Raman spectrum and structure of solid P2Cl4

The Raman spectrum of liquid and solid polycrystalline P₂Cl₄ has been recorded from 30 to 700 cm^–1. The far infrared spectrum of the solid has also been reinvestigated. From these data, it is necessary to reassign the P-P stretch (a_g), the PC1₂ rock (a_u) and the PCl wag (b_u). Three lattice modes were observed in the Raman spectrum whereas none was found in the infrared spectrum. No correlation field splitting was observed for any of the intramolecular fundamentals. Although the vibrational data for the crystalline state is best interpreted in terms of atrans (C_2h, 2/_m) conformation, there is some evidence that another form may be present, in small amounts, in the fluid states. Furthermore, no evidence for the torsional mode, previously assigned at 91 cm^–1, has been found and calculations have been made which indicate that such a frequency would lead to an un-acceptably high barrier to internal rotation of the asymmetric PC1₂ rotor.Taken from the thesis of J. E. Saunders which has been submitted in partial fulfillment of the Ph.D. degree.