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 OH…O and NH…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.