Syntheses and crystal structures of two tetranuclear copper(II) complexes with Schiff bases

Two similar tetranuclear copper(II) complexes with the formulae [Cu4(L1)2(μ1,1-N3)4(μ2-CH3COO)2] and [Cu4(L2)2(μ1,1-N3)2(μ-Br)2Br2(CH3OH)2], where L1 and L2 are the deprotonated forms of 2-[(2-ethylaminoethylimino)methyl]-5-methoxyphenol and 5-methoxy-2-[(2-piperidin-1-ylethylimino)methyl]phenol, respectively, have been synthesized and characterized by spectroscopic methods and single-crystal X-ray diffraction. Both complexes are centrosymmetric tetranuclear copper(II) compounds. The bridging groups in [Cu4(L1)2(μ1,1-N3)4(μ2-CH3COO)2] are μ1,1-azide ligands and μ2-acetate ligands, and those in [Cu4(L2)2(μ1,1-N3)2(μ-Br)2Br2(CH3OH)2] are μ1,1-azide ligands and μ-bromide ligands. Each Cu atom in the complexes is in a square pyramidal geometry.