E.S.R. study of copper dithio- and diselenophosphate

Abstract

Single-crystal E.S.R. studies of Cu(II)diethyldithiophosphate and Cu(II)-diethyldiselenophosphate, diluted in the corresponding Ni(II) complexes, are reported. Enrichment of the magnetic isotope of sulphur (33S) has been used in order to detect the sulphur hyperfine coupling. The g tensor, the metal hyperfine and quadrupole coupling tensors, the phosphorus and selenium hyperfine coupling tensors, and the sulphur hyperfine and quadrupole coupling tensors have been obtained. An almost isotropic coupling of the phosphorus atom has been found. The 33S hyperfine tensor largely differs from previously reported results. As in the case of other Se-containing complexes the principal axes of g and metal hyperfine coupling tensors of Cu(II)diethyldiselenophosphate do not coincide. Different kinds of low intensity ‘extra lines’ have been detected also. They have been interpreted as due to copper-copper interactions and to the dipolar coupling of neighbouring protons with the copper 3d electron. The results of extended Hückel Molecular Orbital calculations confirm the earlier findings that such a calculation is able to reproduce the experimental principal values of the tensors with good accuracy.