DFT and TD-DFT calculations were performed to better understand the photosensitizer-free visible-light-mediated Au-catalyzed cross-coupling between aryldiazonium salts and arylboronic acids. The π–π type complex between the aryldiazonium salt and the arylboronic acid, rather than either the generally accepted gold(I)–aryldiazonium salt complex or the aryldiazonium salt itself, was shown to play the role of a virtual photoinitiator. The oxidation of Au(I) to Au(III), the key aspect of the dual gold/photoredox catalytic aryl–aryl cross-coupling, occurs via the radical addition of an aryl radical rather than an aryldiazo radical on Au(II) species. The transmetalation of the arylboronic acid to Au(III) species was identified as the rate-determining step, and the presence of a tetrafluoroborate anion can assist this process remarkably. The experimentally observed effect of substituents on the aryldiazonium salt and boronic acid on the reactivity was also rationalized.

中文翻译：

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π-π 配合物在芳基重氮盐和芳基硼酸之间使用无光敏剂金/光氧化还原催化的二芳基交叉偶联中的关键作用

进行 DFT 和 TD-DFT 计算以更好地了解无光敏剂的可见光介导的 Au 催化芳基重氮盐和芳基硼酸之间的交叉偶联。芳基重氮盐和芳基硼酸之间的 π-π 型络合物，而不是普遍接受的金 ( I )-芳基重氮盐络合物或芳基重氮盐本身，被证明起到了虚拟光引发剂的作用。Au( I )氧化为 Au( III )，这是双金/光氧化还原催化芳基-芳基交叉偶联的关键方面，通过在 Au( II ) 物种上的芳基自由基而不是芳基重氮自由基的自由基加成发生. 芳基硼酸向Au(III ) 物种被确定为决定速率的步骤，并且四氟硼酸盐阴离子的存在可以显着地帮助该过程。实验观察到的取代基对芳基重氮盐和硼酸对反应性的影响也得到了合理化。