The synthesis and study of redox-active ligand complexes has received much recent attention. We have recently explored the coordination chemistry of arylazo redox-active ligand 1-(2-pyridylazo)-2-phenanthrol (papl) and herein expand the series of complexes to the Group 8 transition metal ion, iron. We report the preparation and structure of a divalent iron complex with the papl anion, Fe(papl)2, which is diamagnetic and features ligand centered redox activity and intense visible electronic transitions. Three polymorphs of the Fe(papl)2complex are reported, including one that exhibits a structural phase transition at low temperature. Oxidation of Fe(papl)2with molecular iodine has produced the low-spin trivalent complex [Fe3+(papl)2]+as an ionic complex with the I3anion. Density functional theory (dft) calculations and data from variable temperature Mössbauer spectroscopy experiments are provided to shed light on the electronic structures of these iron complexes.
Bibliographical noteFunding Information:
MTL acknowledges funding from NSERC, Cummings Foundation (CFI), Canada Research Chairs Program, Brandon and Brock University and the University of Manitoba for providing an adjunct position. MTL thanks Prof. Art van der Est (Brock University) for the use of the EPR facility. TS thanks the Department of Physics & Astronomy at Western Washington University for support of this work.
© 2016 Elsevier Ltd
- Density functional theory
- Iron complexes
- Mössbauer spectroscopy
- Redox active ligands
- X-ray crystallography