Single-crystal electron spin resonance spectrum of dichloro-oxobis(triphenylphosphine oxide)vanadium(IV), a monomeric oxovanadium(IV) compound

Abstract

The single-crystal e.s.r. spectra of the title compound [VOCl₂(OPPh₃)₂], at 298 K and Q-band frequencies, in the crystallographic ab, bc*, and ac* planes are reported. These spectra were interpreted by simulation, which involved diagonalisation of the matrix resulting from the axial spin Hamiltonian (i) and the assumption of a Gaussian line-shape function with linewidths composed of a Van Vleck truncated dipolar contribution plus an addition linewidth. ℋ=β[g_∥H_zŜ_z+g_⊥(H_xŜ_x+H_yŜ_y)]+A_∥Ŝ_zÎ_z+A_⊥(Ŝ_xÎ_x+Ŝ_yÎ_y)(i) The spin-Hamiltonian parameters which gave good simulations were g_∥= 1.930 ± 0.002, g_⊥= 1.974 ± 0.002, A_∥=–(175.0 ± 2.8)× 10^–4 cm^–1 and A_⊥=–(66.1 ± 2.8)× 10^–4 cm^–1. These parameters were used, in conjunction with the published electronic absorption spectrum, to derive the molecular-orbital coefficients in an empirical molecular-orbital scheme for the molecule.