2875-92-5Relevant academic research and scientific papers
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.
Gas phase reaction of nucleogenic dimethylgermylium cations with benzene
Myalochkin,Kochina,Avrorin,Vrazhnov,Sinotova
, p. 1762 - 1766 (2011/02/24)
Reaction of nucleogenic dimethylgermylium cations with benzene in the gas phase was studied by the radiochemical method. The formation of the products of germylation of benzene, dimethylphenylgermane, and phenylgermane is indicative of the formation of dimethylgermylium cations by the β-decay of tritium in the molecule of dimethylditritium germane. Dimethylgermylium cations are shown to undergo a rearrangement in the course of the reaction with benzene, which is consistent with the earlier results of quantum-chemical calculations.
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.
The ground state energy levels and molecular structure of jet-cooled HGeCl and DGeCl from single vibronic level emission spectroscopy
Tackett, Brandon S.,Clouthier, Dennis J.,Pacheco, Kezia L.,Schick, G. Alan
, p. 1 - 6 (2008/10/09)
Single vibronic level dispersed fluorescence spectra of jet-cooled HGeCland DGeCl have been recorded by laser excitation of selected bands of t he A A??1 - X A′1 electronic transition. Twenty-six ground state vibrational levels of HGeCl and 42 of DGeCl were measured, assigned,and fitted to standard anharmonicity expressions, which allowed all the harmonic frequencies to be determined for both isotopomers. A normal co ordinate least squares analysis obtained by fitting the harmonic frequencies yielded reliable values for five of the six force constants. The ground state effective rotational constants and force field data were combined to calculate average (rz) and approximate equilibrium (rez) structures, with rez (GeH) =1.586 (1) ?, rez (GeCl) =2.171 (2) ?, and the bond angle fixed at our CCSD(T)/aug-cc-pVTZ ab initio value of 93.9°. Comparisons show that the derived bond lengths are consistent with those of the appropriate diatomic molecules in their ground electronic states and the bond angle is similar to that of germylene (Ge H2). A Franck-Condon simulation of the vibrational intensities in the 000 band emission spectrum of HGeCl using ab initio force field data shows good agreement with experiment, lending credence to the vibrational analysis of the observed spectra.
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.
The Ge-H bond dissociation energies of organogermanes. A laser-induced photoacoustic study
Clark, K. Brady,Griller, David
, p. 746 - 750 (2008/10/08)
The Ge-H bond dissociation energies (BDE's) of several alkyl- and aryl-substituted germanium hydrides have been measured in hydrocarbon solution at room temperature by a photoacoustic technique. The BDE's of these hydrides are unaffected by alkyl substitution when compared to those for GeH4 and are in the range of 81.6-82.6 kcal/mol. Aryl substitution leads to a slightly weakened Ge-H bond (79.2-80.2 kcal/mol) in the cases of phenyl-, diphenyl-, and triphenylgermane. In an effort to further characterize the formation, spectral and decay properties of the germyl radicals some laser flash photolysis studies were carried out. The rate constants for hydrogen abstraction by tert-butoxy radicals were determined by nanosecond laser flash photolysis and fell in the range (0.7-4.4) × 108 M-1 s-1. The aryl-substituted germyl radicals add to the aromatic rings of the germane precursor. Diphenylgermyl radical adds to diphenylgermane with a rate constant of 2.9 × 105 M-1 s-1, while phenylgermyl radical adds to phenylgermane with a rate constant of 1.2 × 106 M-1 s-1.
ASSISTANCE NUCLEOPHILE DANS DES REACTIONS DE REDUCTION D'ORGANOHALOGENO- ET HALOGENO-GERMANES PAR DES REDUCTEURS DOUX R3M(IVB)-H ET RCHO: GERMYLANIONS, DERIVES FONCTIONNELS DU GERMANIUM
Castel, A.,Riviere, P.,Satge, J.
, p. 137 - 146 (2007/10/02)
Catalytic activity of nuclophiles such as tertiary amines and diazo derivatives in the reduction of halogermanes by means of gentle reductive agents, such as R3M(IVB)-H or RCHO, has been shown.In the particular case of enolisable aldehyde, a competition between nucleophilic substitution at the metal and germanium-halogen bond reduction has been observed.Transposition of enoxygermanes formed through the substitution process, leads to β-germylaldehydes.
SYNTHESE DE COMPOSES A LIAISON MIVB-MERCURE. PRECURSEURS D'ESPECES MONOVALENTES (GERMYNES), ET BIVALENTES (GERMYLENES), DE RADICAUX CENTROMETALLES ET D'INTERMEDIAIRES
Riviere, P.,Castel, A.,Satge, J.
, p. 351 - 367 (2007/10/02)
Polynuclear germyl-mercury compounds are obtained from the reaction of organohydrogermanes PhnGeH4-n or digermanes Ph2nGe2H4-n (n = 1, 2) with dialkylmercury R2Hg.Di- or tri-mercurated geminal polygermates thus synthesized generally present a low stability and undergo thermal- or photodecompositions leading to the corresponding monovalent (germynes), divalent (germylenes) or, trivalent (germanium centered radicals) species and also to intermediate biradicals which could be considered as limit forms of germanium doubly-bonded compounds .Such intermediates have been chemically and spectroscopically characterized.Extension of these reactions to the silicon analogs met with difficulties, and thus previously observed differences between silicon and germanium chemistry were confirmed.
