Photochemical generation of triplet—triplet nitrene pairs in aromatic diazide crystals
作者:S. V. Chapyshev、V. F. Lavitskii、A. V. Akimov、E. Ya. Misochko、A. V. Shastin、D. V. Korchagin、G. V. Shilov、S. M. Aldoshin
DOI:10.1007/s11172-008-0081-0
日期:2008.3
The molecular and crystal structures of 4-amino-2,6-diazido-3,5-dichloropyridine and 6-amino-2,4-diazido-1,3,5-triazine, as well as the paramagnetic photolysis products of their crystals at 77 K, were studied using X-ray diffraction analysis and ESR spectroscopy. Triplet nitrenes generated during the photolysis of diazidopyridine form triplet—triplet nitrene pairs, whose ESR spectrum corresponds to the quintet spin state. The high-spin state (S = 2) results from the exchange interaction between two triplet molecules with the zero-field splitting parameters |D| = 1.0280 cm−1 and |E| = 0.0038 cm−1 and the γ angle between two C—N nitrene bonds equal to 133°. This angle is close to an angle of 136.2° between the C-N bonds of two adjacent molecules in the crystal structure. No formation of the triplet—triplet nitrene pairs is observed during the photolysis of crystalline diazidotriazine, whose molecules lie in the parallel planes.
利用 X 射线衍射分析和 ESR 光谱法研究了 4-氨基-2,6-二叠氮-3,5-二氯吡啶和 6-氨基-2,4-二叠氮-1,3,5-三嗪的分子和晶体结构,以及它们的晶体在 77 K 下的顺磁光解产物。在重氮吡啶的光解过程中生成的三重腈形成三重-三重腈对,其 ESR 光谱与五重自旋态相对应。高自旋态(S = 2)产生于两个三重分子之间的交换相互作用,其零场分裂参数为 |D| = 1.0280 cm-1 和 |E| = 0.0038 cm-1,两个 C-N 腈键之间的 γ 角等于 133°。这个角度接近晶体结构中两个相邻分子的 C-N 键之间的 136.2°夹角。在晶体重氮三嗪的光解过程中,没有观察到三重-三重腈对的形成,其分子位于平行平面上。