Photoextrusion of Molecular Nitrogen from Annulated 5‐Alkylidene‐4,5‐dihydro‐1H‐tetrazoles: Annulated Iminoaziridines and the First Triplet Diazatrimethylenemethane
Photoextrusion of Molecular Nitrogen from Annulated 5‐Alkylidene‐4,5‐dihydro‐1H‐tetrazoles: Annulated Iminoaziridines and the First Triplet Diazatrimethylenemethane
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从环状 5-亚烷基-4,5-二氢-1H-四唑中光挤出分子氮：环状亚氨基氮丙啶和第一个三重态二氮杂三亚甲基甲烷
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
W. Nüdling
中科院分区：
文献类型：
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作者：
H. Quast;A. Fuss;W. Nüdling
用氢化钠或氢化钾使成环的四唑鎓盐4、6、8、10和12去质子化，分别得到亚烷基二氢四唑5、7、9、11和13。尽管5a和B即使在低温下的溶液中也不稳定，但7、9、11和13形成黄色油，在高真空下蒸馏。−在−60°C下辐照7、9和11的[D8]甲苯溶液，除了分子氮外，还产生具有环外CN双键的环状亚氨基氮杂环丙烷，即分别为14、16和18。此外，由11形成等量的具有内环CN双键的异构体19。在此条件下，14、16和18分别进行[2 + 1]环化还原成甲基异氰化物和环亚胺15、17和20。相比之下，19热重排产生18。虽然双桥连亚烷基二氢四唑13 a在光解时仅提供未鉴定的分解产物，但其甲基同系物13 b转化为六氢萘啶22，该六氢萘啶22也在热分解时形成。−在77 K下，在2-甲基四氢呋喃或丁腈基质中辐照13 b，产生三重态双自由基，显示出中心在3362 G的四线EPR谱和具有超精细结构的半场跃迁（在1669 G）。零场分裂参数|D-HC| = 0.031 cm-1，|E-HC| = 0.0014 cm-1的电子顺磁共振谱。基于其EPR谱与三亚甲基甲烷（28）和三（N-甲基亚氨基）甲烷（29）的EPR谱之间的密切相似性，将信号载体指定为二氮杂三亚甲基甲烷结构23。−讨论了导致光化学途径之间观察到的差异的结构特征。
Deprotonation of the annulated tetrazolium salts 4, 6, 8, 10, and 12 with sodium or potassium hydride yields the alkylidenedihydrotetrazoles 5, 7, 9, 11, and 13, respectively. While 5a and b are unstable, even in solution at low temperatures, 7, 9, 11, and 13 form yellow oils that are distilled under high vacuum. − Irradiation of solutions of 7, 9, and 11 in [D8]toluene at −60°C yields, besides molecular nitrogen, annulated iminoaziridines that have an exocyclic CN double bond, i.e. 14, 16, and 18, respectively. In addition, an equal amount of the isomer 19 with the endocyclic CN double bond is formed from 11. On thermolysis, 14, 16, and 18 undergo [2 + 1] cycloreversion into methyl isocyanide and the cyclic imines 15, 17, and 20, respectively. By contrast, 19 rearranges thermally to yield 18. While the doubly bridged alkylidenedihydrotetrazole 13a affords only unidentified decomposition products on photolysis, its methyl homologue 13b is converted into the hexahydronaphthyridine 22 which is also formed on thermolysis. − Irradiation of 13b in a 2-methyltetrahydrofuran or butyronitrile matrix at 77 K yields a triplet diradical showing a four-line EPR spectrum centred at 3362 G and a half-field transition (at 1669 G) with a hyperfine structure. The zero-field splitting parameters |D-hc| = 0.031 cm−1 and |E-hc| = 0.0014 cm−1 are obtained by simulation of the EPR spectrum. The signal-carrier is assigned the diazatrimethylenemethane structure 23 on the basis of the close similarity between its EPR spectrum and those of trimethylenemethane (28) and tris(N-methylimino)methane (29). − Structural features are discussed that are responsible for the observed differences between the photochemical pathways.