Reactivity of sp² Nitrogen and Phosphorus in a Stable Imidazolophosphinine

A polycyclic imidazolophosphinine has been synthesized by collapse of the bridge of an appropriate 7-phosphanorbornene. This stable compound has been characterized by X-ray crystal structure analysis. It is fully planar with a PC bond length of 1.733(4) Å. The lone pair at P is poorly reactive and corresponds to HOMO–3. The compound reacts with a protic acid and methyl iodide at the sp² nitrogen and with AuCl with the α-methoxy substituent, yielding a zwitterionicacylphosphidewhose complexation at P gives a bis-gold complex. Both the protonated product and the bis-gold complex have been characterized by X-ray crystal structure analysis.