Ab initio calculations of the properties of simple alkali and alkaline earth organometallics

A systematic study is reported on the properties of a series of simple organometallic compounds of the type M-R, where M is either an alkali (Li, Na, K) or alkaline earth (Be, Mg, Ca) metal atom and R is one of the organic substituents CH, CH2 or CH3. Electronic structures, equilibrium geometries and dipole moments have been calculated al the SCF and MP2 levels of theory using quite large basis sets. Rather accurate M-C bond dissociation energies have also been obtained by exploiting the highly ionic character of most of the molecules. This involved dissociating to the ionic limit and then employing experimental data to correct to the neutral dissociation limit. The good agreement between SCF and MP2 values obtained by this method leads us to conclude that the calculated dissociation energies are at worst within 0.2 eV of the true values, and in most cases are probably accurate to within 0.1 eV.