Synthesis, crystal structure, spectroscopic (FT-IR, UV–Vis, EPR) and Hirshfeld surface analysis studies of Zn(II)-benzoate coordination dimer

Abstract

Mixed ligand coordination dimer [Zn2(BA)4(NA)2].(BAH), (BAH=Benzoic acid, NA=nicotinamide), synthesized and its supramolecular architecture was investigated. The structural properties of the coordination dimer were characterized by X-ray diffraction (XRD), elemental analysis, spectroscopic methods (EPR, UV–Vis and FT-IR), thermogravimetric analysis and Hirshfeld surface analysis. The complex crystallized in the monoclinic crystal system and the P21/c space group. Two benzoate anions bind to zinc metals as chelates, while the other two-benzoate anions bridge between two metals. The coordinate environment of the Zn1 atom has a nearly ideal square pyramidal geometry and the τ factor defined by Addison is 0.09. The coordination environment of the Zn2 atom has an extremely distorted (4 + 1) pseudo-square pyramidal geometry and the τ factor was found to be 0.35. Hydrogen bonds and π⋯π weak interactions form a three-dimensional supramolecular structure. IR spectroscopic studies of the complex were performed in the middle IR region, focusing mainly on the characteristic vibrations of benzoic acid and nicotinamide, taking into account ligand functional groups within the complex. The EPR spectra of Cu(II)-doped complex were investigated at room and at liquid nitrogen temperature. As a result of EPR analysis, spin hamiltonian parameters were obtained. In addition, zero field splitting parameters of the dimer-complex was obtained as Dobs = 0.60 cm−1 and E ≈ 0. Thermogravimetric Analysis (TGA) was carried out thermal properties. 2D and 3D Hirshfeld analyses were performed in order to quantify the order and nature of intermolecular interactions in crystal network.