Phosphorus Subselenide, P₄Se

Phosphorus Subselenide, P₄Se, may be prepared by heating one atomic proportion of selenium with at least four atomic proportions of phosphorus in the presence of an inert gas. The product obtained may contain a little red phosphorus which can be got rid of by filtration. Phosphorus subselenide is a yellow oily liquid which crystallises at -12° C. and is soluble in carbon disulphide. It is spontaneously inflammable in air and is decomposed by alkalis on heating, with liberation of phosphine.