Considering a Possible Role for [H-Fe₄N(CO)₁₂]^2– in Selective Electrocatalytic CO₂ Reduction to Formate by [Fe₄N(CO)₁₂]⁻

Abstract

Fe 4 N(CO) 12 ] − is a first-row transition element electrocatalyst that selectively produces C−H bonds to give formate from CO 2 in water at −1.2 V vs SCE. We present a thermochemical analysis which probes the possibility that [H-Fe 4 N(CO) 12 ] 2− ((H-1) 2− ) is an intermediate in this process: we show that (H-1) 2− is accessible at −1.2 V vs SCE, but if it were formed, we predict that it would generate H 2 .[Fe 4 N(CO) 12 ] 3− and (H-1) 2− were interrogated spectroscopically, and the product of CO loss, [Fe 4 N(CO) 9 (μ-CO) 2 ] 3− , was synthesized and characterized. Ultimately, we demonstrate that (H-1) 2− is an unlikely participant in the catalytic transformation of CO 2 to formate.

Quantum chemical studies of redox properties and conformational changes of a four-center iron CO2 reduction electrocatalyst

“… 47 The dissociation pathway was found using high temperature ab initio molecular dynamics and relaxed to the minimum energy path to calculate the activation barrier. 48 The calculations predict a structure of 2 3– in remarkable agreement with the X-ray crystal structure that was determined concurrently, 17 lending further confidence to the level of theory used in this study. We also compare the CO dissociation barrier height to the analogous reaction after only one reduction event: 1 2– → 2 2– + CO, and show that dissociation from this electronic state is energetically uphill, though the activation free energy of CO dissociation is similar in both states.…”

“…In an accompanying experimental work, the X-ray crystal structure of 2 3– is reported. 17 Simulations that uncover the mechanisms of side reactions are important to the overall strategy for designing molecular catalysts which are resistant to them. In this respect, this article describes the redox properties and CO dissociation pathway of this complex using computational quantum chemistry to complement the experimental findings and provide atomic-resolution insights.…”

Recent Trends, Benchmarking, and Challenges of Electrochemical Reduction of CO2 by Molecular Catalysts

“…A nonelectrochemical control experiment revealed that (H-1) − is the active form and not (1 − ). In a more recent follow-up study, Taheri et al [63] investigated the possible alternatives to the ECCE scheme proposed in Figure 26. Therefore, as an attempt to improve the hydricity, an analogous [H-Fe 4 N(CO) 12 ] 2− (H-1) 2− was synthesized.…”

“…To achieve this, the authors designed a control experiment where the number of pendant proton donors are varied in a series of Co-aminopyridine complexes. [63] Copyright 2018, American Chemical Society. Finally based on this Adv.…”

Making a Splash in Homogeneous CO2 Hydrogenation: Elucidating the Impact of Solvent on Catalytic Mechanisms

“…Berben reported solvent‐dependent product selectivity for electrocatalytic reduction of CO 2 using the iron cluster [Fe 4 (N)(CO) 12 ] − : high selectivity for formate (96 %) was observed in water, while H 2 was the major product in acetonitrile . Mechanistic studies identified a parallel between the product selectivity and hydricity of [HFe 4 (N)(CO) 12 ] − , a key catalytic intermediate . Hydride transfer from [HFe 4 (N)(CO) 12 ] − to CO 2 is exergonic (−9 kcal mol −1 ) in water, but endergonic (+5 kcal mol −1 ) in acetonitrile (Figure ).…”