Strong evidence for stereoselective 1,3-additions of transient nitrilium phosphane-ylide complexes: synthesis of the first 1-aza-3-phosphabuta-1,3-diene complexes

Synthesis of the first 1-aza-3-phosphabuta-1,3-diene complexes was achieved by heating solutions of 2H-azaphosphirene tungsten complexes, 1-piperidino nitrile and [bis(trimethylsilyl)methylene]chlorophosphane; X-ray structure analysis of one new complex revealed a cisoid position of the chlorine atom and the phosphaalkene unit at the C,N,P-core of the trapped nitrilium phos phane-ylide complex and a distorted heterobutadiene pi -system.