Copper-catalyzed electrochemical atom transfer radical addition (eATRA) is a new method for the creation of new C–C bonds under mild conditions. In this work, we have explored the reactivity of an analogous series of N₄ macrocyclic Cu^II complexes as eATRA precatalysts, which are primed by reduction to their monovalent oxidation state. These complexes were fully characterized structurally, spectroscopically, and electrochemically. A spectrum of radical activation reactivity was found across the series [Cu^I(Me₄cyclen)(NCMe)]⁺ (Me₄cyclen = 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane), [Cu^I(Me₄cyclam)(NCMe)]⁺ (Me₄cyclam = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), and [Cu^I(Me₂py₂clen)(NCMe)]⁺ (Me₂py₂clen = 3,7-dimethyl-3,7-diaza-1,5(2,6)-dipyridinacyclo-octaphane). The rate of radical production by [Cu(Me₂py₂clen)(NCMe)]⁺ was modest, but rapid radical capture to form the organocopper complex [Cu^I(Me₂py₂clen)(CH₂CN)] led to a dramatic acceleration in catalysis, greater than seen in any comparable Cu complex, but this led to rapid radical self-termination instead of radical addition.

中文翻译：

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大环铜(II)配合物作为电化学介导原子转移的催化剂

铜催化电化学原子转移自由基加成（e ATRA）是一种在温和条件下创建新C-C键的新方法。在这项工作中，我们探索了一系列类似的 N ₄大环 Cu ^II配合物作为e ATRA 预催化剂的反应性，这些配合物通过还原至单价氧化态而引发。这些配合物在结构、光谱和电化学方面得到了充分的表征。在 [Cu ^I (Me ₄循环)(NCMe)] ⁺ (Me ₄循环 = 1,4,7,10-四甲基-1,4,7,10-四氮杂环十二烷)系列中发现了自由基活化反应谱， [Cu ^I (Me ₄ cyclam)(NCMe)] ⁺ (Me ₄ cyclam = 1,4,8,11-四甲基-1,4,8,11-四氮杂环十四烷)和[Cu ^I (Me ₂ py ₂ clen) (NCMe)] ⁺ (Me ₂ py ₂ clen = 3,7-二甲基-3,7-二氮杂-1,5(2,6)-二吡啶环辛烷)。 [Cu(Me ₂ py ₂ clen)(NCMe)] ⁺产生自由基的速率适中，但快速自由基捕获形成有机铜络合物 [Cu ^I (Me ₂ py ₂ clen)(CH ₂ CN)] 导致催化的急剧加速，比任何类似的铜络合物都要快，但这导致快速自由基自终止而不是自由基加成。