Electrocatalytic hydrogen production by dinuclear cobalt(ii) compounds containing redox-active diamidate ligands: a combined experimental and theoretical study

Abstract

The chiral dicobalt(II) complex [CoII2(μ2-L)2] (1) (H2L = N2,N6-di(quinolin-8-yl)pyridine-2,6-dicarboxamide) and its tert-butyl analogue [CoII2(μ2-LBu)2] (2) were synthesized and structurally characterized. Addition of one equivalent of AgSbF6 to the dichloromethane solution...

Distinct Bimetallic Cooperativity Among Water Reduction Catalysts Containing [CoIIICoIII], [NiIINiII], and [ZnIIZnII] Cores

“…Post‐catalytic analysis supports the molecular nature of 1 . This cooperativity is predominantly structural, although as described by Papanikolaou et al [11] . the observed HS/LS spin switch may modulate the reactivity of the catalytic Co II site and add an electronic component to cooperativity.…”

“…Full scale 1 H NMR of 1 and details of Figures 3a-c are provided in the Supporting Information as Figures S3 to S6, along with a detailed list of peaks. From the COSY spectrum of 1, the signals at 2.03 ppm (39) and 4.27 ppm (11,15) show no correlation with other peaks, which confirms with the methyl and the aliphatic protons in the 1 H NMR spectrum, respectively. The peak at 3.47 ppm (7'',8'') on the other hand is coupled to the peak at 3.64 ppm (7', 8'), showing the correlation between protons in the aliphatic region ( 1 H NMR spectrum).…”

“…The neighboring HS Co center remains octahedral along the mechanistic path. A similar system by Papanikolaou et al [11] . included ligand‐based reduction with concomitant switch to low spin in both Co II ions.…”

“…The neighboring HS Co center remains octahedral along the mechanistic path. A similar system by Papanikolaou et al [11] included ligand-based reduction with concomitant switch to low spin in both Co II ions. The authors propose that the spin switch modulates the reactivity of the catalytic Co II adding an electronic component to the mostly structural cooperativity.…”

H2 Evolution from Electrocatalysts with Redox-Active Ligands: Mechanistic Insights from Theory and Experiment vis-à-vis Co-Mabiq

“…Adding to the complexity of the HER is that the intermediates and catalytic pathways can differ substantially among metal complexes based on the same or similar ligands. As noted above, thiosemicarbazone complexes operate via all of the aforementioned metal-assisted ligand-centered (Scheme a), ligand-assisted metal-centered (Scheme b), and ligand-centered (Scheme c) mechanisms, depending on the nature of the metal ion. ,, Ligand modifications, and/or the geometry of a complex, can likewise affect the catalytic pathways. ,, The mechanisms of many systems also can be switched by changes to the reaction conditions: changes in the acid strength affect the degree of ligand participation in the HER by metal hangman porphyrins, Rh-Cp, Fe-azadithiolate, and Co-polypyridyl complexes. ,,,,, …”