Electron spin resonance studies on Cu(N-Ethyl imidazole) 4(ClO 4) 2 and Cu(N-Propyl imidazole) 4(ClO 4) 2

Abstract

Electron spin resonance (ESR) studies have been made on the undiluted Cu(N-ethyl imidazole) 4(ClO 4) 2 and Cu(N-propyl imidazole) 4(ClO 4) 2 complexes in their polycrystalline forms at 295 and 77 K. The spectra are characterized by the resolution of cupric ion hyperfine splittings which is not usual. The g- and A-values are typical of square planar symmetry with monodentate ligands. Surprisingly the nitrogen hyperfine splitting could not be resolved either at 295 or at 77 K. The widths of various components in the spectra showed little variation from room temperature to the temperature of liquid nitrogen leading to the conclusion that the contribution to linewidth from spin-lattice relaxation is negligible and a sufficient amount of spin-spin interaction is still present to smear the nitrogen hyperfine splittings. These couid, however, be resolved by effecting a dilution of the copper complexes with 5 per cent of zinc perchlorate. The MO coefficients have been evaluated using ESR and optical absorption data.