Methane Generation from CO with a Molecular Rhenium Catalyst.

The atomic-level tunability of molecular structures is a compelling reason to develop homogeneous catalysts for challenging reactions such as the electrochemical reduction of carbon dioxide to valuable C-C products. Of particular interest is methane, the largest component of natural gas. Herein, we report a series of three isomeric rhenium tricarbonyl complexes coordinated by the asymmetric diimine ligands 2-(isoquinolin-1-yl)-4,5-dihydrooxazole (), 2-(quinolin-2-yl)-4,5-dihydrooxazole (), and 2-(isoquinolin-3-yl)-4,5-dihydrooxazole () that catalyze the reduction of CO to carbon monoxide and methane, albeit the latter with a low efficiency.

Elucidating the Solution-Phase Structure and Behavior of 8-Hydroxyquinoline Zinc in DMSO.

The solution-phase structure and electronic relaxation dynamics of zinc bis-8-hydroxyquinoline [Zn(8HQ)] in dimethyl sulfoxide (DMSO) were examined using a broad array of spectroscopic techniques, complimented by ab initio calculations of molecular structure. The ground-state structure was determined using extended X-ray absorption fine structure (EXAFS) data collected on the Zn K-edge and diffusion ordered spectroscopy (DOSY) NMR. The complex was found to be monomeric and octahedral, with two bidentate 8-hydroxyquinolate ligands and two DMSO molecules coordinated to the zinc through oxygen atoms.

Electrochemical Reduction of CO Catalyzed by Re(pyridine-oxazoline)(CO)Cl Complexes.

A series of rhenium tricarbonyl complexes coordinated by asymmetric diimine ligands containing a pyridine moiety bound to an oxazoline ring were synthesized, structurally and electrochemically characterized, and screened for CO reduction ability. The reported complexes are of the type Re(N-N)(CO)Cl, with N-N = 2-(pyridin-2-yl)-4,5-dihydrooxazole (1), 5-methyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (2), and 5-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (3). The electrocatalytic reduction of CO by these complexes was observed in a variety of solvents and proceeds more quickly in acetonitrile than in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

Electrocatalytic Reduction of CO2 by Group 6 M(CO)6 Species without "Non-Innocent" Ligands.

To understand the electrocatalytic CO2 reduction of metal carbonyl complexes without "non-innocent" ligands, the electrochemical responses of group 6 M(CO)6 (M = Cr, Mo, or W) and group 7 M2(CO)10 (M = Mn or Re) complexes were examined under Ar and CO2 at a glassy carbon electrode. All of the complexes showed changes in their cyclic voltammograms under CO2. The group 6 hexacarbonyl species show a significant increase in current under CO2 during metal-based reduction, corresponding to catalytic reduction of CO2.