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

Two similar tetranuclear copper(II) complexes with the formulae [Cu-4(L1)(2)(mu(1,1)-N-3)(4)(mu(2)-CH3COO)(2)] and [Cu-4(L2)(2)(mu(1,1)-N-3)(2)(mu-Br)(2)Br-2(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 [Cu-4(L1)(2)(mu(1,1)-N-3)(4)(mu(2)-CH3COO)(2)] are mu(1,1)-azide ligands and mu(2)-acetate ligands, and those in [Cu-4(L2)(2)(mu(1,1)-N-3)(2)(mu-Br)(2)Br-2(CH3OH)(2)] are mu(1,1)-azide ligands and mu-bromide ligands. Each Cu atom in the complexes is in a square pyramidal geometry.