UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Hydrogenase biomimetics with redox-active ligands: Electrocatalytic proton reduction by [Fe2(CO)4(κ2-diamine)(μ-edt)] (diamine = 2,2′-bipy, 1,10-phen)

Ghosh, S; Rahaman, A; Holt, KB; Nordlander, E; Richmond, MG; Kabir, SE; Hogarth, G; (2016) Hydrogenase biomimetics with redox-active ligands: Electrocatalytic proton reduction by [Fe2(CO)4(κ2-diamine)(μ-edt)] (diamine = 2,2′-bipy, 1,10-phen). Polyhedron , 116 pp. 127-135. 10.1016/j.poly.2016.05.015. Green open access

[thumbnail of holt_POLY-D-16-00153 (revised 1).pdf]
Preview
Text
holt_POLY-D-16-00153 (revised 1).pdf

Download (1MB) | Preview

Abstract

Diiron complexes bearing redox active diamine ligands have been studied as models of the active site of [FeFe]-hydrogenases. Heating [Fe2(CO)6(μ-edt)] (edt = 1,2-ethanedithiolate) with 2,2′-bipyridine (2,2′-bipy) or 1,10-phenanthroline (1,10-phen) in MeCN in the presence of Me3NO leads to the formation of [Fe2(CO)4(κ2-2,2′-bipy)(μ-edt)] (1-edt) and [Fe2(CO)4(κ2-1,10-phen)(μ-edt)] (2-edt), respectively, in moderate yields. In the solid state the diamine resides in dibasal sites, while both dibasal and apical–basal isomers are present in solution. Both stereoisomers protonate readily upon addition of strong acids. Cyclic voltammetry in MeCN shows that both complexes undergo irreversible oxidation and reduction, proposed to be a one- and two-electron process, respectively. The structures of neutral 2-edt and its corresponding one- and two-electron reduced species have been investigated by DFT calculations. In 2-edt− the added electron occupies a predominantly ligand-based orbital, and the iron–iron bond is maintained, being only slightly elongated. Addition of the second electron affords an open-shell triplet dianion where the second electron populates an Fe–Fe σ* antibonding orbital, resulting in effective scission of the iron–iron bond. The triplet state lies 4.2 kcal mol−1 lower in energy than the closed-shell singlet dianion whose HOMO correlates nicely with the LUMO of the neutral species 2-edt. Electrocatalytic proton reduction by both complexes has been studied in MeCN using CF3CO2H as the proton source. These catalysis studies reveal that while at high acid concentrations the active catalytic species is [Fe2(CO)4(μ-H)(κ2-diamine)(μ-edt)]+, at low acid concentrations the two complexes follow different catalytic mechanisms being associated with differences in their relative rates of protonation.

Type: Article
Title: Hydrogenase biomimetics with redox-active ligands: Electrocatalytic proton reduction by [Fe2(CO)4(κ2-diamine)(μ-edt)] (diamine = 2,2′-bipy, 1,10-phen)
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.poly.2016.05.015
Publisher version: http://dx.doi.org/10.1016/j.poly.2016.05.015
Language: English
Additional information: © 2016 Elsevier Ltd. All rights reserved. This manuscript version is made available under a Creative Commons Attribution Non-commercial Non-derivative 4.0 International license (CC BY-NC-ND 4.0). This license allows you to share, copy, distribute and transmit the work for personal and non-commercial use providing author and publisher attribution is clearly stated. Further details about CC BY licenses are available at http://creativecommons.org/ licenses/by/4.0. Access may be initially restricted by the publisher.
Keywords: Science & Technology, Physical Sciences, Chemistry, Inorganic & Nuclear, Crystallography, Chemistry, Hydrogenase, Biomimic, Redox active ligand, Electrochemistry, Diamine, IRON-ONLY HYDROGENASE, FE-FE HYDROGENASE, H-CLUSTER, ELECTRONIC-STRUCTURE, HYDROXIDE ION, DIIRON COMPLEX, SITE, 1,10-PHENANTHROLINE, 2,2'-BIPYRIDYL, DENSITY
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/1520824
Downloads since deposit
95Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item