Electron spin resonance spectra of dibromo- and dichloro-complexes of vanadium(IV)

Abstract

Reactions of SOCl2 or SOBr2 with a range of 20 vanadyl complexes, [VO(L4)]·(L4= quadridentate or two bidentate ligands), yield solutions containing cis- or trans-dihalogen vanadium(IV) complexes [VX2(L4)]. They are characterised by their e.s.r. spectra and in most cases the unpaired electron is in a dx2–y2 orbital. In some cases both cis and trans isomers can be detected and characterised, because of significant differences in e.s.r. parameters. In the case of [VX2(L4)][X = Cl or Br, L4= tropolonate or perfluoropinacolate], the unpaired electron is in a dz2 orbital and the structure is thought to be trigonal prismatic.