A Reversible Proton Relay Process Mediated by Hydrogen‐Bonding Interactions in [FeFe]Hydrogenase Modeling |
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| Authors: | Kai‐Ti Chu Dr Yu‐Chiao Liu Yi‐Lan Huang Cheng‐Huey Hsu Dr Gene‐Hsiang Lee Prof?Dr Ming‐Hsi Chiang |
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| Affiliation: | 1. Institute of Chemistry, Academia Sinica, Nankang, Taipei 115 (Taiwan);2. Molecular Science and Technology Program, TIGP, Institute of Chemistry, Academia Sinica, Nankang, Taipei 115 (Taiwan);3. Department of Chemistry, National Tsing Hua University, Hsinchu 300 (Taiwan);4. Instrumentation Center, National Taiwan University, Taipei 106 (Taiwan) |
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| Abstract: | A reversible and temperature‐dependent proton‐relay process is demonstrated for a Fe2 complex possessing a terminal thiolate in the presence of nitrogen‐based acids. The terminal sulfur site (St) of the complex forms a hydrogen‐bond interaction with N,N‐dimethylanilinium acid at 183 K. The Fe2 core, instead, is protonated to generate a bridging hydride at 298 K. Reversibility is observed for the tautomerization between the hydrogen‐bonded pair and the Fe–hydride species. X‐ray structural analysis of the hydrogen‐bonded species at 193 K reveals a short N(H)???St contact. Employment of pyridinium acid also results in similar behavior, with reversible proton–hydride interconversion. DFT investigation of the proton‐transfer pathways indicates that the pKa value of the hydrogen‐bonded species is enhanced by 3.2 pKa units when the temperature is decreased from 298 K to 183 K. |
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| Keywords: | [FeFe]hydrogenase hydrogen bonds iron proton transfer S ligands |
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