Synthesis and crystal structure of a tetranuclear five-coordinated copper(II) complex with Schiff-base of N-(3-carboxylsalicylidene)-4-(2-iminoethyl)-morpholine

A tetranuclear copper(II) complex [Cu4L2(CH3COO)2(OH)2]·6H2O, in which L stands for the dianion of N-(3-carboxylsalicylidene)-4-(2-iminoethyl)morpholine, was synthesized and characterized by elemental analysis, IR, UV–Vis, TGA and X-ray single crystal diffraction. The crystal structure shows that the coordination unit is centrosymmetric with all the Cu(II) ions in square pyramidal coordination geometry. The coordination unit consists of two equivalent parts [Cu2L(CH3COO)(OH)], each containing two Cu(II) ions, a tetradentate N2O2 Schiff base dianion L2−, a CH3COO−, and a OH− anion. In [Cu2L(CH3COO)(OH)], the six coordination atoms (N2O4) are nearly coplanar, with Cu(1) and Cu(2) enchased in between; the phenolate oxygen and the OH− oxygen as bridging atoms bind the two Cu(II) ions in close proximity; both O4 around Cu(1) and N2O2 around Cu(2) form the basal plane of the coordination square pyramids. The two parts are connected by sharing two μ3-OH− oxygens and two μ2-CH3COO− oxygens from each other, forming four edge-sharing coordination square pyramids around the four Cu(II) ions. A 3D network is formed through hydrogen bonding along a and c axis, and π–π interaction along b axis.