Crystal Structure and Hirshfeld Analysis of a Poorly Water Soluble Bis(ligand)copper(II) Complex Containing the Metallophore Pyridine-2-Carboxaldehyde 2-Furoyl Hydrazone

The crystal structure of a novel bis(ligand)copper(II) complex of the pyridine-2-carboxaldehyde 2-furoyl hydrazone (HPCFur) metallophore is described, altogether with its Hirshfeld surface analysis. The isolated compound crystallizes in the monoclinic system, space group P2₁/c, with four [Cu(PCFur)₂] molecules in the asymmetric unit. Symmetry around copper is distorted octahedral. HPCFur coordinates in its deprotonated, iminolate form, which impacts the O1−C7 and N2−N3 distances in both ligand units. The complex exhibits a variety of weak, non-conventional intermolecular hydrogen bonds. Hirshfeld analysis and fingerprint plots indicate that, overall, hydrogen bond interactions are responsible for almost 50% of the crystal 3D arrangement, while nondirectional H···H contacts account for 38.0%. To the best of our knowledge, this is the first description of a copper(II) complex containing this ligand. The structural characterization of this poorly water soluble species contributes to a better understanding of the intricate equilibria that take place in biologically relevant ternary peptide/protein-copper-hydrazone systems.