Issue 16, 2018

C–H activation and nucleophilic substitution in a photochemically generated high valent iron complex

Abstract

The photochemical oxidation of a (TAML)FeIII complex 1 using visible light generated Ru(bpy)33+ produces valence tautomers (TAML)FeIV (1+) and (TAML˙+)FeIII (1-TAML˙+), depending on the exogenous anions. The presence of labile Cl or Br results in a ligand-based oxidation and stabilisation of a radical-cationic (TAML˙+)FeIII complex, which subsequently leads to unprecedented C–H activation followed by nucleophilic substitution on the TAML aryl ring. In contrast, exogenous cyanide culminates in metal-based oxidation, yielding the first example of a crystallographically characterised S = 1 [(TAML)FeIV(CN)2]2− species. This is a rare report of an anion-dependent valence tautomerisation in photochemically accessed high valent (TAML)Fe systems with potential applications in the oxidation of pollutants, hydrocarbons, and water. Furthermore, the nucleophilic aromatic halogenation reaction mediated by (TAML˙+)FeIII represents a novel domain for high-valent metal reactivity and highlights the possible intramolecular ligand or substrate modification pathways under highly oxidising conditions. Our findings therefore shine light on high-valent metal oxidants based on TAMLs and other potential non-innocent ligands and open new avenues for oxidation catalyst design.

Graphical abstract: C–H activation and nucleophilic substitution in a photochemically generated high valent iron complex

Supplementary files

Article information

Article type
Edge Article
Submitted
19 12 2017
Accepted
22 3 2018
First published
23 3 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2018,9, 3992-4002

C–H activation and nucleophilic substitution in a photochemically generated high valent iron complex

J. H. Lim, X. Engelmann, S. Corby, R. Ganguly, K. Ray and H. S. Soo, Chem. Sci., 2018, 9, 3992 DOI: 10.1039/C7SC05378A

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