Bio-inspired Carbon Dioxide Activation on Heterobimetallic Complexes

• Applicant: Professor Dr. Ulf-Peter Apfel
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation ; Biological and Biomimetic Chemistry
• Term: from 2014 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 256826550

• Final Report Year: 2021

Final Report Abstract

Within the my Emmy-Noether project, my group could make considerable progress in our aim to activate small molecules such as CO2 and could reach some important mile stones of the project proposal: 1. The synthesis of a modular tripodal ligand platform with different Lewis-acid/base properties was achieved. 2. Formation of monometallic and heterobimetallic Fe, Ni and Mo complexes was successfully performed. 3. We also could establish a Triphos-based Fe-hydride that allows for CO2 conversion into CO or formic acid depending on the solvent applied. 4. We could also show that a selective CO2 uptake into dinickel-azacryptands can be achieved and controlled by different substitution patterns on the central aromatic linker. 5. We are now able to synthesize a cryptand that allows for the selective coordination of two different metal ions in different oxidation states and shows no obvious metal ion scrambling. 6. Bimetallic cryptand complexes were shown to enable photocatalytic CO2 reduction. 7. Based on our assumption that compounds with bimetallic sites and a high sulfur content are able to perform CO2 reduction, we synthesized Fe4.5Ni4.5S8 as a heterogenous enzyme mimic. While showing a superior performance for the hydrogen evolution reaction in aqueous solutions, the material also shows a very good performance for the reduction of CO2. 8. Based on the heterogenous results, the material class of pentlandites was further exploited as a robust, highly conductive platform for electrochemical processes. The variable metallic composition enables to adjust the proton binding strength and with it the subsequent hydrogenation process, might it be the formation of H2, CO2 or any organic residue. Furthermore, we could unequivocally confirm some key claims previously raised in the original Emmy Noether proposal: 1. The substitution pattern in the apex of the tripodal ligands allows for fine-tuning of the electronic properties of the metal ions. 2. “Cage compounds”/azacryptands offer a protective ligand environment and allow for unprecedented metal coordination. However, their synthetic access is laborious, and alterations of the ligand framework are hard to perform. 3. Many of the suggested complexes allow for reaction with CO2 and CS2. 4. The interaction of two metal sites is beneficial for the activation of small molecules. The kind of substrate conversion is controlled by both the metals involved as well as the metal-metal distance.

Publications

• Dalton Trans. 2017, 46, 13251-13262. Spectroscopic and Reactivity Differences in Metal Complexes Derived from Sulfur Containing Triphos Homologs
  A. Petuker, P. Gerschel, S. Piontek, N. Ritterskamp, F. Wittkamp, L. Iffland, R. Miller, U.-P. Apfel
  
• Inorganics 2017, 5, 78. Mechanistic Implications For The Ni(I)-Catalyzed Kumada Cross-Coupling Reaction
  L. Iffland, A. Petuker, M. van Gastel, U.-P. Apfel
  
• ACS Catalysis, 2018, 8, 987-966. Influence of the Fe : Ni Ratio and Reaction Temperature on the Efficiency of (FexNi1-x)9S8 Electrocatalysts Applied in the Hydrogen Evolution Reaction
  S. Piontek, C. Andronescu, A. Zaichenko, B. Konkena, K. junge Puring, B. Marler, H. Antoni, I. Sinev, M. Muhler, D. Mollenhauer, B. Roldan Cuenya, W. Schuhmann, U.-P. Apfel
  
• Angew. Chem. Int. Ed. 2018, 57, 4093-4097. Local surface structure and composition control the hydrogen evolution reaction on iron nickel sulfides
  C. L. Bentley, C. Andronescu, M. Smialkowski, M. Kang, T. Tarnev, B. Marler, P. R. Unwin, U.-P. Apfel, W. Schuhmann
  
• Chem. Comm. 2019, 55, 8792-8795. Seleno-Analogous of Pentlandite (Fe4.5Ni4.5S8-ySey, Y = 1-6): Tuning bulk Fe/Ni Sulphoselenides for Hydrogen Evolution
  M. Smialkowski, D. Siegmund, K. Pellumbi, L. Hensgen, H. Antoni, M. Muhler, U.-P. Apfel
  
• Chem. Sci. 2019, 10, 1075–1081. Bio-Inspired Design: Bulk Iron-Nickel Sulfide Allows for Efficient Solvent-dependent CO2 Reduction
  S. Piontek, K. junge Puring, D. Siegmund, M. Smialkowski, I. Sinev, B. Roldan Cuenya, U.- P. Apfel
  
• Faraday Discussions 2019, 215, 216-226. FexNi9-xS8 (x = 3-6) as Potential Photocatalysts for Solar-Driven Hydrogen Production?
  D. Tetzlaff, C. Simon, D. S. Achilleos, M. Smialkowski, K. junge Puring, A. Bloesser, S. Piontek, H. Kasap, D. Siegmund, E. Reisner, R. Marschall, U.-P. Apfel
  
• Organometallics 2019, 38, 289–299. Solvent-controlled CO2 Reduction by a Triphos-Iron-Hydride Complex
  L. Iffland, A. Khedkar, A. Petuker, M. Lieb, F. Wittkamp, M. van Gastel, M. Roemelt, U.-P. Apfel
  
• Chem. Commun. 2020, 56, 14179-14182. A dinuclear porphyrin-macrocycle as efficient catalyst for the hydrogen evolution reaction
  J. Jökel, F. Schwer, M. von Delius, U.-P. Apfel
  
• Chem. Eur. J. 2020, 26, 9938-9944. Enhancing the CO2-electroreduction of Fe/Ni-pentlandite Catalysts by S/Se exchange
  K. Pellumbi, M. Smialkowski, D. Siegmund, U.-P. Apfel
  
• Chem. Sci. 2020, 11, 12835 - 12842. Sustainable and rapid preparation of nanosized Fe/Ni-pentlandite particles by mechanochemistry
  D. Tetzlaff, K. Pellumbi, D. M. Baier, L. Hoof, H. Shastry Barkur, M. Smialkowski, H. M. A. Amin, S. Grätz, D. Siegmund, L. Borchardt, U.-P. Apfel
  
• Chinese J. Catal. 2020. Bimetallic Fe/Co and Ni/Co-Pentlandite Type Electrocatalysts for the Hydrogen Evolution Reaction
  M. Smialkowski, D. Tetzlaff, L. Hensgen, D. Siegmund, U.-P. Apfel