Photocatalytic Hydrogen Evolution by tris-dithiolene tungsten complexes

Abstract

Herein, we report on the homogeneous photocatalytic evolution of hydrogen by using as reductive catalysts the prismatic symmetric tris -dithiolene complexes of the tungsten, namely [W{S 2 C 2 (Ph) 2 } 3 ] (1) and its monoanion [W{S 2 C 2 (Ph) 2 } 3 ](TBA) (2). Complex 2 is fully characterized by elemental analysis, ESI-MS, IR, UV-Vis and fluorescence spectrophotometry as well as cyclic voltammetry. The photocatalytic system consists of [ReBr(CO) 3 (bpy)] as a photosensitizer, triethanolamine as a sacrificial electron donor and acetic acid as the proton source. Although the activity of the photocatalytic system is rather small (TON=18), it indicates that the homoleptic tris dithiolene complexes can act as proton reductive catalysts with their monoanion form to be more active in accordance with the findings for the bis -dithiolene complexes.

Formate Dehydrogenase Mimics as Catalysts for Carbon Dioxide Reduction

“…Until now, most dithiolene complexes studied for their catalytic activity have been tested for the reduction of protons into H 2 [40,[44][45][46][47][48][49][50][51]. In the first part, we will focus on a few examples of tungsten or molybdenum-bis(dithiolene) complexes that were shown to react with carbon dioxide.…”

Addition of Re‐Bonded Nucleophilic Ligands to Activated Alkynes: A Theoretical Rationalization

“…Rhenium(I) tricarbonyl complexes of the general formula fac-[Re(CO)3(N-N)L] n , where N-N is a 2,2'-bipyridine or 1,10phenanthroline-based diimine ligand and L is neutral (n = +1) or anionic (n = 0) monodentate ligand, are involved in numerous, diverse, and important applications. Among others, that kind of Re compounds has been investigated as photocatalysts and/or electrocatalysts for reducing CO2 and H + (1-16 in Scheme 1), [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] molecular sensors or photoswitches (16)(17)(18)(19)(20) in Scheme 1), [19][20][21][22][23][24][25][26] emitting centers in organic light-emitting diodes (1,11,12,17,18, and 21-23 in Scheme 1), [27] anticancer agents (15 and 24-34 in Scheme 1), [28][29][30][31][32][33][34] cellular and biomolecular imaging agents (1, 2, and 35-39 in Scheme 1), [35]…”

Photocatalytic and electrocatalytic hydrogen production with dithiolene complexes

“…A catalyst is the molecule responsible for the chemical transformation of reactants into products by lowering energy barriers via alternative reaction pathways. Several complexes have proved suitable catalysts towards hydrogen evolution, mainly cobaloximes [62,63], corroles [64], diphosphine complexes [65], and dithiolene complexes [34,59,[66][67][68][69][70]. Most of these catalysts combine middle-transition elements with a relatively robust ligand framework able to sustain the demanding catalytic conditions (different pH values, protonation, solvolysis, etc).…”

“…The overall better activity of the nickel catalyst versus the cobalt was attributed to the greater emission quenching constant of eosin Y by the nickel complex (5.7 x 10 12 vs 2.5 x 10 12 for the cobalt catalyst). Koutsouri and Mitsopoulou [70] reported on a tungsten tris-dithiolene complex and its monoanion that were active hydrogen evolving catalysts.…”