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首页> 外文期刊>Chemistry: A European journal >Generation of cationic [Zr-{tert-butyl enolate}] reactive species: Methyl abstraction versus hydride abstraction
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Generation of cationic [Zr-{tert-butyl enolate}] reactive species: Methyl abstraction versus hydride abstraction

机译：阳离子[Zr- {叔丁基烯醇盐}]反应物种的产生：甲基提取与氢化物提取

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Treatment of the neutral methyl-Zr-enolate [Cp2Zr(Me)[O-(tBuO)C=CMe2}] (1) with one equivalent of B(C6F5)(3) or [HNMe2Ph] [B(C6F5),] as a methyl abstractor in THF at 0degreesC leads to the selective formation of the free ion pair complex [CP2Zr(THF)(O(tBuO)C=CMe2)](+) [anion](-) (2) (anion =MeB(C6F5)(3)(-) B(C6F5)(4) which is relevant to the controlled polymerization of methacrylates. Cation 2 rapidly decomposes at 20degreesC in THF with release of one equivalent of isobutene to form the cationic Zr-carboxylate species [CP2Zr(THF)(O(2)CiPr)](+) (3), through a proposed intramolecular proton transfer process from the tert-butoxy group to the enolate. The reaction of 1 with one equivalent of B(C6F5)(3) or [HNMe2Ph]B-3(C6F5)(4)] in CH2Cl2 leads to the direct, rapid formation of the dimeric mu-isobutyrato-Zr dicationic species [{Cp2Zr[mu-(O(2)CiPr)]}(2)](2+) (4), which gives 3 upon dissolution in THE Contrastingly, when [Ph3C][B(C6F5)(4)] is used to generate the cationic Zr-eno-late species from I in CD2Cl2, a 15:85 mixture of dicationic complexes 4 and [{Cp2Zr[mu-(O2C-C(Me)=CH2)]}(2)](2+) [B(C6F5)(4)](2-) (5-[B(C6F5)(4)](2)) is obtained quantitatively. The formation of 5 is proposed to arise from initial hydride abstraction from a methyl enolate group by Ph3C+, as supported by the parallel production of Ph3CH, and subsequent elimination of methane and isobutene. In addition to standard spectroscopic and analytical characterizations for the isolated complexes 2-5, complexes 4 and 5 have also been structurally characterized by X-ray diffraction studies.
机译：用一当量的B（C6F5）（3）或[HNMe2Ph] [B（C6F5），]处理中性的Zr-烯酸甲酯[Cp2Zr（Me）[O-（tBuO）C = CMe2}]（1）于0℃在THF中作为甲基抽象剂导致自由离子对络合物的选择性形成[CP2Zr（THF）（O（tBuO）C = CMe2）]（+）[阴离子]（-）（2）（阴离子= MeB （C6F5）（3）（-）B（C6F5）（4），与甲基丙烯酸酯的受控聚合有关。阳离子2在THF中于20°C迅速分解，释放出一当量的异丁烯，形成阳离子Zr-羧酸酯类[ CP2Zr（THF）（O（2）CiPr）]（+）（3），通过从叔丁氧基到烯醇化物的分子内质子转移过程提出：1与一当量的B（C6F5）（3）反应）或CH2Cl2中的[HNMe2Ph] B-3（C6F5）（4）]导致直接，快速形成二聚的mu-isobutyrato-Zr dicdicic物种[{Cp2Zr [mu-（O（2）CiPr）]}（ 2）]（2+）（4），当溶解于[Ph3C] [B（C6F5）（4）]生成阳离子Zr-烯醇型物质时，在溶解时给出3从CD2Cl2中的I，是15:85的双金属配合物4和[{Cp2Zr [mu-（O2C-C（Me）= CH2）]}（2）]（2+）[B（C6F5）（4）]的混合物定量获得（2-）（5- [B（C6F5）（4）]（2））。提议5的形成是由于Ph3C +的平行生成以及随后消除甲烷和异丁烯的支持，是由Ph3C +从甲基丙烯酸酯基团中提取氢化物引起的。除了分离的配合物2-5的标准光谱和分析特征外，还通过X射线衍射研究对配合物4和5进行了结构表征。

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