Vibrational Spectra and Structure of Phosphonium and Deutero‐Phosphonium Iodides

Abstract

The infrared spectra of sublimed films of PH₄I and PD₄I were obtained at —78° and —190°C in the region 4000–400 cm^—1. Powder and Nujol mull spectra were obtained at room temperature. The low temperature spectra could be interpreted on the basis of a V_d site symmetry for the PH₄⁺ ion as occurs in the phase III NH₄Br and NH₄I structures. The room temperature spectra are also compatible with the room temperature x‐ray structure, D_4h⁷. No evidence for any sort of transition was found. The hydrogen bond energy in PH₄I is less than 0.5 kcal/mole.