Single crystal electron spin resonance of bis(tetraphenylphosphonium) bis(quinoxaline-2,3-dithiolato)oxovanadate(IV) as a pure compound and diluted in the isomorphous molybdenum(IV) compound

Abstract

Abstract Single crystal e.s.r. spectra at room temperature and Q-band frequencies on [PPh4]2 [(Mo/V)O(qdt=2] (qdt = quinoxaline-2,3-dithiolate) containing ca 3% vanadium gave the spin-Hamiltonian parameters g1 = 1.977 ± 0.001, g2 = 1.985 ± 0.001, g3 = 1.987 ± 0.001, A1 = (−38.5 ± 0.3) × 10−4, A2 = (−45.1 ± 0.3) × 10−4, A3 = (−133.2 ± 0.3) × 10−4 cm−1, and Q′ = −(0.15±0.05) × 10−4 cm−1. The g and A tensor axes are not coincident. The principal values of the g and A tensors have been analysed via an angular overlap treatment. Proton spin-flip transitions were observed in the spectra at X-band frequencies. Single crystal e.s.r. spectra of undiluted [PPh4]2 [VO(qdt)2] at both X- and Q-band frequencies are interpreted in terms of a two-dimensional weak exchange model with J0 = −48 ± 2G (ferromagnetic).