Crystal structure of tetrakis(μ3-2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-6-methoxyphenolato)tetrakis[aquacopper(II)]: a redetermination at 200 K

The crystal structure of the tetranuclear title compound, [Cu4(C12H15NO5)4(H2O)4], has been previously reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem. (2015), 641, 941–947], based on room-temperature data. In the previously published structure, no standard uncertainties are recorded for the deprotonated hydroxymethyl group and water molecule O atoms coordinating to the metal atom indicating that they were not refined; furthermore, the H atoms of some OH groups and water molecules have not been positioned accurately. Since the current structure was determined at a lower temperature, all atoms, including the H atoms of these hydroxy groups and the water molecule, have been determined more accurately resulting in improved standard uncertainties in the bond lengths and angles. Diffraction data were collected at 200 K, rather than the more usual 100 K, due to apparent disordering at lower temperatures. In addition, it is now possible to report intra- and intermolecular O—H...O interactions. In the title complex molecule, which has crystallographic -4 symmetry, the CuII ions are coordinated by the tridentate Schiff base ligands and water molecules, forming a tetranuclear Cu4O4 cubane-like core. The CuII ion adopts a CuNO5 elongated octahedral environment. The coordination environment of CuII at 200 K displays a small contraction of the Cu—N/O bonds, compared with the room-temperature structure. In the crystal lattice, the neutral clusters are linked by intermolecular O—H...O hydrogen bonds into a one-dimensional hydrogen-bonding network propagating along the b axis.