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Published on: August 12, 2019
High-valent iron complexes with tetraamido macrocyclic ligands: structures, Mössbauer spectroscopy, and DFT
Arani Chanda1, Delia-Laura Popescu, Filipe Tiago de Oliveira
1Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
Abstract:
Iron complexes of tetraamido macrocyclic ligands (TAML) are unique synthetic oxidation catalysts. In general, the central Fe(III) ion (S=3/2) is surrounded by four, almost planar, deprotonated amide-N sigma-donors although the full suite with new generation systems includes some substitution of amides with related donor functionalities. Oxidation under different conditions affords a variety of high-valent forms of iron-TAMLs. This review provides a summary and discussion of structural and spectroscopic features of complexes oxidized by one equivalent above the ferric state. These comprise Fe(IV)-TAML high spin (S=2) and intermediate spin (S=1) systems, wherein the oxidation equivalent can be taken from the metal (Fe(IV)) or the ligand (TAML radical-cation Fe(III)), and coupled spin (S=0) systems of mu-oxoiron(IV) dimers. The discussion is principally based on data obtained by X-ray crystallography, Mössbauer spectroscopy, and density functional theory calculations.
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