Role of imidazole co–ligand in the supramolecular network of a Co(II) complex with sulfadiazine: crystal structure, hirshfeld surface analysis and energetic calculations

Abstract

M(II) complexes with sulfadiazine (SDZ) and imidazole (Im) acting as co-ligand, [M(SDZ)2(Im)2] (M=Co, Ni, Cu and Zn), have been synthesized and characterized. The crystal structure of Co(II) complex (1) is reported, and a similar structure for the other three complexes is inferred by elemental analysis, IR and electronic spectra. The Co(II) complex is stabilized by intermolecular N–H⋅⋅⋅N, N–H⋅⋅⋅O and C–H⋅⋅⋅O hydrogen bonds, as well as C–H⋅⋅⋅π interactions. An investigation of those structural motifs via Hirshfeld surface analysis has been performed. Energy framework calculations have been carried out to analyze and visualize the 3D topology of the crystal assembly, indicating that the electrostatic energy is dominant over the dispersion one in the most energetic dimer (Motif 1), unlike two related cobalt-sulfadiazine complexes with other co-ligands where the dispersion component is more relevant. Further, the relative strength of the bifurcated N–H⋅⋅⋅N/O hydrogen bonds has been analyzed using the quantum theory of “atoms-in-molecules” (QTAIM) and molecular electrostatic potential (MEP) surface calculations. The strongest H-bonds occurring with donor groups from co-ligand species (Im, DMF and CH3OH) are found to be imperative in controlling the supramolecular architecture of the corresponding cobalt complex.