, 151±218. Sheldrick, G. M. (1997). SHELXL97 and SHELXS97. University of Go Èttingen, Germany. Solans, X. (1978). CFEO. University of Barcelona, Spain. Spek, A. L. (1990). Acta Cryst. A46, C-34. Tro®menko, S. (1972). Chem. Rev. 72, 289±374. Tro®menko, S. (1986). Prog. Inorg. Chem. 34, 115±210. Tro®menko, S. (1993). Chem. Rev. 93, 943±974. Table 1 Selected geometric parameters (A Ê,). RhÐN2 i 2.095 (2) RhÐN1 2.104 (2) RhÐC6 2.129 (3) RhÐC2 2.137 (2) RhÐC1 2.142 (3) RhÐC5 2.144 (3) RhÐRh i 3.1579 (9) N1ÐN2 1.377 (3) N2 i ÐRhÐN1 83.15 (9) N2 i ÐRhÐC6 160.26 (10) N1ÐRhÐC6 92.33 (10) N2 i ÐRhÐC2 95.28 (11) N1ÐRhÐC2 164.91 (10) C6ÐRhÐC2 93.91 (12) N2 i ÐRhÐC1 93.74 (11) N1ÐRhÐC1 157.72 (10) C6ÐRhÐC1 83.17 (13) C2ÐRhÐC1 37.17 (11) N2 i ÐRhÐC5 161.91 (10) N1ÐRhÐC5 94.84 (10) C6ÐRhÐC5 37.37 (11) C2ÐRhÐC5 81.97 (12) C1ÐRhÐC5 94.66 (12) C9ÐN1ÐRh 130.93 (15) N2ÐN1ÐRh 116.59 (13) C11ÐN2ÐRh i 133.54 (16) N1ÐN2ÐRh i 113.59 (13) Symmetry code: (i) 1 ÿx;y;1 2ÿz. Table 2 Hydrogen-bonding geometry (A Ê,). DÐHADÐH HADADÐHA N15ÐH15Cl1 0.90 (2) 2.45 (2) 3.286 (4) 154 (3) N15ÐH15ACl1 i 0.90 (2) 2.29 (2) 3.188 (4) 175 (2) Symmetry code: (i) 1 ÿx;y;1 2ÿz.