A polynuclear and two dinuclear copper(II) Schiff base complexes: Synthesis, characterization, self-assembly, magnetic property and DFT study

Three elongated (4+1) square pyramidal copper(II) complexes, [Cu-2(L)(2)(mu(1,1)-N-3)(2)]center dot H2O (1), [Cu-2(L)(2)(mu(1,1)-NCO)(2)] (2) and [Cu(L)( mu(1,5)-dca)](n) (3) IHL = 1((2-(methylamino)ethylimino)methyl)naphthalen-2-ol and dca = dicyanamideb have been synthesized using a tridentate N2O donor Schiff base ligand (HL) and characterized. Complexes 1 and 2 are centrosymmetric dimers in which copper(II) centres are connected by asymmetric double end on pseudohalide bridges. Complex 3 features a 1D zigzag chain in which copper(II) centres are connected by end to end dca bridges. Variable temperature (2-300 K) magnetic susceptibility measurements indicate the presence of antiferromagnetic exchange coupling between copper(II) centres in complexes 1 (J = -2313 cm(-1)) and 3 (I = -0.344 cm(-1)), whereas complex 2 shows ferromagnetic exchange coupling between copper(II) centres (J = 0.513 cm(-1)). DFT calculations also corroborate the data. The fluid solution EPR spectra recorded at 293 K are typical of copper(II) species. Significant supramolecular interactions are explored using high level DFT calculations (BP86-D3/def2-TZVP) and characterized by Bader's theory of "atoms-in-molecules". (C) 2017 Elsevier Ltd. All rights reserved.