Hexamethylenetetramine hexahydrate: A new type of clathrate hydrate

Abstract

The crystal structure of hexamethylenetetramine hexahydrate, (CH 2) 6N46E2M), has been determined using three-dimensional x-ray data collected at -20°C. The analysis revealed a novel type of clathrate structure characterized by hydrogen-bonding interaction between the host and guest species. The water molecules form a hydrogen-bonded framework consisting of staggered columns of slightly puckered (H22O)6 rings cross linked to one another. Half of the water protons are in ordered arrangement in the crystal and the other half are twofold disordered. Each hexamethylenetetramine molecule is located in a cage within the clathrate framework, and is hydrogen bonded to the water lattice through three of its four nitrogen atoms.