The one-step oxidation of benzene to phenol represents a significant and promising advancement in modern industries focused on the production of high-value-added chemical products. Nevertheless, challenges persist in achieving sufficient catalytic selectivity and preventing over-oxidation. Inspired by copper enzymes, we present a nonsymmetric dicopper complex ([Cu^II₂(TPMAN)(μ-OH)(H₂O)]³⁺, 1) for the selective oxidation of benzene to phenol. Utilizing H₂O₂ as the oxidant, complex 1 demonstrates remarkable catalytic activity (a TON of 14 000 within 29 hours) and selectivity exceeding 97%, comparable to the finest homogeneous catalyst derived from first-row transition metals. It is noteworthy that the significant substituent effect, alongside a negligible kinetic isotope effect (KIE = 1.05), radical trapping experiments, and an inconsistent standard selectivity test of the ˙OH radicals, all contradict the conventional Fenton mechanism and rebound pathway. Theoretical investigations indicate that the active Cu^II(μ-O˙)Cu^II–OH species generated through the cleavage of the O–O bond in the Cu^II(μ-1,1-OOH)Cu^I intermediate facilitates the hydroxylation of benzene via an electrophilic attack mechanism. The nonsymmetric coordination geometry is crucial in activating H₂O₂ and in the process of O–O bond cleavage.

中文翻译：

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使用非对称二铜催化剂通过 CuII（μ-O ̇）CuII 中间体将苯选择性羟基化为苯酚


苯一步氧化制苯酚代表了专注于生产高附加值化工产品的现代工业的一项重大且有前途的进步。然而，在实现足够的催化选择性和防止过度氧化方面仍然存在挑战。受铜酶的启发，我们提出了一种非对称二铜复合物 （[Cu ^II ₂ （TPMAN）（μ-OH）（H ₂ O）] ³⁺ ， 1），用于将苯选择性氧化成苯酚。利用 H ₂ O ₂ 作为氧化剂，配合物 1 表现出显着的催化活性（29 小时内 TON 为 14 000）和超过 97% 的选择性，可与来自第一排过渡金属的最佳均相催化剂相媲美。值得注意的是，显着的取代基效应，以及可忽略不计的动力学同位素效应 （KIE = 1.05）、自由基捕获实验和 ̇OH 自由基不一致的标准选择性测试，都与传统的 Fenton 机制和反弹途径相矛盾。理论研究表明，通过 Cu （μ-1,1-OOH） Cu 中间体中的 O-O 键裂解产生的活性 Cu ^II （μ-O ̇）Cu ^II -OH 物质促进了苯的羟基化。 ^II 非对称配位几何结构对于激活 H ₂ O ₂ 和 O-O 键裂解过程至关重要。