Some remarks on the Raman spectrum of solid phosphorus pentachloride

Abstract

Abstract Powell c.s. deduced from an X‐ray study that solid PCl 5 has to be considered as [PCl 4 + ] [PCl 6 − ]. From the distances between P and Cl in PCl 4 + and in PCl 6 − given by the authors, force constants f PCl4 + and f PCl6 − have been calculated using Badger 's rule. From these f values and by a comparison with the results of a similar calculation for SiCl 4 it follows that the strongest lines of the Raman spectrum of PCl 5 , namely 358(15) and 451 (7), belong to v 1 (PCl 6 − ) and v 1 (PCl 4 + ) respectively. With these frequencies known, it is possible to make an estimate of the frequencies to be expected for the other Raman‐active vibrations of both ions. A probable assignment of Raman shifts to vibrations of PCl 4 + and PCl 6 − is given. Force constants have been calculated for both ions, using formulae based on Nath 's force field and on the orbital valence force field introduced by Heath and Linnett , Probable frequency values: PCl 4 + 173, 244, 451, 627; PCl 6 − 244, 285, 358.