IONIZATION OF PCL6- IN THE SOLID-STATE UNDER PRESSURE .2. RAMAN-SPECTRA OF PHOSPHORUS PENTACHLORIDE-III

The Raman spectrum of phosphorus pentachloride III, which is obtained by squeezing the ordinary phase II to a few kilobars (see preceding paper), has been recorded at ∼100 Κ and zero pressure. The ratio of the integrated intensities of the PCl4+ and PCl6 ions is much smaller in phase III than in phase II, showing that the ionization PCl 6-→PCl4+ + 2Cl- occurs in the solid at the transition. It appears to be the first example of a pressure-induced ionizing dissociation in a solid. Phase III is similar to, but apparently not identical with, a phase obtained by subliming phase II and condensing the vapor at, apparently, room temperature. The implications of this transformation for the synthesis of inorganic compounds is briefly discussed. © 1979 American Institute of Physics.