Importance of chelate–chelate stacking interactions in crystal structures of square pyramidal copper(II) complexes with two distinct chelating bidentate ligands

Abstract

Two square pyramidal copper(II) complexes, [Cu(bzan)(mdap)(OClO3)] (1) and [Cu(bzan)(dmdap)(OClO3)] (2) [Hbzan=1-benzoylacetone, mdap=N-methyl-1,3-diaminopropane, dmdap=N,N-dimethyl-1,3-diaminopropane], have been prepared and characterized. Single crystal X-ray diffraction studies have confirmed their structures. Both complexes form supramolecular dimers via π/π interactions between the chelate rings. The energies associated with π-stacking interactions to form self-assembled dimers have been computed using DFT calculations. The energy associated with N, C–H/π contributions have also been evaluated. Bader’s theory of “atoms in molecules” (AIM) was also used to further describe the non-covalent π-stacking and N, C–H/π interactions.