Consistent supramolecular motifs and different local symmetries in the structures of 2-amino-5-(4-fluorophenyl)-1,3-thiazole-4-carbaldehyde and 2-amino-5-(4-chlorophenyl)-1,3-thiazole-4-carbaldehyde

The first title compound, C₁₀H₇FN₂OS, crystallizes in space group <i>P</i>1 with two independent mol-ecules in the asymmetric unit, which form a dimer with an <i>R</i> ² ₂(8) motif through pairwise N-H⋯N hydrogen bonds. In the crystal of (I), N-H⋯O hydrogen bonds bind the dimers into zigzag ribbons running along the [100] direction, generating <i>R</i> ⁴ ₄(14) motifs. The second title compound, C₁₀H₇ClN₂OS (space group <i>I</i>2/<i>a</i>), contains one mol-ecule in the asymmetric unit, which forms a dimer with an <i>R</i> ² ₂(8) motif <i>via</i> inversion symmetry. In the extended structure, the mol-ecules form zigzag ribbons in the [100] direction by N-H⋯N and N-H⋯O hydrogen bonds, resulting in consecutive <i>R</i> ⁴ ₁(8)<i>R</i> ² ₁(5)<i>R</i> ² ₂(8)<i>R</i> ² ₁(5)<i>R</i> ⁴ ₁(8) motifs. The Hirshfeld surface analyses of the compounds (I) and (II) indicates that the most important factors influencing the crystal packing are H⋯H inter-actions [21.1% for mol-ecule <i>A</i> of (I), 20.3% for mol-ecule <i>B</i> of (I) and 21.0% for (II)].