ELECTRONIC-STRUCTURES AND D-D SPECTRA OF VANADIUM(IV) AND VO2+ COMPLEXES - DISCRETE VARIATIONAL X-ALPHA CALCULATIONS

Discrete Variational X-alpha(DVX-alpha) calculations at three successive levels of approximation have been carried out for the vanadium(IV) complexes VCl4, [VCl5]-, [VOCl4]2-, [VO(NCS)4]2-, [VO(NCS)4(OH2)]2-, [VO(CN)5]3-, [VO{OC(NH2)2}2Cl2] and [VO(NMe3)2Cl2]. The electronic structures and the nature of the metal-ligand bonding are described and compared with previous theoretical results and a detailed comparison between observed and computed d-d electronic transition energies is presented. Near-quantitative agreement is obtained for the observed band maxima. The calculated assignments from the most accurate calculations are also in agreement with experiment. In contrast to previous theoretical treatments of [VOCl4]2-, which predict the reversed order of the first two absorptions, the DVX-alpha results yield the correct energy-level scheme. The ESR g and A values for this species are also well reproduced theoretically.