Determination of ZFS parameters from the EPR spectra of mono-, di- and trinuclear MnIIcomplexes: impact of magnetic coupling.
A family of new MnIIcompounds, consisting of seven dinuclear, three mononuclear, and four trinuclear ones, were synthesised using benzoic acid derivatives n-RC6H4COOH, where n-R = 2-MeO, 3-MeO, 4-MeO, or 4-tBu, and 2,2'-bipyridine (bpy) or 1,10-phenantroline (phen) as blocking ligands. The crystal structures of nine of these compounds and the magnetic studies of all of them are reported here. Each type of compound was formed depending on the presence or absence of ClO4-ions, the solvent used, and/or the presence of a small amount of water in the reaction medium. The use of the tert-buthylbenzoate ligand gave unexpected results, very likely due to the steric hindrance caused by the voluminoustBu groups. The EPR spectra of each type of compound give some peculiar features that allow its identification. Attempts to fit these spectra have been made in order to determine the ZFS parameters, D and E, of the MnIIion (for mononuclear and dinuclear systems) or of the ground state (for trinuclear systems). For trinuclear systems, the single-ion ZFS parameters estimated from those of the ground state provided a good simulation of the EPR spectra of these compounds. The EPR signals observed in each case have been rationalised according to the energy level distribution and the plausible population in the excited states. In some particular situations, the sign of DMncould be determined from the fit of the EPR spectra of the antiferromagnetic dinuclear compounds, the source of the difference between the spectra lying in the second excited state.
Departament de Química Inorgànica i Orgànica (Secció inorgánica), Universitat de Barcelona, C/Martí i Franquès 1-11, 08028 Barcelona, Spain. luis.escrichetur@gmail.com montse.corbella@qi.ub.es and Laboratoire de Chimie, ENS de Lyon, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
Luis
http://orcid.org/0000-0003-3183-6866
L
Escriche-Tur
Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain.
Mercè
M
Font-Bardia
Laboratoire de Chimie, ENS de Lyon, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
Belén
B
Albela
Departament de Química Inorgànica i Orgànica (Secció inorgánica), Universitat de Barcelona, C/Martí i Franquès 1-11, 08028 Barcelona, Spain. luis.escrichetur@gmail.com montse.corbella@qi.ub.es and Institud de Nanociència i Nanotecnologia de la Universitat de Barcelona (IN2UB), Av. Joan XXIII s/n, 08028 Barcelona, Spain.
Montserrat
M
Corbella