В журнале ChemPlusChem (IF=3,4) опубликована статья, посвященная памяти проф. В.И. Овчеренко (1952-2022). Соавторями с участием сотрудников Лабортории гетероциклических соединений (д.х.н., внс Макарова А.Ю., д.х.н., гнс Зибарева А.В.), Лаборатории электрохимически активных соединений и материалов (к.х.н., снс И.К. Шундриной, д.х.н., зав. лабораторией Л.А. Шундрина, к.х.н.снс И.Г. Иртеговой) и Группы рентгеноструктурного анализа (д.х.н., внс, рук. группы И.Ю. Багрянской) :
Hysteretic Room-Temperature Magnetic Bistability of the Crystalline 4,7-Difluoro-1,3,2-Benzodithiazolyl Radical
Alexander Yurievich Makarov, Alexander A. Buravlev, Galina V. Romanenko, Artem S. Bogomyakov, Boris A. Zakharov, Vitaly A. Morozov, Alexander S. Sukhikh, Inna K. Shundrina, Leonid A. Shundrin, Irina G. Irtegova, Svetlana V. Cherepanova, Irina Yu. Bagryanskaya, Pavel V. Nikulshin, Andrey V. Zibarev
ChemPlusChem, Volume 89, Issue 6, June 2024, e202300736 First published: 08 February 2024
Crystalline 4,7-difluoro-1,3,2-benzodithiazolyl, the first isolated and structurally defined representative of ring-fluorinated Wolmershäuser radicals, reveals room-temperature magnetic bistability (spin-Peierls transition) with the hysteretic loop of 10 K.
Abstract
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.
