Crystal structure of a tetranuclear Cu-II complex with an O,N,N '-donor Schiff base ligand: hexa-mu 2acetato-bis(2-{[(2,2,6,6-tetramethylpiperidin-4-yl)imino] methyl} phenolato-kappa O-3,N,N ')tetracopper(II)

The title compound, [Cu-4(CH3COO)(6)(C16H23N2O)(2)], lies across a twofold rotation axis. The asymmetric unit contains two independent Cu-II ions. The symmetry-unique terminal Cu-II ion is O,N,N'-coordinated by a 2-{[(2,2,6,6-tetramethylpiperidin-4-yl)imino] methyl} phenolate ligand and an O atom from an acetate group in a slightly distorted square-planar coordination environment. The symmetry-unique central Cu-II ion is coordinated by a different O atom from the same acetate group and by four bridging acetate ligands, which connect the asymmetric unit into a dimeric complex and form a distorted square-pyramidal coordination environment. Within the complex there are two symmetryequivalent intramolecular N-H center dot center dot center dot O hydrogen bonds. In the crystal, weak CH center dot center dot center dot O hydrogen bonds link the complex molecules, forming a three-dimensional network.