ESR Study of paramagnetic Nickel Species Obtained by Reduction and Oxidation of Bis(1,3,5-triphenylformazanato)nickel(II)

Article abstract of DOI:10.1246/bcsj.68.3041

Diamagnetic bis(1,3,5-triphenylformazanato)nickel(II) was reduced or oxidized by chemical and electrochemical methods.The paramagnetic Ni(I) and Ni(III) complexes thus obtained were studied by means of ESR spectroscopy.Ni(I) complexes formed by alkali metal reductions showed remarkable changes in their g values, depending on the kinds of alkali metal used.The change of g-values, which related to the ionic radii of the alkali metal ions, was well interpreted by the axial coordination effect due to the alkali metal ions.The electrochemical formation of the Ni(I) complex showed a solvent-dependency; the nickel(II) ion was reduced in DMF solution, but not in acetonitrile.The g-components were 2.030 for g_// and 2.001_<*>.The relation between the two g-components gave a d_x2_-y2 ground state for the Ni(I) ion in the complex.Their anisotropy was very small.The Ni(II) ion oxidized by both chemical and electrochemical methods showed a d_z² ground state.The three g-components were 2.056, 2.039, and 2.000 in DMF, which are similar to those obtained from the other oxidation methods.