Series of Fluorinated Benzimidazole-Substituted Nitronyl Nitroxides: Synthesis, Structure, Acidity, Redox Properties, and Magnetostructural Correlations
作者:Evgeny Tretyakov、Pavel Fedyushin、Nadejda Bakuleva、Alexander Korlyukov、Pavel Dorovatovskii、Nina Gritsan、Alexey Dmitriev、Anna Akyeva、Mikhail Syroeshkin、Dmitri Stass、Mikhail Zykin、Nikolay Efimov、Dominique Luneau
DOI:10.1021/acs.joc.2c01793
日期:——
exchange interactions are weak. According to cyclic voltammetry, paramagnets are oxidized reversibly, while their reduction is a quasi-reversible electron transfer (EC mechanism); experimental redox potentials of radicals correlate well with the calculated values. Quantum chemical assessment of the acidity of benzimidazolyl-substituted nitronyl nitroxides revealed that the introduction of fluorine atoms
合成了一系列特殊的硝基硝基氧:2-(苯并咪唑-2′-基)-4,4,5,5-四甲基-4,5-二氢-1 H-咪唑-3-氧化物-1-氧基单-苯环上的二氟化、三氟化或四氟化。所有顺磁体的结构均通过单晶 X 射线衍射明确证实。研究发现,在晶体中,由于苯并咪唑部分(氢键供体)和硝基硝基氧基团或苯并咪唑环(氢键受体)之间的分子间氢键,自由基组装成链。硝基硝基氧的磁性取决于氢键结合自由基的类型。4-氟-、5-氟-、4,6-二氟-、4,5,6-三氟-、4,5,7-三氟-和4,5,6,7-四氟-的磁性基序衍生物以及非氟化化合物由麦康奈尔 I 型机理形成的铁磁链 ( J / k B ≈ 20–40 K) 组成。在5,6-二氟和4,5-二氟衍生物中,顺磁中心之间的距离很大,因此交换相互作用很弱。根据循环伏安法,顺磁体的氧化是可逆的,而其还原是准可逆的电子转移(EC机制);自由基的实验氧化还原电位与计算值密切相关。