A di‑iron(III) μ-oxido complex as catalyst precursor in the oxidation of alkanes and alkenes

Biswanath Das; Afnan Al-Hunaiti; Akina Carey; Sven Lidin; Serhiy Demeshko; Timo Repo; Ebbe Nordlander

doi:10.1016/j.jinorgbio.2022.111769

A di‑iron(III) μ-oxido complex as catalyst precursor in the oxidation of alkanes and alkenes

J Inorg Biochem. 2022 Jun:231:111769. doi: 10.1016/j.jinorgbio.2022.111769. Epub 2022 Feb 17.

Authors

Biswanath Das¹, Afnan Al-Hunaiti², Akina Carey², Sven Lidin³, Serhiy Demeshko⁴, Timo Repo⁵, Ebbe Nordlander⁶

Affiliations

¹ Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-221 00 Lund, Sweden.
² Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, 00014 Helsinki, Finland.
³ Center for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-221 00 Lund, Sweden.
⁴ Institute for Inorganic Chemistry, Georg-August-University Göttingen, Tammanstrasse 4, D-37077 Göttingen, Germany.
⁵ Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, 00014 Helsinki, Finland. Electronic address: Timo.Repo@helsinki.fi.
⁶ Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-221 00 Lund, Sweden. Electronic address: Ebbe.Nordlander@chemphys.lu.se.

PMID: 35287038
DOI: 10.1016/j.jinorgbio.2022.111769

Abstract

The oxido-bridged diiron(III) complex [Fe₂(μ-O)(μ-OAc)(DPEAMP)₂](OCH₃) (1), based on a new unsymmetrical ligand with an N₄O donor set, viz. [2-((bis(pyridin-2-ylmethyl)amino)methyl)-6-((ethylamino)methyl)-4-methylphenol (HDPEAMP)], has been prepared and characterized by spectroscopic methods and X-ray crystallography. The crystal structure of the complex reveals that each Fe(III) ion is coordinated by three nitrogen and three oxygen donors, two of which are the bridging oxido and acetate ligands. Employing H₂O₂ as a terminal oxidant, 1 is capable of oxidizing a number of alkanes and alkenes with high activity. The catalytic oxidation of 1,2-dimethylcyclohexane results in excellent retention of configuration. Monitoring of the reaction of 1 with H₂O₂ and acetic acid in the absence of substrate, using low-temperature UV-Vis spectroscopy, suggests the in situ formation of a transient Fe(III)₂-peroxido species. While the selectivity and nature of oxidation products implicate a high-valent iron-oxido complex as a key intermediate, the low alcohol/ketone ratios suggest a simultaneous radical-based process.

Keywords: Catalysis; Epoxidation; Hydroxylation; Iron; Metal-oxido complex; Peroxide complex.

Publication types

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

MeSH terms

Alkanes* / chemistry
Alkenes
Catalysis
Crystallography, X-Ray
Hydrogen Peroxide / chemistry
Iron* / chemistry
Ligands
Oxidation-Reduction

Substances

Alkanes
Alkenes
Ligands
Hydrogen Peroxide
Iron