Synthesis and structure of mono-, di- and tri-nuclear copper(II) benzoate complexes with a tridentate N2O donor Schiff base ligand

Three copper(II) complexes [CuL(PhCOOH)(ClO4)] (1), [Cu2L2(PhCOO)](ClO4) (2) and [Cu3L2{(o-NO2)PhCOO}2](ClO4) (3), where HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol, a well known Schiff base ligand, have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Complex 1 crystallizes in triclinic space group P − 1, complex 2 in monoclinic C2 and complex 3 in monoclinic P21/c. The co-ordination polyhedron around each copper atom is best described as an elongated (4 + 1) square pyramid. Complex 1 is mononuclear with a terminal benzoate, complex 2 is dinuclear containing a μ1,3 benzoate whereas complex 3 is trinuclear having a rare μ1,1,3 benzoate binding three copper centers simultaneously.