Shad Hazoor A, Tahir M Nawaz, Chohan Zahid H
Acta Crystallogr Sect E Struct Rep Online. 2008 Dec 13;65(Pt 1):o98-9. doi: 10.1107/S1600536808041214.
The title compound, 0.61C(19)H(17)BrN(4)O(3)S·0.39C(19)H(17)BrN(4)O(3)S, is a Schiff base derived from 5-bromo-salicylaldehyde and 4-amino-N-(4,6-dimethyl-2-pyrimidin-yl)benzene-sulfonamide(sulfamethazine) and is isostructural with its chloro analogue. The geometry of the title mol-ecule points to the enol (OH-C=C-C=N) form as the major tautomer, however two electron-density maxima corresponding to the H atoms of the OH and NH groups, found in the region of a strong intra-molecular N⋯H⋯O hydrogen bond, do not allow the elimination of the presence of the zwitterionic (O(-)-C=C-C=NH(+)) form in the crystal. Refinement of the occupancies of these H atoms gave a 0.61 (7):0.39 (7) ratio of the enolic and zwitterionic forms. The two benzene rings within the mol-ecule are nearly coplanar and the central benzene ring forms a dihedral angle of 84.1 (1)° with the pyrimidine fragment. An inter-molecular N-H⋯O hydrogen bond links mol-ecules into chains extended along the a axis and a C-H⋯O link is also present. The H atoms of one of the methyl groups are disordered over two sites with an occupancy ratio of 0.72 (7):0.28 (7).
标题化合物0.61C(19)H(17)BrN(4)O(3)S·0.39C(19)H(17)BrN(4)O(3)S是一种席夫碱，由5-溴水杨醛和4-氨基-N-(4,6-二甲基-2-嘧啶基)苯磺酰胺（磺胺二甲嘧啶）衍生而来，并且与其氯代类似物同构。标题分子的几何结构表明烯醇式（OH-C=C-C=N）形式是主要互变异构体，然而，在强分子内N⋯H⋯O氢键区域发现的与OH和NH基团的H原子对应的两个电子密度最大值，不排除晶体中两性离子形式（O(-)-C=C-C=NH(+)）的存在。对这些H原子占有率的精修得出烯醇式和两性离子形式的比例为0.61 (7):0.39 (7)。分子内的两个苯环几乎共面，中心苯环与嘧啶片段形成84.1 (1)°的二面角。分子间N-H⋯O氢键将分子连接成沿a轴延伸的链，并且还存在C-H⋯O连接。其中一个甲基的H原子在两个位置上无序分布，占有率比例为0.72 (7):0.28 (7)。
