Beschreibung:
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<jats:title>Abstract</jats:title>
<jats:p>Two polymorphic forms of 1-(4-methylpyridin-2-yl)thiourea (<jats:bold>1</jats:bold>) and the crystal and molecular structures of the 2-aminothiazoles <jats:italic>N</jats:italic>-(4-methylpyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (<jats:bold>2</jats:bold>) and <jats:italic>N</jats:italic>-(4-methylpyridin-2-yl)-4-(pyrazin-2-yl)thiazol-2-amine (<jats:bold>3</jats:bold>), derived from <jats:bold>1</jats:bold> and the respective α-bromoketone via the Hantzsch reaction, are described. Both polymorphic forms <jats:bold>1α</jats:bold> (space group <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic>, <jats:italic>Z</jats:italic> = 4) and <jats:bold>1β</jats:bold> (space group <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>/<jats:italic>n</jats:italic>, <jats:italic>Z</jats:italic> = 8) crystallize in the monoclinic system but exhibit distinctly different intermolecular hydrogen bonding patterns. Compound <jats:bold>2</jats:bold> (orthorhombic, space group <jats:italic>Pca</jats:italic>2<jats:sub>1</jats:sub>, <jats:italic>Z</jats:italic> = 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 <jats:bold>3</jats:bold> (monoclinic, space group <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic>, <jats:italic>Z</jats:italic> = 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.</jats:p>
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<jats:title>Graphic Abstract</jats:title>
<jats:p>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.</jats:p>
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