Electron Paramagnetic Resonance Spectra of Two Zinc-Doped and Nickel-Doped Copper Chloride Pyridine-N-Oxide Complexes

Abstract

The electron paramagnetic resonance spectra of zinc-doped dichlorobispyridine-N-oxide copper(II) [(C5H5NO)2Cu(Zn)Cl2] and zinc-doped dichloromonoaquopyridine-N-oxide copper(II) [C5H5NOCu(Zn)Cl2·H2O] have been observed at liquid-nitrogen temperature. The data could be fit to the usual S=½ spin Hamiltonian. The g values obtained in this study for the copper—zinc pairs agree with the g values obtained for the copper—copper pairs in the pure material to within experimental uncertainty. Copper hyperfine splittings and chlorine superhyperfine splittings were also observed. The magnetic parameters for (C5H5NO)2Cu(Zn)Cl2 are gz=2.323, gx=2.056, gy=2.080, Az=129×10−4 cm−1, Ax=Ay<10×10−4 cm−1, A′=25×10−4 cm−1, and B′=7×10−4 cm−1, while for C5H5NOCu(Zn)Cl2·H2O gz=2.306, gx=2.056, gy=2.083, Az=139×10−4 cm−1, and Ax=Ay<10×10−4 cm−1 obtain. An analysis of the data with a simple LCAO MO approach suggests relatively strong metal—ligand bonds. The data obtained from the study of nickel-doped (C5H5NO)2CuCl2 could be fit to an S=½ spin Hamiltonian with the following magnetic parameters: gz=2.14, gx=2.54, gy=2.49, Az=35×10−4 cm−1, and Ax=Ay<7×10−4 cm−1. For nickel-doped C5H5NOCuCl2·H2O. gz=2.15, gx=2.61, gy=2.50, Az=40×10−4 cm−1, and Ax=Ay<7×10−4 cm−1 were observed. These appear to be the first reported magnetic parameters from dimers which contain exchange-coupled dissimilar transition-metal ions.