Synthesis, structures and Hirshfeld surface analyses of 2-hy-droxy-N'-methyl-acetohydrazide and 2-hy-droxy-N-methyl-acetohydrazide.

The structures of the title compounds 2-hy-droxy-N'-methyl-acetohydrazide, 1, and 2-hy-droxy-N-methyl-acetohydrazide, 2, both C₃H₈N₂O₂, as regioisomers differ in the position of the methyl group relative to the N atoms in 2-hy-droxy-acetohydrazide. In the structure of 1, the 2-hy-droxy-acetohydrazide core [OH-C-C(=O)-NH-NH] is almost planar and the methyl group is rotated relative to this plane. As opposed to 1, in the structure of 2 all non-hydrogen atoms lie in the same plane. The hydroxyl and carbonyl groups in structures 1 and 2 are in trans and cis positions, respectively. The methyl amino group and carbonyl group are in the cis position relative to the C-N bond in structure 1, while the amino group and carbonyl group are in the trans position relative to the C-N bond in stucture 2. In the crystal, mol-ecules of 1 are linked by N-H⋯O and O-H⋯N inter-molecular hydrogen bonds, forming layers parallel to the ab crystallographic plane. A Hirshfeld surface analysis showed that the H⋯H contacts dominate the crystal packing with a contribution of 55.3%. The contribution of the H⋯O/O⋯H inter-action is somewhat smaller, amounting to 30.8%. In the crystal, as a result of the inter-molecular O-H⋯O hydrogen bonds, mol-ecules of 2 form dimers, which are linked by N-H⋯O hydrogen bonds and a three-dimensional supra-molecular network The major contributors to the Hirshfeld surface are H⋯H (58.5%) and H⋯O/O⋯H contacts (31.7%).