The metal-carbon bond in vinylidene, carbonyl, isocyanide and ethylene complexes

Density functional theory (DFT) calculations were carried out for trans -[RhX(L)(PMe3)(2)] (L=C=CH2, C=CHC6H5, CO, 2,6-Me2C6H3NC, C2H4) which served as model compounds for the analysis of the vibrational spectra of related complexes. The characterization of the metal-carbon stretching mode allowed to study the trans influence of a series of ligands on the metalcarbon bond in vinylidene, carbonyl and isocyanide complexes. Furthermore, the comparison of the FT-Raman spectra of the complexes trans-[RhF(CO)(PiPr(3))(2)] and trans-[RhF(C-13=(CH2)-C-13)(PiPr(3))(2)] which possess the same reduced mass (C-13=(CH2)-C-13 vs. CO) allowed for an evaluation of the Rh-C bond strength free of any mass effects and therefore only showing effects of electronic nature. (C) 2002 Elsevier Science BN. All rights reserved.