A Phosphanyl Phosphagermene and Its Reactivity.

Reaction of a nucleophilic germylene Ge[CH(SiMe3)2]2 with the phosphanyl phosphaketene [{(H2C)(NDipp)}2P]PCO induces decarbonylation to form a phosphanyl phosphagermene [{(H2C)(NDipp)}2P]P=Ge[CH(SiMe3)2]2 (1; Dipp=2,6-diisopropyl-phenyl). Addition of CO2 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 (NH2nP), or metal complexes (e. g. Au(PPh3)Cl and ZnEt2). These latter reactions allow for the one-step synthesis of metal phosphide complexes. The synthesis of a phosphanyl phosphagermene described. Two principal reactivity modes were observed for this novel compound. On the one hand, it reacts as a geminal frustrated Lewis pair towards CO2 and nitriles. By contrast, with amines and metal complexes, the P=Ge double bond reacts in 1,2-addition reactions. image