ELECTRONIC-STRUCTURE OF THE GROUND-STATE AND CALCULATED SPECTRUM OF LOW-LYING EXCITED-STATES OF MO(3)X(4)(AQ)(9)(4+) (X=O, S) CLUSTER IONS

The electronic structure of the ground state and electronic transition energies of low-lying states have been calculated using the INDO/S-CI method for Mo(3)X(4)(aq)(9)(4+) cluster ions (X=O, S). It has been shown that the calculated values are in accordance with those observed experimentally, allowing us to assign the bands. The lowest absorption band results from the dipole-forbidden but spin-allowed electron transition 1 (1)A(1)--> 1 (1)A(2) state, and it has been assigned as arising from a metal-based bonding orbital to a metal-based antibonding orbital. The singlet-triplet energy splitting of the two lowest excited states, A(2), E, have been estimated to be about 2400 and 3350 cm(-1), respectively, and a red-shift of the absorption bands has been explained by comparing X= S with X=O for the Mo(3)X(4)(aq)(9)(4+) ions.