Aminophosphaethyne (PCNH2) and its isomers

The potential energy hypersurface of the conversion of aminophosphaethyne (1) to 1‐aza‐3‐phosphaallene (2) has been studied with the MNDO method. The interconversion includes five intermediate species. The structure and energy of 1 and its isomers produced by a hydrogen shift have been calculated also with ab initio molecular orbital theory by a split valence basis set including a polarization function at the P atom. The results reveal that all the isomers are equilibrium structures. The ab initio calculation predicts the carbenaazaphosphirane 3 to be the intermediate lowest in energy. It is suggested that a carbene (3), phosphinidene (4) or azaphosphirene (5) are responsible for the 1‐aza‐2,4‐diphosphole formation.