Electronic structure of the ground state and calculated spectrum of low-lying excited states of Mo 3X 4(aq) 4+9 (X=O, S) cluster ions

Abstract

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 3X 4(aq) 4+ 9 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 1A 1→1 1A 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 3X 4(aq) 4+ 9 ions.