Crystal Spectrum and Magnetism of Tetrakis-Thiourea-Nickel Chloride

Abstract

The polarized crystal spectrum of tetrakis-thoiurea-nickel chloride has been determined. The molecular symmetry is C4v; however, the results indicate that the absorptions arise from a field of lower symmetry, since in C4v symmetry the observed ``parallel'' absorptions would be orbitally forbidden. The intensity of the parallel absorptions are explained by a vibronic mechanism in which vibrations of the proper symmetry give allowed character to forbidden transitions under the site symmetry C4 Factor group interaction may also, at least in part, be responsible for the parallel intensity. The agreement between the assigned transitions and theory for nickel complexes is good assuming a reduction of the Slater—Condon parameters. The magnetic susceptibility of the complex follows a Curie—Weiss law χ=1.14/(T+6°) between 77° and 370°K.