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 Dec. 2017
Accepted
22 Marts 2018
First published
23 Marts 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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