The synthesis and X-ray structural characterisation of an unusual seven-membered diaza-phospha-tetrathia heterocycle

Abstract

When the di-aryl or di-alkyl phenyl phosphonamide (RNH)₂P(O)Ph 1 is treated with sulfur(I) chloride (S₂Cl₂) in base, the product is an unexpected, unusual seven-membered diazatetrathiaphospha heterocycle 3; the X-ray structure and NMR spectra of these two unique heterocycles indicate that they exist in a pseudo-chair conformation with steric congestion limiting the freedom of rotation of the phenyl group; and represent the first known examples of this hetero-ring system.