Cocrystallization of Hexamethylenetetramine (hmt) with Dicarboxylic Acids. Crystal Structures of Molecular Adducts of hmt with Three Different Dicarboxylic Acids

Abstract

Four hydrogen-bonded networks, both one- and two-dimensional structures, hmt·dsda·0.5H₂O (1), hmt·apa (2), hmt·2mbda·H₂O (3) and 2hmt·mbda (4) (hmt = hexamethylenetetramine, dsda = 2,2′-dithiosalicylic acid, apa = adipic acid, mbda = meta-benzenedicarboxylic acid), have been self-assembled with hmt and dicarboxylic acids and characterized by X-ray crystallography. Compound (1) is composed of one-dimensional hydrogen-bonded chains, the hydrogen-bonding interactions arising between the carboxylate groups of the dsda molecules. Each pair of chains is then further interconnected by hydrogen-bond bridges of the type dsda···hmt···H₂O···hmt···dsda, which results in an approximate ladder-like chain. Compound (2) is composed of one-dimensional hydrogen-bonded zigzag chains. The compounds are both organized in layers in which hydrogen-bonding networks are formed regularly. In (3), hmt acts unprecedentedly as an acceptor of four hydrogen bonds. The four-connected hmt and water molecules, and the two-connected mbda molecules, are interlinked through hydrogen-bonding interactions into a two-dimensional highly wavy layer of (4,4) topology. Compound (4) is composed of a one-dimensional hydrogen-bonded ladder-like chain.