Hydrogen-Bridged Digermyl and Germylsilyl Cations

Abstract

The synthesis of the digermyl and germylsilyl hydronium borates 7[B(C 6 F 5 ) 4 ] and 8[B(C 6 F 5 ) 4 ] is reported. Spectroscopic (IR, NMR) and structural data supported by the results of density functional calculations indicate in both cases a symmetric or almost symmetric E−H−E′ three-center−two-electron linkage (7, E = E′ = Ge; 8, E = Si, E′ = Ge). The [B(C 6 F 5 ) 4 ] − and the [HCB 11 H 5 Br 6 ] − salts of both cations are active in catalytic hydrodefluorination reactions of alkyl and benzyl fluorides. No significant effect of the element atom E on the determined turnover numbers was found.

The Si2H radical supported by two N-heterocyclic carbenes

“…2150 cm –1 ). 22 Notably, the ν (Si–H) absorption band of 1H appears in-between that of 1H [B(Ar F ) 4 ] containing a trigonal planar coordinated Si atom ( ν (Si–H) = 2142 cm –1 ), 9 and the Si( ii )-hydride (IMe 4 )SiH(Si t Bu 3 ) containing a strongly pyramidal bonded Si atom (IMe 4 = C[N(Me)CMe] 2 : ν (Si–H) in KBr = 1984 cm –1 ). 11 d Apparently, the ν (Si–H) frequency decreases with increasing pyramidalization of the Si atom, which according to the quantum chemical calculations can be traced back to the decreasing s-character of the Si hybrid orbital in the Si–H bond (see ESI, Tables S11 and S12 † ).…”

Reactive p-block cations stabilized by weakly coordinating anions

“…52 ). 343 Additionally, for germanium and tin ligand-stabilized dimeric cations are known, both synthesized by oxidation of their E( ii ) precursors through elemental sulfur ( Fig. 52 ).…”

Syntheses of a Flobufen Metabolite and Dapoxetine Based on Enantioselective Allylation of Aromatic Aldehydes

“…Although these parameter for the activation of the SiH bond [elongation of the SiH bond, reduction of the 1 J (SiH) and bathochromic shift of the ν as (Si–H)] clearly lack behind those detected for complexes 1 , 4 , or even for cation 3 (Figure 3) the ability of compound 6 to catalyze hydrodefluorination reactions or CO 2 fixation was tested, however without success. Under standard conditions (4.5 mmol fluorodecane, 3 mL triethylsilane, 2.5 mol % of 6 )9b no reaction between decylfluoride and triethylsilane was detected. Similarly, no stoichiometric reaction was observed with CO 2 [ p (CO 2 ) = 0.4 MPa] even at prolonged reaction time and elevated temperatures.…”

“…The good accordance between experimental structural data and theoretical predictions obtained for complex 6 indicates the structure optimization to be well suited for a comparative structural discussion of complexes 4 , 5 , and 6 . In order to complete the picture, the discussion is extended to the structure of cation 3 with a symmetric Si–H–Si bridge 9b,11. For all four compounds 3 , 4 , 5 , and 6 , the results of the computations predict bent Si–H ··· E ( E = Al, Si) linkages and Si–H bonds, which are elongated compared to standard values for Si–H bonds [ d (Si–H) = 148 pm]20 or to the Si–H bond calculated for compound 9 [ d (Si–H) = 148.6 pm].…”