A Phosphanyl‐Phosphagallene that Functions as a Frustrated Lewis Pair

Phosphagallenes ( 1 a / 1 b ) featuring double bonds between phosphorus and gallium were synthesized by reaction of (phosphanyl)phosphaketenes with the gallium carbenoid Ga(Nacnac) (Nacnac=HC[C(Me)N(2,6‐ i ‐Pr 2 C 6 H 3 )] 2 ). The stability of these species is dependent on the saturation of the phosphanyl moiety. 1 a , which bears an unsaturated phosphanyl ring, rearranges in solution to yield a spirocyclic compound ( 2 ) which contains a P=P bond. The saturated variant 1 b is stable even at elevated temperatures. 1 b behaves as a frustrated Lewis pair capable of activation of H 2 and forms a 1:1 adduct with CO 2 .