Synthesis, structure and the Hirshfeld surface analysis of three novel metal-tiron coordination complexes

Abstract

Three novel metal-tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) and other pillared ligand bpy (4,4′-bipyridyl)-centered coordination polymers of the formulae [Cd(tiron)(bpy)2(H2O)2]·0.5(H2O),1, [Co3(tiron-bpy)2(bpy)(H2O)8]·(H2O)2,2, and [Ba2(tiron-bpy)2(H2O)4][solvent],3, were successfully synthesized under hydrothermal conditions. The as-synthesized materials were well characterized by complimentary techniques such as single-crystal X-ray diffraction, powder X-ray diffraction, Fourier-transform infrared spectroscopy and thermogravimetric analysis techniques. The as-synthesized coordination polymers of1and2featured 1D chains, while3shows a layered structure. Co-based2shows linear trinuclear Co(ii) ions and these Co(ii) ions have antiferromagnetic interactions among themselves. The structure of1features a zig-zag chain formed by the linkage between monodentate tiron ligands and octahedral Cd(ii) ions, interconnected by a twisted bpy ligand,2shows a linear chain constructed from corner-sharing trinuclear octahedral Co(ii) ions and coordinated with a tridentate tiron-bpy adduct ligand, whereas3shows nona-coordinated Ba(ii) ions sharing edges with other Ba(ii) ions and connected by hexadentate tiron-bridged structures resulting in a layered structure. In2and3, the bpy nitrogen attacks at theorthoposition of the tiron ligand and forms anin situligand adduct. The central metal ions show an octahedral geometry in1(Cd(ii) ions) and2(Co(ii) ions), but nona-coordination of Ba(ii) ions in3. The short interatomic interactions in the crystal structures were evaluated by mapping the Hirshfeld surface process using pseudo-mirrored 2D fingerprint plots. The major short interatomic interactions H⋯H, O⋯H and C⋯H cover the Hirshfeld surfaces.