Remarkable structural similarities between organic co-crystals and a metal–organic coordination network—insights into hydrogen bonded aliphatic ammonium chlorides

Abstract

The reaction of trans-1,4-diaminocyclohexane and piperazine with hydrochloric acid in dimethylsulfoxide or water led to new co-crystals and chloride salts, namely trans-1,4-diammoniocyclohexane dichloride dimethylsulfoxide 1, trans(ammonio-4-amino)cyclohexane monochloride 2, and piperazinium dichloride hemihydrate 3. The crystal structures show unexpected similarities to already noted organic and metal–organic derivatives. Furthermore, hot-stage microscopy, variable-temperature X-ray diffraction studies, and thermoanalytical measurements revealed decomposition reactions, solvent-free reaction pathways, and phase transition at temperatures between 160 and 210 °C.