Synthesis and properties of tris(dithioacetylacetonato)vanadium(III)

Abstract

The reaction of reduced 3,5-dimethyl-1,2-dithiolium iodide with vanadium trichloride leads to the preparation of tris(dithioacetylacetonato)vanadium(III), [V(SacSac)₃]. The electrochemical, spectroscopic, and magnetic properties of [V(SacSac)₃] have been measured and compared with those of the tris chelates of vanadium(III) with acetylacetonate, [V(acac)₃], and monothioacetylacetonate, [V(Sacac)₃]. All three complexes show one-electron reductions at a platinum electrode in acetone with the ease of reduction being in the order [V(SacSac)₃] > [V(Sacac)₃] > [V(acac)₃]. Proton n.m.r. spectra of the tris chelates show increasing delocalisation of the vanadium(III) unpaired electrons to the ligand with increasing sulphur in the ligand [V(SacSac)₃] > [V(Sacac)₃] > [V(acac)₃]. Magnetic susceptibility measurements in the range 4.2–300 K show a near Curie law behaviour for [V(SacSac)₃] and a near constant magnetic moment whilst for [V(acac)₃] the ³A ground state of the molecule is split by 8.0 cm^–1 leading to a decreasing moment with decreasing temperature.