Copper(Il) and Nickel (II) Complexes of Neutral Tetradentate Schiff Bases

Department of Chemistry, University of Kalyani, Kalyani, Nadia, West Bengal Manuscript Received 5 July 1974; accepted 30 December 1974 Several hydrolytically stable copper (II) and nickel (II) complexes of neutral tetradentate Schiff bases derived by the condensation of 1,3-diaminopropane and 1,3-diaminopropane-2-01 with 2-formyl pyridine (=FPTN and FPTNOL) and 2-acetylpyridine APTN and APTNOL) have been synthesized. The complexes have been characterised by electronic spectra, magnetic suscsptibilites, infrared spectra, molar conductivities and elemental analyses. All of these complexes contain a 1:1 ratio of tetradentate ligand to metal (II) salt. Copper (II) complexes of the type [Cu(L)I] ClO4 are found to be five-coordinate, while [Cu(L)] (ClO4)2 cemplexes are tetragonal or sequare planar in structure. The infrared spectra of the copper (II) and nickel (II) chelates support the Schiff base formulation of the ligands and provide evidence for the coordination of the pyridyl groups. A tetragonal crystal field model provides a basis for the interpretation of the visible and near infrared electronic spectra of nickel (II) complexes with the tetradentate ligands occupying the square planar arrangement. The complexes Ni (L) X2. nH2O, where L= FPTN, FPTNOL, APTN, APTNOL ; X = Cl, NO2 or NCS, behave as 2:1 electrolytes in aqueous solution and give rise to a common species [Ni(L)(H2O)2].2+ In aqueous solution the complex ion [Ni(L)(H2O)2]2+ reacts with neutral monodentate donors to yield [Ni(L)(donor)2]2+.