Imines and derivatives. Part 20. N-phosphinoyloxaziridines: synthesis and structural characterisation by nuclear magnetic resonance spectroscopy and a crystal structure of 3-(4-chlorophenyl)-2-(diphenylphosphinoyl)oxaziridine

Abstract

The preparation of a new class of oxaziridines containing an N-phosphinoyl group is described. The compounds were otained by peroxyacid oxidation of N-phosphinoyl imines under basic or neutral conditions, and characterised by n.m.r. spectroscopy. Relevant 2JPC, 3JPH, and 1JCH coupling constants are reported. An X-ray structure analysis of the title compound establishes that the 2-diphenylphosphinoyl group is trans to the 3-aryl ring. The P–N bond length (1.76Å) is abnormally high for an aminophosphorus (V) compound and the nitrogen atom is pyramidal (Σ= 280°). This geometry is interpreted in terms of an unusually low degree of π-bonding between nitrogen and phosphorus due to the high s-character of the nitrogen lone pair.