2,4‐ N , N ′‐Bis(dialkylamido)‐2,4‐dithioxo‐1,3,2λ 5 ,4λ 5 ‐dithiadiphosphetanes

Dialkylamide derivatives of the monometadithioxaphosphoric acid stabilised by pyridine as a donor, i.e. [(C 5 H 5 N)PS 2 NR 2 ], readily react with AlCl 3 . The elimination of the donor and formation of the adduct C 5 H 5 N·AlCl 3 liberates the unstable σ 3 λ 5 ‐phosphoranes (PS 2 NR 2 ). The latter are stabilised by [2+2] “cycloaddition‐dimerization” leading to the title compounds [PS 2 NR 2 ] 2 in nearly quantitative yields. The synthesis and characterisation of two compounds possessing NR 2 substituents of very different basicities clearly demonstrate the generalisation of such a procedure as an easy way of accessing further derivatives in this class. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)