Dimethyl germylene insertion into a strained C-Ge bond and matrix isolation of tetramethyl digermene Me2Ge=GeMe2

Bleckmann, P.; Minkwitz, R.; Neumann, Wilhelm P.; Schriewer, Michael; Thibud, M.; Watta, Bärbel

doi:10.1016/s0040-4039(01)81206-5

Cited by 44 publications

(19 citation statements)

References 13 publications

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“…7,7 0 -dimethyl-1,4,5,6-tetraphenyl-2,3-benzo-7-germanorbornadiene (GeNB) is the most frequently used source of dimethylgermylene for chemical synthesis. This compound is thermally or photochemically decomposed with the formation of dimethylgermylene and 1,2,3,4-tetraphenylnaphthalene (TPN) [1,[30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Kaletina

Korolev

2010

Res Chem Intermed

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Dimethylgermylene and its Ge=Ge doubly bonded dimer, tetramethyldigermene, have been characterized directly in solution by 308-nm laser flash photolysis in n-hexane solution, as well as 254-nm photolysis in hydrocarbon glasses at t = 77 K. An absorption band maximum of k max & 430 nm and molar absorption coefficient of e & 2,700 M -1 cm -1 have been shown to be attributable to low-temperature glasses, while the absorption band maximum of k max & 480 nm and molar absorption coefficient of e & 2,400 M -1 cm -1 have been shown to be related to dimethylgermylene in n-hexane solution. The molar absorption coefficient of tetramethyldigermene (k max & 380 nm) was determined to be e & 84,000 M -1 cm -1 . The germylene is formed via (formal) cheletropic photocycloreversion of 7,7 0 -dimethylgerma-1,4,5,6-tetraphenyl-2,3-benzo-norbornadiene. Tetramethyldigermene and 1,2,3,4-tetraphenylnaphthalene in the triplet state were formed, together with dimethylgermylene. We attempted to explain the various contradictory interpretations of experimental data existing in the literature on this reaction.

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Section: Introductionmentioning

confidence: 99%

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Kaletina

Korolev

2010

Res Chem Intermed

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“…7 Exploring the behavior of the latter species upon thermolysis, the tetramethyldigermene Me 2 GeGeMe 2 was generated for the first time; 8 similar to the case for other heavy alkenes, 9 tetramethyldigermene could be trapped by anthracene, giving rise to (Me 2 Ge) 2 A in a [4+2] Diels−Alder cycloaddition process. 7,8 Our recent synthesis and isolation of unprotected 7-phosphanorbornadienes obtained directly from the reaction of select dichlorophosphines with MgA·3THF 6 made us wonder if 7-germanorbornadienes could be accessed similarly. Addition of solid MgA·3THF (1 equiv) to a chilled (−35°C) tetrahydrofuran (THF) solution of Me 2 GeCl 2 (1 equiv) effected an immediate color change to pale yellow.…”

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confidence: 96%

Synthesis, Characterization, and Thermolysis of Dibenzo-7-dimethylgermanorbornadiene

2015

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The dibenzo-7-dimethylgermanorbornadiene Me 2 GeA (A = C 14 H 10 ) has been synthesized in one step by treatment of MgA·3THF with Me 2 GeCl 2 in tetrahydrofuran (−35°C ) and isolated in 69% yield. The thermolysis of Me 2 GeA in toluene leads to the effective expansion of the bicyclic framework to the dibenzo-7,8-tetramethyldigermabicyclo[2.2.2]octadiene (Me 2 Ge) 2 A, isolated in 71% yield (based on germanium). The bicyclic compounds Me 2 GeA and (Me 2 Ge) 2 A have been characterized by single-crystal X-ray diffraction studies and their structures discussed.

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“…Despite the formulation of Me 2 Ge A as a source of dimethylgermylene, with loss of anthracene as a driving force, heating Me 2 Ge A (70–85 ◦ C) in the presence of a variety of unsaturated substrates such as 1,3-cyclohexadiene, 2,3-dimethylbutadiene, or trans , trans -1,4-diphenylbutadiene did not give rise to the anticipated germanium-containing products (S1.2 in the Supporting Information). Instead, formation of (Me 2 Ge) 2 A , was observed by 1 H NMR spectroscopy, resulting from formal transfer of dimethylgermylene to Me 2 Ge A , accompanied by the formation of one equivalent of anthracene, according to eq : (Me 2 Ge) 2 A has been described previously, and one synthetic route of note involves intercepting the transient tetramethyldigermene (Me 2 GeGeMe 2 ) with anthracene in a [2+4] cycloaddition . In the pursuit of observing dimethylgermylene transfer to substrates other than Me 2 Ge A , we turned to the elements of the d block in search of a molecular transition-metal complex that might facilitate dimethylgermylene transfer.…”

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confidence: 98%

“…Clearly, Me 2 Ge A is a better (kinetic) trap for dimethylgermylene than 2,3-dimethylbutadiene. This result is in line with previous discussions in the literature, where the naphthalene analogue of Me 2 Ge A was described as a “powerful germylene scavenger” by virtue of the large ring strain energy resulting from the acute C–Ge–C angle (for example, 77.72° in Me 2 Ge A ), enforced by the [2.2.1]-bicyclic framework.…”

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confidence: 99%

Identification of Reactive Intermediates Relevant to Dimethylgermylene Group Transfer Reactions of an Anthracene-Based Precursor

2019

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Dimethylgermylene ([Me2Ge]) group transfer from the anthracene-based precursor dibenzo-7-dimethylgermanorbornadiene (Me2GeA; A = C14H10, anthracene) was investigated. Transfer of [Me2Ge] from Me2GeA to 2,3-dimethylbutadiene to give a dihydrogermole (2) was mediated by a platinum metallagermacycle (1), formed by oxidative addition of the platinum(0) species (Ph3P)2Pt(C2H4) into the strained Ge–C bond of Me2GeA with concomitant loss of ethylene. Metallagermacycle 1 was characterized by multinuclear NMR spectroscopy, single-crystal X-ray diffraction, and elemental analysis. The strained Ge–C bond of Me2GeA was also found to undergo an addition reaction with pyridine, resulting in the [2.2.3]-bicyclic compound 3. Kinetics experiments on both the platinum- and pyridine-promoted systems implicate low-valent dimethylgermylene-containing species as reaction intermediates.

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Dimethyl germylene insertion into a strained C-Ge bond and matrix isolation of tetramethyl digermene Me2Ge=GeMe2

Cited by 44 publications

References 13 publications

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Synthesis, Characterization, and Thermolysis of Dibenzo-7-dimethylgermanorbornadiene

Identification of Reactive Intermediates Relevant to Dimethylgermylene Group Transfer Reactions of an Anthracene-Based Precursor

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