The Structural Chemistry of Organosilicon Compounds

Kaftory, Menahem; Kapon, Moshe; Botoshansky, Mark

doi:10.1002/0470857250.ch5

Cited by 187 publications

(227 citation statements)

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“…The fourmembered Si 4 ring is square-planar with endocyclic Si-Si bond lengths of 2.347(2) Å, which are slightly shorter than those of known cyclopolysilanes. [27] The EPR spectrum of 10 showed a multiplet signal with g = 2.0025 and a( 14 N) = 0.35 mT, consisting of 15 of the expected 17 lines due to coupling of the unpaired electron with the eight 14 N nuclei (I = 1). Such an EPR spectrum pattern agrees well with the formulation of odd-electron delocalization over the Si 4 ring, which is supported by the EPR spectrum simulation.…”

Section: Cyclic Ion Radicals Of Heavier Group 14 Elementsmentioning

confidence: 96%

“…The biradical structure of 24 was supported by theoretical calculations, which revealed the absence of the Ge-Ge bonding, showing that the HOMO of the molecule consisted mainly of a nonbonding combination of the two lone-pair p-orbitals centered on the two Ge atoms. The second biradicaloid, 1,3-diaza-2,4-distannacyclobutane-1,3-diyl 26, was prepared by the rather unusual reaction of the chloro(amino)stannylene dimer [Sn{N(SiMe 3 ) 2 }(μ-Cl)] 2 (27) and AgOCN in diethyl ether (Scheme 17). [44] This compound featured an unusual solvent-dependent behavior of its 119 Sn NMR chemical shift: δ = -87 (C 6 D 6 ), -83 (toluene/C 6 D 6 ), -102 (CD 2 Cl 2 ), -140 (THF/C 6 D 6 ), -285 (HMPA/toluene/C 6 D 6 ).…”

Section: Heavier Group 14 Elements Centered Biradicalsmentioning

confidence: 99%

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Si‐, Ge‐, and Sn‐Centered Free Radicals: From Phantom Species toGrams‐Order‐Scale Materials

Lee

Sekiguchi

2005

Eur J Inorg Chem

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Recent developments in the field of the stable free radicals of heavier group 14 elements are reviewed, covering both neutral and charged radical species. The electronic and crystal‐structural features of these radicals, both in the solid state and in solution, are compared with each other. The most important parameters affecting the stability, geometry and electronic configuration of the radicals are discussed on the basis of the latest experimental and computational data. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Section: Cyclic Ion Radicals Of Heavier Group 14 Elementsmentioning

confidence: 96%

Section: Heavier Group 14 Elements Centered Biradicalsmentioning

confidence: 99%

Si‐, Ge‐, and Sn‐Centered Free Radicals: From Phantom Species toGrams‐Order‐Scale Materials

Lee

Sekiguchi

2005

Eur J Inorg Chem

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“…The endocyclic Si1-Si2 and ARTICLE Si2-Si3 bond distances, 2.2906(6) and 2.2556(6) Å, respectively, are between the typical Si À Si (ca. 2.36 Å) 27 and Si ¼ Si bond distances (2.118-2.289 Å) 31,32 , and close to those of N-heterocyclic carbene-coordinated cyclotrisilene (trisilacyclopropene) (2.2700(5)Å) 26 , indicating a significant double-bond character in Si1 À Si2 and Si2 À Si3 bonds. The geometry around Si2 is considerably pyramidalized with the sum of bond angles around Si2 (except the angles involving Si2 À N1 bond) of 312.63(4)°, whereas that around Si3 is almost planar with the sum of bond angles around Si3 (except the bond angles involving Si1 À Si3 bond), 359.30(4)°.…”

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confidence: 59%

“…2c). The nitrogen atom of DMAP coordinates to Si2 atom with the Si2 À N1 distance of 1.8764(14) Å, which is moderately longer than the typical Si À N distance (1.71-1.74 Å) 27 . The Si1 atom has no substituent and the Si1 À Si3 distance is 2.6215(6) Å, which is considerably longer than those of known tetrasilabicyclo[1.1.0]butanes (2.367-2.412 Å) 28,29 , but still shorter than the longest Si À Si distance reported so far (2.697 Å for (t-Bu) 3 SiSi(t-Bu) 3 ) 30 .…”

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confidence: 93%

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 average Si-O bond length of 3a, 3b and 3c is 1.636 Å, similar to the known average value of Si-O bond lengths (1.629 Å). 27 Simplified models of 3a, 3b and 3c show the characteristic stereochemistry of isomers due to the different positions of trimethylsilyl substituents in the Ttc groups (Fig. 4).…”

mentioning

confidence: 99%