Vibrational spectra and the force field of the HCCo3 group in HCCo3(CO)9. Analogies with spectra from adsorbed species on (111) metal surfaces

Abstract

Infrared and Raman spectra of HCCo₃(CO)₉ and DCCo₃(CO)₉ are reported and assignments are made of the bands associated with vibrations of the HCCo₃ grouping. A force field for the latter is determined from the experimental data. The characteristic wavenumbers for the ν_CH and δ_CH modes of the cluster compound, in which the hydrocarbon grouping is bonded to an equilateral triangle of metal atoms, are very similar to those obtained by dissociative adsorption of acetylene on NI(111) planes which have triangular adsorption sites. This provides support for the assignment of the bands observed on Ni to a surface CH group.