AN NMR STUDY OF THE REACTIONS OF CHLOROPHOSPHINES WITH AlC13. PHOSPHENIUM CATIONS FEATURING A S-P-N LINKAGE

Abstract

The N-P+−S phosphenium cations1, 2 and 3 have been prepared by treatment of the respective precursor chlorophosphines4, 5 and 6 with the stoichiometric quantity of AlCl3 in CH2C12 solution. The cations 3 are noteworthy that they are the first aliphatic phospheniurn cations featuring a P-S bond. That the values of 31P chemical shifts of phosphenium cations 3 are larger than those of aliphatic N-P+−N and N-P+−Cl cations characterize a relative inferior π-donor ability of RS group to R2N group and to Cl. The exo conformation of group at sulfur to dialkylamino group in 3 is proposed on the rare steric effect on 31P chemical shifts of substitutes at sulfur.