Matrix isolation and mass spectrometric studies on the vaporisation of chromium(III) chloride. The characterisation of molecular CrCl4 and CrCl3

Abstract

Mass spectrometric and matrix isolation i.r. studies on the vaporisation of solid chromium(III) chloride over the temperature range 550–800 °C reveal three different molecular chromium halides. At the lowest temperatures, CrCl₄ is identified as the most volatile species and its tetrahedral structure confirmed by isotope patterns. At ca. 600°C, a new molecular species, CrCl₃, appears and its structure is similarly shown to be planar (D_3h). Further heating to ca. 780°C results in the formation of molecular CrCl₂. The results are discussed in the light of previous studies on transition metal halid systems.