Different packing motifs mediated by hydrogen bonds in the hydrochloride salts of two pyridoxal N-acylhydrazone derivatives
Year: 2025
Type: article
Abstract: The crystal structures of two hydrochloride salts of pyridoxal–N-acylhydrazone–Q (Q = heterocyclic aromatic ring) derivatives, viz. (E)-3-hydroxy-5-(hydroxymethyl)-2-methyl-4-{[(pyridin-4-ylformamido)imino]methyl}pyridin-1-ium chloride dihydrate, C14H15N4O3 +·Cl−·2H2O, (I), and (E)-3-hydroxy-5-(hydroxymethyl)-2-methyl-4-{[(pyrimidin-2-ylformamido)imino]methyl}pyridin-1-ium chloride dihydrate, C13H14N5O3 +·Cl−·2H2O, (II) are described. The cations, which are protonated at the pyridine N atom of the pyridoxal ring, have similar overall conformations: the dihedral angles between the pyridoxal ring and the terminal aromatic ring are 12.63 (12) and 6.11 (15)° for (I) and (II), respectively. Each cation features an intramolecular O—H...N hydrogen bond, which closes an S(6) ring, but a difference arises in the conformation of the C—C—C—O fragment terminated by the the ring carbon atom bonded to the side chain and the O atom of the hydroxymethyl group: gauche for (I) and anti for (II). The extended structures of (I) and (II) feature numerous strong (N—H and O—H donors) and weak (C—H donor) hydrogen bonds. In (I), the NHp (pyridine) grouping links to the terminal N atom of the pendant unprotonated pyridine ring of an adjacent cation to generate [010] chains, whereas the NHh (hydrazide) and OHhm (hydroxymethyl) moieties link to chloride ion acceptors. In (II), the NHp and OHhm groupings bond to chloride anions whereas NHh bonds to a water molecule. Hydrogen-bonded chains of water molecules occur in (I) and centrosymmetric tetramers in (II). The Hirshfeld surfaces of (I) and (II) are computed and the structures of related compounds are briefly compared.
Institutions: Fundação Oswaldo Cruz, University of Aberdeen
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $500
OpenAlex ID: W4414158252