Preparation, crystal structure, and spectroscopic properties of vanadium(III) tris-(OO-diethyl phosphorodithioate), V[PS2(OEt)2]3

Abstract

Reaction of OO′-diethyl hydrogen phosphorodithioate HPS₂(OEt)₂ with vanadyl sulphate pentahydrate causes reduction to the vanadium(III) compound, V[PS₂(OEt)₂]₃, also obtainable from vanadium trichloride. It crystallises from ethanol in space group C2/c, with cell dimensions: a= 8·644 ± 0·005; b= 18·487 ± 0·008; c= 17·688 ± 0·007 Å, β= 93 ± 0·10, and Z= 4. The structure has been solved using conventional Patterson and Fourier techniques to a final R of 0·077 for 1124 observed independent intensities. The vanadium atom is co-ordinated to the three ligands in a trigonally distorted octahedral environment. While solution electronic spectra show only the bands expected for O_h symmetry, polarised crystal spectra resolve the trigonal distortions and allow an assignment in D₃ symmetry. On dilution in the isomorphous indium compound, vibrational structure is seen at room temperature. The vibrational interval of 800 cm^–1(±50) is difficult to explain in terms of the vibrations of the chromophore. The compound is susceptible to oxidation, dissolution in both non-co-ordinating and basic solvents giving rise to vanadyl species, the e.s.r. spectra of which, in both kinds of solvents, indicate the presence of appreciable interaction between the VO²⁺ and the phosphorus atom in the ring, and the probable absence of polymeric species.