NEW NICKEL(II) COMPLEXES INCORPORATING DISSYMMETRIC TETRADENTATE SCHIFF BASE LIGANDS DERIVED FROM AMINOTHIOETHER PYRIDINE WITH N2OS CHROMOPHORES: SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION AND CRYSTAL STRUCTURES OF [Ni(pytIsal)]ClO4 and [Ni(pytAzosal)]ClO4.H2O
Nezamaddin Daneshvar,*a Lotf A.
Saghatforoush,b Ali A. Khandar,c and
Ali A. Entezami d
a,b,c Department of Inorganic Chemistry , Faculty of Chemistry, Univrsity of Tabriz, Tabriz, Iran
d Department of Organic Chemistry, Faculty of Chemistry, University of Tabriz
* Corresponding author. fax: +98-411-3340191, Tel: +98-411-3393146, e-mail: firstname.lastname@example.org
The synthesis of nickel (II) complexes with five dissymmetric Schiff base ligands (abbreviataed pytIsalH, pytBrsalH, pytNO2salH, pytOMesalH, and pytAzosalH) which were prepared from aminothioether pyridine and a salicylaldehyde derivative, are described. The ligands were characterized by 1H,13C NMR, FTIR and elemental analysis. The complexes of these ligands were synthesized by treating an ethanolic solution of appropriate ligand with equimolar amount of Ni(ClO4)2.6H2O and methanolic NaOH or alternatively by a more direct route in which the two reactants are added to a solution of the ligand immediately after formation of the ligand and prior to any isolation. The complexes were characterized by elemental analysis, FTIR, electronic spectra and molar conductivity. The complex [Ni(pytIsal)]ClO4 (6) crystallizes in triclinc space group with a = 12.188(2) Å, b = 13.312(3) Å , c = 13.348(3) Å, a = 115.48(3)o, b = 90.78(3)o, g = 90.90(3), Z = 4, R1 = 0.0617 for 4276 reflections with I>2σ(I). The complex [Ni(pytAzosal)]ClO4.H2O (10) crystallizes in orthorhombic space group P212121 with a = 7.093(5) Å, b = 9.277(6) Å, c = 34.62(3) Å, a = 90o, b = 90o, g = 90o, Z = 4, R1 = 0.0635 for 2185 reflections with I>2σ(I). The coordination geometry of nickel ions in the complexes with mixed N, S and O donor atoms is square planar with a slight tetrahedron distortion. All of the complexes were found to be 1:1 electrolyte systems in acetonitrile. Cyclic voltammetry studies indicates that the complexes [Ni(pytXsal)]ClO4 (X = I and OMe) show quasi-reversible reduction to Ni(I) while this process for X = Azo and NO2 is reversible and irreversible, respectively.