- 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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- On the synthesis, structure, and reactivity of tetramesityldigermene
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Tetramesityldigermene (1) can be synthesized cleanly and quantitatively by photolysis of hexamesitylcyclotrigermane (2) in THF at low temperature. A solution of tetramesityldigermene (1) in THF is stable for several weeks at room temperature; the digermene does not dissociate or rearrange. The molecular structure of tetramesityldigermene (1) has been determined using X-ray crystallography. The effectiveness of the new protocol for the synthesis of tetramesityldigermene (1) and its derivatives has been demonstrated in the study of the addition of carboxylic acids to tetramesityldigermene (1).
- Hurni, Krysten L.,Rupar, Paul A.,Payne, Nicholas C.,Baines, Kim M.
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p. 5569 - 5575
(2008/10/09)
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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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