ELECTRONIC BAND ASSIGNMENTS OF HIGH-SPIN AND LOW-SPIN NI[R'(2),P(NR)(2)]

Absorption spectra in the VIS and MR region of the title compounds hav e been measured from KBr discs at temperatures down to 2 K. The parama gnetic complexes (R' = phenyl,R = (i)propyl or methyl,Si) have pseudo- tetrahedral coordination in the crystal and the similar diamagnetic co mplex Ni[(i)pr(2)P(Nmethyl)(2)](2) is almost planar. All chelates have a small bite angle (76-78 degrees). The electronic spectra are close to what is expected from distorted tetrahedral and quadratic Ni(II) co mplexes, respectively. Angular overlap model calculations, carried out using valence angles from the X-ray structure analysis, flow assignme nts of the measured peaks to electronic levels in D-2d or D-2 point sy mmetry. The model parameters obtained compare well with those of other NiN4 complex chromophores. (C) 1998. Published by Elsevier Science B. V. All rights reserved.