Formation of 2H‐1,2‐Azaphosphole Tungsten Complexes by Trapping Reactions of Nitrilium Phosphane Ylide Complexes

The novel heterocyclic ligand system in 2 is formed by thermal decomposition of 2H-azaphosphirene tungsten complexes in the presence of dimethylacetylenedicar-boxylate (DMAD). The formation of the 2H-1,2-azaphosphole tungsten complexes 2 is interpreted as the reaction of the novel ylidic intermediates 1 with DMAD. The latter are very promising in view of the potential of knowm nitrile ylides in heterocycle syntheses. Ar = p-MeOC6H4, Ph, p-F3CC6H4.