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.