TY - JOUR

T1 - Hysteretic Room-Temperature Magnetic Bistability of the Crystalline 4,7-Difluoro-1,3,2-Benzodithiazolyl Radical

AU - Makarov, Alexander Yu

AU - Buravlev, Alexander A

AU - Romanenko, Galina V

AU - Bogomyakov, Artem S

AU - Zakharov, Boris A

AU - Morozov, Vitaly A

AU - Sukhikh, Alexander S

AU - Shundrina, Inna K

AU - Shundrin, Leonid A

AU - Irtegova, Irina G

AU - Cherepanova, Svetlana V

AU - Bagryanskaya, Irina Yu

AU - Nikulshin, Pavel V

AU - Zibarev, Andrey V

N1 - The authors are grateful to the Russian Science Foundation (project no. 23‐13‐00014; magnetochemistry and XRD at the International Tomography Center), and to the Ministry for Science and Higher Education of Russian Federation (projects 121031700313‐8, 122040800264‐3 and 122040800263‐6 at the Institutes of Inorganic and Organic Chemistry, and Strategic Academic Leadership Program at the Novosibirsk State University) for financial support of this work. Instrumental support of the work at the Multi‐Access Chemical Research Center (Institute of Organic Chemistry) and the XRD Facility (Institute of Inorganic Chemistry) is gratefully acknowledged. Priority 2030. © 2024 Wiley-VCH GmbH.

PY - 2024/6

Y1 - 2024/6

N2 - The title radical R⋅, synthesized by reduction of the corresponding cation R+, is thermally stable up to ~380 K in the crystalline state under anaerobic conditions. With SQUID magnetometry, single-crystal and powder XRD, solid-state EPR and TG-DSC, reversible spin-Peierls transition between diamagnetic and paramagnetic states featuring ~10 K hysteretic loop is observed for R⋅ in the temperature range ~310-325 K; ΔH=~2.03 kJ mol-1 and ΔS=~6.23 J mol-1 K-1. The transition is accompanied by mechanical movement of the crystals, i. e., by thermosalient behavior. The low-temperature diamagnetic P-1 polymorph of R⋅ consists of R⋅2 π-dimers arranged in (…R⋅2…)n π-stacks; whereas the high-temperature paramagnetic P21/c polymorph, of uniform (…R⋅…)n π-stacks. With the XRD geometries, CASSCF and broken-symmetry DFT jointly suggest strong antiferromagnetic (AF) interactions within R⋅2 and weak between R⋅2 for the (…R⋅2…)n stacks; and moderate AF interactions between R⋅ for the (…R⋅…)n stacks. The fully hydrocarbon archetype of R⋅ does not reveal the aforementioned properties. Thus, the fluorinated 1,3,2-benzodithiazolyls pave a new pathway in the design and synthesis of metal-less magnetically-bistable materials.

AB - The title radical R⋅, synthesized by reduction of the corresponding cation R+, is thermally stable up to ~380 K in the crystalline state under anaerobic conditions. With SQUID magnetometry, single-crystal and powder XRD, solid-state EPR and TG-DSC, reversible spin-Peierls transition between diamagnetic and paramagnetic states featuring ~10 K hysteretic loop is observed for R⋅ in the temperature range ~310-325 K; ΔH=~2.03 kJ mol-1 and ΔS=~6.23 J mol-1 K-1. The transition is accompanied by mechanical movement of the crystals, i. e., by thermosalient behavior. The low-temperature diamagnetic P-1 polymorph of R⋅ consists of R⋅2 π-dimers arranged in (…R⋅2…)n π-stacks; whereas the high-temperature paramagnetic P21/c polymorph, of uniform (…R⋅…)n π-stacks. With the XRD geometries, CASSCF and broken-symmetry DFT jointly suggest strong antiferromagnetic (AF) interactions within R⋅2 and weak between R⋅2 for the (…R⋅2…)n stacks; and moderate AF interactions between R⋅ for the (…R⋅…)n stacks. The fully hydrocarbon archetype of R⋅ does not reveal the aforementioned properties. Thus, the fluorinated 1,3,2-benzodithiazolyls pave a new pathway in the design and synthesis of metal-less magnetically-bistable materials.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85185942081&origin=inward&txGid=73fb296d3f1b876e05f7c4089c08fb02

U2 - 10.1002/cplu.202300736

DO - 10.1002/cplu.202300736

M3 - Article

C2 - 38332534

VL - 89

JO - ChemPlusChem

JF - ChemPlusChem

SN - 2192-6506

IS - 6

M1 - e202300736

ER -