Phosphine sulfide explained

A phosphine sulfide is an organophosphorus compound with the formula R₃PS. They are typically colorless, air-stable solids. A common example of a tertiary phosphine sulfide is triphenylphosphine sulfide. Phosphine sulfides are sometimes intermediates in the synthesis of tertiary phosphines. Phosphine sulfides are tetrahedral.

Synthesis

Phosphine sulfides are usually prepared by the oxidation of tertiary phosphines with elemental sulfur. The heat of formation of phosphine sulfides from tertiary phosphines and elemental sulfur scale with the basicity of the phosphine.^[1]

Enthalpy for sulfiding various tertiary phosphines

Tertiary phosphine	∆H (kcal/mol) for reaction with S8	Tertiary phosphine sulfide	CAS No
PCy3	-30.9 ± 1.9	S=PCy3	42201-98-9
PBu3	-28.9 ± 0.3	S=PBu3	3084-50-2	-	PMe3	-27.1 ± 0.4	S=PMe3	2404-55-9
PMe2Ph	-26.0 ±0.5	S=PMe2Ph	1707-00-2
PMePh2	-23.8 ±0.3	S=PMePh2	13639-74-2
PPh3	-21.5 ±0.3	S=PPh3	3878-45-3

References

1. 10.1021/ic9715862. Thermochemistry of Sulfur Atom Transfer. Enthalpies of Reaction of Phosphines with Sulfur, Selenium, and Tellurium, and of Desulfurization of Triphenylarsenic Sulfide, Triphenylantimony Sulfide, and Benzyl Trisulfide. 1998. Capps. Kenneth B.. Wixmerten. Bodo. Bauer. Andreas. Hoff. Carl D.. Inorganic Chemistry. 37. 12. 2861–2864.