The harmonic force fields of dimethyl zinc, cadmium and mercury: a joint theoretical and experimental study

The harmonic force fields of the title compounds have been calculated at the ab initio SCF level using effective core potentials and polarized double-zeta basis sets. After scaling, the theoretical wavenumbers are in good agreement with experiment both for the parent compounds and the perdeuterated isotopomers, and the ¹²C→¹³C shifts are well reproduced. Constraining all but three off-diagonal force constants to their ab initio values in a least squares refinement, semi-empirical harmonic force fields have been derived which account well for all available experimental data. The CH stretching motions are analyzed in terms of an harmonic local mode approach