Theoretical study for the excited states of MoO4−nS2−n (n=0∼4) and MoSe2−4

Ground and excited states of six molybdenum complexes, MoO4−nS2−n (n=0∼4) and MoSe2−4, are systematically studied by symmetry adapted cluster (SAC) and SAC-CI theories. In the ground states, the ionicity of MoO2−4 is much larger than those of MoS2−4 and MoSe2−4. The calculated electronic spectra compare well with the observed spectra. New systematic assignments of the spectra are given. Most of the peaks are assigned to the electron-transfer type transitions from ligands to the metal. Many assignments are different from the previous ones. The observed relationships in the electronic spectra of these complexes are examined and corrected. The solvation effect is argued briefly.