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Dinuclear manganese(iii) complexes with bioinspired coordination and variable linkers showing weak exchange effects: a synthetic, structural, spectroscopic and computation studyElectronic supplementary information (ESI) available: Computational details and discussion of theoretically determined EPR properties; packing features of 1, 3 (Fig. S1) and 2 (Fig. S2), cyclic voltammograms of 1 and 2 (Fig. S3), HFEPR spectra of 1 and 2 (Fig. S4-S7), fragment of the experimental HFEPR spectrum of 1 and e

Three dimanganese( iii ) complexes have been synthesised and fully characterised by standard spectroscopic methods and spectroelectrochemistry. Each Mn III ion is chelated by a salen type ligand (H 2 L), but there is variation in the bridging group: LMn(OOCCH&z.dbd;CHCOO)MnL, LMn(OOCC 6 H 4 COO)...

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Main Authors: Shova, Sergiu, Vlad, Angelica, Cazacu, Maria, Krzystek, J, Ozarowski, Andrew, Mal ek, Michal, Bucinsky, Lukas, Rapta, Peter, Cano, Joan, Telser, Joshua, Arion, Vladimir B
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Language:English
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Summary:Three dimanganese( iii ) complexes have been synthesised and fully characterised by standard spectroscopic methods and spectroelectrochemistry. Each Mn III ion is chelated by a salen type ligand (H 2 L), but there is variation in the bridging group: LMn(OOCCH&z.dbd;CHCOO)MnL, LMn(OOCC 6 H 4 COO)MnL, and LMn(OOCC 6 H 4 C 6 H 4 COO)MnL. X-ray diffraction revealed an axial compression of each six-coordinate high-spin d 4 Mn III ion, which is a Jahn-Teller-active ion. Temperature dependent magnetic susceptibility and variable temperature-variable field (VTVH) magnetisation measurements, as well as high-frequency and -field EPR (HFEPR) spectroscopy were used to accurately describe the magnetic properties of the complexes, not only the single-ion spin Hamiltonian parameters: g -values and zero-field splitting (ZFS) parameters D and E , but also the exchange interaction constant J between the two ions, which has been seldom determined for a di-Mn III complex, particularly when there is more than a single bridging atom. Quantum chemical calculations reproduced well the electronic and geometric structure of these unusual complexes, and, in particular, their electronic absorption spectra along with the spin Hamiltonian and exchange parameters. High-resolution HFEPR indicates weak exchange interactions between Mn III ions in agreement with DFT calculations.
ISSN:1477-9226
1477-9234
DOI:10.1039/c8dt04596h