Recent Advances in the N-Heterocyclic Carbene-Supported Chemistry of Silicon

Rivard, Eric

doi:10.1007/430_2013_94

Cited by 12 publications

(1 citation statement)

References 118 publications

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“…Stabilization of highly reactive low-valent main-group element species by utilizing N-heterocyclic carbenes (NHCs) as particularly strong σ-donors led in recent years to a plethora of novel compounds with intriguing synthetic potential and to a flourishing, rapidly developing field in chemistry . Appealing examples in low-valent silicon chemistry include the Si 0 compounds (Idipp)SiSi(Idipp) ( 1 , Idipp = C[N(dipp)CH] 2 , dipp = C 6 H 3 -2,6- i Pr 2 ) and Si(bNHC) (bNHC = bidentate N-heterocyclic carbene), the Si I halides Si 2 X 2 (Idipp) 2 (X = Cl, Br, I), the NHC-adducts of the Si II halides SiX 2 (X = Cl–I), Si(X)R (X = Cl, H; R = aryl, amino), and of the disilenylsilylene SiR(SiRSiR 2 ), or the NHC-stabilized cations [Si 2 ] + , [SiR] + and Si 2+ . ,, The same strategy also enabled the trapping of silagermenylidenes (R 2 SiGe), phosphasilenylidenes (RPSi) and disilavinylidenes (R 2 SiSi) …”

Section: Introductionmentioning

confidence: 99%

Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-Valent Silicon Chemistry

et al. 2016

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Protonation and alkylation of (Idipp)Si═Si(Idipp) (1) afforded the mixed-valent disilicon(I)-borates [(Idipp)(R)Si(II)═Si(0)(Idipp)][B(Ar(F))4] (1R[B(Ar(F))4]; R = H, Me, Et; Ar(F) = C6H3-3,5-(CF3)2; Idipp = C[N(C6H3-2,6-iPr2)CH]2) as red to orange colored, highly air-sensitive solids, which were characterized by single-crystal X-ray diffraction, IR spectroscopy and multinuclear NMR spectroscopy. Dynamic NMR studies in solution revealed a degenerate isomerization (topomerization) of the "σ-bonded" tautomers of 1H[B(Ar(F))4], which proceeds according to quantum chemical calculations via a NHC-stabilized (NHC = N-heterocyclic carbene) disilahydronium ion ("π-bonded" isomer) and is reminiscent of the degenerate rearrangement of carbenium ions formed upon protonation of olefins. The topomerization of 1H[B(Ar(F))4] provides the first example of a reversible 1,2-H migration along a Si═Si bond observed in a molecular system. In contrast, 1Me[B(Ar(F))4] adopts a "rigid" structure in solution due to the higher energy required for the interconversion of the "σ-bonded" isomer into a putative NHC-stabilized disilamethonium ion. Addition of alkali metal borates to 1 afforded the alkali metal disilicon(0) borates 1M[BAr4] (M = Li, Ar = C6F5; M = Na, Ar = Ar(F)) as brown, air-sensitive solids. Single-crystal X-ray diffraction analyses and NMR spectroscopic studies of 1M[BAr4] suggest in concert with quantum chemical calculations that encapsulation of the alkali metal cations in the cavity of 1 predominantly occurs via electrostatic cation-π interactions with the Si═Si π-bond and the peripheral NHC aryl rings. Displacement of the [Si(NHC)] fragments by the isolobal fragments [PR] and [SiR](-) interrelates the cations [(NHC)(R)Si═Si(NHC)](+) to a series of familiar, multiply bonded Si and P compounds as verified by analyses of their electronic structures.

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Section: Introductionmentioning

confidence: 99%

Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-Valent Silicon Chemistry

et al. 2016

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SiSi Double Bonds: Synthesis of an NHC‐Stabilized Disilavinylidene

et al. 2015

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An efficient two-step synthesis of the first NHCstabilized disilavinylidene (Z)-(SIdipp)Si = Si(Br)Tbb (2; SIdipp = C[N(C 6 H 3 -2,6-iPr 2 )CH 2 ] 2 ,T bb = C 6 H 2 -2,6-[CH-(SiMe 3 ) 2 ] 2 -4-tBu, NHC = N-heterocyclic carbene) is reported. The first step of the procedure involved a2 :1 reaction of SiBr 2 (SIdipp) with the 1,2-dibromodisilene (E)-Tbb(Br)Si = Si(Br)Tbba t1 00 8 8C, whicha fforded selectively an unprecedented NHC-stabilized bromo(silyl)silylene,n amely SiBr-(SiBr 2 Tbb)(SIdipp) (1). Alternatively,c ompound 1 could be obtained from the 2:1reaction of SiBr 2 (SIdipp) with LiTbb at low temperature. 1 was then selectively reduced with C 8 Kt o give the NHC-stabilized disilavinylidene 2.B oth low-valent silicon compounds were comprehensively characterized by Xray diffraction analysis,m ultinuclear NMR spectroscopy, and elemental analyses.A dditionally,t he electronic structure of 2 was studied by various quantum-chemical methods.

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SiSi Double Bonds: Synthesis of an NHC‐Stabilized Disilavinylidene

et al. 2015

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An efficient two-step synthesis of the first NHC-stabilized disilavinylidene (Z)-(SIdipp)Si=Si(Br)Tbb (2; SIdipp=C[N(C6H3-2,6-iPr2)CH2]2, Tbb=C6H2-2,6-[CH(SiMe3)2]2-4-tBu, NHC=N-heterocyclic carbene) is reported. The first step of the procedure involved a 2:1 reaction of SiBr2(SIdipp) with the 1,2-dibromodisilene (E)-Tbb(Br)Si=Si(Br)Tbb at 100 °C, which afforded selectively an unprecedented NHC-stabilized bromo(silyl)silylene, namely SiBr(SiBr2Tbb)(SIdipp) (1). Alternatively, compound 1 could be obtained from the 2:1 reaction of SiBr2(SIdipp) with LiTbb at low temperature. 1 was then selectively reduced with C8K to give the NHC-stabilized disilavinylidene 2. Both low-valent silicon compounds were comprehensively characterized by X-ray diffraction analysis, multinuclear NMR spectroscopy, and elemental analyses. Additionally, the electronic structure of 2 was studied by various quantum-chemical methods.

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Recent Advances in the N-Heterocyclic Carbene-Supported Chemistry of Silicon

Abstract: This review serves to highlight recent developments in the use of N-heterocyclic carbene donors to stabilize reactive bonding environments involving silicon.

Cited by 12 publications

References 118 publications

Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-Valent Silicon Chemistry

Addition of Small Electrophiles to N-Heterocyclic-Carbene-Stabilized Disilicon(0): A Revisit of the Isolobal Concept in Low-Valent Silicon Chemistry

SiSi Double Bonds: Synthesis of an NHC‐Stabilized Disilavinylidene

SiSi Double Bonds: Synthesis of an NHC‐Stabilized Disilavinylidene

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