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 d_x²–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 d_z² orbital and the structure is thought to be trigonal prismatic.