Trans- and cis-selective Lewis acid catalyzed hydrogermylation of alkynes

[reactions: see text] The first examples of Lewis acid catalyzed hydrogermylation of alkynes have been demonstrated. It was found that this method has much higher functional group compatibility compared to the known Lewis acid catalyzed hydrosilylation and hydrostannation reactions. Remarkably, the stereochemical outcome of this hydrogermylation reaction depends on the nature of the alkyne used: proceeding via a trans-addition pathway with simple alkynes and cis-addition with propiolates. Mechanistic studies strongly support the proposed rationale on the origins of cis-selectivity in the hydrogermylation of activated alkynes.     

Homolytic hydrogermylation of alkenes with dibutylchlorogermane

In the presence of Et₃B-dry air, dibutylchlorogermane (Bu₂GeClH) reacted smoothly with alkenes at room temperature to give hydrogermylation products in high yields. This homolytic hydrogermylation was applicable to various alkenes including electron-deficient, electron-rich, and internal alkenes. Under the same conditions, tributylgermane (Bu₃GeH) showed much lower reactivity than Bu₂GeClH. The Et₃B-initiated reaction of 1,6-dienes with Bu₂GeClH gave germylmethylated cyclopentanes.     

Stèrèchimie de l;hydrogermylation des composès insaturès catalysèe par des complexe du rhodium et du platine : I. Hydrogermylation des olèfines

The homogenous catalysed hydrogermylation of olefins has been studied. It is reported that chlorotris(triphenylphosphine)rhodium and cis-dichlorobis(triphenylphosphine)platinum are very effective catalysts for hydrogermylation. Styrene leads to two adducts, the ratio of whcih depends both on teh catalyst and teh organogermane.     

Gas Phase Reaction of Tetrachlorogermane with Conjugated Dienes in the Presence of Hexachlorodisilane Initiator

Studies of the reaction of GeCl₄ with acyclic conjugated dienes (1,3-butadiene, 2-methyl-1,3- butadiene, 2,3-dimethyl-1,3-butadiene) and cyclopentadiene in the presence of Si₂Cl₆ initiator were carried out. With acyclic dienes, corresponding 1,1-dichloro-1-germacyclo-3-pentenes and 1,1-dichloro-1-silacyclo-3- pentenes are preferrably formed. With cyclopentadiene the main reaction products are cyclopentenyltrichlorogermanes and cyclopentenyltrichlorosilanes formed respectively by hydrogermylation and hydrosilylation of the starting diene. The explanation of the established rule is offered.     

Composes organometalliques a cycle moyen : IV. Hydrogermylation transannulaire

New medium-sized cyclic organogermanium compounds were synthetized. Transannular hydrogermylation was observed with 7-methyl-7-germacycloundecene, giving an organometallic bicyclic derivative. ab]Nous avons synthétisé de nouveaux composés germaniés fonctionnels cycliques de taille moyenne et nous avons observe, dans le cas du méthyl-7 germa-7 cycloundécène une réaction d'hydrogermylation transannulaire conduisant à un dérivé bicyclique organométallique.     

Orthogonally Bimetallized Phosphane-ene Photopolymer Networks

The development of batteries and fuel cells has brought to light a need for carbon anode materials doped homogeneously with electrocatalytic metals. In particular, combinations of electrocatalysts in carbon have shown promising activity. A method to derive functional carbon materials is the pyrolysis of metallopolymers. This work describes the synthesis of a bifunctional phosphonium-based system derived from a phosphane-ene network. The olefin functionality can be leveraged in a hydrogermylation reaction to functionalize the material with Ge. Unaffected by this radical addition, the bromide counterion of the phosphonium cation can be used to subsequently incorporate a second metal in an ion-complexation reaction with CuBr₂. The characterization of the polymers and the derived ceramics are discussed.     

New synthetic routes to allylic germatranes

Allylic germatranes derived from triethanolamine can be prepared with moderate control of regioselectivity by two complementary routes. The first of these is through the preparation of the precursor allylic germanium trichlorides by a transmetallation reaction between germanium(IV) chloride and the corresponding allylic tributylstannanes followed by alcoholysis and reaction with triethanolamine. The second route is via the palladium-catalyzed hydrogermylation of conjugated dienes by germatrane, N(CH₂CH₂O)₃GeH. The former route gives mixtures of E and Z stereoisomers, whereas the second route gives exclusively Z products.     

Activation of the Ge-H bond of Et3GeH in photochemical reaction with molybdenum(0) carbonyl complexes and hydrogermylation of norbornadiene

The germane intermediate σ-complexes, characterized by high-field resonances in the region from −6 to −8 ppm, have been detected during the ¹H NMR spectroscopy monitoring of the photochemical reaction of Et₃GeH with Mo(CO)₆, [Mo(CO)₄(η⁴-cod)], and [Mo(CO)₄(η⁴-nbd)] in the NMR tube. The activation of the Ge-H bond of germane in photochemical reaction of the norbornadiene (nbd) complex [Mo(CO)₄(η⁴-nbd)] has been applied in the hydrogermylation of norbornadiene, which leads to the formation of triethylgermylnorbornene.     

Hydrogermylation of silyl-substituted ethylenes with trimethylgermane and trichlorogermane etherate

Investigation of the reaction of some vinylsilanes of the general formula Cl_3?n (CH₃) _n SiCH=CH₂ (n = 0,1,2,3) and 1,2-bis(trimethylsilyl)ethylene with trimethylgermane and trichlorogermane etherate was carried out. It was established that hydrogermylation only at the use of HGeCl₃·2Et₂O was sensitive to the nature of the substituting silyl groups in vinylsilanes. Nucleophilic mechanism of the reaction of trichlorogermane etherate with vinylsilanes is suggested.     

Reaction of the superacid HGeCl3 with aromatic compounds. 5. Hydrogermylation of benzene,toluene, m-xylene,and mesitylene at high pressure

Conclusion Trichlorogermane under pressure can effect the noncatalytic hydrogermylation of aromatic multiple bonds in benzene and its simpler methyl derivatives with the preferential formation of the corresponding bisgermyl derivatives of cyclohexene. The reaction is accelerated by the introduction of methyl groups into the molecule in agreement with the electrophilic nature of trichlorogermane, and the considerable accelerating effect of high pressure can be considered as evidence of a slow stage in this process, proceeding via a molecular mechanism.For communication 4, see [1].For the preliminary communication, see [2].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 882–886, April, 1987.The authors wish to thank M. Ya. Botnikov for assistance in carrying out the GLC-mass spectrometry studies.     

Germylated steroids

Steroids germylated in position 16 were prepared for the first time by hydrogermylation of conjugated steroid enones. The addition of trichlorogermane to a conjugated Δ¹⁶-double bond leads not only to an α-isomer, which is typical of steroids, but to a β-isomer as well. The isolated Δ⁵-double bond is not involved in this reaction. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 179–180, January, 1998.     

Reaction Mechanism of the Hydrogermylation/Hydrostannylation of Unactivated Alkenes with Two‐Coordinate EII Hydrides (E=Ge,Sn): A Theoretical Study

Quantum chemical calculations using density functional theory with the TPSS+D3(BJ) and M06‐2X+D3(ABC) functionals have been carried out to understand the mechanisms of catalyst‐free hydrogermylation/hydrostannylation reactions between the two‐coordinate hydrido‐tetrylenes :E(H)(L⁺) (E=Ge or Sn, L⁺=N(Ar⁺)(SiiPr₃); Ar⁺=C₆H₂{C(H)Ph₂}₂iPr‐2,6,4) and a range of unactivated terminal (C₂H₃R, R=H, Ph, or tBu) and cyclic [(CH)₂(CH₂)₂(CH₂)_n, n=1, 2, or 4] alkenes. The calculations suggest that the addition reactions of the germylenes and stannylenes to the cyclic and acyclic alkenes occur as one‐step processes through formal [2+2] addition of the E?H fragment across the C?C π bond. The reactions have moderate barriers and are weakly exergonic. The steric bulk of the tetrylene amido groups has little influence on the activation barriers and on the reaction energies of the anti‐Markovnikov pathway, but the Markovnikov addition is clearly disfavored by the size of the substituents. The addition of the tetrylenes to the cyclic alkenes is less exergonic than the addition to the terminal alkenes, which agrees with the experimentally observed reversibility of the former reactions. The hydrogermylation reactions have lower activation energies and are more exergonic than the stannylene addition. An energy decomposition analysis of the transition state for the hydrogermylation of cyclohexene shows that the reaction takes place with simultaneous formation of the Ge?C and (Ge)H?C′ bonds. The dominant orbitals of the germylene are the σ‐type lone pair MO of Ge, which serves as a donor orbital, and the vacant p(π) MO of Ge, which acts as acceptor orbital for the π* and π MOs of the olefin. Inspection of the transition states of some selected reactions suggests that the differences between the activation energies come from a delicate balance between the deformation energies of the interacting species and their interaction energies.     

Study of the reaction of the superacid HGeCl3 with olefins by the chemically induced dynamic nuclear polarization method

Conclusions In reactions of the superacid HGeCl₃ with 2-methylbutene-2,2,3-dimethyl-2-butene and styrene, leading to hydrogermylation products of the indicated olefins, we have observed chemically induced dynamic nuclear polarization effects which are clear evidence for the presence of radical stages in the reactions.Translated from Izvestiya Akademii Nauk SSSR, No. 7, pp. 1617–1620, July, 1987.     

Influence of surface states on electron transport through intrinsic Ge nanowires

Solution-grown single-crystal Ge nanowires were used as conductive channels in field effect transistor devices to study the influence of surface states on their electron transport properties. Nanowires contacted with Pt electrodes using focused ion beam metal deposition exhibited linear current-voltage (IV) curves at room temperature with apparent resistivities ranging from 10(1) to 10(-1) Omega cm. In all cases, the nanowire conductance decreased with positive external electric fields applied perpendicular to the nanowire surface by a gate electrode, characteristic of p-type carrier accumulation at the nanowire surface. The field-induced change in conductance exhibited a time-dependent relaxation, with response time and magnitude of current decrease that depended on the nanowire surface chemistry. Nanowires treated with an organic passivation layer using a thermally initiated hydrogermylation reaction exhibited 2 orders of magnitude slower current relaxation and a smaller decrease in current relative to "bare" nanowires with oxidized surfaces.     

Hydrosilylation,hydrogermylation and hydrostannylation of 1-alkenylsilatranes

Conclusions The hydrosilylation and hydrogermylation of 1-vinyl- and 1-allylsilatranes in the presence of Rhacac(CO)₂ and the hdyrostannylation of these silatranes in the absence of catalyst leads to the formation of the corresponding terminal adducts in high yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 488–489, February, 1986.     

New biosurfactants based on germylated fatty compounds

A simple and efficient method for producing amphiphilic germylated compounds has been developed by hydrogermylation of fatty acid methyl esters. The germylated precursors afford a micelle‐type assembly in various solvents as evident by the formation of nano‐objects, micrometer spheres and lamellar forms. This offers a promising route to synthetically useful monomers for structured materials. Copyright © 2008 John Wiley & Sons, Ltd.     

Alkyl-terminated crystalline Ge nanoparticles prepared from NaGe: Synthesis, functionalization and optical properties

High purity NaGe was directly prepared by a low-temperature reaction of NaH and Ge. The product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. This material is a useful starting reagent for the preparation of Ge nanoparticles. Hydrogen-terminated germanium (Ge) nanoparticles were prepared by reaction of NaGe with NH₄Br. These Ge nanoparticles could be prepared as amorphous or crystalline nanoparticles in quantitative yields and with a narrow size distribution. The nanoparticles were functionalized via thermally initiated hydrogermylation with 1-eicosyne, CH₃(CH₂)₁₇C≡CH to produce alkyl-terminated Ge nanoparticles. The modified Ge nanoparticles were characterized by powder XRD, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and Raman spectroscopy, and photoluminescence (PL) spectroscopy. The alkyl-functionalized Ge nanoparticles can be expected to have promising applications in many technological and biological areas.     

Use of catalytic systems based on Ni in hydrogermylation of some 1,3-dienes with diethylbromogermane

Conclusions A catalytic system composed of Ni(acac)₂ and PPh₃ is an efficient catalyst for the hydrogermylation of conjugated dienes of variable structure with diethylbromogermane. The process is selective and leads to a 1,4-cis addition products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 930–932, April, 1984.     

Trans-selective hydrogermylation of alkynes promoted by methyliron and bis(germyl)hydridoiron complexes as a catalyst precursor

Catalytic trans-selective hydrogermylation of terminal and internal alkynes was attained by a methyliron complex, CpFe(CO)(2)(Me), and a bis(germyl)hydridoiron(IV) complex as a catalyst precursor. The structures of (Z)-triphenyl-(2-phenylethenyl)germane and the bis(germyl)hydridoiron(IV) complexes CpFe(CO)(H)(GeR(3))(2) (R = Et, Ph) were confirmed by single crystal X-ray diffraction studies.     

Consecutive Transformations of Tetrafluoropropenes: Hydrogermylation and Catalytic C−F Activation Steps at a Lewis Acidic Aluminum Fluoride

Functionalization reactions of the refrigerants HFO‐1234yf (2,3,3,3‐tetrafluoropropene) and HFO‐1234ze (1,3,3,3‐tetrafluoropropene) were developed. The selectivity and reactivity towards CF₃ groups of C−F activation reactions can be controlled by employing either a germane or a silane as the hydrogen source. Unique transformations were designed to accomplish consecutive hydrogermylation and C−F activation steps. This allowed for an unprecedented transformation of an olefinic C−F bond into a C−H bond by heterogeneous catalysis. These reactions are catalyzed by nanoscopic aluminum chlorofluoride (ACF) under very mild conditions.