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Weak antiferromagnetic exchange and ferromagnetic alignment of Fe(II) (S = 2) spins in differently charged {HAT.(Fe(II)Cl2)3}n (n = 2- and 3-) assemblies of hexaazatriphenylenes (HAT)статья
- Авторы: Mikhailenko Maxim V., Khasanov Salavat S., Shestakov Alexader F., Kuzmin Aleksey V., Otsuka Akihiro, Yamochi Hideki, Kitagawa Hiroshi, Konarev Dmitri V.
- Журнал: Chemistry - A European Journal
- Том: 28
- Номер: 10
- Год издания: 2022
- Издательство: John Wiley & Sons Ltd.
- Местоположение издательства: United Kingdom
- Первая страница: e202104165
- DOI: 10.1002/chem.202104165
- Аннотация: Hexaazatrianthracene (HATA) and hexaazatriphenylenehexacarbonitrile{HAT(CN)6} are reduced by metallic ironin the presence of crystal violet (CV+)(Cl(-)). Anionic ligands are produced, which simultaneously coordinate three Fe(II)Cl2 to form (CV+)2{HATA·(Fe(II)Cl2)3}(2-)·3C6H4Cl2 (1) and(CV+)3{HAT(CN)6.(Fe(II)Cl2)3}(3-)·0.5CVCl·2.5 C6H4Cl2 (2). High-spin (S=2) Fe(II) atoms in both structures are arranged in equilateraltriangles at a distance of 7 Å. An antiferromagnetic exchange is observed between Fe(II) in {HATA·(Fe(II)Cl2)3}(2-) (1) with a Weisstemperature (Θ) of -80 K, the PHI estimated exchange interaction (J) is -4.7 cm(-1). The {HAT(CN)6·(Fe(II)Cl2)3}(3-) assemblyis obtained in 2. The formation of HAT(CN)6(.3-) is supported by the appearance of an intense EPR signal with g=2.0037. The magnetic behavior of 2 is described by a strong antiferromagnetic coupling between the Fe(II) and HAT(CN)6(.3-) spins with J1= -164 cm(-1) (-2 J formalism) and bya weaker antiferromagnetic coupling between the Fe(II) spins with J2=-15.4 cm(-1). The stronger coupling results in the spins of the three Fe(II)Cl2 units to be aligned parallel to eachother in the assembly. As a result, an increase of the χMT values is observed with the decrease of temperature from 9.82 at 300 K up to 15.06 emu·K/mol at 6 K, and the Weiss temperature is also positive being at +23 K. Thus, a changein the charge and spin state of the HAT-type ligand to (.3-) results in ferromagnetic alignment of the FeII spins, yielding a high-spin (S = 11/2) system. DFT calculations showed that, due to the high symmetry and nearly degenerated LUMO of both HATA and HAT(CN)6, their complexes with Fe(II)Cl2 have avariety of closely lying excited high-spin states with multiplicity up to S=15/2.
- Добавил в систему: Конарев Дмитрий Валентинович