An infrared and Raman spectroscopic study of some Group 1B halide complexes containing an M₄X₄ core

Abstract

The infrared and Raman spectra of [Et₃PcuI]₄ and [Et₃AsCuI]₄ have been measured, and bands have been assigned to vibrations of the ligand and of the T_d Cu₄I₄ core. The far-infrared spectra show two strong T₂ v(CuI) bands at about 90 and 140 cm^-1, the higher frequency member of which has a Raman counterpart which shows possible longitudinal-transverse splitting. The Raman spectra also show an intense band at about 50 cm^-1. Similar features have been observed in the low-frequency vibrational spectra of [Et₂S]₃ [CuI]₄, [C₅H₅NcuI]₄, [C₅H₁₁NAgI]₄, [Et₃PAgBr]₄ and [Et₃PagCl]₄, although the last two compounds gave only a single broad band in the v(MX) region.