Descriptions of azoheteroaromatic compounds in their cis-isomeric form in the solid state are almost non-existent. Cis-2,2′-azopyridine is a known compound which structure differentiates from the trans-isomer based on spectroscopic evidence (UV–Vis absorption, 1H, and 13C NMR spectroscopy) and with studies regarding its stability, thermal reversion to the trans-isomer, and dipole moment in solution. However, the structure of this compound in the solid state has been unresolved. Herein, we present the crystal structure of cis-2,2′-azopyridine that forms red prismatic crystals in the monoclinic space group C2/c. The unit cell parameters are: a = 23.485 (4), b = 5.9241 (12), c = 21.656 (4) Å, and V = 2717.1 (9) Å3 with 12 molecules per unit cell. Molecules are arranged as two helical conformers (P and M) with C–N=N–C torsion angles and aromatic ring planes’ angles comparable to those reported for cis-azobenzene. The rare structural determination of an azoheteroaromatic cis-isomer of 2-azopyridine that was synthesized, isolated and crystallized is presented. X-ray structure analysis reveals that the molecule forms dimeric complexes containing both M- and P-helical conformers as well as infinite stacked columns in the solid state through a combination of C–H⋯N hydrogen bonds, C–H⋯π interactions and lone pair⋯π contacts.
在固态中,关于其顺式异构体形式的偶氮杂芳香化合物的描述几乎不存在。顺式-2,2'-偶氮
吡啶是一种已知化合物,其结构在光谱证据(紫外-可见吸收、1H和13C核磁共振光谱)以及关于其稳定性、向反式异构体的热反转和溶液中的偶极矩的研究中与反式异构体不同。然而,该化合物在固态中的结构尚未解决。在此,我们展示了形成红色棱柱晶体的顺式-2,2'-偶氮
吡啶的晶体结构,属于单斜空间群C2/c。单位晶胞参数为:a = 23.485 (4) Å,b = 5.9241 (12) Å,c = 21.656 (4) Å,体积V = 2717.1 (9) ų,单位晶胞中含有12个分子。分子排列为两种螺旋构象(P和M),其C–N=N–C扭转角和芳环平面的角度与已报道的顺式
偶氮苯相当。本文呈现了合成、分离和结晶得到的2-偶氮
吡啶的偶氮杂芳香族顺式异构体的稀少结构确定。X射线结构分析表明,分子在固态中通过C–H⋯N氢键、C–H⋯π相互作用和孤对⋯π接触形成包含M-和P-螺旋构象的二聚体复合物以及无限堆叠柱。