Non-covalent interactions in organic-inorganic hybrid compounds derived from amino amides

Abstract Here, we report the synthesis of six organic-inorganic hybrid compounds from amino amides and tetrachlorozincate anions to study the processes underlying the modulation of hydrogen bonds and π∙∙∙π interactions in these salts. Thus, 2-((2-ammoniopropanamido)-methyl)-1H-benzimidazole-3-ium tetrachlorozincate 7, 2-(1-(2-ammoniopropanamido)-ethyl)-1H-benzimidazole-3-ium tetrachlorozincate 8, 2-((2-ammonio-3-methylbutanamido)methyl)-1H-benzimidazole-3-ium tetrachlorozincate 9, 2-(1-(2-ammonio-3-methylbutanamido)-2-methylpropyl)-1H-benzimidazole-3-ium tetrachlorozincate 10, 2-((2-ammonio-4-methylpentanamido)methyl)-1H-benzimidazole-3-ium tetrachlorozincate 11, and 2-(1-(2-ammonio-4-methylpentanamido)-3-methylbutyl)-1H-benzimidazoel-3-ium tetrachlorozincate 12 were obtained from the corresponding hydrochlorides (1–6). Crystallographic experiments using compounds 7–12 revealed that the presence of bulky substituents situated on C10 and C13 reduces the efficacy of stacking phenomena. Moreover, the ZnCl42− ∙∙∙H–N hydrogen bonds induce the polarization of the imidazole ring and the π∙∙∙π interactions occur through the “dipole-induced dipole” mechanism. In the case of N–H∙∙∙solvent interactions, the stacking phenomena occur preferentially through the “induced dipole-induced dipole” mechanism.