The activation and splitting of the strong nitrogen-nitrogen bond in the N2 molecule is a difficult chemical transformation that plays an important role in the production of base chemicals. It is carried out industrially in the Haber–Bosch process, which relies on fossil hydrogen sources. Alternative methods of dinitrogen activation that have a lower environmental impact are being investigated on a laboratory scale using thermal, electrochemical, and photochemical methods.
We use density functional theory and wave function methods to gain a better understanding of the functional principles and boundary conditions for dinitrogen activation with molecular complexes. To this end, we investigate both thermal and photochemical reaction pathways.
Publications:
Escomel, Léon ; Martins, Frederico F. ; Vendier, Laure ; Coffinet, Anaïs ; Queyriaux, Nicolas ; Krewald, Vera ; Simonneau, Antoine (2024) Coordination of Al(C6F5)3vs. B(C6F5)3 on group 6 end-on dinitrogen complexes: chemical and structural divergences. In: Chemical Science, 15 (29)
doi: 10.1039/d4sc02713b Artikel, Bibliographie
Martins, Frederico F. ; Krewald, Vera (2023) Cooperative dinitrogen activation: identifying the push‐pull effects of transition metals and Lewis acids in molecular orbital diagrams. In: European Journal of Inorganic Chemistry, 26 (35)
doi: 10.1002/ejic.202300268 Artikel, Bibliographie
Fritz, Maximilian ; Rupp, Severine ; Kiene, Ciara Isabel ; Kisan, Sesha ; Telser, Joshua ; Würtele, Christian ; Krewald, Vera ; Schneider, Sven (2022) Photoelectrochemical Conversion of Dinitrogen to Benzonitrile: Selectivity Control by Electrophile‐ versus Proton‐Coupled Electron Transfer.In: Angewandte Chemie International Edition, 61 (35)
doi: 10.1002/anie.202205922 Artikel, Bibliographie
Schluschaß, Bastian ; Borter, Jan-Hendrik ; Rupp, Severine ; Demeshko, Serhiy ; Herwig, Christian ; Limberg, Christian ; Maciulis, Nicholas A. ; Schneider, Jessica ; Würtele, Christian ; Krewald, Vera ; Schwarzer, Dirk ; Schneider, Sven (2021) Cyanate Formation via Photolytic Splitting of Dinitrogen. In: JACS Au – an open access journal of the American Chemical Society, 1 (6)
doi: 10.1021/jacsau.1c00117 Artikel, Bibliographie
Krewald, Vera (2018) Dinitrogen photoactivation: status quo and future perspectives. In: Dalton Transactions, 47 (31)
doi: 10.1039/c8dt00418h Artikel, Bibliographie
Schendzielorz, Florian ; Finger, Markus ; Abbenseth, Josh ; Würtele, Christian ; Krewald, Vera ; Schneider, Sven (2018) Metal-Ligand Cooperative Synthesis of Benzonitrile by Electrochemical Reduction and Photolytic Splitting of Dinitrogen. In: Angewandte Chemie International Edition, 58 (3)
doi: 10.1002/anie.201812125 Artikel, Bibliographie
Krewald, Vera ; González, Leticia (2018) A Valence-Delocalised Osmium Dimer capable of Dinitrogen Photocleavage: Ab Initio Insights into Its Electronic Structure. In: Chemistry – A European Journal, 24 (20)
doi: 10.1002/chem.201704651 Artikel, Bibliographie
The reduction of dioxygen is an important step in fuel cell chemistry. Currently, platinum-based catalysts are used in fuel cells, which is a significant cost factor that hinders their widespread use.
We develop models for so-called FeNC catalysts, which represent a green alternative to platinum-based catalysts. In these catalysts, an iron ion with four nitrogen-based ligands is assumed to be the catalytically active center; however, the exact structure is still unclear. The combination of experimental and calculated spectroscopy data, in particular Mössbauer spectroscopy, is central to this research area, as we aim to decipher the atomic-level composition of the catalytically active centers. In this context, we also study molecular model complexes with FeN4 environments. We collaborate with Prof. Dr. Ulrike Kramm AK Kramm and colleagues in the SFB “Iron, upgraded!” Eisen neu gedacht on these topics.
Publications:
Rhein, Niklas von ; Low, Jian Liang ; Gallenkamp, Charlotte ; Paulus, Beate ; Krewald, Vera (2025) Pyrrolic FeN₄ models for FeNC catalysts: the influence of planarity on electronic properties and Mössbauer parameters. In: Phys. Chem. Chem. Phys., 27 (19)
doi: 10.1039/D5CP00443H Artikel, Bibliographie
Song, Young-Joon ; Gallenkamp, Charlotte ; Lleopart, Genis ; Krewald, Vera ; Valentí, Roser (2024) Influence of graphene on the electronic and magnetic properties of an iron(III) porphyrin chloride complex. In: Physical Chemistry Chemical Physics, 26 (41)
doi: 10.1039/d4cp01551g Artikel, Bibliographie
Artikel, Bibliographie
Heppe, Nils ; Gallenkamp, Charlotte ; Snitkoff-Sol, Rifael Z. ; Paul, Stephen D. ; Segura-Salas, Nicole ; Haak, Hendrik ; Moritz, Dominik C. ; Kaiser, Bernhard ; Jaegermann, Wolfram ; Potapkin, Vasily ; Jafari, Atefeh ; Schünemann, Volker ; Leupold, Olaf ; Elbaz, Lior ; Krewald, Vera ; Kramm, Ulrike I. (2024) Applying nuclear forward scattering as in situ and operando tool for the characterization of FeN4 moieties in the hydrogen evolution reaction. In: Journal of the American Chemical Society, 146 (18)
doi: 10.1021/jacs.4c00436 Artikel, Bibliographie
Gallenkamp, Charlotte ; Kramm, Ulrike I. ; Krewald, Vera (2024) FeN4 environments upon reduction: a computational analysis of spin states, spectroscopic properties, and active species. In: JACS Au – an open access journal of the American Chemical Society
doi: 10.1021/jacsau.3c00714 Artikel, Bibliographie
Heppe, Nils ; Gallenkamp, Charlotte ; Paul, Stephen Daniel ; Segura-Salas, Nicole ; Rhein, Niklas von ; Kaiser, Bernd ; Jaegermann, Wolfram ; Jafari, Atefeh ; Sergueev, Ilya ; Krewald, Vera ; Kramm, Ulrike I. (2023) Substituent effects in iron porphyrin catalysts for the hydrogen evolution reaction. In: Chemistry – A European Journal, 29 (10)
doi: 10.1002/chem.202202465 Artikel, Bibliographie
Ni, Lingmei ; Gallenkamp, Charlotte ; Wagner, Stephan ; Bill, Eckhard ; Krewald, Vera ; Kramm, Ulrike I. (2022) Identification of the catalytically dominant iron environment in iron- and nitrogen-doped carbon catalysts for the oxygen reduction reaction. In: Journal of the American Chemical Society, 144 (37)
doi: 10.1021/jacs.2c04865 Artikel, Bibliographie
Ni, Lingmei ; Gallenkamp, Charlotte ; Paul, Stephen ; Kübler, Markus ; Theis, Pascal ; Chabbra, Sonia ; Hofmann, Kathrin ; Bill, Eckhard ; Schnegg, Alexander ; Albert, Barbara ; Krewald, Vera ; Kramm, Ulrike I. (2021) Active Site Identification in FeNC Catalysts and Their Assignment to the Oxygen Reduction Reaction Pathway by In Situ 57Fe Mössbauer Spectroscopy. In: Advanced Energy and Sustainability Research
doi: 10.1002/aesr.202000064 Artikel, Bibliographie
Gallenkamp, Charlotte ; Kramm, Ulrike I. ; Krewald, Vera (2021) Spectroscopic discernibility of dopants and axial ligands in pyridinic FeN4 environments relevant to single-atom catalysts. In: Chemical Communications, 57
doi: 10.1039/D0CC06237E Artikel, Bibliographie
Together with experimental collaboration partners, we investigate various reactions and catalytic transformations involving transition metal complexes. By calculating the structures and properties of catalytic intermediates, we contribute to the elucidation of reaction mechanisms. A recurring theme is the identification of catalytically active species from a pre-catalyst.
Publications:
Kothe, Thomas ; Diefenbach, Martin ; Tagliavini, Valeria ; Dechert, Sebastian ; Krewald, Vera ; Meyer, Franc (2025) Intramolecular agostic interactions and dynamics of a methyl group at a preorganized dinickel(II) site. In: Inorganic Chemistry, 64 (3)
doi: 10.1021/acs.inorgchem.4c04255 Artikel, Bibliographie
Pocock, Emily ; Diefenbach, Martin ; Hood, Thomas M. ; Nunn, Michael ; Richards, Emma ; Krewald, Vera ; Webster, Ruth L. (2024) Synthetic and mechanistic studies into the reductive functionalization of nitro compounds catalyzed by an iron(salen) complex. In: Journal of the American Chemical Society, 146 (29)
doi: 10.1021/jacs.4c02797 Artikel, Bibliographie
Cao, Qun ; Diefenbach, Martin ; Maguire, Calum ; Krewald, Vera ; Muldoon, Mark J. ; Hintermair, Ulrich (2024) Water Co-catalysis in aerobic Olefin epoxidation mediated by Ruthenium Oxo complexes. In: Chemical Science
doi: 10.1039/D3SC05516G Artikel, Bibliographie
Hood, Thomas M. ; Lau, Samantha ; Diefenbach, Martin ; Firmstone, Leah ; Mahon, Mary ; Krewald, Vera ; Webster, Ruth L. (2023) The Complex Reactivity of [(salen)Fe]2(μ-O) with HBpin and Its Implications in Catalysis. In: ACS Catalysis, 13
doi: 10.1021/acscatal.3c02898 Artikel, Bibliographie
Barrett, Adam N. ; Diefenbach, Martin ; Mahon, Mary F. ; Krewald, Vera ; Webster, Ruth L. (2022) An Iron‐Catalyzed Route to Dewar 1,3,5‐Triphosphabenzene and Subsequent Reactivity. In: Angewandte Chemie, (Early Access)
doi: 10.1002/ange.202208663 Artikel, Bibliographie
Provis-Evans, Cei ; Lau, Samantha ; Krewald, Vera ; Webster, Ruth (2020) Regioselective Alkyne Cyclotrimerization with an In Situ-Generated [Fe(II)H(salen)]·Bpin Catalyst. In: ACS Catalysis, 2020
doi: 10.1021/acscatal.0c03068 Artikel, Bibliographie
