Amino and mu-imino tetraphosphorus trisulfide compounds: NMR evidence for invertomers and bridged cages with an alpha- or beta-P4S3 skeleton

Abstract

Reaction of alpha- or beta-P4S3I2 with RNH(2) (R = H, Me, Bu(t) or Ph) led to new imino-bridged cage skeletons in alpha- or beta-P4S3(mu-NR), as well as both exo,exo- and endo,exo-isomers of either alpha- or beta-P4S3(NHR)(2) (except for R = H). Cage compounds P4S2(mu-NR) (R = Bu(t) or Ph) and alpha-P4S2(mu-NR)(2), with structures analogous to P4S3 and alpha-P4S4, respectively,have been identified as decomposition products. The new compounds were characterised in solution by full analysis of their P-31 NMR spectra. The configuration at bridging nitrogen in alpha-P4S3(mu-NR) was planar. An ab initio computation of molecular geometry of alpha-P4S3(mu-NH) is reported. Mechanistic arguments are advanced to rationalise the formation of isomers endo,exo-alpha-P4S3(NHR)(2), in contrast to corresponding reactions with secondary amines, which give only exo,exo-alpha-P4S3(NR(1)R(2))(2).