TY - JOUR

T1 - Effects of Difluorophenyl Substituents on Structural, Redox, and Magnetic Properties of Blatter Radicals

AU - Gulyaev, Dmitry

AU - Serykh, Andrey

AU - Tretyakov, Evgeny

AU - Akyeva, Anna

AU - Syroeshkin, Mikhail

AU - Gorbunov, Dmitry E.

AU - Maltseva, Svetlana V.

AU - Gritsan, Nina P.

AU - Romanenko, Galina

AU - Bogomyakov, Artem

N1 - D.G. (Dmitry Gorbunov), S.M. and N.G. acknowledge the core funding from the Russian Federal Ministry of Science and Higher Education (FWGF-2021-0002) and the Research Resource Center “Irkutsk Supercomputer Center SB RAS” for the computational resources. The authors wish to thank A. Korlyukov (INEOS RAS) for single crystal analyses of 3a at 100 K. Публикация для корректировки.

PY - 2023/8

Y1 - 2023/8

N2 - Blatter radicals 1-(3,4-difluorophenyl)-(1a) and 1-(2,4-difluorophenyl)-3-phenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl (1b) were prepared in good yields through oxidation of the corresponding amidrazones using MnO2 in dry CH2Cl2. Cyclic voltammetry showed that both radicals are oxidized and reduced chemically and electrochemically reversibly in accordance with −1/0 and 0/+1 processes. EPR spectroscopy indicated that spin density is mainly delocalized on the triazinyl moiety of the heterocycle. The structure of all paramagnets was unambiguously confirmed by single-crystal X-ray diffraction, and two different 1D chains of alternating radicals were identified. 3,4-difluorophenyl-derivatives 1a are packed into columns composed of two kinds of alternating centrosymmetric dimers, having comparatively short intermolecular distances. In crystals of 2,4-difluorophenyl-derivative 1b, the parallel arrangement of bicyclic moieties and phenyl rings favors the formation of 1D regular chains wherein the radicals are related by translation parallel to the crystallographic stacking axis. Magnetic susceptibility measurements in the 2–300 K region showed that in crystals of the radicals, strong antiferromagnetic interactions are dominant. Subsequent fitting of the dependence of χT on T with 12-membered looped stacks gave the following best-fit parameters: for 1a, g = 2.01 ± 0.05, J1/kB = −292 ± 10 K (according to BS-DFT calculations J2 = 0.12 × J1 and J3 = 0.61 × J1); for 1b, g = 2.04 ± 0.01 J1/kB = −222 ± 17 K. For comparison, in a nonfluorinated related radical, there are only very weak intermolecular interactions along the columns (J/kB = −2.2 ± 0.2 K). These results illustrate the magnitude of the influence of the difluorophenyl substituents introduced into Blatter radicals on their structure and magnetic properties.

AB - Blatter radicals 1-(3,4-difluorophenyl)-(1a) and 1-(2,4-difluorophenyl)-3-phenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl (1b) were prepared in good yields through oxidation of the corresponding amidrazones using MnO2 in dry CH2Cl2. Cyclic voltammetry showed that both radicals are oxidized and reduced chemically and electrochemically reversibly in accordance with −1/0 and 0/+1 processes. EPR spectroscopy indicated that spin density is mainly delocalized on the triazinyl moiety of the heterocycle. The structure of all paramagnets was unambiguously confirmed by single-crystal X-ray diffraction, and two different 1D chains of alternating radicals were identified. 3,4-difluorophenyl-derivatives 1a are packed into columns composed of two kinds of alternating centrosymmetric dimers, having comparatively short intermolecular distances. In crystals of 2,4-difluorophenyl-derivative 1b, the parallel arrangement of bicyclic moieties and phenyl rings favors the formation of 1D regular chains wherein the radicals are related by translation parallel to the crystallographic stacking axis. Magnetic susceptibility measurements in the 2–300 K region showed that in crystals of the radicals, strong antiferromagnetic interactions are dominant. Subsequent fitting of the dependence of χT on T with 12-membered looped stacks gave the following best-fit parameters: for 1a, g = 2.01 ± 0.05, J1/kB = −292 ± 10 K (according to BS-DFT calculations J2 = 0.12 × J1 and J3 = 0.61 × J1); for 1b, g = 2.04 ± 0.01 J1/kB = −222 ± 17 K. For comparison, in a nonfluorinated related radical, there are only very weak intermolecular interactions along the columns (J/kB = −2.2 ± 0.2 K). These results illustrate the magnitude of the influence of the difluorophenyl substituents introduced into Blatter radicals on their structure and magnetic properties.

KW - Blatter radicals

KW - antiferromagnetically coupled chains

KW - electrochemically reversible processes

KW - fluorinated organic compounds

KW - magneto-structural correlations

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85169076747&origin=inward&txGid=1598f9b80fd3ccc8144aa0cc4cd165cf

UR - https://www.mendeley.com/catalogue/090f432c-f670-31fc-b9a0-52dd8c73f3ca/

U2 - 10.3390/catal13081206

DO - 10.3390/catal13081206

M3 - Article

VL - 13

JO - Catalysts

JF - Catalysts

SN - 2073-4344

IS - 8

M1 - 1206

ER -