Far-infrared reflectance spectra of A2CuCl4,2H2O (A = NH4, K, or Rb) single crystals: copper–chlorine vibrations of the distorted octahedral aquochlorocuprate(II) anion

Abstract

The polarised far-i.r. reflectance spectra of A₂CuCl₄,2H₂O (A = NH₄, K, or Rb) single crystals have been recorded in the region 40–400 cm^–1. These have permitted the observation and assignment of most of the predicted bands, including one at ca. 180 cm^–1 due predominantly to the ‘long’ Cu–Cl stretching mode. Anomalies in the reflectance spectra of (111) faces of these crystals are discussed.