Vanadium(IV) porphyrins: synthesis and spectrochemical characterization of dihalogenovanadium(IV) porphyrins. Extended X-ray absorption fine structural study of dibromo(2,3,7,8,12,13,17,18-octaethylporphyrinato) vanadium(IV)

Abstract

The action of SOX₂ or (COX)₂ on oxovanadium(IV) porphyrin complexes [V^IVL(O)](L = porphyrinate) under mild conditions affords the corresponding dihalogenovanadium(IV) porphyrins [V^IVLX₂](X = Cl or Br). These very reactive complexes are remarkable precursors to low-valent vanadium porphyrins. Extended X-ray absorption fine structure spectroscopy at the Br K edge confirms the trans configuration and INDO/S calculations suggest that the absence of an e.s.r. signal is due to an orbitally degenerate ground state.