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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Chiral copper-bipyridine complexes: Synthesis, characterization and mechanistic studies on asymmetric cyclopropanation
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Chiral copper-bipyridine complexes: Synthesis, characterization and mechanistic studies on asymmetric cyclopropanation

机译：手性铜联吡啶配合物：不对称环丙烷化反应的合成，表征及机理研究

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摘要

Chiral bipyridine ligands of different steric properties when reacted with CuCl_2 formed orange, yellow or green solids of new copper(II) complexes, [Cu(L)Cl_2] (L = L2-6), in good yield. Together with [Cu(L_1)Cl_2], these complexes were characterized in solution by UV-Vis spectroscopy and cyclic voltammetry. The complexes give d-d transitions between 860 and 970 nm, and exhibit one quasi-reversible Cu(II)/Cu(I) couple between +0.405 V and +0.516 V versus NHE. Two of the copper(II) complexes, [Cu(L_5)Cl_2] and [Cu(L_6)Cl_2], and a copper(I) complex of L1, [Cu(L_1)Cl], were characterized by X-ray crystallography. The triflate derivatives of both the Cu(I) and Cu(II) complexes are active catalysts towards the cyclopropanation of ethyl diazoacetate with styrene. The asymmetric induction suffers when the size difference between the alkyl and alkoxyl groups was minimized. The mechanism of the cyclopropanation was studied with kinetic and competition experiments. The rate is first order in catalyst and ethyl diazoacetate, inverse order with styrene and is strongly affected by the counterion.
机译：当与CuCl_2反应时，具有不同空间性质的手性联吡啶配体形成了新的铜（II）配合物[Cu（L）Cl_2]（L = L2-6）的橙色，黄色或绿色固体，收率很高。这些配合物与[Cu（L_1）Cl_2]一起通过紫外-可见光谱和循环伏安法在溶液中表征。配合物在860和970 nm之间产生d-d跃迁，并且相对NHE表现出一个在+0.405 V和+0.516 V之间的准可逆Cu（II）/ Cu（I）偶联。通过X射线晶体学表征了两个铜（II）配合物[Cu（L_5）Cl_2]和[Cu（L_6）Cl_2]和L1的铜（I）配合物[Cu（L_1）Cl]。 。 Cu（I）和Cu（II）配合物的三氟甲磺酸酯衍生物是重氮乙酸乙酯与苯乙烯环丙烷化的活性催化剂。当烷基和烷氧基之间的大小差异最小化时，不对称感应受到影响。通过动力学和竞争实验研究了环丙烷化的机理。该速率在催化剂和重氮乙酸乙酯中为一级，与苯乙烯相反，并且受抗衡离子的影响很大。

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