Magnetic Susceptibility, Anisotropy, and ESR Studies on Some Copper Dialkyldithiocarbamates

Abstract

The method of measuring the magnetic anisotropy of single crystals is briefly described, and a suitable calibrant for this type of work is suggested. The magnetic anisotropy, average susceptibility, and g values have been measured on several Cu(II) N, N dialkyldithiocarbamates where the Cu ion has been shown to be in a square pyramidal environment. The magnetic anisotropy is very low, while the principal molecular susceptibilities (K‖ and K⊥) obey a Curie–Weiss Law with θ ≃ 10°K between 80°–300°K. The single crystal g values and the average moments are very close to the spin-only values. The linewidth of the diethyl and di-n-butyl derivatives shows an unusual narrowing which is partly attributed to an exchange interaction through the bridging sulfur atoms within the Cu dimer unit. The expressions for K‖ and K⊥ have been deduced, and the experimental data has been fitted. The ligand-field parameters are greatly reduced from their free-ion values, the spin–orbit coupling constant, the orbital reduction parameter, and the exchange integral being slightly anisotropic. The spin–Hamiltonian parameters of the Cu diethyldithiocarbamate diluted in the analogous Ni and Zn derivatives have been obtained and the stereochemical implications discussed. They have also been used in the discussion of the σ and π bonding in these compounds.