Chantrapromma Suchada, Fun Hoong-Kun, Padaki Mahesh, Suwunwong Thitipone, Isloor Arun M
Acta Crystallogr Sect E Struct Rep Online. 2010 Feb 17;66(Pt 3):o641-2. doi: 10.1107/S1600536810005210.
There are two mol-ecules in the asymmetric unit of the title compound, C(23)H(21)BrN(2)O(4), which differ in the conformation of their ethoxy residues, i.e. almost co-planar with the pyridine ring in one mol-ecule [C-O-C-C = -174.0 (2)°] but almost perpendicular in the other [C-O-C-C = 92.8 (3)°]. The dihedral angles between the central pyridine ring and the 4-bromo-phenyl and 2,4,5-trimethoxy-phenyl rings are 11.05 (12) and 63.78 (12)°, respectively, in one mol-ecule; the corres-ponding angles in the other mol-ecule are 30.38 (13) and 65.38 (13)°, respectively. In the crystal structure, pairs of mol-ecules are arranged in a face-to-face sandwich structure which further stacks along the b axis. The crystal packing features C-H⋯π inter-actions and Br⋯O [3.5417 (17) Å], Br⋯C [3.748 (3) Å], C⋯N [3.376 (4) Å] and C⋯O [3.351 (3)-3.409 (3) Å] contacts. Finally, π⋯π inter-actions [centroid⋯centroid distances = 3.6346 (19) and 3.6882 (19) Å] are observed.
标题化合物C₂₃H₂₁BrN₂O₄的不对称单元中有两个分子，它们乙氧基的构象不同，即在一个分子中乙氧基几乎与吡啶环共平面[C - O - C - C = -174.0(2)°]，而在另一个分子中几乎垂直[C - O - C - C = 92.8(3)°]。在一个分子中，中心吡啶环与4 - 溴苯基和2,4,5 - 三甲氧基苯基环之间的二面角分别为11.05(12)°和63.78(12)°；另一个分子中的相应角度分别为30.38(13)°和65.38(13)°。在晶体结构中，分子对以面对面的夹心结构排列，并沿b轴进一步堆积。晶体堆积具有C - H⋯π相互作用以及Br⋯O [3.5417(17) Å]、Br⋯C [3.748(3) Å]、C⋯N [3.376(4) Å]和C⋯O [3.351(3) - 3.409(3) Å]接触。最后，观察到了π⋯π相互作用[质心⋯质心距离 = 3.6346(19)和3.6882(19) Å]。
