CRYSTAL SPECTRUM OF RARE-EARTH HEXAHALIDE COMPLEXES, MCL63- - ABSORPTION SPECTRUM OF [(C6H5)3PH]3NDCL6

The site symmetry of Nd3+ in single-crystal [(C 6H5)3PH]3NdCl6 is predicted by considerations of molar absorptivity, vibronic spectra, and stoichiometry. A calculation of the crystalline-field splitting of 4f 3 J levels appears to predict a sixfold octahedral site symmetry with a slight distortion along one of the axes, in agreement with the observed spectrum. In addition, the observed spectrum indicates the occurrence of two slightly inequivalent sites of Nd3+. The effects of the small distortion away from octahedral symmetry and the spectrum due to two inequivalent sites are sufficiently small (5% of the average J-manifold crystalline-field splitting), however, as not to affect a first-order crystal-field analysis of the dominant portion of the spectrum. The crystal-field parameters based on octahedral symmetry, B4 = 282 cm-1 and B6 = 74.7 cm-1, predict a splitting of crystal quantum states in good agreement with experiment.