A Novel Organometallic Polymer of Osmium(0), [Os(2,2′-bipyridine)(CO)2]n: Its Electrosynthesis and Electrocatalytic Properties Towards CO2 Reduction

Abstract

A new kind of organometallic polymer of osmium(0) [Os0(bpy)(CO)2]n (bpy = 2,2′‐bipyridine) has been prepared as a thin film on an electrode surface by electrochemical reduction of the mononuclear trans(Cl)‐[OsII(bpy)(CO)2Cl2] precursor complex. This modified electrode proves to be a good electrocatalyst for the reduction of CO2 in aqueous media.

Novel Complexes trans(Cl)-[Os(bpy)(CO)(CH3CN)Cl2]n (n = 0, +1; bpy = 2,2′-Bipyridine): Photo- and Electrochemical Syntheses and Comparative Study of Their Bonding and Redox Properties

“…The cyclic voltammogram (CV) of the photoproduct 2 dissolved in CH 3 CN/10 Ϫ1  TBAP indeed shows a completely reversible Os II /Os III redox couple at E 1/2 ϭ 0.45 V vs. Ag/Ag ϩ that is positioned less positively by 0.80 V than the one-electron oxidation of parent complex 1. [19] This observation agrees with the strong σ-donor ability of the CH 3 CN ligand compared to the expulsed π-acceptor carbonyl ligand, thereby stabilizing the formal osmium() oxidation state in 2 ϩ . Exhaustive oxidation of complex 2 at 0.55 V upon bulk electrolysis or within a thin-layer spectroelectrochemical cell produced the corresponding inherently stable cation 2 ϩ quantitatively.…”

“…[25] Unlike the completely irreversible reduction of the dicarbonyl precursor 1 in CH 3 CN electrolyte at room temperature and moderate cyclic voltammetric scan rates, [19] complex 2 is reduced under the same experimental conditions in a nearly chemically reversible one-electron step at E 1/2 ϭ Ϫ1.80 V (I pa /I pc ϭ 0.93 at v ϭ 100 mV s Ϫ1 ). As mentioned above, the π*(bpy) LUMO energy for complex 2 is slightly higher than complex 1, which is reversibly reduced at a less negative potential: E 1/2 Ϫ1.64 V (THF, 293 K) [19] and Ϫ1.62 V (PrCN, 273 K). Exhaustive electrolysis of 2 in acetonitrile at Ϫ1.90 V leads to the formation of a dark film, weakly adherent to the working electrode surface, together with a green solution containing 1 mol-equiv.…”

“…Apart from its synthesis and brief spectroscopic characterisation, [18] only a preliminary electrochemical study has recently been reported. [19] In addition, an analogous complex 1a with 4,4Ј-dimethyl-2,2Ј-bipyridine (dmb) was prepared as a precursor of the luminescent complex trans(SnPh 3 )-[Os(dmb)(CO) 2 (SnPh 3 ) 2 ]. [20Ϫ22] As a part of our continued studies of bonding properties and reactivity of complex 1 and its derivatives, we describe in the present work its charge-transfer photochemical reactivity [Equation (1)] and electrochemical oxidation [Equation (2)], both promoting CO substitution reaction by the donor solvent acetonitrile.…”

Heterosite Effects in Novel Heteronuclear Clusters [Os2Ru(CO)11(PPh3)] and [Os2Ru(CO)10(2‐acetylpyridine‐N‐isopropylimine)]

“…In agreement with the literature [31] and the results for [Os 3 (CO) 10 (α-diimine)], [60] this product is proposed to be the dinuclear complex [ [61][62][63][64] The interest in these open-chain polymers [M(CO) 2 (α-diimine)] n (M = Ru, Os) mainly derives from their electrocatalytic activity towards reduction of carbon dioxide. [63,[65][66][67] From the DFT results (Table 5, Figure 6) it is clear that the LUMO of cluster 3 is for about 65 % the lowest π*(iPrAcPy) orbital. Further, the LUMO has also got a nonnegligible σ*(Ru-Os2) character.…”

Voltammetric behaviour, homogeneous charge transport dynamics and electrocatalytic properties of an Os2+ functionalised pyrrole monomer

“…Modified electrodes that contain transition metal polypyridyl complexes have attracted a great deal of interest with their catalytic activities towards hydrogenation [1], photochemical reactions [2,3], oxidation of organics [4,5] and carbon dioxide reduction [6,7]. Also films containing these transition metal complexes have been employed in electroanalytic sensors [8][9][10].…”