Ligating properties of tridentate Schiff base ligands, 2-[[(2-pyridinylmethyl)imino]methyl] phenol (HSALIMP) and 2-[[[2-(2-pyridinyl)ethyl]imino]methyl]phenol (HSALIEP) with zinc(II), cadmium(II), nickel(II) and manganese(III) ions. X-ray crystal structur

A series of zinc(II), cadmium (II), nickel(II) and manganese (III) complexes with two potentially tridentate (NNO) Schiff base ligands, 2-[[(2-pyridinylmethyl)imino]methyl]phenol (HSALIMP) and 2-[[[2-(2-pyridinyl)ethyl]imino]methyl]phenol (HSALIEP) have been synthesized and structurally characterized through IR, 1H, 13C, and 2-D NMR spectroscopy and in two cases by X-ray crystallography. The Schiff base ligands HSALIMP and HSALIEP are generated from 1+1 condensation of salicylaldehyde with 2-aminomethylpyridine and 2(2-aminoethyl)pyridine, respectively. HSALIMP behaves as a tridentate (NNO) or a bidentate (NN) ligand, depending upon the nature of the anion. On reaction with zinc(II) salts HSALIMP gives two types of complexes, (a) [Zn(SALIMP)X]2·yH2O (X=NO3, y=0 (I); X=I, y=3 (II) and (b) [Zn(HSALIMP)Cl2]·H2O (III). HSALIMP reacts with nickel(II) bromide to form a mononuclear complex [Ni(HSALIMP)2Br2] (VIII), in which one metal ion combines with two neutral HSALIMP ligands. However HSALIEP, a similar ligand with one additional carbon atom in the chain, acts as a tridentate ligand (NNO), with the phenolate oxygen deprotonated, irrespective of the nature of the anion, forming dimeric compounds of 1:1 metal:ligand stoichiometry with zinc(II) and cadmium(II) ions, [Zn(SALIEP)X]2·yH2O (X=NO3, y=0 (IV); X=Cl, y=2 (V); X=I, y=1 (VI), [Cd(SALIEP) (NO3)]2·C2H5OH (VII) and a monomeric complex of 1:2 metal:ligand stoichiometry with manganese(III) ion, [Mn(SALIEP)2](ClO4) (IX). The single crystal X-ray structures of the [Zn(SALIEP)(NO3)]2 (IV) dimer, [Mn(SALIEP)2](ClO4) (IX), and [Zn(AMP)2(NO3)2] (X), a minor product obtained from the filtrate of I, have been determined. IV consists of centrosymmetric dimer in which deprotonated phenolates bridge the two five-coordinate metal atoms and link the two halves of the dimer. The structure of IX consists of a centrosymmetric molecule in which the manganese(III) ion is bound to two tridentate SALIEP ligands in a nearly regular octahedral arrangement. The structure of X consists of a centrosymmetric monomer in which the six coordinate octahedral zinc(II) ion is bonded equtorially to two bidentate 2-aminomethylpyridine ligands and axially to two monodentate nitrate groups.