Infrared spectra of methylmanganese pentacarbonyl and methylrhenium pentacarbonyl species: methyl group geometry and the effects of internal rotation

Pressure-tuning vibrational spectra of the heterobimetallic complexes, Ph3MCo(CO)4 (M=Sn, Pb)

“…[9,10], and incoherent inelastic neutron scattering diffraction [2]. Of current special interest to our research on organometallic carbonyl complexes are the vibrational spectroscopic properties of metal-metal bonded species of the type, Ph 3 MCo(CO) 4 (M = Si, Sn, Pb), which form part of the prototypical class of trigonal-bipyramidal, C 3v -symmetry derivatives with the general formula LCo(CO) 4 [11][12][13]. However, these particular metal-metal bonded complexes exhibit much higher thermal stability when L = Ph 3 M (M = Si, Sn, Pb) than when L = alkyl or H. It has been suggested that this situation may be attributed to the stronger M-Co p-bonding interactions, because only when L is a p-acceptor ligand are the complexes more thermally stable [13].…”

“…However, these particular metal-metal bonded complexes exhibit much higher thermal stability when L = Ph 3 M (M = Si, Sn, Pb) than when L = alkyl or H. It has been suggested that this situation may be attributed to the stronger M-Co p-bonding interactions, because only when L is a p-acceptor ligand are the complexes more thermally stable [13]. Infrared studies of the CO stretching modes and valence force-field calculations for various LCo(CO) 4 complexes have provided evidence for p-interactions in the metal-metal bonds [14][15][16][17][18]. Moreover, the IR and Raman spectra of the closely related complexes, X 3 MCo(CO) 4 (M = Si, Ge, Sn; X = Cl, Br, I), have been examined and vibrational assignments have been proposed [19,20].…”

“…Infrared studies of the CO stretching modes and valence force-field calculations for various LCo(CO) 4 complexes have provided evidence for p-interactions in the metal-metal bonds [14][15][16][17][18]. Moreover, the IR and Raman spectra of the closely related complexes, X 3 MCo(CO) 4 (M = Si, Ge, Sn; X = Cl, Br, I), have been examined and vibrational assignments have been proposed [19,20]. The molecular electric dipole moments for a series of LM(CO) 4 complexes, including the Ph 3 MCo(CO) 4 (M = Si, Sn, Pb) derivatives, have been reported [21], which indicate that charge-transfer in the M-Co bond is mainly determined by the inductive properties of the attached ligands L. The same conclusion was reached for the Sn-Fe bond in (g 5 -C 5 H 5 )Fe(CO) 2 -(SnPh 3 ) and related derivatives [22].…”

“…Moreover, the IR and Raman spectra of the closely related complexes, X 3 MCo(CO) 4 (M = Si, Ge, Sn; X = Cl, Br, I), have been examined and vibrational assignments have been proposed [19,20]. The molecular electric dipole moments for a series of LM(CO) 4 complexes, including the Ph 3 MCo(CO) 4 (M = Si, Sn, Pb) derivatives, have been reported [21], which indicate that charge-transfer in the M-Co bond is mainly determined by the inductive properties of the attached ligands L. The same conclusion was reached for the Sn-Fe bond in (g 5 -C 5 H 5 )Fe(CO) 2 -(SnPh 3 ) and related derivatives [22]. More recently, we have published some X-ray diffraction and multinuclear NMR spectroscopic data that have some bearing on the electronic environment and chemical bonding in the Ph 3 MCo(CO) 4 (M = Si, Sn, Pb) derivatives [23].…”

“…Several homopolymetallic clusters, such as Ru 3 (CO) 12 [29], [Au 9 (PPh 3 ) 8 ][PF 6 ] 3 [30], ½Pt 3 ðCOÞ 6 2À n ðn ¼ 3-5Þ [31], and HOs 3 (CO) 10 (l,g 2 -NC 5 H 4 ) [32] have also been examined. We report here the results of a pressure-tuning FT-Raman and IR spectroscopic study of the heterobimetallic complexes Ph 3 SnCo-(CO) 4 and Ph 3 PbCo(CO) 4 . In addition to providing information on the effect of high pressures on the structures of these materials, these high-pressure vibrational measurements afford additional insights into the relative p-backbonding capabilities of the Ph 3 M ligands, the nature of the Sn-Co and Pb-Co bonding, and the charge-transfer effects in the two complexes.…”