The synthesis of triethylsilyllithium and triethylgermyllithium and the investigation of some of their reactions

Vyazankin, N. S.; Razuvaev, G. A.; Gladyshev, E. N.; Korneva, S.P.

doi:10.1016/s0022-328x(00)91090-8

Cited by 70 publications

(12 citation statements)

References 2 publications

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“…Neopentyllithium gave a complicated mixture containing some CB 11 Me 11 CH 2 - t -Bu - . Triethylsilyllithium prepared from triethylsilane via bis(triethylsilyl)mercury afforded mainly CB 11 Me 11 Et - . Treatment with carbon monoxide for 3 h followed by the addition of methanol yielded a mixture in which MeOCO−CB 11 Me 11 - and MeO−CB 11 Me 11 - dominated and some CB 11 Me 11 H - was present.…”

Section: Resultsmentioning

confidence: 99%

CB₁₁Me₁₁ Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

et al. 2006

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In pentane solution, 2 equiv of the icosahedral CB(11)Me(12)(*) radical cleaves the Si-Si bond of hexaalkyldisilanes by boron to silicon methyl transfer with formation of 2 equiv of methyltrialkylsilanes. The loss of a methyl radical converts the CB(11)Me(12)(*) radical into an internally charge-compensated "boronium ylide" CB(11)Me(11) with a naked vertex, which can be formally viewed as a deprotonated hypercloso carborane. It has been isolated as an air-sensitive solid, stable only below approximately -60 degrees C. The naked vertex appears to be in position 12 since the material reacts instantaneously with alcohols and ethers to form the 12-alkoxy anions 12-CB(11)Me(11)OR. It reacts with many other nucleophiles to yield more complex mixtures containing similar products. DFT calculations for the four CB(11)Me(11) isomers give closed-shell ground-state electronic structures. For the isomer with naked vertex 12, a DFT computational search failed to reveal any skeletal dimers, apparently due to excessive methyl-methyl repulsions, and only a cyclic dimer bound through weak interactions of one of the 7-methyl hydrogen atoms on each cage with the empty exocyclic orbitals on B12 of the other cage was found. Natural hybrid orbital populations suggest that the three possible isomers of monomeric boronium ylides are close to true singlet ylides, with triplet states approximately 50 kcal/mol higher. The calculated electronic structure of the carbonium ylide is close to a singlet carbene, with a triplet state approximately 16 kcal/mol higher. An attempted preparation of Me(3)C(+)CB(11)Me(12)(-) yielded neopentane and products consistent with a sequential loss of methyl groups from the carborane cage with a transient formation of similar boronium ylides. Probable mechanisms of these methyl transfer reactions are considered, and the possibly quite general role of "ylide" structures in Lewis acid induced substitution reactions on the boron vertices of carboranes and boranes is noted.

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Section: Resultsmentioning

confidence: 99%

CB₁₁Me₁₁ Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

et al. 2006

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“…The synthesis of this class of compounds has been studied thoroughly in organic synthesis. [20] As the preparation of alkylgermyllithium species cannot be easily achieved, [21][22][23] another synthetic route had to be selected starting with alkylchlorogermanes as reactants, as these compounds are easier to handle than the corresponding alkylgermanes. The shortest way to obtain monoacylgermane derivatives is a palladium complex catalyzed reaction which has been described by Yamamoto et al [24] In an optimized procedure hexamethyldigermane was converted with benzoyl chloride in the presence of allylpalladium-(II)-chloride and triethyl phosphite as a supporting ligand at elevated temperature for several hours without further solvent, to give 1 in good yield (78%).…”

Section: Synthesismentioning

confidence: 99%

New Photocleavable Structures, 4

Ganster¹,

Fischer²,

Moszner³

et al. 2007

Macromol. Rapid Commun.

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As highly reactive acylphosphine oxide‐based photoinitiators (PIs) are limited in the application for dental materials by their absorption behavior, we were interested to prepare acylgermane 1. UV‐Vis absorption maximum of the important n–π* transition was red shifted about 30 nm compared to monoacylphosphine oxides. Photo‐DSC results with a dental LED lamp showed nearly the same reactivity for 1 compared to camphorquinone (CQ), while monoacylphosphine oxides are not reactive. In broadband irradiation experiments, significantly higher reactivity compared to CQ was found. Application‐oriented tests showed sufficient storage stability of the formulation and excellent photobleaching behavior.magnified image

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“…17,18 The observed low initiator efficiency and broad MWD may be ascribed to a number of important factors. For instance, Vyazankin et al 24 reported that the reaction of triethylsilyllithium with styrene in benzene at 20 °C gave moderate yields (23%) of the expected (CH 3 CH 2 ) 3 -SiCH 2 CPhHLi compound. We thus believe that the stability of silyl anions in THF/HMPA mixtures, as well as the rate of conversion from (CH 3 ) 3 SiOK to potassium silyl anions, are also crucial factors in order to increase the initiator efficiency f. Stability of the Silyl Anions.…”

Section: Anionic Polymerization Of Styrene Using An Initiator Solutio...mentioning

confidence: 99%

Climbing Back up the Nucleophilic Reactivity Scale. Use of Cyclosila Derivatives as Reactivity Boosters in Anionic Polymerization

et al. 1998

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It has been well-known for a very long time that, for anionic homo-polymerization or sequential copolymerization to occur, it is mandatory that the relative nucleophilic reactivity of the initiating species be equal to or larger than the one of the (co)monomer. However, the results described in this paper demonstrate that such a classic rule can be circumvented in some cases. Indeed, it is reported for the first time that potassium trimethylsilanolate, and “living” potassium poly(ethylene oxide), both of which are unable to initiate styrene or methyl methacrylate (MMA) polymerization, can be converted from oxyanionic active ends to silyl anionic ones by reacting with cyclic disila derivatives, so allowing the homopolymerization and sequential (co)polymerization of styrene or MMA to proceed in a controlled manner.

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The synthesis of triethylsilyllithium and triethylgermyllithium and the investigation of some of their reactions

Cited by 70 publications

References 2 publications

CB₁₁Me₁₁ Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

CB₁₁Me₁₁ Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

New Photocleavable Structures, 4

Climbing Back up the Nucleophilic Reactivity Scale. Use of Cyclosila Derivatives as Reactivity Boosters in Anionic Polymerization

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The synthesis of triethylsilyllithium and triethylgermyllithium and the investigation of some of their reactions

Cited by 70 publications

References 2 publications

CB11Me11 Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

CB11Me11 Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

New Photocleavable Structures, 4

Climbing Back up the Nucleophilic Reactivity Scale. Use of Cyclosila Derivatives as Reactivity Boosters in Anionic Polymerization

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Product

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CB₁₁Me₁₁ Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex

CB₁₁Me₁₁ Boronium Ylides: Carba-closo-dodecaboranes with a Naked Boron Vertex