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

Ionic co-crystals are co-crystals between organic mol-ecules and inorganic salt coformers. Co-crystals of pharmaceuticals are of inter-est 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 tolu-amide/zinc(II) chloride co-crystal salts, namely, bis-(benzamide-κO)di-chlorido-zinc(II), [ZnCl(2)(C(7)H(7)NO)(2)], di-chlor-ido-bis-(2-methyl-benzamide-κO)zinc(II), [ZnCl(2)(C(8)H(9)NO)(2)], di-chlorido-bis-(3-methyl-benzamide-κO)zinc(II), [ZnCl(2)(C(8)H(9)NO)(2)], di-chlorido-bis-(4-methyl-benzamide-κO)zinc(II), [ZnCl(2)(C(8)H(9)NO)(2)], and di-chlorido-bis-(4-hy-droxy-benzamide-κO)zinc(II), [ZnCl(2)(C(7)H(7)NO(2))(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.