Category: General

The latest issue of the journal Organometallics, published just yesterday, is a special issue on CO₂ conversion, with our own Assoc. Prof. Kathrin H. Hopmann as editor. Be sure to read the editorial she has written with Prof. N. Iwasawa from the Tokyo Institute of Technology and Prof. N. Hazari from Yale University !
She also designed the cover in collaboration with Dr. J. Darmon from Princeton University.

The article from Marc Obst, Ashot Gevorgyan, Annette Bayer, and Kathrin Hopmann on Copper-Catalyzed Carboxylations is also included in this issue. Congratulations!

Due to the spread of COVID19, we are postponing the Industry Panel  (Roskilde, Denmark) and Annual (Hveragerði, Iceland) meetings . Check our Activities page for updates and additional information.
Stay safe and see you when we see you!

Abstract
Carbon dioxide utilization through electrocatalysis is a promising pathway toward a more sustainable future. In this work the electrocatalytic reduction of carbon dioxide by Re^I and Ru^II 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.

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For a list of publications by the members of NordCO₂, see our Publications page!

Abstract
We have developed a carbonylative approach to the synthesis of diversely substituted 2-aroylbenzoate esters featuring a new protocol for the carbonylative coupling of aryl bromides with boronic acids and a new strategy to favour carbonylative over non-carbonylative reactions. Two different synthetic pathways – (i) the alkoxycarbonylation of 2-bromo benzophenones and (ii) the carbonylative Suzuki–Miyaura coupling of 2-bromobenzoate esters – were evaluated. The latter approach provided a broader substrate tolerance, and thus was the preferred pathway. We observed that 2-substituted aryl bromides were challenging substrates for carbonylative chemistry favouring the non-carbonylative pathway. However, we found that carbonylative Suzuki–Miyaura couplings can be improved by slow addition of the boronic acid, suppressing the unwanted direct Suzuki coupling and, thus increasing the yield of the carbonylative reaction.

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For a list of publications by the members of NordCO₂, see our Publications page!

Abstract
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.

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For a list of publications by NordCO2 members, see our Publications page!