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首页> 外文期刊>Chemistry: A European journal >Heteroleptic [n]Chromoarenophanes: ansa Complexes Derived from [Cr(η~5-C_5H_5)(η~6-C_6H_6)]
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Heteroleptic [n]Chromoarenophanes: ansa Complexes Derived from [Cr(η~5-C_5H_5)(η~6-C_6H_6)]

机译：杀菌剂[n]色肾上腺素：[Cr（η〜5-C_5H_5）（η〜6-C_6H_6）衍生的ansa配合物

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摘要

The synthesis of ansa complexes has been studied intensively owing to their importance as homogeneous catalysts and as precursors of metal-containing polymers. However, paramagnetic non-metallocene derivatives are rare and have been limited to examples with vanadium and titanium. Herein, we report an efficient procedure for the selective dilithiation of paramagnetic sandwich complex [Cr-(η~5-C_5H_5)(η~6-C_6H_6)], which allows the preparation of a series of [n]chromoarenophanes (n=1, 2, 3) that feature silicon, germanium, and tin atoms at the bridging positions. The electronic and structural properties of these complexes were probed by X-ray diffraction analysis, cyclic voltammetry, and by UV/Vis and EPR spectroscopy. The spectroscopic parameters for the strained and less strained complexes (i.e., with multiple-atom linkers) indicate that the unpaired electron resides primarily in a d_(z~2) orbital on chromium(I); this result was also supported by density functional theory (DFT) calculations. We did not observe a correlation between the experimental UV/Vis and EPR data and the degree of molecular distortion in these ansa complexes. The treatment of tin-bridged complex [Cr-(η~5-C_5H_4)(η~6-C_6H_5)SntBu_2] with [Pt-(PEt_3)_3] results in the non-regioselective insertion of the low-valent Pt~0 fragment into the C_(ipso)-Sn bonds in both the five- and six-membered rings, thereby furnishing a bimetallic complex. This observed reactivity suggests that ansa complexes of this type are promising starting materials for the synthesis of bimetallic complexes in general and also underline their potential to undergo ring-opening processes to yield new metal-containing polymers.
机译：由于其作为均相催化剂和含金属聚合物的前体的重要性，人们对ansa配合物的合成进行了深入研究。但是，顺磁性非金属茂衍生物很少见，并且仅限于钒和钛的例子。在这里，我们报告了一种有效的顺磁夹心复合物[Cr-（η〜5-C_5H_5）（η〜6-C_6H_6）]选择性脱锂的方法，该方法可以制备一系列[n]邻苯二酚[n] ，2、3）在桥连位置具有硅，锗和锡原子。这些配合物的电子和结构性质通过X射线衍射分析，循环伏安法以及UV / Vis和EPR光谱进行探测。应变和应变较小的配合物（即具有多个原子的连接子）的光谱参数表明，未配对的电子主要存在于铬（I）的d_（z〜2）轨道上。密度泛函理论（DFT）计算也支持该结果。我们没有观察到实验的UV / Vis和EPR数据与这些ansa配合物中的分子畸变程度之间存在相关性。用[Pt-（PEt_3）_3]处理锡桥复合物[Cr-（η〜5-C_5H_4）（η〜6-C_6H_5）SntBu_2]会导致低价Pt〜0的非区域选择性插入在五元环和六元环中都断裂成C_（ipso）-Sn键，从而形成双金属配合物。这种观察到的反应性表明，这种类型的ansa配合物通常是合成双金属配合物的有前途的原料，也强调了它们进行开环过程以产生新的含金属聚合物的潜力。

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