VALENCE ISOMERISM BETWEEN STERICALLY PROTECTED METHYLENEPHOSPHINE P-SULFIDE AND 1,2-THIAPHOSPHIRANE

Reaction of phenylmethylene)(2,4,6-tri-t-butylphenyl)phosphine with el emental sulfur afforded yl-2-(2,4,6-tri-t-butylphenyl)-1,2-thiaphosphi rane 2-sulfide via methylenephosphine P-sulfide. Desulfurization react ion of the thiaphosphirane 2-sulfide with tris(dimethylamino)phosphine gave l-2-(2,4,6-tri-t-butylphenyl)-1,2-thiaphosphirane. Valence isome rization occurred between the methylenephosphine P-sulfide and the thi aphosphirane by heat or by photo-irradiation. The structures of the me thylenephosphine, the methylenephosphine P-sulfide, and the thiaphosph irane were analyzed by X-ray crystallography.