In ac omparative study of the electrocatalytic CO 2 reduction, cobalt meso-tetraphenylporphyrin(CoTPP) is used as am odel molecular catalyst under both homogeneous and heterogeneous conditions.Inthe former case,employing N,Ndimethylformamide as solvent, CoTPP performs poorly as an electrocatalyst giving low product selectivity in aslow reaction at ah igh overpotential. However,u pon straightforward immobilization of CoTPP onto carbon nanotubes,aremarkable enhancement of the electrocatalytic abilities is seen with CO 2 becoming selectively reduced to CO (> 90 %) at al ow overpotential in aqueous medium. This effect is ascribed to the particular environment created by the aqueous medium at the catalytic site of the immobilized catalyst that facilitates the adsorption and further reaction of CO 2 .T his work highlights the significance of assessing an immobilized molecular catalyst from more than homogeneous measurements alone.

Electrocatalysis is a promising tool for utilizing carbon dioxide as a feedstock in the chemical industry. However, controlling the selectivity for different CO2 reduction products remains a major challenge. We report a series of manganese carbonyl complexes with elaborated bipyridine or phenanthroline ligands that can reduce CO2 to either formic acid, if the ligand structure contains strategically positioned tertiary amines, or CO, if the amine groups are absent in the ligand or are placed far from the metal center. The amine-modified complexes are benchmarked to be among the most active catalysts for reducing CO2 to formic acid, with a maximum turnover frequency of up to 5500 s–1 at an overpotential of 630 mV. The conversion even works at overpotentials as low as 300 mV, although through an alternative mechanism. Mechanistically, the formation of a Mn–hydride species aided by in situ protonated amine groups was determined to be a key intermediate by cyclic voltammetry, 1H NMR, DFT calculations, and infrared spectroelectrochemistry.

Carbon dioxide utilization through electrocatalysis is a promising pathway toward a more sustainable future. In this work the electrocatalytic reduction of carbon dioxide by ReI and RuII bipyridine complexes bearing pendant amines (N,N′-(([2,2′-bipyridine]-6,6′-diylbis­(2,1-phenylene))­bis­(methylene))­bis­(N-ethylethanamine) (dEAbpy)) is evaluated. In both cases, the major reduction product is carbon monoxide accompanied by some formic acid, although the yield of the latter never reaches the predominant level known from the corresponding Mn­(dEAbpy)­(CO)3Br complex. This demonstrates the profound effect of the identity of the metal center, in addition to the ligand, for the product distribution. In this work, we report the synthesis procedures and X-ray diffraction studies along with electrochemical and infrared spectroelectrochemical studies of Re­(dEAbpy)­(CO)3Cl and Ru­(dEAbpy)­(CO)2Cl2 to propose a mechanism for the CO2 reduction reaction.

In ac omparative study of the electrocatalytic CO 2 reduction, cobalt meso-tetraphenylporphyrin(CoTPP) is used as am odel molecular catalyst under both homogeneous and heterogeneous conditions.Inthe former case,employing N,Ndimethylformamide as solvent, CoTPP performs poorly as an electrocatalyst giving low product selectivity in aslow reaction at ah igh overpotential. However,u pon straightforward immobilization of CoTPP onto carbon nanotubes,aremarkable enhancement of the electrocatalytic abilities is seen with CO 2 becoming selectively reduced to CO (> 90 %) at al ow overpotential in aqueous medium. This effect is ascribed to the particular environment created by the aqueous medium at the catalytic site of the immobilized catalyst that facilitates the adsorption and further reaction of CO 2 .T his work highlights the significance of assessing an immobilized molecular catalyst from more than homogeneous measurements alone.

Significant efforts have been devoted over the last few years to develop efficient molecular electrocatalysts for the electrochemical reduction of carbon dioxide to carbon monoxide, the latter being an industrially important feedstock for the synthesis of bulk and fine chemicals. Whereas these efforts primarily focus on this formal oxygen abstraction step, there are no reports on the exploitation of the chemistry for scalable applications in carbonylation reactions. Here we describe the design and application of an inexpensive and user-friendly electrochemical set-up combined with the two-chamber technology for performing Pd-catalysed carbonylation reactions including amino- and alkoxycarbonylations, as well as carbonylative Sonogashira and Suzuki couplings with near stoichiometric carbon monoxide. The combined two-reaction process allows for milligram to gram synthesis of pharmaceutically relevant compounds. Moreover, this technology can be adapted to the use of atmospheric carbon dioxide.