Sulphur Iminophosphoranes

In addition to the electrophilic alkylation, the phosphinyl-benzophospho-lide 25 reacted also with sulphur, BH3-thf, and trimethylsilyl azide under selective conversion of the Ph2P-moiety to give the corresponding thioxophos-phorane, borane-adduct, and iminophosphorane, respectively [33, 37], and quaternisation with chloro-acetonitrile followed by deprotonation gave access to a zwitterionic phosphonio-benzophosphohde with an exocyclic ylide-substituent [37]. 

C. The compound formed from PFs and the sulphur di-imide (62), previously thought to be a quinquecovalent phosphorane, has been shown to be the iminophosphorane (63). 

Silylated iminophosphoranes of the type (42) have been shown to react with SO3 insertion of SO3 into the silazane bond occurs, to give (43). In the case of the bifunctional methylene(bisiminophosphorane) (44), silylated sulphuric acid splits off, and the phosphaza-sulphone (45) is formed. 

A variety of sulphur and seleno iminophosphoranes have been prepared, for example (Figure 7.17). 

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