Lee Kevin Y C, Polyansky Dmitry E, Grills David C, Fettinger James C, Aceves Marcos, Berben Louise A
Department of Chemistry, University of California, Davis, California 95616, United States.
Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States.
ACS Org Inorg Au. 2024 Oct 4;4(6):649-657. doi: 10.1021/acsorginorgau.4c00041. eCollection 2024 Dec 4.
It is well-known that addition of a cationic functional group to a molecule lowers the necessary applied potential for an electron transfer (ET) event. This report studies the effect of a proton (a cation) on the mechanism of electrochemically driven hydride transfer (HT) catalysis. Protonated, air-stable [HFeN(triethyl phosphine (PEt))(CO)] (H) was synthesized by reaction of PEt with [FeN(CO)] ( ) in tetrahydrofuran, with addition of benzoic acid to the reaction mixture. The reduction potential of H4 is -1.70 V vs SCE which is 350 mV anodic of the reduction potential for . Reactivity studies are consistent with HT to CO or to H (carbonic acid), as the chemical event following ET, when the electrocatalysis is performed under 1 atm of CO or N, respectively. Taken together, the chemical and electrochemical studies of mechanism suggest an ECEC mechanism for the reduction of CO to formate or H to H, promoted by H. This stands in contrast to an ET, two chemical steps, followed by an ET (ECCE) mechanism that is promoted by the less electron rich catalyst , since must be reduced to before H can be accessed.
众所周知，在分子中添加阳离子官能团会降低电子转移（ET）事件所需的外加电势。本报告研究了质子（一种阳离子）对电化学驱动的氢化物转移（HT）催化机理的影响。通过在四氢呋喃中使三乙膦（PEt）与[FeN(CO)]（ ）反应，并向反应混合物中添加苯甲酸，合成了质子化的、空气稳定的[HFeN(三乙膦（PEt）)(CO)]（H）。H4的还原电势相对于饱和甘汞电极（SCE）为 -1.70 V，比 的还原电势正350 mV。反应性研究表明，当分别在1 atm的CO或N气氛下进行电催化时，作为ET后的化学事件，HT发生在CO或H（碳酸）上。综合来看，机理的化学和电化学研究表明，由H促进的将CO还原为甲酸盐或H还原为H的过程存在ECEC机理。这与由电子丰富度较低的催化剂 促进的ET、两个化学步骤，随后是ET（ECCE）机理形成对比，因为在能够得到H 之前， 必须先还原为 。
