The First Isolable Dialkylsilylene

Kira, Mitsuo; Ishida, Shintaro; Iwamoto, Takeaki; Kabuto, Chizuko

doi:10.1021/ja9925305

Cited by 426 publications

(385 citation statements)

References 24 publications

(22 reference statements)

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“…10 A cyclic alkyl silylene, which is stable at 0 °C, was reported by Kira but it isomerizes in solution via a 1,2-migration of an adjacent trimethylsilyl group to give a silene. 11 Other examples include the bisamido derivative Si(NPr i 2)2 which exists in a monomer/dimer equilibrium with the SiSi double-bonded disilene {Si(NPr i 2)2}2 , 12 as well as Si{N(SiMe3)2}2, which persists for more than 12 h at -20 °C but decomposes into a complex mixture of products at increased temperatures. 13 We now report that the reduction of the silicon(IV) precursor, Br2Si(SAr Me 6 )2 (1) (Ar Me 6 = C6H3-2,6(C6H2-2,4,6-Me3)2), affords the silicon dithiolate, Si(SAr Me 6 )2 (2), which has a monomeric, two-coordinate structure and is an example of a stable acyclic two-coordinate silylene.…”

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Isolation of a Stable, Acyclic, Two-Coordinate Silylene

et al. 2012

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The synthesis and characterization of a stable, acyclic two-coordinate silylene, Si(SArMe6 )2 [ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2], by reduction of Br2Si(SArMe6 )2 with a magnesium(I) reductant is described. It features a V-shaped silicon coordination with a S–Si–S angle of 90.52(2)° and an average Si–S distance of 2.158(3) Å. Although it reacts readily with an alkyl halide, it does not react with hydrogen under ambient conditions, probably as a result of the ca. 4.3 eV energy difference between the frontier silicon lone pair and 3p orbitals.

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Isolation of a Stable, Acyclic, Two-Coordinate Silylene

et al. 2012

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“…The geometry around Pd1 and Pd2 atoms are slightly different from each other. The Si1-Pd1-P1 angle is 147.66(8), while Si1-Pd2-P2 angle is 171.15 (6). The P1 and P2 atoms are slightly deviated from the central three-membered ring plane with the dihedral angles Si1-Pd2-Pd1-P1 and Si1-Pd1-Pd2-P2 of À172:59ð18Þ and À169:50ð7Þ .…”

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confidence: 99%

“…5 In the present paper, we report the synthesis, structure, and an interesting reaction of novel dinuclear palladium complex having one bridging silylene unit (6) using isolable dialkylsilylene 7, which we have recently synthesized as a silylene stabilized kinetically by a bulky 1,1,4,4-tetrakis(trimethylsilyl)butane-1,4-diyl ligand. 6 To the best of our knowledge, complex 6 is the first mono(-silylene) dipalladium complex without Pd-H-Si bonding or other bridging ligands and, hence, will be useful as a prototypical dipalladasilacyclopropane to investigate the electronic structure and reactions of the ring system (Chart 1).…”

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Dinuclear Palladium Complex with a Bridging Dialkylsilylene Ligand

Watanabe¹,

Iwamoto²,

Kabuto³

et al. 2007

Chemistry Letters

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A novel dinuclear palladium complex with one bridging dialkylsilylene ligand 6 was synthesized by the reaction of isolable dialkylsilylene 7 (R 2 Si:) with two equiv of bis(tricyclohexyl)-phosphinepalladium (8). Complex 6 as a prototypical dipalladasilacyclopropane reacts with molecular hydrogen to give dihydrosilane 10 (R 2 SiH 2 ) together with 8 and metallic palladium.Multinuclear transition-metal complexes with bridging silyl and/or silylene groups have received much attention because they show unique structural and bonding properties and would be key intermediates of transformation of silane mediated by transition-metal complexes.1 Although various multinuclear group-10 metal complexes with bridging silyl and/or silylene units have been extensively studied, there have been few reports on the corresponding dipalladium complexes. Osakada et al. have synthesized [L n Pd(-SiH(R)Ph)] 2 (1) as the first silylbridged dimeric palladium complexes with three-center-twoelectron Si-H-Pd bond.2 Fürstner et al. and Herrmann et al. have reported dipalladium complexes with two bridging N-heterocyclic silylenes (2-4) that were prepared by the reactions of stable N-heterocyclic silylenes with palladium(0) complexes. 3,4 Suginome, Ito, et al. have synthesized dipalladium complex 5, in which -silylene and -isocyanide ligands coordinate to the two palladium atoms. 5 In the present paper, we report the synthesis, structure, and an interesting reaction of novel dinuclear palladium complex having one bridging silylene unit (6) using isolable dialkylsilylene 7, which we have recently synthesized as a silylene stabilized kinetically by a bulky 1,1,4,4-tetrakis(trimethylsilyl)butane-1,4-diyl ligand.6 To the best of our knowledge, complex 6 is the first mono(-silylene) dipalladium complex without Pd-H-Si bonding or other bridging ligands and, hence, will be useful as a prototypical dipalladasilacyclopropane to investigate the electronic structure and reactions of the ring system (Chart 1).Complex 6 was synthesized by the treatment of dialkylsilylene 7 with bis(tricyclohexylphosphine)palladium (8, 2.1 equiv) in toluene at room temperature (eq 1).7 Recrystallization from toluene gave analytically pure 6 in 24% yield as air-and moisture-sensitive dark blue-purple crystals with the decomposition temperature of 203 C. The structure of 6 was determined by NMR spectroscopy, elemental analysis, and X-ray crystallography. 8,9(1) 2.1 equiv (Cy 3 P) 2 Pd (8) toluene, rt 7 6 (24% yield) Figure 1 shows the molecular structure of 6 determined by X-ray analysis. The Pd 2 unit is disordered over two positions with almost the same site occupancy factors [0.486(3) for Pd1(Pd2) and 0.514(3) for Pd1 0 (Pd2 0 )]. The geometry around the Si1-Pd1-Pd2 ring and Si1-Pd1 0 -Pd2 0 ring are similar to each other. The dialkylsilylene unit bridges over the two palladium atoms and the silacyclopentane ring is nearly perpendicular to the SiPd 2 three-membered ring; the dihedral angle between C1-Si1-C4 and Pd1-Si1-Pd2 (Pd1 0 -Si1-Pd2 0 ) planes is 91.62 (92.28 ). Ea...

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“…As 5 is a thermal isomerization product of dialkylsilylene 6 (ref. 25), the generation of 1 and 6 was indicated by the thermolysis of 2.…”

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A heavy analogue of the smallest bridgehead alkene stabilized by a base

2014

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Bicyclo[1.1.0]but-1(2)-ene (BBE), one of the smallest bridgehead alkenes and C 4 H 4 isomers, exists theoretically as a reactive intermediate, but has not been observed experimentally. Here we successfully synthesize the silicon analogue of BBE, tetrasilabicyclo[1.1.0]but-1(2)-ene (Si 4 BBE), in a base-stabilized form. The results of X-ray diffraction analysis and theoretical study indicate that Si 4 BBE predominantly exists as a zwitterionic structure involving a tetrasilahomocyclopropenylium cation and a silyl anion rather than a bicyclic structure with a localized highly strained double bond. The reaction of base-stabilized Si 4 BBE with triphenylborane affords the [2 þ 2] cycloadduct of Si 4 BBE and the dimer of an isomer of Si 4 BBE, tetrasilabicyclo[1.1.0]butan-2-ylidene (Si 4 BBY). The facile isomerization between Si 4 BBE and Si 4 BBY is supported by theoretical calculations and trapping reactions. Structure and properties of a heavy analogue of the smallest bridgehead alkene are disclosed.

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The First Isolable Dialkylsilylene

Cited by 426 publications

References 24 publications

Isolation of a Stable, Acyclic, Two-Coordinate Silylene

Isolation of a Stable, Acyclic, Two-Coordinate Silylene

Dinuclear Palladium Complex with a Bridging Dialkylsilylene Ligand

A heavy analogue of the smallest bridgehead alkene stabilized by a base

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