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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Photochemistry of Crystalline Chlorodiazirines: The Influence of Conformational Disorder and Intermolecular Cl…N=N Interactions on the Solid-State Reactivity of Singlet Chlorocarbenes
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Photochemistry of Crystalline Chlorodiazirines: The Influence of Conformational Disorder and Intermolecular Cl…N=N Interactions on the Solid-State Reactivity of Singlet Chlorocarbenes

机译：晶体氯二叠氮基的光化学：构象紊乱和分子间Cl…N = N相互作用对单线态碳卡宾固态反应性的影响

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摘要

A photochemical study was carried out with 3-substituted 3-chlorodiazirines with 4-biphenyl-(4a), (4-biphenyl)-methyl- (4b), 2-(4-biphenyl)ethyl- (4c), and 1,1-dimethyl-1-(4-biphenyl)methyl (4d) substituents. The chlorodiazirines were prepared from the corresponding amidines (7) by a procedure involving oxidation with tert-butyl hypochlorite under phase-transfer catalysis. The crystalline nature of 4a-d was established by differential scanning calorimetric analysis, which revealed melting endotherms prior to thermal decomposition. Photochemical results in crystalline solids were analogous to those observed in solution, and the products were analyzed in terms of the corresponding singlet-state chlorocarbene intermediates (5a-d). Irradiation of 4a in solution and in crystals resulted in formation of azine 9a by reaction of carbene 5a with its precursor. Equally selective, diazirine 4d gave alkene 6d as the only product by a 1,2-Ph migration from carbene 5d. In contrast, irradiation of compounds 4b and 4c resulted in formation of two alkenes by 1,2-H shifts and formation of azines by reactions of the carbenes with their precursors. The low selectivity of 4b was rationalized in terms of structural data from single-crystal X-ray diffraction analysis, which revealed two disordered diazirine conformers and close Cl…N contacts between adjacent molecules. Rapid conformational equilibration in the solid state was also suggested by solid-state ~(13)C CPMAS NMR. Similar structural effects are also postulated to account for the solid-state reactivity of 4c.
机译：用3-取代的3-氯二嗪与4-联苯基-（4a），（4-联苯基）-甲基-（4b），2-（4-联苯基）乙基-（4c）和1进行了光化学研究1-二甲基-1-（4-联苯基）甲基（4d）取代基。由相应的am（7）通过包括在相转移催化下用次氯酸叔丁酯氧化的方法制备氯二嗪。 4a-d的晶体性质是通过差示扫描量热分析确定的，该分析揭示了在热分解之前的熔融吸热。结晶固体中的光化学结果类似于溶液中观察到的结果，并且根据相应的单重态氯卡宾中间体（5a-d）分析了产物。通过卡宾5a与其前体的反应，在溶液中和晶体中辐照4a导致形成嗪9a。同样选择性的二嗪4d通过从卡宾5d迁移1,2-Ph生成了唯一的烯烃6d产物。相反，化合物4b和4c的辐照导致通过1，2-H位移形成两个烯烃，以及通过卡宾与其前体的反应形成嗪。根据单晶X射线衍射分析获得的结构数据合理化了4b的低选择性，该结构数据揭示了两个无序的重氮二嗪构象异构体和相邻分子之间紧密的Cl…N接触。固态〜（13）C CPMAS NMR也表明了固态的快速构象平衡。还假定类似的结构效应可解释4c的固态反应性。

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