Crystal structures and hydrogen-bonding analysis of a series of benzamide complexes of zinc(II) chloride

Ionic co-crystals are co-crystals between organic molecules and inorganic salt coformers. Co-crystals of pharmaceuticals are of interest to help control polymorph formation and potentially improve stability and other physical properties. We describe the preparation, crystal structures, and hydrogen bonding of five different 2:1 benzamide or toluamide/zinc(II) chloride co-crystal salts, namely, bis(benzamide-kappa O)dichloridozinc(II), [ZnCl2(C7H7NO)(2)], dichloridobis(2-methylbenzamide-kappa O)zinc(II), [ZnCl2(C8H9NO)(2)], dichloridobis(3-methylbenzamide-kappa O)zinc(II), [ZnCl2(C8H9NO)(2)], dichloridobis(4-methylbenzamide-kappa O)zinc(II), [ZnCl2(C8H9NO)(2)], and dichloridobis(4-hydroxybenzamide-kappa O)zinc(II), [ZnCl2(C7H7NO2)(2)]. All of the complexes contain hydrogen bonds between the amide N-H group and the amide carbonyl oxygen atoms or the chlorine atoms, forming extended networks.