Two new 1,2,4-triazine-containing sulfonamide derivatives, namely, 4-bromo-N-(5,6-diphenyl-2H-1,2,4-triazin-3-ylidene)benzenesulfonamide, C21H15BrN4O4S, 3a, and methyl 2-[(5,6-diphenyl-1,2,4-triazin-3-yl)sulfamoyl]methyl}benzoate, C24H20N4O4S, 3b, which crystallize in the different sulfonimide and sulfonamide tautomeric forms, respectively, were synthesized and characterized by spectroscopic, X-ray diffraction and theoretical calculation methods. Both molecules adopt a very similar conformation of the common part of the structure and the differences occur within the substituents on the sulfonamide group. The amino groups characteristic for the existing tautomeric forms are involved in strong intermolecular N—H...N and N—H...O hydrogen bonds in 3a and 3b, respectively. The Hirshfeld surface analysis showed that H...H contacts constitute a high percentage of the intermolecular interactions. Theoretical calculations at the ab initio DFT/B3LYP/6-311++G(d,p) level showed that the two tautomeric forms observed for 3a and 3b can co-exist in chloroform, ethanol and water solutions, with a distinct predominance of the sulfonamide form; the participation of the sulfonimide form increases with increasing solvent polarity.
合成了两种新的含 1,2,4-三嗪的磺酰胺衍生物,即 4-溴-N-(5,6-二苯基-2H-1,2,4-三嗪-3-亚基)苯磺酰胺 C21H15BrN4O4S, 3a 和 2-[(5,6-二苯基-1,2,4-三嗪-3-基)氨基磺酰基]甲基}苯甲酸甲酯、C24H20N4O4S, 3b 分别以不同的磺酰亚胺和磺酰胺同分异构形式结晶。这两种分子的共同结构部分的构象非常相似,不同之处在于磺酰胺基团上的取代基。在 3a 和 3b 中,现有同分异构体所特有的氨基分别参与了强分子间 N-H...N 和 N-H...O 氢键。Hirshfeld 表面分析表明,H...H 接触在分子间相互作用中占很大比例。在 ab initio DFT/B3LYP/6-311++G(d,p) 水平上进行的理论计算表明,在氯仿、乙醇和水溶液中可以观察到 3a 和 3b 的两种同分异构形式,其中磺酰胺形式明显占优势;磺酰亚胺形式的参与程度随着溶剂极性的增加而增加。