Ligand controlled reactivity: a trans-bent and twisted geometry enables dihydrogen activation and enhanced catalytic activity for NHC-stabilised dialumenes.

The synthesis of stable heavier analogues of nitriles as monomeric tetrylene−phosphinidenes Mes TerEP(IDipp) (E = Ge, Sn; Mes Ter = 2,6-Mes 2 C 6 H 3 , IDipp = C([N-(2,6-iPr 2 C 6 H 4 )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 ( Mes Ter)(Ar)Sn = P(IDipp) (Ar = C 6 F 4 [B(F)(C 6 F 5 ) 2 ]). Going further, we demonstrated the potential of tetrylene−phosphinidene complexes in catalytic hydroboration of carbonyl compounds.

Since the first heavy alkene analogues of germanium and tin were isolated in 1976, followed by West’s disilene in 1981, the chemistry of stable group 14 dimetallenes and dimetallynes advanced...

Despite the earth abundance and easy availability of silicon, only few examples of isolable neutral silicon centered Lewis superacids are precedent in the literature. To approach the general drawbacks of limited solubility and unselective deactivation pathways, we introduce a Lewis superacid, based on perfluorinated pinacol substituents. The compound is easily synthesized on a gram-scale as the corresponding acetonitrile mono-adduct 1•(MeCN) and was fully characterized, including single crystal X-ray diffraction analysis (SC-XRD) and state-of-the-art computations. Lewis acidity investigations by the Gutmann-Beckett method and fluoride abstraction experiments indicate a Lewis superacidic nature. The challenging SiÀF bond activation of Et 3 SiF is realized and promising catalytic properties are demonstrated, consolidating the potential applicability of silicon centered Lewis acids in synthetic catalysis.

By use of the ethylene-bridged bidentate bis-NHI (NHI = N-heterocyclic imine) ligand 1 toward the complexation of ECl2·(dioxane) (E = Ge, Sn) the synthesis of the first bis-NHI-stabilized chlorogermyliumylidene 2a[GeCl3] and chlorostannyliumylidene 2b[SnCl3] by Lewis base mediated autoionization was achieved. Using additional TMSOTf enabled the isolation of the corresponding triflate salts 2a[OTf] and 2b[OTf] in moderate yields. The obtained tetryliumylidene ions were fully characterized, including single-crystal X-ray diffraction analysis, and additionally investigated by density functional theory calculations. Reaction of 2a[OTf] with NaBH4 led to the formation of a push–pull-stabilized hydridogermyliumylidene complex by Cl/H exchange. The same reaction with the stannyliumylidene led to transmetalation, yielding the corresponding dihydroboronium complex. Also, reactions with LiAlH4 in both cases afforded the transmetalation product.