Electron spin resonance studies of axial ligation to cobalt (II)complexes. Part 2. Interaction with phosphorus ligands. Analysis of the cobalt bonding parameters and the phosphorus hyperfine coupling

Abstract

Electron spin resonance spectra have been recorded for frozen solutions of six different low-spin cobalt(II) complexes with a range of up to seven phosphines or phosphites as ligands co-ordinated in the axial position. A detailed analysis of the various assumptions used in the theory of the low-spin d⁷ ion (d_z²) is given together with, for the first time, a full analysis of the phosphorus hyperfine tensor. A tentative correlation is made relating the polarisation contribution to the ³¹P hyperfine tensor with the energy separation of the d_xz and d_yz orbitals.