Manganese and Rhenium Tricarbonyl Complexes Equipped with Proton Relays in the Electrochemical CO₂ Reduction Reaction

Abstract

The minireview focuses on the electrochemical CO2 reduction catalysed by manganese and rhenium tricarbonyl complexes with α‐diimine ligands having pendant proton relays attached to the α‐diimine ligand. Since the pioneering work on [Re(CO)3(Lbpy)Cl], 1Cl, as molecular electrocatalyst in the CO2 reduction reaction in the 80's, some effort has been made to understand the mechanism of the catalytic cycle and to improve the efficiency of the conversion (Lbpy = 2,2'‐bipyrdine). Later it was shown that the corresponding Mn complex, [Mn(CO)3(Lbpy)Br], 2Br, is also active in the CO2‐to‐CO conversion. As the 2 electrons reduction of CO2 is coupled to the transfer of 2 protons, pendent proton relays have been introduced in the ligand framework with the aim to improve the proton management during catalysis, to stabilize intermediates, and to alter the redox and the pH‐dependent properties of the catalyst. We summarise in this review the outcome of these studies on the performance of the catalyst, in particular, with regard to the position of the proton relay and thus, its influence on the electronic structure, the reaction steps, and the kinetics.

Promoting photocatalytic CO2 reduction through facile electronic modification of N-annulated perylene diimide rhenium bipyridine dyads

“…10 The versatile bpy ligand has been modified with a variety of substituents to change both the electronic properties and/or the second-sphere H-bonding character of the catalyst. [11][12][13][14][15][16][17][18] And while Re(bpy) alone can be used as an effective CO 2 reduction photocatalyst, [19][20][21][22][23][24] the photocatalytic CO 2 reduction performance is greatly enhanced via the direct functionalization of Re(bpy) with photosensitizing (PS) units. [25][26][27][28][29][30][31] The development of ruthenium(II) diimine photosensitized Re(bpy) supramolecular dyads has been extensively reported by the Ishitani group.…”

Investigation of Cyclam Based Re‐Complexes as Potential Electrocatalysts for the CO2 Reduction Reaction

“…[23,24] In order to further understand the electrocatalytic CO 2 RR performance of complex 1 a broad variety of modulations of the bpy ligand and furthermore substitutions of bpy for comparable ligand platforms (e. g. pyNHC, pypz, pyiz) were investigated. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Among the large number of modified rhenium complexes and within the most studied class, the 4,4'substituted bpy rhenium complexes, the t Bu-derivative Re-(bpy-t Bu)(CO) 3 Cl (bpy-t Bu = 4,4'-di-tert-butyl-2,2'-bipyridine) is particularly noteworthy.…”

Click-Derived Triazoles and Triazolylidenes of Manganese for Electrocatalytic Reduction of CO2

“…In 2011, Deronzier and co-workers demonstrated for the first time the electrochemical reduction of CO 2 mediated by fac-[Mn(bpy)(CO) 3 Br] (bpy = 2,2-bipyridine) complexes [12]. Later, several groups have investigated in detail the electrocatalytic activity of related pyridine-based Mn complexes [13][14][15][16][17]. The replacement of the bipyridyl ligand by mixed pyridyl-N-heterocyclic carbene ligands (NHC) has been explored by the Agarwal group (Scheme 1).…”