Herein, we report the synthesis and characterization of two manganese tricarbonyl complexes, Mn (HL)(CO) Br (1 a-Br) and Mn (MeL)(CO) Br (1 b-Br) (where HL=2-(2'-pyridyl)benzimidazole; MeL=1-methyl-2-(2'-pyridy)benzimidazole) and assayed their electrocatalytic properties for CO reduction. A redox-active pyridine benzimidazole ancillary ligand in complex 1 a-Br displayed unique hydrogen atom transfer ability to facilitate electrocatalytic CO conversion at a markedly lower reduction potential than that observed for 1 b-Br. Notably, a one-electron reduction of 1 a-Br yields a structurally characterized H-bonded binuclear Mn(I) adduct (2 a') rather than the typically observed Mn(0)-Mn(0) dimer, suggesting a novel method for CO activation.
View Article and Find Full Text PDFElectrocatalytic reduction of carbon dioxide (CO) by transition-metal catalysts is an attractive means for storing renewably sourced electricity in chemical bonds. Metal coordination compounds represent highly tunable platforms ideal for studying the fundamental stepwise transformations of CO into its reduced products. However, metal complexes can decompose upon extended electrolysis and form chemically distinct molecular species or, in some cases, catalytically active electrode deposits.
View Article and Find Full Text PDFThe non-innocence of diamidodipyrrin is explored in a series of cobaltous complexes with novel binding motifs. By varying the coordination modes, a reversible one-electron reduction is remarkably shifted by nearly 200 mV in a single metal-ligand platform. Our study illustrates a new strategy for modifying the redox activity of porphyrin-like scaffolds.
View Article and Find Full Text PDFThe recent finding that hydropersulfides (RSSH) are biologically prevalent in mammalian systems has prompted further investigation of their chemical properties in order to provide a basis for understanding their potential functions, if any. Hydropersulfides have been touted as hyper-reactive thiol-like species that possess increased nucleophilicity and reducing capabilities compared to their thiol counterparts. Herein, using persulfide generating model systems, the ability of RSSH species to act as one-electron reductants has been examined.
View Article and Find Full Text PDFThe recent discovery of significant hydropersulfide (RSSH) levels in mammalian tissues, fluids and cells has led to numerous questions regarding their possible physiological function. Cysteine hydropersulfides have been found in free cysteine, small molecule peptides as well as in proteins. Based on their chemical properties and likely cellular conditions associated with their biosynthesis, it has been proposed that they can serve a protective function.
View Article and Find Full Text PDFRecent reports indicate the ubiquitous prevalence of hydropersulfides (RSSH) in mammalian systems. The biological utility of these and related species is currently a matter of significant speculation. The function, lifetime and fate of hydropersulfides will be assuredly based on their chemical properties and reactivity.
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