- The Addition of Nitriles to a Molecular Digermene: Reversible Addition and Comparison to Surface Reactivity
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The addition of acetonitrile, propionitrile, and acrylonitrile to tetramesityldigermene was investigated and compared to the addition of acetonitrile and acrylonitrile to germanium dimers on the Ge(100)-2×1 surface. In each case, a 1,2,3-azadigermetine was formed as the major product. As on the surface, the addition of nitriles to digermenes was found to be reversible, providing the first example of a reversible cycloaddition of a ditetrelene. No evidence for a six-membered cyclic ketenimine was observed as noted in the surface chemistry, suggesting that the surface ketenimine might only form between two adjacent dimers rather than on a single dimer. The comparative chemistry provides important insights that are not possible by the independent study of each system. A tale of two digermenes: The addition of acetonitrile, propionitrile, and acrylonitrile to tetramesityldigermene was examined to compare the structures of the molecular adducts with the structures of the nitrile adducts formed on the Ge(100)-2×1 surface and to provide further insight into the surface chemistry. The addition of nitriles was found to be reversible, and no evidence for cyclic ketenimines was found.
- Hardwick, Julie A.,Baines, Kim M.
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supporting information
p. 6600 - 6603
(2015/06/08)
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- Reactivity studies of N-heterocyclic carbene complexes of germanium(II)
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The chemistry of three N-heterocyclic carbene (NHC) complexes of GeR 2, where R = Cl (1), OtBu (2), Mes (3) (Mes = 2,4,6-trimethylphenyl), toward 2,3-dimethylbutadiene (DMB), 3,5-di-tert- butylorthoquinone, methyl iodide, pivalic acid, and benzophenone is reported. Upon heating, 2 and 3 cyclize with DMB to yield a germacyclopentene and free NHC. In contrast, 1 does not react with DMB. PB1PBE/6-311+G(d,p) model chemistry shows that the cycloaddition reactions of NHC-GeX2 (X = F, Cl) with butadiene are not thermodynamically favorable. 3,5-Di-tert-butylorthoquinone reacts rapidly with 1-3 to form cyclic products; in the case of 1 and 2, the NHC remains coordinated to the germanium, resulting in a hypervalent species. Compounds 1-3 react with methyl iodide by displacement of I-; in each case [NHC-GeR2Me]+ is produced. Only compound 3 reacts in a controlled fashion with pivalic acid; both 1:1 and 1:2 adducts were characterized. Benzophenone failed to react with 1 or 2 but did undergo cycloaddition with 3. In comparison with uncomplexed GeR2 species, the NHC-GeR2 complexes are less reactive. The prospect of using NHC-GeR2 as a synthon for GeR2 appears to be reaction specific.
- Rupar, Paul A.,Staroverov, Viktor N.,Baines, Kim M.
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p. 4871 - 4881
(2011/02/22)
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- Steady-state photolysis of dimesitylbis(trimethylsilyl)germane
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The photolysis of dimesitylbis(trimethylsilyl)germane (3) in hexanes or THF, at low temperature, has been investigated as a potential method for the preparative-scale synthesis of tetramesityldigermene (5). A product mixture, consisting of hexamethyldisilane, mesitylene, 2-trimethylsilylmesitylene (7), a new germacyclobutene (8), and an unidentified polymer, was obtained. No evidence for the formation of tetramesityldigermene (5) was observed.
- Hurni, Krysten L.,Baines, Kim M.
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p. 668 - 674
(2008/09/19)
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- Stabilization of a transient diorganogermylene by an N-heterocyclic carbene
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The synthesis of a carbene-stabilized transient germylene is presented; the resulting complex liberates free germylene upon heating, forms a stable adduct with BH3, and reacts with MeLi to displace the carbene.
- Rupar, Paul A.,Jennings, Michael C.,Ragogna, Paul J.,Baines, Kim M.
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p. 4109 - 4111
(2008/10/09)
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- Organogermanium reactive intermediates. The direct detection and characterization of transient germylenes and digermenes in solution
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Diphenylgermylene (Ph2Ge) and its Ge=Ge doubly bonded dimer, tetraphenyldigermene (6a), have been characterized directly in solution for the first time by laser flash photolysis methods. The germylene is formed via (formal) cheletropic photocycloreversion of 3,4-dimethyl-1,1- diphenylgermacyclopent-3-ene (4a), which is shown to proceed in high chemical (>95%) and quantum yield (Φ = 0.62) by steady-state trapping experiments with methanol, acetic acid, isoprene, and triethylsilane. Flash photolysis of 4a in dry deoxygenated hexane at 23°C leads to the prompt formation of a transient assigned to Ph2Ge (∈max = 500 nm; ∈max = 1650 M-1 cm-1), which decays with second-order kinetics (τ ≈ 3 μs), with the concomitant growth of a second transient species that is assigned to digermene 6a (τ ≈ 40 μs; λmax = 440 nm). Analogous results are obtained from 1,1-dimesityl- and 1,1-dimethyl-3,4-dimethylgermacyclopent-3-ene (4b and 4c, respectively), which afford Mes2Ge (τ = 20 μs; λmax = 560 nm) and Me2Ge (τ ≈ 2 μs; λs; λmax = 480 nm), respectively, as well as the corresponding digermenes, tetramesityl- (6b; λmax = 410 nm) and tetramethyldigermene (6c; λmax = 370 nm). The results for the mesityl compound are compared to the analogous ones from laser flash photolysis of the known Mes2Ge/6b precursor, hexamesitylcyclotrigermane. The spectra of the three germylenes and two of the digermenes are in excellent agreement with calculated spectra, derived from time-dependent DFT calculations. Absolute rate constants for dimerization of Ph2Ge and Mes2Ge and for their reaction with n-butylamine and acetic acid in hexane at 23°C are also reported.
- Leigh, William J.,Harrington, Cameron R.,Vargas-Baca, Ignacio
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p. 16105 - 16116
(2007/10/03)
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- Thermolysis of hexamesitylsiladigermirane or hexamesitylcyclotrigermane in the presence of 2,3-dimethylbutadiene or water
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The thermolysis of hexamesitylsiladigermirane and hexamesitylcyclotrigermane in the presence of 2,3-dimethylbutadiene (DMB) or water has been investigated. Thermolysis of hexamesitylsiladigermirane (1) in the presence of DMB results in the formation of two major compounds: 1,1-dimesityl-3,4-dimethyl-1-germacyclopent-3-ene (3) and 1-mesityl-1-(trimesitylsilyl)-3,4-dimethyl-1-germacyclopent-3-ene (4). Compounds 3 and 4 are most probably formed by initial thermal regioselective cleavage of the siladigermirane to give tetramesitylgermasilene and dimesitylgermylene, which is immediately trapped by the diene. The germasilene does not appear to react with DMB but rather, under the reaction conditions, undergoes a 1,2-mesityl shift at a faster rate to give a silylgermylene, which is subsequently trapped by the diene. Similarly, thermolysis of hexamesitylcyclotrigermane (5) in the presence of DMB yields compounds 3 and 1-mesityl-1-(trimesitylgermyl)-3,4-dimethyl-1-germacyclopent-3-ene (6), in contrast to an earlier report. Again, the intermediate digermene rearranges to a germylgermylene, which is the species trapped, at a faster rate than reaction with DMB. Thermolysis of 1 or 5, in the presence of water, results in the formation of products clearly derived from the addition of water across the double bond of the intermediate germasilene or digermene. Unlike the addition of methanol, the addition of water across the germasilene is not completely regioselective. The synthetic utility and mechanistic implications of this reaction are discussed.
- Baines, Kim M.,Cooke, Jeffrey A.,Dixon, Craig E.,Liu, Hui Wen,Netherton, Matthew R.
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p. 631 - 634
(2008/10/08)
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- 3-Alkylidenethiagermiranes
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Dimethyl- and diphenylgermylenes react with di-tert-butylthioketene to give 4-alkylidene-1,2,3-thiadigermetanes 2 and 4, the products of the insertion of germylenes into 3-alkylidenethiagermiranes. Dimesitylgermylene generated by the thermolysis of hexamesitylcyclotrigermane (12) at 80°C reacts with di-tert-butylthioketene to produce a stable 3-alkylidenethiagermirane, 13. Photolysis of 13 produces dimesitylgermylene and di-tert-butylthioketene via germathiocarbonyl ylide 17, which is intensely blue in color with a maximum band at 580 nm. 13 reacts with dimethylgermylene to yield the corresponding 4-alkylidene-1,2,3-thiadigermetane 22. Oxidation of 13 by m-chloroperbenzoic acid gives 3-alkylidene-1,2,4-oxathiagermetane S-oxide 23.
- Ando, Wataru,Tsumuraya, Takeshi
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p. 1467 - 1472
(2008/10/08)
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- Thermolysis of Cyclotrigermane: Simple Preparation of Digermetanes containing a Germanium-Germanium Bond
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Thermolysis of hexamesitylcyclotrigermane in the presence of paraformaldehyde, thiobenzophenone, and phenylacetylene at 80 deg C produces the corresponding adducts with tetramesityldigermene.
- Ando, Wataru,Tsumuraya, Takeshi
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p. 770 - 771
(2007/10/02)
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- Synthesis and chemistry of thiagermiranes
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Dimethylgermylene (1) reacts with thioketones 3 and 9 to give 1,3,2,4-dithiadigermolanes 4 and 10, the ultimate products of formation of thiagermiranes 6 and 11 and subsequent addition of dimethylgermanethione (7). Dimesitylgermylene (16) reacts with adamantanethione (3) to give 3-(2-adamantyl)-2,2-dimesityl-1,2-thiagermirane (18). Photolysis of thiagermirane 18 yields dimesitylgermylene (16) and adamantanethione (3) derived from germathiocarbonyl ylide 22. Oxidation of thiagermirane 18 by mCPBA gives 3-(2-adamantyl)-4,4-dimesityl-1,2,4-oxathiagermetane S-oxide (27). X-ray analyses were done for thiagermirane 18 and 1,2,4-oxathiagermetane S-oxide 27.
- Tsumuraya, Takeshi,Sato, Sadao,Ando, Wataru
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p. 161 - 167
(2008/10/08)
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- Synthesis of the first germa-1-pyrazoline and its decomposition via a germirane intermediate
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The first germapyrazoline, 4-germa-1-pyrazoline (2), has been obtained by cycloaddition of diazomethane to the Ge=C bond of the germene (1).Thermal or photochemical decomposition of 2 via a germirane intermediate (4) gives 9-methyl-enefluorene and dimesitylgermylene, which can be trapped by 2,3-dimethylbutadiene.
- Egorov, M. P.,Kolesnikov, S. P.,Nefedov, O. M.,Krebs, A.
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- Photolysis of cyclotrigermane. Synthesis and chemistry of digermiranes and digermetanes containing sulfur and selenium
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Photolysis of hexamesitylcyclotrigermane (1) produces tetramesityldigermene (4) and dimesitylgermylene (5) which react with elemental sulfur to give 2,2,3,3-tetramesitylthiadigermirane (2) and 2,2,4,4-tetramesityl-1,3,2,4-dithiadigermetane (3). Selenium also reacts with digermene 4 to afford 2,2,3,3-tetramesitylselenadigermirane (7). Photolysis of 2 with 2,3-dimethyl-1,3-butadiene produces only products from dimesitylgermylene (5) and dimesitylgermanethione (6). The reactions of 2 with pyridine N-oxide, sulfur, and selenium yield digermetanes containing O, S, and Se.
- Tsumuraya, Takeshi,Sato, Sadao,Ando, Wataru
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p. 2015 - 2019
(2008/10/08)
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- ASSISTANCE NUCLEOPHILE DANS DES REACTIONS D'ORGANO-HALOGENO- ET -HALOGENO-HYDROGERMANES: GERMYLANIONS, GERMYLENES, DERIVES FONCTIONNELS DU GERMANIUM
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Substitution reactions of halogermanes under nucleophilic assistance of tertiary amines or diazo derivatives leading readily to various functional derivatives of germanium have been carried out.Dehydrohalogenation of acidic halohydrogemanes under nucleophilic assistance is a useful way to divalent species, and the germylenes formed are stabilized by complexation with the nucleophilic agent.The reactions proceed via intermediate halogermylanions which lead to the formation of more stable germylenes.The transient halogemylanions have been characterized by means of their nuclophilic additions to carbonyl derivatives.Nucleophilic substitutions of halogermanes using these germylanions lead to the formation of polygermanes.
- Riviere, P.,Castel, A.,Satge, J.
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p. 123 - 136
(2007/10/02)
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