Analysis of the charge-transfer spectra of some first-transition-series tetrahalide complexes

Abstract

The charge-transfer spectra of 10 tetrahalide complexes of the first transition series have been measured at 77°K in the form of evaporated films or rigid glassy solutions. To assign the spectra in detail, theoretical expressions are developed, using vector coupling methods, to describe the first-order effect of spin-orbit coupling at both the metal and the ligand nucleus on the terms arising from each of the excited charge-transfer configurations. Theoretical expressions for the intensities of charge-transfer transitions are also derived by the same method and tested by substituting approximate LCAO eigenvectors. The assignments established by these arguments lead to the conclusion that the highest occupied orbitals of mainly ligand character occur throughout in the order le<3h<h with a total energy spread of about 15 kK.