precursor for a variety of hexasilacyclohexane derivatives, was synthesized by the reaction of [pedeta·SiH2Cl]2[Si6Cl12·2Cl] (1) with allylmagnesium bromide. In addition, an effective synthetic route of dodecachlorohexasilacyclohexane 3 from trichlorosilane was found. Deallylmethoxylation of 4 with catalytic amount of iodine and methanol yielded dodecamethoxyhexasilacyclohexane 5 almost quantitatively, but
The mixed Si5Ge heterocycle (SiCl2)5(GeMe2) and its Cl− diadduct were synthesized in a highly selective fashion. The assembly mechanism was investigated to explain why precisely one GeMe2 group is incorporated, and reactivity studies were performed.
“Inverse Sandwich” Complexes of Perhalogenated Cyclohexasilane
作者:Xuliang Dai、Douglas L. Schulz、Christopher W. Braun、Angel Ugrinov、Philip Boudjouk
DOI:10.1021/om1000716
日期:2010.5.24
Perhalogenated cyclohexasilanes, Si6X12 (X = Cl, Br), were prepared by reaction of Si6H12 with molecular chlorine or bromine in cold (-89 degrees C) dichloromethane. Single-crystal structural determination by X-ray analysis shows that the six silicon atoms comprising Si6Br12 adopt a chair conformation in the solid state. The addition of p-tolunitrile to Si6X12 (X = Cl, Br) leads to the rapid formation of colorless precipitates. Si6Br12 center dot 2(p-CH3C6H4CN) adopts an "inverse sandwich" structure where the N atoms of the p-tolunitrile molecules are mu(6) bonded and are located above and below the planar hexagonal Si-6 ring.
Lewis Acidity of Si<sub>6</sub>Cl<sub>12</sub> and Its Role as Convenient SiCl<sub>2</sub> Source
The free cyclohexasilane Si6Cl12 (1) was obtained in 66% yield from the corresponding Cl- diadduct [nBu(4)N](2)[1.2Cl] and AlCl3 in C6H6. The substituted cyclohexasilane 1,1-(Cl3Si)(2)Si6Cl10 (2), however, cannot be liberated from [nBu(4)N](2)[2.2Cl] under comparable reaction conditions. Instead, a mixture of several products was obtained, from which the oligosilane Si19Cl36 (3) crystallized in low yields. X-ray crystallography revealed 3 to consist of two Si-5 rings, bridged by one silicon atom. Compound 1 possesses Lewis acidic sites above and below the ring centroid. Competition experiments reveal that their corresponding acid strengths are comparable to that of BCl3. The reaction of 1 with 6 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (Idipp) leads to a complete breakdown of the cyclic scaffold and furnishes the dichlorosilylene adduct Idipp-SiCl2.
UV/Vis-spektroskopische Untersuchungen an Cyclosilanderivaten