Structural features and coordination behavior of a new morpholine-based N-acylhydrazone towards copper(II)

Structural characterization of a new hydrazone ligand and its trinuclear copper(II) complex. The ligand exhibited an unusual conformation stabilized by a bifurcated intramolecular hydrogen bond, as confirmed by X-ray diffraction and supported by theoretical calculations. Upon coordination, the deprotonated ligand acts as a binucleating scaffold connecting three copper(II) centers with two distinct coordination environments. The central metal ion adopts an octahedral geometry coordinated by two bidentate ligands and two water molecules, whereas the two symmetry-related peripheral copper(II) ions display nearly ideal square-pyramidal geometries, coordinated by tridentate ligands and two chloride ions. This unprecedented structural arrangement highlights the versatility of the ligand and provides a promising platform for the development of multinuclear copper complexes.