Isomorph supramolecular coordination compounds of cobalt(II) and nickel(II) based on pyridine-2,4-dicarboxylic acid and creatinine adduct

Abstract

Pyridine-2,4-dicarboxylic acid (py-2,4-dcH2) and creatinine (creat) with MCl2·6H2O (M = CoII and NiII) formed two isomorph supramolecular coordination compounds. Their three-dimensional supramolecular architecture is formed not only by simple proton transfer from pyridine-2,4-dicarboxylic acid to creatinine, but also by other very important non-covalent interactions, especially the ion pairing, hydrogen bonds, C–H···π, N–H···π and C–O···π interactions. In these complexes, pyridine-2,4-dicarboxylate acts as a bidentate ligand and the lattice is composed of anionic hexacoordinated complex, [M(py-2,4-dc)2(H2O)2]2− (M = CoII and NiII), creatinium counter ion, (creatH)+, and two uncoordinated water molecules. The complexation equilibrium and stabilities of proton transfer, binary and ternary complexes of pyridine-2,4-dicarboxylic acid as a primary ligand and creatinine as a secondary ligand with Co2+ and Ni2+ transition metal ions in comparison with X-ray crystal structures in solid state have studied.