Carbon-silicon and carbon-carbon bond formation by elimination reactions at metal N-heterocyclic carbene complexes.
Carbon-silicon and carbon-carbon bond formation by elimination reactions at metal N-heterocyclic carbene complexes.
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DOI：
10.1021/ja204209t
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发表时间：
2011-08
影响因子：
15
通讯作者：
P. Arnold;Zoë R. Turner;R. Bellabarba;R. Tooze
中科院分区：
文献类型：
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作者：
P. Arnold;Zoë R. Turner;R. Bellabarba;R. Tooze
(L)MR(2)和(L)(2)MR(M=SC，Y；L={1-C(NDippCH(2)CH(2)CH(2)N)}CH(2)CME(2)O)，DIPP=2，6-(I)Pr(2)-C(6)H(3)；R=CH(2)SIME(3)，CH(2)CME(3)，通过在金属-卡宾键上加E-X形成两性离子咪唑金属络合物(L(E))MR(2)X，其中L(E)={1-EC(NDippCH(2)CH(2)N)}CH(2)CME(2)O，E是p-嵌段官能团，如SIR(3)，PR(2)或SnR(3)，X是卤化物。“ATE”络合物(L(Li))Scr(3)很容易获得，最好的描述是Li卡宾加合物，({1-Li(THF)C(NDippCH(2)CH(2)N)}CH(2)CMe(2)O)Sc(CH(2)SiMe(3))(3)，，因为结构表征表明烷氧基配体桥接两种金属和卡宾Li-以迄今记录的最短的Li-C键距离。这可以通过消除卤化锂盐的歧化反应转化为烷基化或硅烷化的咪唑衍生物，(L(E))Scr(3)(E=SIME(3)或CPH(3))。所有E功能化的咪唑类化合物在升温到室温或略高于室温时都会自发消除官能化的碳氢化合物，形成新的有机产物ER，即形成C-Si、C-P和C-Sn键，并分别重新形成无机金属卡宾(L)MR(X)或(L)(2)MX络合物。加热三(烷基)络合物(L(E))MR(3)形成C-C或C-Si键的有机产物，这似乎是通过相同的消除路线进行的。(L)(2)Sc(CH(2)SIME(3))与碘五氟苯发生“反义”加成反应，生成金属芳基络合物(L)(2)Sc(C(6)F(5))，并释放出碘代烷Me(3)SiH(2)I，这也是由于N-杂环卡宾基的可逆官能化所促成的。
Two functional groups can be delivered at once to organo-rare earth complexes, (L)MR(2) and (L)(2)MR (M = Sc, Y; L = ({1-C(NDippCH(2)CH(2)N)}CH(2)CMe(2)O), Dipp = 2,6-(i)Pr(2)-C(6)H(3); R = CH(2)SiMe(3), CH(2)CMe(3)), via the addition of E-X across the metal-carbene bond to form a zwitterionic imidazolinium-metal complex, (L(E))MR(2)X, where L(E) = {1-EC(NDippCH(2)CH(2)N)}CH(2)CMe(2)O, E is a p-block functional group such as SiR(3), PR(2), or SnR(3), and X is a halide. The "ate" complex (L(Li))ScR(3) is readily accessible and is best described as a Li carbene adduct, ({1-Li(THF)C(NDippCH(2)CH(2)N)}CH(2)CMe(2)O)Sc(CH(2)SiMe(3))(3), since structural characterization shows the alkoxide ligand bridging the two metals and the carbene Li-bound with the shortest yet recorded Li-C bond distance. This can be converted via lithium halide-eliminating salt metathesis reactions to alkylated or silylated imidazolinium derivatives, (L(E))ScR(3) (E = SiMe(3) or CPh(3)). All the E-functionalized imidazolinium complexes spontaneously eliminate functionalized hydrocarbyl compounds upon warming to room temperature or slightly above, forming new organic products ER, i.e., forming C-Si, C-P, and C-Sn bonds, and re-forming the inorganic metal carbene (L)MR(X) or (L)(2)MX complex, respectively. Warming the tris(alkyl) complexes (L(E))MR(3) forms organic products arising from C-C or C-Si bond formation, which appears to proceed via the same elimination route. Treatment of (L)(2)Sc(CH(2)SiMe(3)) with iodopentafluorobenzene results in the "reverse sense" addition, which upon thermolysis forms the metal aryl complex (L)(2)Sc(C(6)F(5)) and releases the iodoalkane Me(3)SiCH(2)I, again facilitated by the reversible functionalization of the N-heterocyclic carbene group in these tethered systems.