24 research outputs found

    Synthesis of Phosphine-Functionalized Silicon Cubane and Its Oxidative Addition, Giving a Bis(silyl)copper Complex

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    A new strategy for the introduction of a second type of Si atom to silicon cubanes has been developed starting from the tricyclic hexasilane dianion [Ar6Si6]2– (Ar = 2,4,6-Me3C6H2). Treatment of the dianion with Ar′SiCl3, followed by KC8, gave new types of octasilacubanes Ar6Ar′2Si8 [Ar′ = 2,4,6-iPr2C6H2 (3a), 2-Ph2PC6H4 (3b)] in high yields. Remarkably, treatment of cubane 3b bearing with two phosphine groups with 2 equiv of CuCl in CH2Cl2 yielded the bis(silyl)copper complex via the selective oxidative addition of the newly formed Si–Si bond to Cu ion. Single-crystal X-ray analysis indicated the unique square-planar, four-coordinate Cu cation paired with the [CuCl2]− counteranion

    Metal-Free, Stereospecific Bis-Silylation of Functionalized Alkynes with NHC-Supported Silylaminosilylene

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    The NHC-supported silylaminosilylene Ar­(SiMe<sub>3</sub>)­N­(Cl)­Si­(I<i>i</i>Pr) (<b>1</b>; Ar = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>, I<i>i</i>Pr = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) is an efficient and stereospecific bis-silylation reagent for a range of functionalized alkynes to yield cis-1,2-bis-silylated alkenes via a 1,4-silyl migration from the amino nitrogen atom to an alkyne carbon atom. The reaction is regio- and stereospecific for terminal alkynes with an electron-withdrawing substituent, thus providing a facile access to 1,2-bis-silylated alkenes with two different silyl groups

    Selective Silylation of Nitriles with an NHC-Stabilized Silylene to 1,2-Disilylimines and Subsequent Synthesis of Silaaziridines

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    The highly regioselective synthesis of <i>trans</i>-1,2-disilylimines have been achieved by the bis-silylation of nitriles with the NHC-stabilized silylene NHC-Si­(NArSiMe<sub>3</sub>)Cl (<b>1</b>; Ar = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>, NHC = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene). The bis-silylation involves the migration of the SiMe<sub>3</sub> group on the nitrogen atom in the silylene to the carbon atom of the nitrile functionality. The 1,2-disilylimine products feature an NHC-stabilized silaimine moiety and could undergo nucleophilic attack by phenyllithium reagents to yield novel silaaziridines with an NHC-stabilized exocyclic SiN double bond

    Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

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    The reaction of HC­[(CBu<sup><i>t</i></sup>)­(NAr)]<sub>2</sub>Li with BCl<sub>3</sub> yielded the azaallyl boron dichloride [ArNC­(Bu<sup><i>t</i></sup>)­C­(H)­C­(Bu<sup><i>t</i></sup>)­N­(Ar)]­BCl<sub>2</sub> (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu<sup><i>t</i></sup>)­(NAr)]<sub>2</sub>BCl<sub>2</sub> (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe<sub>3</sub>)<sub>2</sub> and MesLi (Mes = 2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>) resulted in the cyclopropanation of the CBu<sup><i>t</i></sup> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt<sub>2</sub> gave substitution products

    Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

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    The reaction of HC­[(CBu<sup><i>t</i></sup>)­(NAr)]<sub>2</sub>Li with BCl<sub>3</sub> yielded the azaallyl boron dichloride [ArNC­(Bu<sup><i>t</i></sup>)­C­(H)­C­(Bu<sup><i>t</i></sup>)­N­(Ar)]­BCl<sub>2</sub> (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu<sup><i>t</i></sup>)­(NAr)]<sub>2</sub>BCl<sub>2</sub> (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe<sub>3</sub>)<sub>2</sub> and MesLi (Mes = 2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>) resulted in the cyclopropanation of the CBu<sup><i>t</i></sup> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt<sub>2</sub> gave substitution products

    Cyclopropanation and Isomerization Reactions of β-Diketiminato Boron Complexes

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    The reaction of HC­[(CBu<sup><i>t</i></sup>)­(NAr)]<sub>2</sub>Li with BCl<sub>3</sub> yielded the azaallyl boron dichloride [ArNC­(Bu<sup><i>t</i></sup>)­C­(H)­C­(Bu<sup><i>t</i></sup>)­N­(Ar)]­BCl<sub>2</sub> (<b>1</b>), which can be converted to the β-diketiminato boron dichloride HC­[(CBu<sup><i>t</i></sup>)­(NAr)]<sub>2</sub>BCl<sub>2</sub> (<b>2</b>) upon heating at 40 °C. Reaction of <b>1</b> with the bulky lithium salts LiN­(SiMe<sub>3</sub>)<sub>2</sub> and MesLi (Mes = 2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>) resulted in the cyclopropanation of the CBu<sup><i>t</i></sup> group via the deprotonation of the methyl group, while reactions with PhLi and LiNEt<sub>2</sub> gave substitution products

    Controlled Oxidation of an NHC-Stabilized Phosphinoaminosilylene with Dioxygen

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    Reaction of the N-heterocyclic carbene-stabilized phosphinoaminosilylene ArN­(SiMe<sub>3</sub>)­Si­(I<sup><i>i</i></sup>Pr)­PPh<sub>2</sub> (Ar = 2,6-<sup><i>i</i></sup>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>, I<sup><i>i</i></sup>Pr = 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene) (<b>2</b>) with dioxygen resulted in the formation of the two products ArN = Si­(I<sup><i>i</i></sup>Pr)­(OSiMe<sub>3</sub>)­(OPPh<sub>2</sub>) (<b>3</b>) and ArN = Si­(I<sup><i>i</i></sup>Pr)­(OSiMe<sub>3</sub>)­PPh<sub>2</sub> (<b>4</b>), and the ratios of the two products can be controlled by the reaction temperatures and dioxygen concentrations

    Disilicon Dicarbonyl Complex: Synthesis and Protonation of CO with O–H Bond

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    Reaction of solid NHB-stabilized disilyne (NHB)SiSi(NHB) (1, NHB = [ArN(CMe)2NAr]B, Ar = 2,6-iPr2C6H3) with 1 atm of carbon monoxide yielded the first 1,2-disilicon dicarbonyl complex (NHB)(OC)SiSi(CO)(NHB) (2). Hydrolysis and methanolysis of 2 led to the C–C coupling and protonation of two CO oxygen atoms giving disilacyclobutene derivatives 3 and 4. In contrast, reaction of 2 with iodomethane resulted in the oxidative addition to the silicon atoms with the formation of 1,2-diiodo-disilane 5 with the liberation of CO molecules. Single-crystal X-ray diffraction analysis of 2 disclosed the coordination of CO to the two silicon atoms with a unique 1,2-dicarbonyl-disilane skeleton, in which the pronounced backbonding from the lone pairs of silicon p orbitals to CO π* orbitals was elucidated by DFT calculations
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