THE SINGLE-CRYSTAL ELECTRON-SPIN-RESONANCE SPECTRA OF BIS CHLORO BIS(N,N'-SUBSTITUTED UREA)OXOVANADIUM(IV) COMPOUNDS DILUTED IN THE CORRESPONDING TRIS-CHLORO BIS(N,N'-SUBSTITUTED)UREA INDIUM(III) COMPOUNDS

Single crystal ESR spectra of VOCI2L2 (where L = N,N,N', N'-tetramethyl urea (tmu), N,N'-dimethylethyleneurea, N,N'-dimethylpropyleneurea, tris(dimethylamino)phosphincoxide) diluted in the corresponding In-phi-cl3L2, at Q-band frequencies are reported. The ESR data are consitent with C2 point symmetry for VOCI2(tum)2 whilst the other compounds approximate very closely to this point symmetry. A rotation of the g and A tensor axes in the plane perpendicular to the terminal VO vector fall in the range 8-15-degrees for the four compounds studied. The spin Hamiltonian parameters for VOCI2(tum)2, in conjunction with the published polarized electronic absorption spectra, have been analysed via angular overlap calculations. For VOCI2(tum)2 unusual ligand hyperine splittings were observed. These were analysed by spectrum simulation in terms of two equivalent chlorine atoms where the chlorine hyperfine and nuclear quadrupole tensors are of comparable magnitude.