Reactions of tetraphosphorus trisulphide with organic disulphides under ultraviolet irradiation, and with sulphuryl chloride
Abstract
P4S3 under glass-filtered u.v. irradiation is rapidly cleaved by alkyl and aryl disulphides to give tetrathiophosphate esters, SP(SR)3, and trithiophosphite esters, P(SR)3(R = Me or Ph), in quantitative yield, as measured in the product mixture by 31P and 1H n.m.r. spectroscopy. No sulphurisation of P4S3 was found. In a competition reaction, MeSSMe and PhSSPh reacted to a similar extent with P4S3 to give all eight possible products SxP (SPh)n(SMe)3 –n(x= 0 or 1, n= 0–3) in relative quantities within each oxidation state approximating to a statistical distribution of ligands, but there was more MeS substitution of the phosphorus(V) products and more PhS substitution of the phosphorus(III) products. Reaction of MeSSPh with P4S3 gave similar results. Redistribution of ligands took place when a mixture of P(SMe)3 and P(SPh)3 was photolysed, and photolysis of a mixture of P(SMe)3 and MeSSPh caused the PhS group to be distributed between the trithiophosphite and disulphide sites. P(SMe)3 and P(SPh)3 were not sulphurised by MeSSMe and PhSSPh respectively, but P(SMe)3 was sulphurised to SP(SMe)3 to a small extent by MeSSPh. P4S3 is similarly cleaved by sulphuryl chloride, but under thermal conditions, to give SPCl3 and PCl3, with no evidence for intermediates.