mono-transposition generates E- or Z-olefins depending on the steric properties and denticity of the ligand employed. Mechanistic studies reveal that the aryl iodide additive acts as a redox buffer for nickel in the Z-selective reaction, generating the most-selective NiII–H that outcompetes a less Z-selective NiI–H species. For the E-selective reaction, the phosphonium salt plays a dual role as an acid
镍催化的动态烯烃单转位根据所用
配体的空间性质和齿数产生E-或Z-烯烃。机理研究表明,芳基
碘化物添加剂在Z选择性反应中充当
镍的氧化还原缓冲剂,生成选择性最高的 Ni II -H,从而击败Z选择性较低的 Ni I -H 物种。对于E-选择性反应,
鏻盐起到酸和
配体的双重作用,原位形成膦结合的阳离子Ni−H催化剂。