Paramagnetic Resonance and Optical Study of Cupric Amine Complexes

Abstract

The EPR spectra of complexes of CuCl2, CuBr2, CuF2, and Cu (NO3)2 with primary, secondary, and tertiary amines were obtained at 77°K and room temperature. In a nonpolar solvent, 1:1 ether/ethanol, the g value and the hyperfine splitting constant were found to depend on both the amine ligands and the anion, whereas in water, the g value and hyperfine constant depend on the amine ligands but do not depend on the anions. Optical spectra of these systems taken at room temperature also show the same amine ligand and anion dependence. The anion dependence of the spin-Hamiltonian parameters can be explained by admitting admixtures of excited states with 4s character into the singly occupied orbital through vibronic coupling. This vibronic coupling assumption is also consistent with the effect of the amine ligands on the contact hyperfine interaction.