Precise regulation of the active site of molecular catalysts is appealing because it could catch a glimpse of the catalytic mechanism and possibly provide a new strategy for catalyst design. A ruthenium complex [Ru(dpp_{Me, COMe})(bipy)(Cl)] (CSU-3) containing -Me and -COMe substituted dipyridylpyrrole as pincer ligand was designed and synthesized. Complex CSU-3 featured the Cl- ligand at axial position as active site for ammonia oxidation (AO), which is structurally analogous with AO catalyst [Ru(trpy)(dmabpy)(NH3)][PF6]2 (1) bearing terpyridine ligand, but is different from AO catalyst [Ru(dpp)(bipy)(NH₃)] (CSU-2) containing unsubstituted dipyridylpyrrole as hemilabile ligand with active site at equatorial position. To insight into the role of active-site and ligand regulation in AO reaction, structure, electrochemical properties of CSU-3 and its catalytic performance and mechanism for AO reaction are comparably studied. Complex CSU-3 has good selective catalytic perforamnce for oxidation of ammonia to hydrazine with turnover frequency (TOF) of 258.8 h^-1 and N₂H₄ formation selectivity of 84.7% at Eapp of 1.0 V . The DFT calculation reveal N₂H₄ as a dominant product is generated via an ammonia nucleophilic attack of Ruthenium(IV)-imide to form N₂H₄ followed by N₂H₄-by-NH₃ substitution

中文翻译：

---

了解控制单核钌配合物氧化反应的因素


精确调控分子催化剂的活性位点很有吸引力，因为它可以窥见催化机制，并可能为催化剂设计提供新的策略。设计合成了含有 -Me 和 -COMe 取代的二吡啶吡咯作为钳形配体的钌配合物 [Ru（dpp_{Me， COMe}）（bipy）（Cl）] （CSU-3）。复合物 CSU-3 的轴向位置的 Cl- 配体作为氨氧化 （AO） 的活性位点，其结构类似于 AO 催化剂 [Ru（trpy）（dmabpy）（NH3）][PF6]2 （1） 携带三吡啶配体，但不同于含有未取代的二吡啶吡咯作为半半配体的 AO 催化剂 [Ru（dpp）（bipy）（NH₃）] （CSU-2） 在赤道位置具有活性位点。为了深入了解活性位点和配体调控在 AO 反应中的作用，对 CSU-3 的结构、电化学性质及其催化性能和 AO 反应机理进行了比较研究。复合物 CSU-3 对氨氧化成肼具有良好的选择性催化渗透，周转频率 （TOF） 为 258.8 ^h-1，N ₂H₄ 形成选择性为 84.7%，在 1.0 V 的 Eapp 下。DFT 计算显示，N₂H₄ 作为主要产物是通过钌 （IV） -酰亚胺的氨亲核攻击形成 N₂H₄，然后是 N₂H₄ by-NH₃ 取代而产生