Easy access to silicon(0) and silicon(II) compounds.
Easy access to silicon(0) and silicon(II) compounds.
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DOI：
10.1021/ic400357p
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发表时间：
2013-03
影响因子：
4.6
通讯作者：
K. Mondal;Prinson P. Samuel;M. Tretiakov;Amit Pratap Singh;H. Roesky;A. Stückl;Benedikt Niepoetter;E. Carl;H. Wolf;R. Herbst‐Irmer;D. Stalke
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文献类型：
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作者：
K. Mondal;Prinson P. Samuel;M. Tretiakov;Amit Pratap Singh;H. Roesky;A. Stückl;Benedikt Niepoetter;E. Carl;H. Wolf;R. Herbst‐Irmer;D. Stalke
已经开发了通式 (L(n)•)2SiX2 (n = 1, 2) 的二卤化硅桥联双自由基的两种不同合成方法。首先，NHC:SiX2 和 L(n): (L(n): = 环状烷基（氨基）卡宾以 1:3 摩尔比进行复分解反应，生成产物 2 (n = 1, X = Cl)、4 (n = 2, X = Cl)、6 (n = 1, X = Br) 和 7 (n = 2, X = Br)。这些反应还会产生偶联 NHC (3, 5) 在 C-C 键形成下，NHC:SiBr2 和 L(n) 之间的复分解反应（L(m) = 环烷基（氨基）卡宾取代的 N-杂环卡宾；m = 3, n = 1 (3) 和 m = 4, n =2 (5)）的形成速度更快：与 NHC:SiCl2 相比。 (L(1): =:C(CH2)(CMe2)2N-2,6-iPr2C6H3) 与非亲核碱基 LiN(iPr)2 以 1:1 摩尔比显示了合成双自由基 (L(1)•)2SiCl2 (2) 的前所未有的方法。二氯化硅桥联双自由基 (2, 4) 的蓝色块在一定条件下可稳定六个月以上。化合物 2 和 4 在 185 至 195 °C 的温度范围内熔化，但在固态下比在溶液中更稳定。此外，在紫外-可见光谱中观察到产物的分解。当用 RLi (R = Ph、Me、tBu) 处理时，(L(n):)2Si(0) (n = 1 (9), 2 (10)) 也分别被还原为脱卤产物 9 和 10。循环伏安测量表明 10 可以不可逆地经历单电子氧化和还原。
Two different synthetic methodologies of silicon dihalide bridged biradicals of the general formula (L(n)•)2SiX2 (n = 1, 2) have been developed. First, the metathesis reaction between NHC:SiX2 and L(n): (L(n): = 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-C 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 L(n): when compared with that of NHC:SiCl2. Second, the reaction of L(1):SiCl4 (8) (L(1): =: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 (L(1)•)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 °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-vis spectra. Moreover, compounds 2 and 4 were further converted to stable singlet biradicaloid dicarbene-coordinated (L(n):)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.