Oxysulphides of Phosphorus

A number of phosphorus oxysulphides have been well characterised and there is evidence for the existence of many more. 

Most members of the series P40io ,S (n = 0-10) have now been characterised. The existence of P4O6S4 and P4S6O4 has been known for some time and these molecules are isostructural with the series end members P4O10 and P4S10 [31-34], The first of these, P4O6S4, mp = 110°C, can be made by heating the trioxide with sulphur (4.74) or a sulphide-oxide mixture (4.119). 

The structure of this oxysulphide in the vapour and solid states is similar to that of P4O10, except that the terminal O atoms in the latter are replaced by S. Controlled hydrolysis of this compound yields initially the species. 

The remaining members of the series P40io, S have been obtained by fractional crystallisation from melts of the appropriate ratios of P4O10/P4S10. 

Photolysis of the P4S3/O3 complex formed in solid argon yields two isomers of P4S3O which are believed to have structures (4.123). Photolysis of P4S10/O3 mixtures under similar conditions produces some P4S9O which may correspond to the P4S10 structure with a single terminal S atom replaced by O [35-39]. Oxyselenides are also known (Chapter 9.11). 

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