N-Heterocyclic Carbene-Stabilized Germanium and Tin Analogues of Heavier Nitriles: Synthesis, Reactivity, and Catalytic Application.

The synthesis of stable heavier analogues of nitriles as monomeric tetrylene-phosphinidenes MesTerEP(IDipp) (E = Ge, Sn; MesTer = 2,6-Mes2C6H3, IDipp = C([N-(2,6-iPr2C6H4)CH]2) was achieved by taking advantage of NHC (N-heterocyclic carbene, here IDipp) coordination to the low-valent phosphorus center. Multiple bonding character of the E-P bonds was examined experimentally and computationally. Both germanium and tin compounds undergo [2+2] cycloaddition with diphenylketene, whereas reaction of the tin derivative with tris(pentafluorophenyl)borane provided unique "push-pull" phosphastannene (MesTer)(Ar)Sn = P(IDipp) (Ar = C6F4[B(F)(C6F5)2]). Going further, we demonstrated the potential of tetrylene-phosphinidene complexes in catalytic hydroboration of carbonyl compounds.