| Abstract: | When alcohol solutions of copper salts are mixed with pyridine-2-aldehyde (PyA) and aliphatic diamines (A) (either ethylene diamine or 1,3-propane diamine) at pH ≤ 6.5, a copper complex containing a molecule of the pyridine derivative and a molecule of the diamine is formed, or a complex containing an additional molecule of the pyridine aldehyde is formed, depending on the PyA concentration in the solution. When the molar concentrations are Cu2+: 2PyA: A, and the pH ≥ 10, the copper (II) ion is reduced to monovalent copper, and a Schiff base of the copper complex is formed. When alcoholic solutions of copper, 2-acetylpyridine (AcPy), and aliphatic diamines are mixed in concentration ratios of Cu2+: 2AcPy: A, and pH > 9.5, again, the copper ion is reduced and a Schiff base is obtained. At pH = 7.5 a triple complex is obtained only from the copper chloride, containing either or one or two molecules of acetylpyridine, depending on the concentration of the latter in the solution. |
