Synthesis, Crystal Structure, Hirshfeld Surface, RDG, ELF, LOL, DFT, and Molecular Docking Studies of a Binuclear Copper(II) Carboxylate Complex.

This study describes the fabrication and examination of binuclear copper(II) phenylacetate (PAA) complex with metronidazole (mnz), formulated as [Cu2(μ-PAA)4(mnz)2](mnz)2(H2O)2 (1). The complex was synthesized at room temperature and the product was characterized via FTIR, UV-Vis, and PXRD. The single-crystal X-ray diffraction of complex 1 reveals that it crystallizes in the triclinic space group P-1. The SCXRD illustrated that complex 1 adopts a bidentate bridging mode with an almost ideal square-pyramidal geometry (τ5 descriptor). Complex 1 is stabilized by extended hydrogen-bonding networks, as confirmed by Hirshfeld surface analysis and 2D fingerprint plots. Quantitative analysis demonstrated that H···H interactions dominate the crystal packing (49.6% in 1), indicating that van der Waals forces are the major contributors to solid-state stability. DFT calculations confirmed the structural stability and electronic features of the binuclear copper complex. FMO analysis revealed a narrow HOMO-LUMO energy gap (1.39 eV), indicating enhanced electronic responsiveness and chemical reactivity. RDG analysis indicated that molecular stability arises from a balance of coordination-driven attractive interactions, weak dispersive forces, and localized steric effects. Furthermore, docking study against the SARS-CoV-2 main protease showed favorable binding affinity (-7.97 kcal/mol), suggesting potential biological relevance of the complex as a metal-based bioactive scaffold.