2875-92-5Relevant articles and documents
Germyl- and germylene-bridged complexes of Rh/Ir and subsequent chemistry of a bridging germylene group
Mobarok, Md Hosnay,McDonald, Robert,Ferguson, Michael J.,Cowie, Martin
, p. 4020 - 4034 (2012/05/31)
A series of neutral and cationic germylene-bridged complexes and a neutral germyl(germylene) complex have been synthesized and characterized by NMR spectroscopy and X-ray crystallography. Reaction of 1 equiv of primary germanes, RGeH3 (R = Ph, tBu), with [RhIr(CO)3(dppm) 2] (1) at low-temperature yields [RhIr(GeH2R)(H)(CO) 3(dppm)2] (R = Ph (3) or tBu (4)), the products of single Ge-H bond activation, which upon warming transform to the germylene-bridged dihydrides, [RhIr(H)2(CO)2(μ-GeHR) (dppm)2] (R = Ph (5) or tBu (6)) by activation of a second Ge-H bond accompanied by CO loss. Both classes of compounds have the diphosphines folded back in a "cradle-shaped" geometry. Although compound 5 reacts with additional phenylgermane at -40 °C to give a germylene-bridged/germyl product, [RhIr(GeH2Ph)(H) 2(CO)2(κ1-dppm)(μ-GeHPh)(μ-H)(dppm) ] (7), warming results in decomposition. However, reaction of 5 with 1 equiv of diphenylgermane at ambient temperature results in a novel mixed bis(μ-germylene) complex, [RhIr(CO)2(μ-GeHPh)(μ-GePh 2)(dppm)2] (8), containing both mono- and disubstituted germylene fragments. Reaction of 1 equiv of diphenylgermane with complex 1 produces a similar monogermylene-bridged product, [RhIr(H)2(CO) 2(μ-GePh2)(dppm)2] (9), while reaction of 1 with 2 equiv of diphenylgermane yields the germyl/germylene product [RhIr(H)(GeHPh2)(CO)3(κ1-dppm)(μ- GePh2)(dppm)] (10). The above reactions, incorporating first one and then a second equivalent of primary and secondary germanes, were studied by low-temperature multinuclear NMR spectroscopy, revealing details about the stepwise activations of multiple Ge-H bonds. Reaction of diphenylgermane with the cationic complex [RhIr(CH3)(CO)2(dppm) 2][CF3SO3] (2) leads to a cationic A-frame-type germylene- and hydride-bridged product, [RhIr(CO)2(μ-H)(μ- GePh2)(dppm)2][CF3SO3] (3), which reversibly activates H2, yielding a germyl-bridged dihydride and reacts stoichiometrically with water, methanol, and HCl to yield the respective germanol, germamethoxy, and germylchloride products.
Preparation, structure, and reactivity of discrete branched oligogermanes
Amadoruge, Monika L.,Golen, James A.,Rheingold, Arnold L.,Weinert, Charles S.
, p. 1979 - 1984 (2009/02/01)
The hydrogermolysis reaction of PhGeH3 serves in the synthesis of discrete branched oligogermanes. Treatment of PhGeH3 with 3 equiv of the α-germyl nitriles R3GeCH2CN (R3 = Ph3 or Bu2CH2CH2OEt), which are generated in situ from the corresponding amides R3GeNMe2 and CH3CN, furnishes the tetragermanes PhGe(GePh3) 3 and PhGe(GeBu2CH2CH2OEt) 3 in excellent yield. The crystal structure of PhGe(GePh 3)3 was determined. This compound is the first branched oligogermane to be structurally characterized. Reaction of the tetragermane PhGe(GeBu2CH2CH2OEt)3 with Bu i2AlH generated the intermediate hydride PhGe(GeBu 2H)3. Subsequent treatment of PhGe(GeBu2H) 3 with the synthons R2Ge(NMe2)CH 2CH2OEt (R = Bu, Et, Ph) in CH3CN solution furnished the heptagermanes PhGe(GeBu2GeR2CH 2CH2OEt)3 (R = Bu, Et, Ph). The latter process also proceeds through the in situ formation of the α-germyl nitriles R2Ge(CH2CN)CH2CH2OEt.
Temperature dependence of germylene reactions with acetylene, trimethylsilane, and phenylgermane
Alexander, Ula N.,King, Keith D.,Lawrance, Warren D.
, p. 529 - 534 (2008/10/08)
Gas-phase reaction rate constants have been determined over the temperature range 295-436 K for the reactions of germylene, GeH2, with acetylene (GeH2 addition across a triple bond), trimethylsilane (GeH2 insertion into a Si-H bond), and phenylgermane. The room-temperature rate constant for germylene reacting with benzene has been measured and is found to be a factor of ~300 smaller than that for phenylgermane, indicating that the latter reacts by GeH2 insertion into the Ge-H bonds. A negative temperature dependence is observed in all cases. The activation energies, obtained from weighted linear fits to the data over the experimental temperature range, are -3.5±0.3, -11.0±0.4, and -3.6±0.3 kJ mol-1 for acetylene, trimethylsilane, and phenylgermane, respectively, while the respective frequency factors, log(A/cm3 molecule-1 s-1), are -10.5±0.1, -11.8±0.1, -10.1±0.1.
