Vanadium(II) chemistry. Part III. Spectroscopic and magnetic properties of the double chlorides

Abstract

The chloride complexes AVCl₃(H₂O)₆(A = NH₄ or Rb), NH₄VCl₃(H₂O)₃, Cs₂VCl₄(H₂O)₂, and BVCl₃(B = Me₄N or Rb) have been prepared and investigated by magnetic and electronic spectral measurements down to liquid–nitrogen temperatures, and by i.r. spectra. The ‘hexahydrates’ have structures of the type A[V(H₂O)₆]Cl₃, containing octahedral hexa-aquovanadium(II) ions. Magnetically-dilute structures of the type NH₄[VCl₃(H₂O)₃] and Cs₂[VCl₄(H₂O)₂] are indicated by the lack of magnetic interaction in these compounds and by the moderate deviations from O_h symmetry shown in their electronic spectra. The anhydrous compounds, BVCl₃, are markedly antiferromagnetic. Their reflectance spectra contain more bands than expected from O_h symmetry, but this is probably due to the presence of anomalously-intense, spin-forbidden bands rather than to deviations from O_h symmetry.