An electron spin resonance spectral study of bis(dimethylglyoximato)-cobalt(II) and some phosphine and phosphite adducts

Abstract

E.s.r. spectra, at both X- and Q-band frequencies, were measured for frozen solutions of [Co(Hdmg)₂](H₂dmg = dimethylglyoxime) and its adducts with a range of fourteen phosphines and phosphites. All spectra were indicative of a ²A₁[a(d_z²)+b(d_x²–y²)] ground state, and from analysis of the cobalt and phosphorus hyperfine tensors and the g tensor, wavefunction and bonding parameters were calculated. The Q-band results unambiguously reveal rhombic symmetry for all adducts, with the formation of 1 : 1 adducts for all the bases with identical substituents and 1 : 2 adducts for the bases with mixed substituents. Attempts to assign the ground state to the [Co(Hdmg)₂] complex in a diamagnetic matrix of [Ni(Hdmg)₂] were also made.