Lone pair•••π interactions on the stabilization of intra and intermolecular arrangements of coordination compounds with 2-methyl imidazole and benzimidazole derivatives

Spectroscopic and single crystal X-ray diffraction studies of coordination compounds of Co-II, Ni-II, Zn-II, and Pd-II with phenylsulfonyl imidazole and benzimidazole derivatives (2-mfsiz, 2-mfsbz) were performed. The relevance of non-covalent interactions on the stabilization of intra and intermolecular arrangements in the ligands and their coordination compounds was investigated. The imidazole 2-mfsiz ligand presents two enantiomeric conformers, where the ethylphenylsulfone moiety stabilizes intermolecular lone pair(S-O-(phe)) and H<bold> contacts</bold>, while its tetrahedral coordination compounds, [M(2-mfsiz)(2)X-2] (M2+=Co, Ni, Zn; X=Cl, Br) showed intramolecular lone pair<bold> interactions </bold>(S-O-(iz)). On the other hand, compounds [Cu-2(2-mfsiz)(2)(mu(2)-AcO)(4)] and trans-[Pd(2-mfsiz)(2)Cl-2] do not present lone pair<bold> interactions due to the metal ion geometry </bold>(square base pyramidal or square planar), which leads to formation of ((iz)(phe)) interactions. For the benzimidazole ligand 2-mfsbz, an intramolecular, H-(phe)(bz) contact was observed, remaining in its tetrahedral and octahedral coordination compounds, [M(2-mfsbz)(2)X-2] (M2+=Co, Zn; X=Cl, Br, NO3). This interaction limits the free rotation of the ethylphenylsulfone moiety for stabilization of an intermolecular lone pair<bold> interaction </bold>(S-O-(iz)). The dimeric [Zn-2(2-mfsiz)(2)(mu(2)-AcO)(4)] compound has a ((bz)(phe)) contact. Theoretical calculations confirmed the non-covalent interactions in the ligands and their coordination compounds. [GRAPHICS] .