Tris(tert-butyl)phosphine sulfide, a phosphine sulfide with three bulky substituents.

The title compound, C12H27PS, has crystallographic C3 symmetry. The bond angles at phosphorus are tetrahedral [C--P--S 109.31 (12) degrees and C--P--C 109.63 (12) degrees ] and the P--C bond length is 1.899 (4) A. The shortest intermolecular contacts exist between methyl H atoms and the S atom (3.09, 3.12 and 3.28 A). A survey of various phosphine sulfides containing three equal ligands (Me3PS, Et3PS, Cy3PS, tBu3PS, etc.) shows the influence of substituents with different steric demand on the geometry at phosphorus and on the P--C bond length.