phosphorus heptasulfide

\\-|heptə+\ noun

Etymology: heptasulfide from hepta- + sulfide

: a yellow crystalline compound P₄S₇ made by heating a mixture of phosphorus and sulfur in a ratio of about 4 to 7 equivalents, regarded formerly as a trisulfide, and used chiefly in the synthesis of organic sulfur compounds (as thiophene); tetra-phosphorus heptasulfide