Tetra­kis(μ₃-2-{[1,1-bis­(hy­droxy­meth­yl)-2-oxidoeth­yl]imino­meth­yl}-6-nitro­pheno­lato)tetra­copper(II)

The title cluster, [Cu₄(C₁₁H₁₂N₂O₆)₄], was obtained from the Cu⁰–FeCl₂·4H₂O–H₄L–Et₃N–DMF reaction system (in air), where H₄L is 2-hy­droxy­methyl-2{[(2-hy­droxy-3-nitro­phen­yl)methyl­idene]amino}­propane-1,3-diol and DMF is di­methyl­formamide. The asymmetric unit consists of one Cu²⁺ ion and one dianionic ligand; a -4 symmetry element generates the cluster, which contains a {Cu₄O₄} cubane-like core. The metal ion has an elongated square-based pyramidal CuNO₄ coordination geometry with the N atom in a basal site. An intra­molecular O—H...O hydrogen bond is observed. The solvent mol­ecules were found to be highly disordered and their contribution to the scattering was removed with the SQUEEZE procedure in PLATON [Spek (2009). Acta Cryst. D65, 148–155], which indicated a solvent cavity of volume 3131 ų containing approximately 749 electrons. These solvent molecules are not considered in the given chemical formula.