In the paper are described experimental and theoretical studies to investigate the electronic structures of [ML2]- (M(III) = Cu, L = pdt and pds, pyrazine-2,3-dithiolate and -diselonate; M(III) = Au, L = pds) with the aim of elucidating the nature of the bonding and to establish the innocent–noninnocent character of the ligand in these complexes. Calculations based on DFT methods have been performed to obtain geometry optimizations, harmonic frequencies, IR intensities and Raman scattering activities. The energetic sequence and nature of the redox-active molecular orbitals help to elucidate the observed electrochemical behaviour.