The reactions of 4-chloro-1,3,5,7-tetramethyl-2,2,6,6-tetraoxa-2,6-dithia-1,3,5,7-tetraaza-4λ5-phosphaspiro[3.3]heptane (1) with trimethylsilyl compounds and sodium azide led to a series of spirocyclic N,N′-dimethylsulphamide-substituted phosphoranes (2—5). The nature of the pentaaza-spirophosphorane (4) was confirmed by an X-ray crystal structure determination (C2/c, a = 991.8(4), b = 1185.6(6), c = 1224.9(5) pm,β = 108.64(3)°, Z = 4, R = 0.041 for 1065 unique observed reflections); a crystallographic twofold axis passes through phosphorus and the nitrogen atom of the NMe2 group. The geometry at phosphorus is to a good approximation trigonal bipyramidal. The azido-spirophosphorane (5) undergoes Staudinger-type reactions with phosphorus(III) compounds (PPh3, dppm) to form the mixed-valence phosphorus compounds 6—8. The reaction of N,N′-dimethylsulphamide or N,N′-dimethyl-N,N′-bis(trimethylsilyl)-sulphamide with dichlorophosphines RPCl2 (R = Me, Ph) in a molar ratio 1:2 leads to the formation of the acyclic N,N′-dimethylsulphamide-bridged diphosphorus compounds 9 and 10, respectively. The spectroscopic properties (and, for 4, the X-ray crystal structure) of the products are compared with those of analogous urea-bridged phosphorus compounds.
