3074
Inorg. Chem. 1990, 29, 3074-3080 Contribution from the Chemistry Department, University of Tasmania, Box 252C, Hobart, T A S 7001, Australia
Electronic Spectra and Bonding Parameters of Three Planar Complexes tans -CuCI2N2 Where N Is a Heterocyclic Amine Robbie G. McDonald and Michael A. Hitchman* Received November 9, 1989 The electronic spectra of single crystals of the planar, four-coordinate complexes CuC12L2,L = 1-phenyl-3,5-dimethylpyrazole (pdmp), 2,6-dimethylpyridine (2,6-lut), and 2,3-dimethylpyridine (2,3-lut) and the molecular g values of CuCI,(2,6-l~t)~ are reported. The temperature dependence of the band shape of the lowest energy transition of CuCl,(pdmp), suggests that a low-energy vibrational mode of aBsymmetry couples with the electronic transition, and this is also suggested by the spacing between the peaks comprising the fine structure observed in the low-temperature spectrum of CuCI2(2,6-lut),. This latter spacing differs from the energy of both as vibrational modes contributing to the band shape, which is in effect an interference pattern resulting from the addition of several progressions. The d-orbital energy sequence in the complexes is dzz < d,, < dyz < d,
