Modulating Effect of Ligand Charge on the Electronic Properties of 2Ni–2S Structures and Implications for Biological 2M–2S Sites
| Autor: | Michael Roemelt, Christina Römelt, Andreas Berkefeld, Gunnar Jeschke, Hartmut Schubert |
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| Rok vydání: | 2020 |
| Předmět: |
Molecular Structure
Chemistry Ligand Electron Spin Resonance Spectroscopy Electrons Electronic structure Inner sphere electron transfer Ligands Electron transport chain law.invention Inorganic Chemistry Electron transfer Nickel Chemical physics law Density functional theory Physical and Theoretical Chemistry Isostructural Electron paramagnetic resonance Density Functional Theory Sulfur |
| Zdroj: | Inorganic Chemistry. 59:17234-17243 |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/acs.inorgchem.0c02467 |
| Popis: | Sulfur-bridged bimetallic 2M-2S type structures are essential cofactors that participate in biological long-range electron transport and metabolism. Metal-sulfur bond covalency is a decisive property for inner sphere (through-bond) type electron transfer that dominates in buried or hydrophobic protein environments. This work reports on a combined experimental and computational study of the effect of ligand charge on the electronic structure of a 2Ni-2S model site that adopts the biologically relevant S = 1/2 redox state. Starting out from an isostructural dinickel(1.5+)-dithiophenolate platform with sulfur-bridged tetrahedral Ni sites, η2:η2-μ-coordination of the S = 1/2 [2Ni-2S]+ core to either a neutral π-system or strongly σ-donating cyclohexadienido renders its electronic structure substantially different. Density functional theory analysis corroborates pulse and continuous wave electron paramagnetic resonance data that associate co-ligand charge with the significant change in the mechanism and size of electron-31P nuclear spin hyperfine coupling to a phosphine reporter ligand at each nickel center. An increasing level of charge donation attenuates direct and through-bridge electronic coupling of the metal sites, resulting in a stronger electronic coupling of the 2Ni-2S core to its terminal phosphine donors. Drawing a connection to biological 2M-2S sites, our 2Ni-2S system indicates that a fine balance of intracore and core-protein electronic coupling is key to biological function for which the degree of charge donation by peripheral donors appears to be a significant parameter. |
| Databáze: | OpenAIRE |
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