A polynuclear helical and two dinuclear copper(II) complexes of a monocondensed N,N,O donor Schiff base with pseudohalides as co-ligand

Three copper(II) complexes, [Cu2L2(mu(1,1)-NCO)(NCO)] (1), [Cu2L2(mu(1,3)-NCS)(NCS)] (2) and [CuL(mu(1,5)-dca)](n)center dot nH(2)O (3), where HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol, have been prepared and characterized by elemental analysis, IR and UV-Vis spectroscopy, single crystal X-ray diffraction studies and by cyclic voltammetry. Complexes 1 and 3 crystallize in monoclinic space group P2(1)/n and complex 2 in monoclinic P2(1/)/c. In complex 1, OCN shows mu(1,1) bridging mode; in complex 2, SCN shows mu(1,3) bridging mode whereas in complex 3, N(CN)(2)(-) shows mu(1,5) bridging mode. The tridentate Schiff base ligand reacts with copper(II) to occupy its three equatorial positions. The coordination polyhedra around one of the copper center in compounds 1 and 2 are best described as an elongated (4 + 1) square pyramid, whereas the coordination polyhedra around other copper center is square planer. The copper atom in compound 3 has a slightly distorted square pyramidal environment. Significant C-H/pi interactions are observed in both complexes 1 and 2. Complex 3 is an example of MOFs containing penta-cordinated Cu(II) ions linked together by N(CN)(2)(-) to yield 1D infinite P and M-helical chains. (C) 2012 Elsevier B. V. All rights reserved.