λ 3 ‐Pyrroloazaphosphinines with Relatively Stable P=C Double Bonds

The first pyrroloazaphosphinines with nitrogen at the junction, 7a and 7b , have been prepared by a special route involving the collapse of the phosphorus bridges of appropriate 7‐phosphanorbornenes. The parent molecule 7a has a strictly planar azaphosphinine ring with some electronic delocalization according to DFT computations. Its P=C double bond does not react with 2,3‐dimethylbutadiene unless P is coordinated to Mo(CO) 5 . Compound 7a reacts with Cu I to give a new type of polymeric complex [–Cu‐µ 2 ‐ 7a –] n in which P acts as a bridging ligand and the ligand planes are antiparallel. The benzo‐annulated and bromo‐substituted 7b displays a skewed ring according to DFT computations and its P=C double bond is reactive toward 2,3‐dimethylbutadiene without complexation.