Molecular Structure of Carbene Analogues:  A Computational Study

Systematic computational studies on the dihydrides and dihalides of group 14 elements have been performed, for their ground state and first excited state. We present equilibrium geometries of the lowest lying singlet and triplet states and singlet−triplet energy separation data on the whole series obtained by the CCSD(T) method. Scalar relativistic effects are taken into account by applying effective core potentials (ECP) from the fourth period on. The performance of two sets of core potentials is compared and set against previous theoretical results and available experimental information. Expected trends and anomalies in the variation of geometrical parameters are discussed.