Gas phase kinetic and theoretical studies of reactions of germylenes and dimethylstannylene

Боганов, С. Е.; Egorov, Mikhail P.; Faustov, V. I.; Krylova, I. V.; Нефедов, О. М.; Becerra, Rosa; Walsh, Robin

doi:10.1007/s11172-005-0285-5

Cited by 38 publications

(63 citation statements)

References 106 publications

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“…Several of the reactions of these species were found to be reversible, such as the [2+1]-cycloaddition reactions with alkenes and dienes, and Lewis acid-base complexation with tertiary amines; they are nonetheless very fast, with forward rate constants on the order of 10 9 -10 10 (mol/L) -1 s -1 in hexane at room temperature. The absolute rate constants measured for the reactions of GeMe 2 with the C-C unsaturated compounds and oxygen in solution (11) were found to agree quite well with earlier data reported by Walsh and coworkers (6,12) for reactions with the same or similar substrates in the gas phase. The solution-phase data for the two germylenes showed GeMe 2 to be significantly more reactive than its phenylated counterpart in every reaction that was studied.…”

Section: Introductionsupporting

confidence: 86%

Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution

Leigh¹,

Dumbrava²,

Lollmahomed³

2006

Can. J. Chem.

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Photolysis of 1,3,4-trimethyl-1-phenylgermacyclopent-3-ene (5) in hydrocarbon solvents containing isoprene, methanol, or acetic acid affords 2,3-dimethyl-1,3-butadiene (DMB) and the expected trapping products of methyl phenylgermylene (GeMePh) in chemical yields exceeding 90%. The germylene has been detected in hexane solution by laser flash photolysis as a short-lived species (τ ~ 2 µs) exhibiting a UV-vis absorption spectrum centered at λmax = 490 nm. It decays with second-order kinetics and a rate constant close to the diffusion-controlled limit, with the concomitant growth of a second longer-lived transient (λmax = 420 nm) that is assigned to a mixture of (E)- and (Z)-1,2-dimethyl-1,2-diphenyldigermene (4). Absolute rate constants have been determined for the reactions of the germylene with primary and tertiary amines (n-BuNH2 and Et3N, respectively), acetic acid (AcOH), a terminal alkyne and alkene, isoprene, DMB, CCl4, and the group 14 hydrides Et3SiH and Bu3SnH. GeMePh is slightly more reactive than GePh2 towards all the reagents studied in this work; both are significantly less reactive than GeMe2 toward the same substrates. Absolute rate constants for the reactions of 4 have also been measured or assigned upper limits in every case and are compared to previously reported values for tetraphenyl- and tetramethyl-digermene with the same reagents.Key words: germylene, digermene, kinetics, laser flash photolysis, germirane, germirene, vinylgermirane, complex, UV–vis spectrum, insertion, addition.

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Section: Introductionsupporting

confidence: 86%

Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution

Leigh¹,

Dumbrava²,

Lollmahomed³

2006

Can. J. Chem.

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“…The structure of TS2 resembles that of p-complexes, which are often intermediates of interactions of heavier analogs of silylenes, i.e. germylenes and stannylenes, with unsaturated compounds [19].…”

Section: Suprafacial Rearrangement: Ts2 and Ts3mentioning

confidence: 99%

Computational study of 2-vinylsilirane to silacyclopent-3-ene rearrangement

Rynin

Kulikov

Faustov

et al. 2010

Journal of Molecular Structure: THEOCHEM

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“…This is due to a higher diatomic state stabilization energy of GeMe 2 (30.1 kcal mol -1 ) compared to that of GeH 2 (28.4 kcal mol -1 ). 16 The presence of Me groups at the Ge atoms in molecules 4b and 4d leads to high activation barriers TS2b and TS2d to the opening of the three mem bered rings and formation of secondary germylenes 5b and 5d. This can be explained by the 1,2 shift of the Me group (ring opening in 4b and 4d) rather than proton migration (germiranes 4a and 4c).…”

Section: Systemmentioning

confidence: 99%

Isomerization and decomposition of germiranes: a density functional study

et al. 2005

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The formation and decomposition pathways of germiranes (germacyclopropanes), i.e., products of reactions of the GeH 2 and GeMe 2 germylenes with ethylene, tetramethylethylene, buta 1,2,3 triene, and tetramethylbuta 1,2,3 triene, were studied using the density functional approach (PBE/TZ2P approximation). The thermodynamic stabilities of the structures under consideration were evaluated by calculating the Gibbs free energies under normal condi tions (∆G°2 98 ). Addition of germylenes to the C=C bond can proceed as a single step process without a barrier or involve the formation of a π complex (the barrier to this process is lower than the sum of the energies of isolated reactants). Stability of the germiranes formed is determined by their stability to retrodecomposition into the initial germylene and olefin and to the three membered ring opening followed by simultaneous 1,2 migration of the substituent at the Ge atom and formation of the secondary germylene. Alkyl substituents can efficiently block the opening of the three membered ring and transformation of the cyclic structure into the secondary germylene, simultaneously decreasing the germirane stability to retrodecomposition. Decomposition into germylene and olefin under normal conditions is thermally favorable for hexamethylgermirane (∆G°2 98 = -5.7 kcal mol -1 ), being thermally forbidden for the other germiranes studied in this work (∆G°2 98 > 0). The activation energy (E a ) for the germirane ring opening depends on the substituents at the germanium atom, namely, E a ≤ 10 kcal mol -1 for unsubstituted germiranes and E a > 30 kcal mol -1 for methyl substituted germiranes. Taking the experimentally isolated germirane as an example, it was shown how the introduction of sub stituents and modification of the carbon skeleton make it possible to stabilize the germa cyclopropane system.

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Gas phase kinetic and theoretical studies of reactions of germylenes and dimethylstannylene

Cited by 38 publications

References 106 publications

Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution

Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution

Computational study of 2-vinylsilirane to silacyclopent-3-ene rearrangement

Isomerization and decomposition of germiranes: a density functional study

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