The single-crystal electron spin resonance spectrum of oxobis(2-methylquinolin-8-olato)vanadium(IV) as a pure compound and diluted in chlorobis(2-methylquinolin-8-olato)gallium(III)

Abstract

Single-crystal e.s.r. spectra of the compound [VO(mquin)₂], diluted in [GaCl(mquin)₂](mquin = 2-methylquinolin-8-olate), at room temperature and Q-band frequencies are consistent with the retention of C₂ molecular symmetry in the diluted system. The spin-Hamiltonian parameters g_zz= 1.949 ± 0.002, g_xx= 1.988 ± 0.002, g_yy= 1.983 ± 0.002, A_zz=–(157.3 ± 0.5)× 10^–4, A_xx=–(50.8 ± 0.5)× 10^–4, A_yy=–(55.0 ± 0.5)× 10^–4, and A_xy=A_yx=(3.0 ± 0.5)× 10^–4 cm^–1 in conjunction with the electronic absorption spectra have been analysed via both angular overlap calculations and by constrained minimisation of a composite function of the expressions for the spin-Hamiltonian parameters to estimate the d-orbital mixing in the complex. A comparison of the results of these two approaches is made. The angular variation of the peak–peak linewidth of the first-derivative spectra in crystals of undiluted [VO(mquin)₂] indicates an isotropic exchange between adjacent vanadium centres, in a three-dimensional arrangement, with |J|= 380 ± 20 G.