Synthesis, structural and physicochemical properties of a series of manganese(II) complexes with a novel N5 tripodal-amidate ligand and their potential use as water oxidation catalysts

Papanikolaou, M. G., Hadjithoma, S., Gallos, J. K., Miras, H. N. , Plakatouras, J. C., Keramidas, A. D. and Kabanos, T. A. (2021) Synthesis, structural and physicochemical properties of a series of manganese(II) complexes with a novel N5 tripodal-amidate ligand and their potential use as water oxidation catalysts. Polyhedron, 204, 115260. (doi: 10.1016/j.poly.2021.115260)

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Abstract

Water oxidation plays a crucial role in both natural and artificial photosynthesis, which is an attractive solution to the depletion of fossil fuels as energy sources due to the increasing consumption. Thus, the search for oxygen evolution reaction catalysts is a hot topic of research. Reaction of the N5-tripodal amidate ligand, N-{2-[(bis(pyridine-2-ylmethyl)amino)methyl]phenyl}picolinamide (Htrip) with MIIX2 (X = Cl-, Br-, I-), in anhydrous ethyl alcohol, and C2H5ONa yields the complexes [MnII(trip)Cl] (1), [MnII(trip)Br] (2), and [MnII(trip)I] (3). Single crystal X-ray structure analysis of 1–3 revealed that the manganese(II) atom in the three manganese compounds occupies the center of a distorted octahedral coordination sphere consisting of two pyridine, one picoline and one amino nitrogen atoms on the equatorial plane, while the axial positions are occupied by one amido nitrogen atom and the halogen anion. The three manganese(II) complexes 1–3 constitute the first examples of mononuclear {MnII(N5trip)X} species to be reported. Magnetic susceptibility measurements showed that these complexes are high-spin d5 systems. Cyclic voltametric study of 1–3 revealed an unexpected two electron, electrochemically reversible redox process, assigned to the oxidation of MnII to MnIV. The electrochemical properties for oxygen evolution reaction of complexes 1–3 showed that the oxidized trip- ligand is responsible for the electrocatalytic oxidation of water to dioxygen.

Item Type:Articles
Additional Information:The research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the HFRI PhD Fellowship grant (Fellowship Number: 1213). The authors wish to thank Assistant Professor Dr. Angelos G. Kalampounias, Department of Chemistry, University of Ioannina for helping in recording FTIR spectra and the Unit ORBITRAP-LS-MS of the University of Glasgow for supporting this work. This work was co-funded by the European Regional Development Fund and the Republic of Cyprus through the Research and Innovation Foundation (Project: EXCELLENCE/1216/0515)
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Moiras, Professor Haralampos
Creator Roles:
Miras, H. N.Methodology, Writing – original draft, Writing – review and editing
Authors: Papanikolaou, M. G., Hadjithoma, S., Gallos, J. K., Miras, H. N., Plakatouras, J. C., Keramidas, A. D., and Kabanos, T. A.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Polyhedron
Publisher:Elsevier
ISSN:0277-5387
ISSN (Online):1873-3719
Published Online:07 May 2021
Copyright Holders:Copyright © 2021 Elsevier Ltd.
First Published:First published in Polyhedron 204:115260
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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