Vibrational and chlorine-35 nuclear quadrupole resonance spectra of some complexes of ICl4– and AuCl4–. Part 1. Two crystal modifications of trichlorosulphonium tetrachloroiodate, [SCl3][ICl4]

Abstract

Two crystal modifications of [SCl₃][ICl₄] have been characterised by elemental analysis, and Raman and n.q.r. spectroscopy. Analysis of the spectra indicates that both form I (stable) and form II (metastable) involve dis-tortion from square planarity (D_4h) of the ICl₄^– ions, a conclusion independently confirmed recently by an X-ray diffraction study of form I. On the basis of the Raman and n.q.r. spectra, the distortion in form II is similar to that observed in Na[ICl₄]·2H₂O. The origins of these distortions are discussed in terms of secondary bonding interactions in the solid state.