Direct hydrogenation of CO2 to CO, the reverse water-gas shift reaction, is an attractive route to CO2 utilization. However, the use of molecular catalysts is impeded by the general reactivity of metal hydrides with CO2. Insertion into M-H bonds results in formates (MO(O)CH), whereas the abnormal insertion to the hydroxycarbonyl isomer (MC(O)OH), which is the key intermediate for CO-selective catalysis, has never been directly observed. We here report that the selectivity of CO2 insertion into a Ni-H bond can be inverted from normal to abnormal insertion upon switching from thermal to photochemical conditions. Mechanistic examination for abnormal insertion indicates photochemical N-H reductive elimination as the pivotal step that leads to an umpolung of the hydride ligand. This study conceptually introduces metal-ligand cooperation for selectivity control in photochemical transformations.
CITATION STYLE
Schneck, F., Ahrens, J., Finger, M., Stückl, A. C., Würtele, C., Schwarzer, D., & Schneider, S. (2018). The elusive abnormal CO2 insertion enabled by metal-ligand cooperative photochemical selectivity inversion. Nature Communications, 9(1). https://doi.org/10.1038/s41467-018-03239-3
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