Easy Access to Silicon(0) and Silicon(II) Compounds

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• 作者：Kartik Chandra Mondal ; Prinson P. Samuel ; Mykyta Tretiakov ; Amit Pratap Singh ; Herbert W. Roesky ; A. Claudia St眉ckl ; Benedikt Niep枚tter ; Elena Carl ; Hilke Wolf ; Regine Herbst-Irmer ; Dietmar Stalke
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：April 15, 2013
• 年：2013
• 卷：52
• 期：8
• 页码：4736-4743
• 全文大小：405K
• 年卷期：v.52,no.8(April 15, 2013)
• ISSN：1520-510X

文摘

Two different synthetic methodologies of silicon dihalide bridged biradicals of the general formula (Lⁿ鈥?₂SiX₂ (n = 1, 2) have been developed. First, the metathesis reaction between NHC:SiX₂ and Lⁿ: (Lⁿ: = cyclic akyl(amino) carbene in a 1:3 molar ratio leads to the products 2 (n = 1, X = Cl), 4 (n = 2, X = Cl), 6 (n = 1, X = Br), and 7 (n = 2, X = Br). These reactions also produce coupled NHCs (3, 5) under C鈥揅 bond formation. The formation of the coupled NHCs (L^m = cyclic alkyl(amino) carbene substituted N-heterocyclic carbene; m = 3, n = 1 (3) and m = 4, n =2 (5)) is faster during the metathesis reaction between NHC:SiBr₂ and Lⁿ: when compared with that of NHC:SiCl₂. Second, the reaction of L¹:SiCl₄ (8) (L¹: =:C(CH₂)(CMe₂)₂N-2,6-iPr₂C₆H₃) with a non-nucleophilic base LiN(iPr)₂ in a 1:1 molar ratio shows an unprecedented methodology for the synthesis of the biradical (L¹鈥?₂SiCl₂ (2). The blue blocks of silicon dichloride bridged biradicals (2, 4) are stable for more than six months under an inert atmosphere and in air for one week. Compounds 2 and 4 melt in the temperature range of 185 to 195 掳C. The dibromide (6, 7) analogue is more prone to decomposition in the solution but comparatively more stable in the solid state than in the solution. Decomposition of the products has been observed in the UV鈥搗is spectra. Moreover, compounds 2 and 4 were further converted to stable singlet biradicaloid dicarbene-coordinated (Lⁿ:)₂Si(0) (n = 1 (9), 2 (10)) under KC₈ reduction. Compounds 2 and 4 were also reduced to dehalogenated products 9 and 10, respectively when treated with RLi (R = Ph, Me, tBu). Cyclic voltametry measurements show that 10 can irreversibly undergo both one electron oxidation and reduction.