Some studies in inorganic complexes. XXII. Reactions of nickel(II) with chelating heterocyclic bases

Abstract

Spin-free six-coordinate complexes of nickel(II) and the heterocyclic ligands 2-aminomethylpyridine, 2-methylaminomethylpyridine, 2-(2- aminoethyl)pyridine, and 2-aminomethyl-6-methylpyridine have been prepared and studied. Various hydrated and anhydrous nickel(II) complexes with the anions sulphate, nitrate, halide, and perchlorate were obtained with nickel ion to ligand stoicheiometric ratios of 1 : 1, 1 : 2, and 1 : 3, and in a number of instances water molecule and anion attachments to the coordination sphere are reported; the sulphate complexes are considered to be of the bridged type. Also, certain mixed-ligand solid complexes and mixed-ligand cationic species in aqueous solution were prepared. Physical measurements used to elucidate structures included molecular conductances in suitable solvents, solubility observations, infrared spectrophotometry, pyrolysis methods, and measurements of magnetic susceptibility. Complex cations in aqueous solution were characterized by visible and near-infrared spectrophotometry.