Electron spin resonance study of some copper complexes

Abstract

ESR investigations on single crystals of Cu, Ni(dtp)? have led to details of the binding of the copper ion in the molecule. In addition to the ??bond, the ??bonds also have strong covalent character. Direct evidence of this is seen in the observation of h.f. structure from the ³³P phosphorus ligands. The presence of two different A_P coupling constants shows that the complex is distorted. It has been demonstrated how the local symmetry around Cu dominates the Cu spin Hamiltonian parameters, although ligand h.f. parameters suggest considerable distortion. The use of ligand h.f. parameters to study the details of hybridization of the ligand orbitals, which are very sensitive to distortions, has been clearly shown. It is shown how it is possible to understand the nature of the g and h.f. tensors in Cu complexes of very low symmetry. However, accurate values of a large number of parameters, precise structural information and more reliable atomic parameters (for Se, e.g.) would be necessary before accurate quantitative calculations of g?shifts could be arrived at for these complexes.