Lone pair···π interactions on the stabilization of intra and intermolecular arrangements of coordination compounds with 2-methyl imidazole and benzimidazole derivatives
<p>Spectroscopic and single crystal X-ray diffraction studies of coordination compounds of Co<sup>II</sup>, Ni<sup>II</sup>, Zn<sup>II</sup>, and Pd<sup>II</sup> 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···π (S–O···π<sub>(phe)</sub>) and H···π contacts, while its tetrahedral coordination compounds, [M(2-mfsiz)<sub>2</sub>X<sub>2</sub>] (M<sup>2+</sup> = Co, Ni, Zn; X = Cl, Br) showed intramolecular lone pair···π interactions (S–O···π<sub>(iz)</sub>). On the other hand, compounds [Cu<sub>2</sub>(2-mfsiz)<sub>2</sub>(µ<sub>2</sub>-AcO)<sub>4</sub>] and <i>trans-</i>[Pd(2-mfsiz)<sub>2</sub>Cl<sub>2</sub>] do not present lone pair···π interactions due to the metal ion geometry (square base pyramidal or square planar), which leads to formation of π<sub>(iz)</sub>···π<sub>(phe)</sub> interactions. For the benzimidazole ligand 2-mfsbz, an intramolecular, H<sub>(phe)</sub>···π<sub>(bz)</sub> contact was observed, remaining in its tetrahedral and octahedral coordination compounds, [M(2-mfsbz)<sub>2</sub>X<sub>2</sub>] (M<sup>2+</sup> = Co, Zn; X = Cl, Br, NO<sub>3</sub>). This interaction limits the free rotation of the ethylphenylsulfone moiety for stabilization of an intermolecular lone pair···π interaction (S–O···π<sub>(iz)</sub>). The dimeric [Zn<sub>2</sub>(2-mfsiz)<sub>2</sub>(µ<sup>2</sup>-AcO)<sub>4</sub>] compound has a π<sub>(bz)</sub>···π<sub>(phe)</sub> contact. Theoretical calculations confirmed the non-covalent interactions in the ligands and their coordination compounds.</p
