We present a Pt-catalyzed direct coupling of benzene to biphenyl. This catalytic reaction employs a cyclometalated platinum(ii) complex [PtMe(bhq)(SMe2)] (bhq = benzo[h]quinolate) with PhI(OAc)2 as an oxidant and does not require an acid, a co-catalyst or a solvent. The reaction kinetics and characterization of potential catalytic species are reported. The reaction is first-order in Pt and second-order in benzene, which implicates the second C-H activation step as rate-determining. A Pt(ii)/Pt(iv) catalytic cycle is suggested. The reaction commences by oxidation of the Pt(ii) complex to give the platinum(iv) species [Pt(bhq)(SMe2)(OAc)2](OAc) followed by C-H activation of benzene to afford the intermediate [PtPh(bhq)(SMe2)(OAc)](OAc) concurrently with the release of HOAc. A second benzene molecule reacts similarly to give the diphenyl intermediate [PtPh2(bhq)(SMe2)](OAc). C-C bond forming reductive elimination ensues to regenerate Pt(ii) and complete the catalytic cycle. The proposed mechanism has been examined by DFT computations, which provide support to experimental findings.

中文翻译：

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苯与PhI（OAc）2的苯催化Pt氧化均偶联的发现和机理研究。

我们提出苯到联苯的Pt催化直接偶联。该催化反应使用环金属化的铂（ii）络合物[PtMe（bhq）（SMe2）]（bhq =苯并[h]喹啉酸酯），用PhI（OAc）2作为氧化剂，不需要酸，助催化剂或溶剂。报道了反应动力学和潜在催化物质的表征。该反应在Pt中是一级反应，在苯中是二级反应，这意味着第二个CH活化步骤决定了速率。建议使用Pt（ii）/ Pt（iv）催化循环。反应开始于氧化Pt（ii）络合物，得到铂（iv）物种[Pt（bhq）（SMe2）（OAc）2]（OAc），然后CH活化苯，得到中间体[PtPh（bhq ）（SMe2）（OAc）]（OAc）与HOAc的发布同时进行。第二个苯分子以类似的方式反应，生成二苯中间体[PtPh2（bhq）（SMe2）]（OAc）。随后形成CC键的还原性消除使Pt（ii）再生并完成催化循环。提议的机制已通过DFT计算进行了检验，为实验结果提供了支持。