CO2‐Reduktion Harnstoffgruppen in einem Eisenporphyrinkatalysator führen zu einer mehrfachen Stabilisierung von CO2 durch Wasserstoffbrücken. Wie Z. Halime, A. Aukauloo et al. in ihrer Zuschrift auf S. 4552 zeigen, hat der Katalysator eine hohe Aktivität in der CO2‐Reduktion.

An efficient and selective four-electron plus four-proton (4e − ∕4H þ ) reduction of O 2 to water by decamethylferrocene and trifluoroacetic acid can be catalyzed by a synthetic analog of the heme a 3 ∕Cu B site in cytochrome c oxidase ( 6 LFeCu) or its Cu-free version ( 6 LFe) in acetone. A detailed mechanistic-kinetic study on the homogeneous catalytic system reveals spectroscopically detectable intermediates and that the rate-determining step changes from the O 2 -binding process at 25°C room temperature (RT) to the O-O bond cleavage of a newly observed Fe III -OOH species at lower temperature (−60°C). At RT, the rate of O 2 -binding to 6 LFeCu is significantly faster than that for 6 LFe, whereas the rates of the O-O bond cleavage of the Fe III -OOH species observed (−60°C) with either the 6 LFeCu or 6 LFe catalyst are nearly the same. Thus, the role of the Cu ion is to assist the heme and lead to faster O 2 -binding at RT. However, the proximate Cu ion has no effect on the O-O bond cleavage of the Fe III -OOH species at low temperature.heme/copper | dioxygen reduction | ferric hydroperoxo | kinetic mechanism | enzyme model