Günter Kreisel

A single-crystal esr study on a tetrahedrally coordinated vanadium(IV) compound: tetramesitylvanadium(IV)

Abstract A single-crystal ESR study on tetramesitylvanadium(IV) diluted in the corresponding Ti IV compound is reported. The complete g tensor and metal hyperfine coupling tensor was obtained and the directions of their principal axes within the molecular frame were determined. In the x,y plane the pricipal axes of the g and the 51 V hyperfine tensor are not coincident, indicating a distortion of the elongated VC 4 tetrahedron by low-symmetry ligand-field components. Interpretation of the tensor parameters by means of a D 2d ligandfield model gives values for the effective spin-orbit coupling constant, the hyperfine parameters P and K and for the dd ligand-field transitions. Analysis of the anisotropy of the metal hyperfine interaction shows that the unpaired electron resides primarily on the vanadium atom in the B 1 strate, mainly composed of 3 d x 2 - y 2 character. Hyperfine interactions with ligand protons are small and only poorly resolved in the spectra recorded at T  4.2 K.