THEORETICAL-STUDIES OF THE METALLACYCLOPROPENES C-[MX2C2H2] (M = C, SI, GE, SN - X = H, F)

The geometries of the metallacyclopropenes c-[MX2C2H2] (M = C, Si, Ge, Sn; X = H, F) are predicted by using the 3-21G(d) basis set and SCF wave functions. The nature of the ring bonding is investigated via analysis of the total electron density and is found to have little or no π-complex character. As a further probe of the electronic structure, bent bond lengths and intrinsic vibrational frequencies are computed. The classical barrier heights and the thermodynamics of the reaction MX2 + HC≡CH → c-[MX2C2H2] are predicted by using MP2/3-21G(d) energies. © 1990 American Chemical Society.