Organometallic Chemistry for Enabling Carbon Dioxide Utilization

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Organometallics, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.organomet.0c00229.In photosynthesis, carbon dioxide is used as the carbon source; indeed, most carbon atoms in the structure of a massive tree—the trunk, the branches, the leaves—originate from CO2. This insight has profound implications for chemical synthesis: complex molecular structures are built from something as simple and inert as CO2. Scientists have long been fascinated by this concept, and chemists have tried to reproduce it by generating artificial systems for the transformation of CO2 into more valuable products. Over the past two decades, chemical conversion of CO2 has developed into a major research field. Several comprehensive reviews have summarized advances on coupling CO2 with nucleophiles to form carboxylic acids, carbonates, or carbamates or on reducing CO2 to C1 species such as formate and methanol. The reviews of this field also emphasize an important point: chemical utilization of CO2 is not a strategy to mitigate climate change. CO2 is, however, a renewable carbon feedstock that can replace nonrenewable fossil-fuel-based starting materials. Therefore, methods for the efficient conversion of CO2 should be viewed as an integral part in the development of sustainable chemical processes. The 22 articles in this Special Issue highlight the many ways in which organometallic chemistry can help solve challenges related to CO2 utilization: organometallic complexes can be used in thermal, electrochemical, or photochemical conversion of CO2 to various products such as formate, carbon monoxide, carboxylic acids, acrylates, and polycarbonates. Remarkably, the work presented here involves the activation of CO2 with 15 different metals, including the first-row transition metals titanium, manganese, iron, cobalt, nickel, and copper, the second-row elements ruthenium and rhodium, the third-row species rhenium, platinum, and iridium, the actinide uranium, and the main-group metals cesium, magnesium, and aluminum. One may think, there are many roads to Rome; however, an important point is that the various metals have distinct strengths in terms of selectivity and activity for chemical CO2 utilization. The behavior of these different metals in CO2 conversion can further be modulated through introduction of different ligands

Improved Conditions for the Visible-Light Driven Hydrocarboxylation by Rh(I) and Photoredox Dual Catalysts Based on the Mechanistic Analyses

The improved catalytic conditions and detailed reaction mechanism of the visible-light driven hydrocarboxylation of alkenes with CO2 by the Rh(I) and photoredox dual catalysts were investigated. The use of the benzimidazoline derivative, BI(OH)H, as a sacrificial electron donor was found to increase the yield of the hydrocarboxylated product by accelerating the reduction process. In addition, the incorporation of the cyclometalated Ir(III) complex as a second photosensitizer with [Ru(bpy)3]2+ photosensitizer also resulted in the promotion of the reduction process, supporting that the catalytic cycle includes two photochemical elementary processes: photoinduced electron and energy transfers