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相当数量的奇特反应,仅当有过渡金属络合物存在时才能发生。有机物分子若与过渡金属形成了络合物,它就完全改变了有机物的性质,并将发生很多与游离分子完全不同的反应。烯烃、多烯烃和芳烃能与多种金属形成络合物,并在碳碳偶联反应中,烯烃配体,多烯烃配体与亲核试剂的加成反应和亚烷基配体与亲核试剂的环加成反应都表现出高的区域选择性。络合金属促进的碳碳偶联反应的区域选择性不仅与络合配体本身的结构有关而且也与外界反应条件有关。这可用空间位阻效应解释,亦可从亲核
A significant amount of peculiar reactions occur only in the presence of transition metal complexes. If organic molecules form a complex with the transition metal, it completely alters the properties of the organics and will react quite differently than free molecules. Olefins, polyolefins, and aromatics are capable of forming complexes with a wide variety of metals and in the carbon-carbon coupling reaction, addition reactions of olefinic ligands, polyene ligands and nucleophiles and addition of alkylene ligands and nucleophiles Reagent cycloaddition reactions showed high regioselectivity. The regioselectivity of complex metal-promoted carbon-carbon coupling reactions is not only related to the structure of the complexing ligand itself but also to the external reaction conditions. This can be steric hindrance effect explained, but also from the nucleophilic