Synthesis, crystal structure, Hirshfeld surface analysis and determination of antioxidant activity for a new mononuclear tris-oxalato-chromium(III) complex

Abstract The new metal-organic material tris-5-methylbenzimidazolium(trioxalatochromate(III)) trihydrate ((C8H9N2)3 [Cr(C2O4)3].3H2O) was prepared using slow evaporation method at room temperature and characterized by X-ray diffraction, spectroscopy and thermal analysis. In the crystal structure, the Cr(III) ion is surrounded by six oxygen atoms from three oxalate ligands, forming a distorted octahedral environment. The charge compensation is accomplished by the incorporation of 5-methylbenzimidazolium cations. Crystal packing is mostly governed by strong O-H...O and N-H...O hydrogen bond interactions. Intermolecular interactions in the crystal structure were quantified by Hirshfeld surface analysis. TGA showed that the synthesized complex possesses considerable stability. Optical absorption reveals a band gap energy indicating the semi-conductive nature of the title compound. In addition, three tests, 1,1-diphenyl-2-picrylhydrazyl (DPPH), ABTS radical scavenging and ferric reducing power (FRAP) methods, were done and successfully showing significant antioxidant activities.