A Phosphanyl Phosphagermene and its Reactivity.

Reaction of a nucleophilic germylene Ge[CH(SiMe 3 ) 2 ] 2 with the phosphanyl phosphaketene [{(H 2 C)(NDipp)} 2 P]PCO induces decarbonylation to form a phosphanyl phosphagermene [{(H 2 C)(NDipp)} 2 P]P=Ge[CH(SiMe 3 ) 2 ] 2 (1; Dipp=2,6-diisopropyl-phenyl). Addition of CO 2 or MeCN to 1 results in [3+2]-cycloaddition reactions to afford five-membered heterocycles. This mode of reactivity is reminiscent of that observed for frustrated Lewis pairs, with the pendant phosphanyl group acting as a base and the germanium center as a Lewis acid. Contrastingly, 1,2-addition across the P=Ge bond was observed when using ammonia, small primary amines (NH 2 n P), or metal complexes (e. g. Au(PPh 3 )Cl and ZnEt 2 ). These latter reactions allow for the one-step synthesis of metal phosphide complexes.