Sypaseuth Fanni D, Matlachowski Corinna, Weber Manuela, Schwalbe Matthias, Tzschucke C Christoph
Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin (Germany).
Chemistry. 2015 Apr 20;21(17):6564-71. doi: 10.1002/chem.201404367. Epub 2015 Mar 10.
Eight Ir(bpy)Cp*Cl -type complexes (bpy= bipyridine, Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) containing differently substituted bipyridine ligands were synthesized and characterized. Cyclic voltammetry (CV) of the complexes in Ar-saturated acetonitrile solutions showed that the redox behavior of the complexes could be fine tuned by the electronic properties of the substituted bipyridine ligands. Further CV in CO2 -saturated MeCN/H2 O (9:1, v/v) solutions showed catalytic currents for CO2 reduction. In controlled potential electrolysis experiments (MeCN/MeOH (1:1, v/v), Eapp =-1.80 V vs Ag/AgCl), all of the complexes showed moderate activity in the electrocatalytic reduction of CO2 with good stability over at least 15 hours. This electrocatalytic process was selective toward formic acid, with only traces of dihydrogen or carbon monoxide and occasionally formaldehyde as byproducts. However, the turnover frequencies and current efficiencies were quite low. No direct correlation between the redox potentials of the complexes and their catalytic activity was observed.
合成并表征了八个含有不同取代联吡啶配体的Ir(bpy)Cp*Cl型配合物（bpy = 联吡啶，Cp* = 1,2,3,4,5 - 五甲基环戊二烯基）。这些配合物在氩气饱和乙腈溶液中的循环伏安法（CV）表明，配合物的氧化还原行为可通过取代联吡啶配体的电子性质进行微调。在二氧化碳饱和的MeCN/H2O（9:1，v/v）溶液中的进一步CV显示出二氧化碳还原的催化电流。在控制电位电解实验（MeCN/MeOH（1:1，v/v），相对于Ag/AgCl，Eapp = -1.80 V）中，所有配合物在二氧化碳的电催化还原中均表现出中等活性，且在至少15小时内具有良好的稳定性。该电催化过程对甲酸具有选择性，仅有痕量的氢气或一氧化碳以及偶尔的甲醛作为副产物。然而，周转频率和电流效率相当低。未观察到配合物的氧化还原电位与其催化活性之间存在直接相关性。
