Use of electron spin resonance spectroscopy to study the interaction between cobalt schiff base complexes and phosphines or phosphites in solution

Abstract

E.s.r. measurements on frozen solutions of a wide range of phosphine or phosphite adducts of Co(II) Schiff base complexes have give well resolved spectra exhibiting cobalt and phosphorus hyperfined structure. From analysis of the 31P hyperfine tensor, the RPR bond can be deduced in the phosphine or phosphite, PR 3. The calculated spin densities in the cobalt and phosphorus orbitals allows a determination of the relative contributions of σ-and π-bonding in the CoP bond and their influence upon the phosphine or phosphite bond angle. From a full analysis of the 31P polarisation tensor, a correlation is found between its magnitude and the magnitude of the splitting of the cobalt d xz and d yz orbitals. In analyzing the 59Co spin Hamiltonia parameter, used is made of the theory of McGarvey and the approximation of Attanasio.