Two polymorphic forms of 1-(4-methylpyridin-2-yl)thiourea (1) and the crystal and molecular structures of the 2-aminothiazoles N-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (2) and N-(4-methylpyridin-2-yl)-4-(pyrazin-2-yl)thiazol-2-amine (3), derived from 1 and the respective α-bromoketone via the Hantzsch reaction, are described. Both polymorphic forms 1α (space group P21/c, Z = 4) and 1β (space group P21/n, Z = 8) crystallize in the monoclinic system but exhibit distinctly different intermolecular hydrogen bonding patterns. Compound 2 (orthorhombic, space group Pca21, Z = 8) forms polymeric N–H⋯N hydrogen-bonded zigzag tapes in the polar crystal structure, with a significant twisting between the thiazole and pyridine rings. In contrast, the crystal structure of 3 (monoclinic, space group P21/c, Z = 4) features nearly planar centrosymmetric N–H⋯N hydrogen-bonded dimers, which are laterally joined through long C–H⋯N contacts, affording a π⋯π stacked layered structure. Two polymorphs of 1-(4-methylpyridin-2-yl)thiourea and the crystal and molecular structures of two 2-aminothiazoles, derived from 1-(4-methylpyridin-2-yl)thiourea and α-bromoketones via Hantzsch reaction, are reported.

中文翻译：

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1-(4-甲基吡啶-2-基)硫脲的两种多晶型物和两种衍生的 2-氨基噻唑的结构表征

1-(4-methylpyridin-2-yl)thiourea (1) 的两种多晶型和 2-aminothiazoles N-(4-methylpyridin-2-yl)-4-(pyridin-2-yl) 的晶体和分子结构)噻唑-2-胺(2)和N-(4-甲基吡啶-2-基)-4-(吡嗪-2-基)噻唑-2-胺(3)，衍生自1和各自的α-溴酮通过描述了 Hantzsch 反应。两种多晶型 1α（空间群 P21/c，Z = 4）和 1β（空间群 P21/n，Z = 8）在单斜晶系中结晶，但表现出明显不同的分子间氢键模式。化合物 2（斜方晶系，空间群 Pca21，Z = 8）在极性晶体结构中形成聚合的 N–H⋯N 氢键锯齿带，噻唑环和吡啶环之间有明显的扭曲。相比之下，3（单斜，空间群 P21/c，Z = 4) 具有近乎平面的中心对称 N–H⋯N 氢键二聚体，它们通过长 C–H⋯N 接触横向连接，提供 π⋯π 堆叠层状结构。1-(4-甲基吡啶-2-基)硫脲的两种多晶型物和两种 2-氨基噻唑的晶体和分子结构，通过 Hantzsch 反应衍生自 1-(4-甲基吡啶-2-基)硫脲和 α-溴酮，是报道。