Reduction of CO2 using a rhenium bipyridine complex containing ancillary BODIPY moieties

Abstract

The reduction of carbon dioxide to chemical fuels such as carbon monoxide is an important challenge in the field of renewable energy conversion. Given the thermodynamic stability of carbon dioxide, it is difficult to efficiently activate this substrate in a selective fashion and the development of new electrocatalysts for CO2 reduction is of prime importance. To this end, we have prepared and studied a new fac-ReI(CO)3 complex supported by a bipyridine ligand containing ancillary BODIPY moieties ([Re(BB2)(CO)3Cl]). Voltammetry experiments revealed that this system displays a rich redox chemistry under N2, as [Re(BB2)(CO)3Cl] can be reduced by up to four electrons at modest potentials. These redox events have been characterized as the ReI/0 couple, and three ligand based reductions – two of which are localized on the BODIPY units. The ability of the BB2 ligand to serve as a non-innocent redox reservoir is manifest in an enhanced electrocatalysis with CO2 as compared to an unsubstituted Re-bipyridine complex lacking BODIPY units ([Re(bpy)(CO)3Cl]). The second order rate constant for reduction of CO2 by [Re(BB2)(CO)3Cl] was measured to be k = 3400 M−1s−1 at an applied potential of −2.0 V versus SCE, which is roughly three times greater than the corresponding unsubstituted Re-bipyridine homologue. Photophysical and photochemical studies were also carried out to determine if [Re(BB2)(CO)3Cl] was a competent platform for CO2 reduction using visible light. These experiments showed that this complex supports unusual excited state dynamics that precludes efficient CO2 reduction and are distinct from those that are typically observed for fac-ReI(CO)3 complexes.

Mesoporous Silica Micromotors with a Reversible Temperature Regulated On–Off Polyphosphazene Switch

“…In most of the reported systems, Pt metal has been widely used as catalyst, though here we selected cobalt as a potential low‐cost alternative in our design of micromotors. The cobalt bipyridine complex formation within the pores of the microparticles MP‐SiBPy was carried out as reported in literature, yielding the material MP‐SiBPy‐Co . The coordination between the anchored ligand sites (SiBPy) and cobalt acetate was formed under reflux in toluene.…”

Push or Pull? Proton Responsive Ligand Effects in Rhenium Tricarbonyl CO2 Reduction Catalysts

“…The fac-[Re(α-diimine)(CO) 3 X] n+ (X = halide; n = 0 or X = neutral ligand, n = 1) family of complexes selectively catalyzes the reduction of CO 2 to CO. [7][8][9][10][11][12][13][14][15][16][17][18][19] Electrocatalysis is effective in solution and using surface-bound catalysts while photochemical systems have been identified with or without separate sensitizers. Mechanistic studies have revealed one-electron or two-electron pathways for catalysis.…”

Electrochemically induced transformations of bi- and trinuclear heterometallic vinylidene complexes containing Re, Pd and Fe

“…Heterometallic complexes and clusters have attracted considerable attention since they exhibit catalytic properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and, therefore, may serve as model systems for understanding the rearrangements of organic molecules on polymetallic surfaces [18][19][20]. Indeed, polynuclear metal species exhibit the ability to change the chemical properties of the coordinated ligands and, thus, to activate new rearrangements as a consequence of the cooperativity effects of the metal centers working in concert [21][22][23][24][25].…”

“…The results of the electrochemical study of binuclear μ-vinylidene complexes Cp(CO) 2 MnM(-C=CHPh)LL (M = Pt, Pd, L, L = CO, P(OPr-i) 3, PPh 3, P(OPh) 3 , L-L = Ph 2 P(CH 2 ) n PPh 2 , n = 1 (dppm), 2 (dppe), 3 (dppp)) [52][53][54][55][56][57], Cp(CO) 2 RePt(μ-C 1 =C 2 HPh)L 2 (L 2 = 2 PPh 3 , dppm, dppe, dppp) [58], dimeric compounds [Cp(CO) 2 M(µ-C=CHPh)CuCl] 2 (M = Mn, Re) [59][60][61] and trinuclear clusters CpMnFePt( 3 -C=CHPh)(CO) 5 LL ' (L, L ' = CO, PPh 3 , P(OPr-i) 3 , L-L = dppm) [53][54][55][56] were reported in our previous papers. The redox properties of vinylidene clusters ( 3 -C=CHPh)FeCo 2 (CO) 7 dppm, ( 3 -C=CHPh)FeCo 2 (CO) 9 [62,63].…”