Melamine-mediated self-assembly of a Cu(II)–methylmalonate complex assisted by π⁺–π⁺ and anti-electrostatic H-bonding interactions

A Cu(II)-methylmalonate complex, (C₃H₇N₆)₄[Cu(II)(C₄H₄O₄)₂](H₂O)₄Cl₂ (1) (where C₃H₇N₆ = protonated melamine, C₄H₄O₄ = methylmalonic acid), has been synthesized from aqueous media and its crystal structure was determined by single-crystal X-ray diffraction. The anionic Cu(II)-methylmalonate complex mediated formation of interesting supramolecular assemblies in the solid state by means of ionic interactions with protonated melamine. Moreover, other forces such as antielectrostatic H-bonding and π⁺–π⁺ interactions also play a crucial role in defining the final 3-D architecture of 1. An interesting stacking among protonated melamine molecules is studied by DFT calculations. Lattice water molecules and chlorides form various hydrogen bonds to take part in the self-assembly processes.