MOLECULAR GEOMETRIES OF DISILANE, SILYLGERMANE AND DIGERMANE - IS THERE A DISCREPANCY BETWEEN EXPERIMENT AND THEORY

Equilibrium geometries of the staggered conformers of disilane, silylg ermane, and digermane were located at the CCSD(T), CCSD, CISD, MP2, DF T, and HF levels of theory, using a number of valence double- and trip le-zeta basis sets augmented by polarization functions. Contrary to do ubts expressed by Oberhammer, Lobreyer and Sundermeyer (OLS), the corr elated levels of theory, used in conjunction with valence triple-zeta basis sets augmented by f-poIarization functions on heavy atoms, are c apable of reproducing all experimental parameters that are well establ ished. The present results describe a microwave HGeH bond angle in Ge2 H6 that is 2 degrees larger than the somewhat questionable experimenta l value. The theoretical data presented suggest that the assumptions b y OLS of intrinsically related GeH and SiH bond lengths and of equal H SiH and HGeH angles in H3SiGeH3 are not justified.