A Redox-Induced Spin-State Cascade in a Mixed-Valent Fe3 (μ3 -O) Triangle

Evgen V Govor; Karrar Al-Ameed; Indranil Chakraborty; Carla S Coste; Olena Govor; Yiannis Sanakis; John E McGrady; Raphael G Raptis

doi:10.1002/anie.201610534

A Redox-Induced Spin-State Cascade in a Mixed-Valent Fe₃ (μ₃ -O) Triangle

Angew Chem Int Ed Engl. 2017 Jan 9;56(2):582-586. doi: 10.1002/anie.201610534. Epub 2016 Dec 5.

Authors

Evgen V Govor¹, Karrar Al-Ameed^{2

3}, Indranil Chakraborty⁴, Carla S Coste⁴, Olena Govor¹, Yiannis Sanakis⁵, John E McGrady², Raphael G Raptis¹

Affiliations

¹ Department of Chemistry and Biochemistry and the Biomedical Sciences Institute, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA.
² Department of Chemistry, University of Oxford, South Parks Road, OX1 3QZ, UK.
³ Faculty of Science, University of Kufa, Kufa St., Najaf, Iraq.
⁴ Department of Chemistry, University of Puerto Rico, San Juan, PR, 00934, USA.
⁵ Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", Ag. Paraskevi, 15310, Attiki, Greece.

PMID: 27918131
DOI: 10.1002/anie.201610534

Abstract

One-electron reduction of a pyrazolate-bridged triangular Fe₃ (μ₃ -O) core induces a cascade wherein all three metal centers switch from high-spin Fe³⁺ to low-spin Fe^2.66+ . This hypothesis is supported by spectroscopic data (¹ H-NMR, UV-vis-NIR, infra-red, ⁵⁷ Fe-Mössbauer, EPR), X-ray crystallographic characterization of the cluster in both oxidation states and also density functional theory. The reduction induces substantial contraction in all bond lengths around the metal centers, along with diagnostic shifts in the spectroscopic parameters. This is, to the best of our knowledge, the first example of a one-electron redox event causing concerted change in multiple iron centers.

Keywords: Mössbauer spectroscopy; density functional theory; high-spin/low-spin transition; iron complexes; mixed-valence.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't