pH ? METRIC STUDIES OF METAL COMPLEXES OF TRIAZOLE IN WATER-METHANOL
Abstract
Author(s): Olagboye S. A and Okoronkwo E.A
Ni(II) and Co(II) metal complexes of 1,2,3-triazole have been studied in water –methanol medium by pH –metric titration with the standard glass electrode, ionic strength 0.1M KNO3 and buffer soluti on at the pH 7 and 9. The titrations were carried out for the ligand against 0.05M NaOH solution as well as metal-ligand against NaOH at different temperature 35, 45 and 55oC. The p ka value (stability constant) were determined at respective Ni(II) 2.51, 2.60, 2.38 and Cu(II) 2.55, 2.30 and 2.20 and the results revealed that metal complex decreases with increasing temperature, the larger the value of the stability constant the further the reaction to the right . This implies that the complex ions with larger stability constant are more stable than the ones with smaller one. Thermodynamics studies result determined at 308k 318k and 323k respectively was calculated as follows: Cobalt (II) ?H = -52310.86 KJmol-1, ?S = -110.36 and ?G = -18320.63, - KJmol-117217.05 and - 16113.48 KJmol-1, Nickel(II) ?H = -43457.21 KJmol-1, ?S = -86.32 and ?G = -16822.41, -16005.14 and -15141.87 KJmol-1. Negative values of ?H, indicated exothermic reaction while negative Gibb’s free energy explained the spontaneity of the metal-ligand systems and the feasibility of metal complexes.
