配体交换在分子催化调节中的重要性：氧化亚氮与铼联吡啶羰基络合物的电化学还原机制,ACS Catalysis

当前位置： X-MOL 学术 › ACS Catal. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

配体交换在分子催化调节中的重要性：氧化亚氮与铼联吡啶羰基络合物的电化学还原机制
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-06-06 , DOI: 10.1021/acscatal.3c01495
Rana Deeba ₁ , Sylvie Chardon-Noblat ₁ , Cyrille Costentin ₁

Affiliation

涉及过渡金属络合物作为催化剂的电化学反应的分子催化需要获得自由金属配位点以结合底物。这意味着作为反应产物或副产物产生的强配位配体可能不利于有效催化，因为它可以结合金属中心并阻断或减慢催化过程。通过对氧化亚氮与铼联吡啶基三羰基配合物 [Re(bpy)(CO) 3 X] n + (X = CH 3 CN) 的电化学还原机制的彻底光谱电化学研究，揭示_和说明^了这种自_调节现象, 氯^- , ñ= 0 或 1) 作为催化剂。我们表明，双还原的 [Re ⁰ (bpy ^•– )(CO) ₃ ] ⁻由 [Re(bpy)(CO) ₃ X] ^{n +}电生成，很容易与 N ₂ O 反应并产生羟基络合物 [ Re ^I (bpy)(CO) ₃ (OH)]。由于反应产物氢氧化物是比乙腈或氯化物更强的配位配体，因此在 [Re ⁰ (bpy ^•– )(CO) ₃ ] ⁻由 [Re(bpy) (CO) ₃ X] ^{n +}. ^{大量催化仅在对应于 [Re I} (bpy)(CO) ₃ (OH)]的第二次还原的电位下触发。尽管如此，我们表明，单还原的 [Re ^I (bpy ^•– )(CO) ₃ X] ⁽ⁿ⁻¹⁾⁺ (X = CH ₃ CN, Cl ^{– ) 对 N}₂ O 的内层还原速度较慢，原因是乙腈和氯化物在这些物种中的不稳定性。由于氢氧化物不太不稳定并且不能被置换以创建 N 2 O 的开放配位位置_，_因此单还原的 [Re ^I (bpy^•– )(CO) ₃ (OH)] ⁻发生。然而，我们最终证明过量的游离氯化物能够取代氢氧化物，然后为更快的内球过程开辟道路。这个非凡的例子强调了配体交换在调节以过渡金属络合物为催化剂的电化学反应的分子催化中的关键作用，这可能是一种普遍现象。

"点击查看英文标题和摘要"

Importance of Ligand Exchange in the Modulation of Molecular Catalysis: Mechanism of the Electrochemical Reduction of Nitrous Oxide with Rhenium Bipyridyl Carbonyl Complexes

Molecular catalysis of electrochemical reactions involving transition-metal complexes as catalysts requires getting a free metal coordination site to bind the substrate. It implies that the generation of a strong coordinating ligand as a product or coproduct of the reaction might be detrimental for an efficient catalysis because it can bind the metal center and block or slow down the catalytic process. This self-modulation phenomenon is revealed and illustrated via a thorough spectro-electrochemical investigation of the mechanism of the electrochemical reduction of nitrous oxide with rhenium bipyridyl triscarbonyl complexes [Re(bpy)(CO)₃X]ⁿ⁺ (X = CH₃CN, Cl^–, n = 0 or 1) as a catalyst. We show that the bi-reduced [Re⁰(bpy^•–)(CO)₃]⁻, electrogenerated from [Re(bpy)(CO)₃X]ⁿ⁺, readily reacts with N₂O and produces the hydroxo complex [Re^I(bpy)(CO)₃(OH)]. Because hydroxide, a product of the reaction, is a stronger coordinating ligand than acetonitrile or chloride, catalysis does not occur significantly at a potential where [Re⁰(bpy^•–)(CO)₃]⁻ is generated from [Re(bpy)(CO)₃X]ⁿ⁺. Substantial catalysis is only triggered at a potential corresponding to the second reduction of [Re^I(bpy)(CO)₃(OH)]. Nonetheless, we show that a slower innersphere reduction of N₂O by the mono-reduced [Re^I(bpy^•–)(CO)₃X]⁽ⁿ⁻¹⁾⁺ (X = CH₃CN, Cl^–) occurs due to the lability of acetonitrile and chloride in these species. Because hydroxide is less labile and cannot be displaced to create an open coordination position for N₂O, only an even slower outersphere reduction of N₂O by the mono-reduced [Re^I(bpy^•–)(CO)₃(OH)]⁻ takes place. However, we finally show that an excess of free chlorides is able to displace hydroxide and then open the way for a faster innersphere process. This remarkable example emphasizes the critical role of ligand exchange in modulating molecular catalysis of electrochemical reactions with transition-metal complexes as catalysts, a likely general phenomenon.

更新日期：2023-06-06

点击分享查看原文

点击收藏

阅读更多本刊最新论文本刊介绍/投稿指南

全部期刊列表>>