New cadmium(II) coordination complexes based on pentaatomic N-heterocycles and thiocyanate ion as ligands: Synthesis, crystal structure, spectroscopic characterizations, and Hirshfeld surface analysis

Abstract

Two novel cadmium(II) coordination complexes, [Cd(bpt)2(SCN)2] 1 and [Cd2(bpo)(µ-SCN)4]n2, (bpt = 2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole and bpo = 2,5-bis(pyridin-2-yl)-1,3,4-oxadiazole), have been synthesized and fully characterized by using FTIR, NMR, and UV–Vis spectroscopic techniques, as well as single crystal X-ray diffraction (SC-XRD). The complex 1 is a mononuclear, while the complex 2 is coordination polymer where bpo ligand and SCN−are in bridging modes, with two non-equivalent Cd ions. The coordination geometry is distorted octahedral in both complexes. The crystal of complex 1 is stabilized by C–H⋯N/C/S hydrogen bonds and π⋯π stacking interactions while the crystal packing of polymeric complex 2 is stabilized by C–H⋯S and π⋯π stacking interactions. Hirshfeld surface analysis was undertaken to investigate further the intermolecular interactions responsible for stabilization of the supramolecular assembly of 1 and 2. The calculated band gap energy (Eg) values of the Cd(II) complexes from the UV–Vis spectra indicated interesting semiconducting properties.