The optimized geometries of ME2(PH3)(4) complexes (hi = Mo, W; E = S, Se, Te) have been calculated using nonlocal. quasi-relativistic density functional theory. In all cases the most stable structure was found to have C-4v symmetry. Comparison with crystallographic data (D-2d symmetry) for ME2(PMe3)(4) (M = Mo, E = S, Se, Te; M = W, E = Se, Te) reveals excellent agreement between theory and experiment, The ground-state electronic structures Of all six title complexes are found to resemble those obtained fr om previous local density functional (X alpha) calculations and hence to differ from db initio molecular orbital schemes that place the metal d(xy)-localized level several electronvolts below the chalcogen p(pi) lone pair highest occupied molecular orbital, Electronic transition energies an calculated using the transition state method, A consistent assignment of the electronic absorption spectra of WE2(PMe3)(4) and MoE2(Ph2PCH2CH2PPh2)(2) (E = S, Se, Te) is proposed. This assignment is different from either the experimental or ab initio conclusions, though on the key question of the origin of the lowest energy band the present density functional data reinforce previous ab initio conclusions that it is due to a chalcogen p(pi) --> pi* promotion and not the anticipated ligand field transition. Thus the density functional and nb initio approaches agree when used to calculate physically observable electronic promotion energies, although their groundstate molecular orbital orderings differ considerably.