Structural study, spectroscopic characterization, thermal behavior, DFT calculations and antimicrobial properties of a new hybrid compound, (C7H9N2)2[HgCl4]·H2O

A new bis(benzamidinium)tetrachloridomercurate(II) monohydrate, (C7H9N2)2[HgCl4]·H2O, was synthesized by slow evaporation at room temperature and characterized by powder XRD, IR, Raman, UV-vis spectroscopy and thermal analysis. Single-crystal X-ray diffraction analysis indicates that the asymmetric unit of the title compound is formed by tetrachloridomercurate [HgCl4]2− anion, a protonated organic cation (C7H9N2)2+ and one free water crystallization molecule. The cohesion of the structure is insured by N–H···Cl, O–H···Cl and N–H ···O hydrogen bonds and π-π stacking interactions. The density functional theory (DFT)-optimized structure at the B3LYP/6-311++G(2d,2p) level is compared with the experimentally determined molecular structure. Comprehensive experimental and theoretical structural studies on the compound are carried out through IR and UV-vis spectroscopies. The compound was characterized by thermal analysis to determine its thermal behavior with respect to the temperature. The in vitro antibacterial activity of the compound against different bacterial strains was evaluated. The three-dimensional Hirshfeld surface (3 D-HS) and the two-dimensional fingerprint plots (2 D-FP) reveal that the structure is dominated by H···Cl/Cl···H (51.0%) and H···H (32.3%) contacts.