Mono, di and heptanuclear metal(II) complexes based on symmetric and asymmetric tetradentate Salamo-type ligands: Syntheses, structures and spectroscopic properties

Mono, di and heptanuclear metal(II) complexes with chemical formulae [Cu(L-1)] (1), [Co-2(L-2)(2)]center dot 2CH(3)CN (2) and [Ni-7(L-3)(3)(mu(3)-OEt)(2)(mu(3)-OH)(6)(EtOH)(6)] (3) have been synthesized by variational tetradentate Salamo-type ligands based on 3,5-dichlorosalicylaldehyde, and characterized by elemental analyses, FT-IR, UV-Vis spectra and X-ray crystallography. The Cu(II) complex 1 is a mononuclear complex with tetracoordinate Cu(II) atom lies in the N2O2 coordination sphere. The Co(II) complex 2 is a dinuclear complex with a central Co2O2 bridged unit via Co-O bonds to form a head-to-head dimer, the pentacoordinate Co(II) atoms (Col and Co2) have a distorted square pyramidal (tau(1) = 0.454) and trigonal bipyramidal (tau(2) = 0.538) geometries, respectively. Interestingly, the Ni(II) complex 3 is a novel heptanuclear complex with an unprecedented 3:7 ligand to metal stoichiometry. Furthermore, fluorescence properties of the Cu (II) and Ni(II) complexes have been studied. (C) 2016 Elsevier Ltd. All rights reserved.