Infrared and Raman spectra of some phosphorus sulphides

Abstract

The solid-state i.r. and Raman spectra of the four crystalline phosphorus sulphides, P₄S₃, P₄S₅, P₄S₇, are P₄S₁₀ are reported. The Raman spectra of the melts formed by all four compounds, and the vapours formed from P₄S₃, P₄S₇, and P₄S₁₀ are also recorded. Only P₄S₃ retains the same structure in all three phases. P₄S₅ disproportionates in the melt to P₄S₃ and P₄S₇ and further species which were not identified. Both P₄S₇ and P₄S₁₀ lose terminal sulphur in the gase phase. The Raman spectrum of sulphur obscures the Raman spectra of remaining phosphorus sulphur species. The melt spectra of both these compounds are identical with the solid state spectra, although the dark colour of the melts suggests that some terminal sulphur is already dissociating. The spectra of P₄S₃ and P₄S₁₀ are assigned in terms of the solid state symmetry.