Synthesis, structure and isomerization of A2SiSiB2-type tetrakis(trialkylsilyl)disilenes

Iwamoto, Takeaki; Okita, Junichiro; Kabuto, Chizuko; Kira, Mitsuo

doi:10.1016/s0022-328x(03)00436-4

Cited by 22 publications

(9 citation statements)

References 30 publications

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“…23,24 As can easily be rationalized by qualitative orbital overlap arguments the ³³* separation must decrease with increasing deviation from planarity. Larger angles ª and¸necessarily result in a narrower HOMOLUMO gap and thus a red shift in the longest wavelength UVvis absorption.…”

Section: ç Introductionmentioning

confidence: 94%

The Versatile Chemistry of Disilenides: Disila Analogues of Vinyl Anions as Synthons in Low-valent Silicon Chemistry

Scheschkewitz

2010

Chemistry Letters

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Since the first isolation of a disila analog to vinyl anion synthons, namely lithium disilenide Tip 2 Si=Si(Tip)Li (Tip: 2,4,6-triisopropylphenyl), the number of available disilenides and their synthetic applications have rapidly expanded. Derivatives with aryl, silyl, alkyl, and hydrogen substituents have been reported and even one cyclic derivative is available. Disilenides can be used to introduce the Si=Si unit to a variety of organic and inorganic substrates. Depending on whether products feature sufficiently reactive residual functionality, the Si=Si bond is either retained or undergoes further (so far intramolecular) transformations. Heteroatom-substituted disilenes are easily accessible via disilenides. Using Tip 2 Si=Si(Tip)Li as a starting material, for instance, a variety of otherwise inaccessible compounds can be prepared: conjugated systems with more than one Si=Si unit, © 1 -transition-metal complexes, functional homo-and heteronuclear silacycles, and molecular silicon clusters with substituent-free vertices. In this review article, an account on the chemistry of disilenides is given.

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Section: ç Introductionmentioning

confidence: 94%

The Versatile Chemistry of Disilenides: Disila Analogues of Vinyl Anions as Synthons in Low-valent Silicon Chemistry

Scheschkewitz

2010

Chemistry Letters

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“…(Chart 3) [42]. As shown in Scheme 1, the germa-metallation of di(t-butyldimethylsilyl)dihydridogermane 11 with t-butyllithium giving hydridogermyllithium 12 [43] followed by its reaction with chlorohydridosilane 13 affords di(t-butyldimethylsilyl)[di (t-butyldimethylsilyl)germyl]silane 14 in a quantitative yield.…”

Section: Synthesis Of Tetra(t-butyldimethylsilyl)germasilene (8b)mentioning

confidence: 99%

“…As shown in our previous papers, tetrakis(diisopropylmethylsilyl)disilene (16) and tetrakis(triisopropylsilyl)disilene (17) [40] and their germanium congeners 18 and 19 [41] are slightly trans-bent (bent angle θ; 5.3-10.2°) without twisting, while 1,1-bis(tbutyldimethylsilyl)-substituted disilenes 9 and 10 are twist (twist angles τ ; 10.3°(av) and 28.0°, respectively) without bending (Chart 3). [42] The diverse mode for deformation suggests that whereas tetrasilyldimetallenes are intrinsically planar, severe steric repulsion if it exists is avoided by two modes, (1) trans-bending or (2) twisting around the double bond, depending on the shape of the substituents; among a limited number of known tetrasilyldimetallenes, 1,1-bis(tbutyldimethylsilyl)-substituted dimetallenes 8a-8c, 9, and 10 prefer twisting rather than trans-bending, while 16-19 take trans-bending. Sekiguchi et al have observed the largest twist angle (τ = 54.5°) for tetrakis(di-t-butylmethylsilyl)disilene (20) [46].…”

Section: Comparison Of Molecular Structure Among 8a-8cmentioning

confidence: 99%

“…The bond dissociation energy and the stability of a double bond of heaver group-14 elements may increase by introducing trialkylsilyl substituents as first predicted theoretically by Apeloig et al [39] and elucidated experimentally by us [40][41][42]. We wish herein to report the comparison of structure among a series of acyclic E=E'-type doubly bonded compounds 8a-8c (8a, E, E' = Si; 8b, E = Si, E' = Ge; 8c, E, E' = Ge), which bear the same t-butyldimethylsilyl substituents at the unsaturated atoms (Chart 2).…”

Section: Introductionmentioning

confidence: 97%

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Structure and Reactions of an Isolable Ge=Si Doubly Bonded Compound, Tetra(t-butyldimethylsilyl)germasilene

Iwamoto

Okita

Yoshida

et al. 2010

Silicon

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Tetra(t-butyldimethylsilyl)germasilene (8b) was synthesized using di(t-butyldimethylsilyl)hydridogermyllithium prepared by the germa-metallation of the corresponding dihydridogermane. Tetrasilylgermasilene 8b was obtained as single crystals by recrystallization from hexane at room temperature. The molecular structure of 8b is similar to those of the corresponding disilene 8a and digermene 8c but with an intermediate unsaturated bond length and twist angle between those of 8a and 8c. The reactions of 8b with methanol and 2,3-dimethylbutadiene gave the corresponding adducts. Equilibrium between 8b and the corresponding (trisilylsilyl)(silyl)germylene is suggested by the reaction of 8b with triethylsilane giving the germylene insertion product into the Si-H bond.

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“…13 29; 38 and silyl-substituted disilenes: (E )-Ph(t-Bu 3 Si)Si=Si(Ph)Sit-Bu 3 30, 39 (t-BuMe 2 Si) 2 Si=Si(Sii -Pr 3 ) 2 31, 40 (t-BuMe 2 Si) 2 Si=Si(SiMei -Pr 2 ) 2 32, 40 and (E )-Me 3 Si(i -Pr 3 Si)Si=Si(SiMe 3 )Sii -Pr 3 33 41 (Table 5.1). It was prepared by the 254 nm photolysis of the trisilane precursor Mes 2 Si(SiMe 3 ) 2 through the transient Mes 2 Si • •, which dimerized, giving 1 (Scheme 5.1).…”

Section: Synthesismentioning

confidence: 99%

Heavy Analogs of Alkenes, 1,3‐Dienes, Allenes and Alkynes: Multiply Bonded Derivatives of Si, Ge, Sn and Pb

Lee

Sekiguchi

2010

Organometallic Compounds of Low‐Coordinate Si, Ge, Sn and Pb

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Unsaturated hydrocarbons, alkenes, alkynes and dienes are among the most fundamental classes of organic compounds. The great variety and richness of organic chemistry are to a large extent caused by the disposition of carbon to form highly reactive carbon-carbon and carbon-heteroatom multiple bonds. Standard textbooks on organic chemistry describe the C=C double bond as one made of a σ -bond, formed by the linear end-on overlap of sp 2 -hybrid orbitals of each carbon partner (sp 2 -sp 2 interaction), and a π -bond, formed by the side-on overlap of unhybridized 2p-orbitals (2p π -2p π interaction). Analogously, the carbon-carbon triple bond consists of a σ -bond, formed by the linear end-on overlap of the two sp-hybrids (sp-sp interaction), and two mutually orthogonal π -bonds, each formed by the side-on overlap of unhybridized 2p-orbitals (2p π -2p π interaction). Because the s-character of the hybrid orbitals used for the formation of carbon-carbon bonds progressively increases from the single (sp 3 -sp 3 ) to the double (sp 2 -sp 2 ) and triple (sp-sp) bonds, C=C double bonds are shorter (and stronger) than C-C single bonds, and C≡C triple bonds are shorter (and stronger) than C=C double bonds. In accord with their hybridization types, the geometry of the carbon-carbon double bond in alkenes R 2 C=CR 2 is planar with an idealized R-C=C bond angle of 120 • , and the geometry of the carbon-carbon triple bond in alkynes R-C≡C-R is linear with an idealized R-C≡C bond angle of 180 • .The structures and bonding of the alkene analogs of heavy group 14 elements, both in the crystalline form and in solution, are sharply distinctive from those of their organic counterparts (alkenes); therefore, before proceeding to the discussion on each class of heavy alkenes we will briefly comment on the specific structural features of the title compounds. Structure and bondingIn contrast to organic alkenes, which are typically planar and feature diagnostically short double bonds (av. 1.34Å for >C=C< vs av. 1.54Å for >C-C<), their analogs of the heavy group 14 elements >E=E< (E = Si-Pb) revealed diverse types of structural modes sharply distinctive from those of their organic counterparts. Thus, apart from the stretching of the E=E bond descending group 14, there are two fundamental structural deformations characteristic of heavy alkenes >E=E< and leading to their departure from planarity: trans-bending at E centers and twisting about the E=E bond. The peculiar trans-bending geometry, resulting in the overall pyramidalization at the heavy group 14 elements, was rationalized in the framework of two different MO models providing alternative explanations for this phenomenon. 5 The first qualitative model considered formation of the double bond as a result of the interaction of two monomeric carbene units, taking into account the different groundstate multiplicities of carbenes and their heavy analogs. Thus, interaction of the two monomeric carbenes, which typically have triplet ground states (or alternatively, singlet ground states with ...

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Synthesis, structure and isomerization of A2SiSiB2-type tetrakis(trialkylsilyl)disilenes

Cited by 22 publications

References 30 publications

The Versatile Chemistry of Disilenides: Disila Analogues of Vinyl Anions as Synthons in Low-valent Silicon Chemistry

The Versatile Chemistry of Disilenides: Disila Analogues of Vinyl Anions as Synthons in Low-valent Silicon Chemistry

Structure and Reactions of an Isolable Ge=Si Doubly Bonded Compound, Tetra(t-butyldimethylsilyl)germasilene

Heavy Analogs of Alkenes, 1,3‐Dienes, Allenes and Alkynes: Multiply Bonded Derivatives of Si, Ge, Sn and Pb

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