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The First Conducting Spin Crossover Compound Combining Mn(III) Cation Complex with Electroactive TCNQ Demonstrating an Abrupt Spin Transition with Hysteresis of 50 Kстатья
Статья опубликована в высокорейтинговом журнале
Статья опубликована в журнале из списка Web of Science и/или Scopus- Авторы: Kazakova A.V., Tiunova A.V., Korchagin D.V., Shilov G.V., Yagubskii E.B., Zverev V.N., Yang S.C., Lin J.Y., Lee J.F., Maximova O.V., Vasiliev A.N.
- Журнал: Chemistry - A European Journal
- Год издания: 2019
- Издательство: John Wiley & Sons Ltd.
- Местоположение издательства: United Kingdom
- DOI: 10.1002/chem.201901792
- Аннотация: We present the synthesis, crystal structure, electric and magnetic properties of the spincrossover salt [Mn(5-Cl-sal-N-1,5,8,12)]TCNQ1.52CH3CN, (I), containing distinct conductive and magnetic blocks along with the solvent acetonitrile molecules. As a magnetic unit it employs the Mn(III) ion with Schiff base ligand [Mn(5-Cl-sal-N-1,5,8,12)]+while the conducting unit is the π−electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ−). The title compound (I) exhibits the semiconducting behavior with room temperature conductivity RT110-4ohm-1cm-1and activation gap Ea0.20 eV. In the range 73 123 K, it experiences hysteretic phase transition accompanied by a crossover between low spin S = 1 and high spin S = 2 states of Mn(III) ions and changes in bond lengths within MnN4O2octahedra. The pronounced shrinkage of basal Mn–N bonds at thespin crossover in (I) suggests that the dx2-y2orbital is occupied/deoccupied at this transition. Interestingly, the Br isomorphic counterpart [Mn(5-Br-sal-N-1,5,8,12)]TCNQ1.52CH3CN, (II), of the title compound evidences no spin crossover phenomena and remains in the high-spin state in temperature range 2-300 K. The comparison of Cl and Br compounds allows distinguishing the thermal and spin-crossover contributions to the overall bond lengths variation. The difference in magnetic behavior of these salts is ascribed to intermolecular supramolecular effects on the spin transition. In both compound, there is discrete hydrogen bonding between cations and cations and anions. However, this hydrogen bonding in crystals II is much stronger, than in I. The relatively close arrangement of [Mn(5-Br-sal-N-1,5,8,12)]+cations probably precludes their spin transformation.
- Добавил в систему: Васильев Александр Николаевич