The two-coordinate compound (IPr)Fe[N(SiMe₃)DIPP] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; DIPP = 2,6-diisopropylphenyl) catalyzes the cyclotrimerization of alkynes to arenes. Treatment of the Fe complex with 1 equiv of diphenylacetylene results in the formation of a bimetallic bridging alkyne complex, along with dissociation of IPr from Fe. At elevated temperatures, the bridging alkyne complex undergoes oxidative coupling to form a dimetallacyclopentadiene complex, formally by a one-electron oxidation at each metal center. Each complex catalyzes the cyclotrimerization of diphenylacetylene. Kinetic studies exhibit first-order dependence on the bimetallic complexes, providing further support for the presence of these species in the catalytic cycle. DFT calculations support the experimental mechanistic data and suggest that the catalytic cycle is completed by binding of an alkyne to the diene complex, followed by insertion to form a hexatriene species that then undergoes ring closure to form an inverse sandwich complex, [DIPP(Me₃Si)N]Fe(η⁶-arene)Fe[N(SiMe₃)DIPP]. The arene product is then displaced by alkyne to close the catalytic cycle.

中文翻译：

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二配位铁预催化剂进行炔烃环三聚的双金属机理

二配位化合物（IPr）Fe [N（SiMe ₃）DIPP]（IPr ＝ 1，3-双（2，6-二异丙基苯基）咪唑啉-2-亚烷基； DIPP ＝ 2，6-二异丙基苯基）催化炔烃向芳烃的环三聚。用1当量的二苯基乙炔处理Fe配合物会形成双金属桥联炔配合物，并伴随着IPr与Fe的解离。在升高的温度下，桥联炔络合物进行氧化偶联以形成双金属环戊二烯络合物，形式上是通过在每个金属中心进行单电子氧化。每种络合物催化二苯乙炔的环三聚。动力学研究显示出对双金属配合物的一阶依赖性，为这些物种在催化循环中的存在提供了进一步的支持。₃ Si）的N]的Fe（η ⁶ -arene）的Fe [N（森达₃）磷酰化。芳烃产物然后被炔烃置换以关闭催化循环。