Stability constants of some,bivalent metal ions with naphthofuran-2-carbohydrazide Schiff base

Abstract

The stability constants of 1 : 1 and 1 : 2 metal complexes formed between Th-IV, UO2II, Cu-II, Pb-II, Co-II, Ni-II, Zn-II, Cd-II, Ba-II, Ca-II and Mg-II metal ions with Schiff bases NHPC, NHMePC, NHMeOPC and NHClPC were determined by potentiometric titration technique. Calvin-Bjerrum pH titration method as modified by Irving-Rossotti was used to calculate the pK(III)(II), log K-ML(M) and log K-ML2(ML), values in 60 : 40% (v/v) alcohol-water medium at 30 +/- 0.1 degrees C temperature and at constant ionic strength of 0.1 M NaClO4. The correlation between log K values and some of the fundamental properties of the metal ions are discussed. The negative Delta G(o) values indicate that complex formation is spontaneous one.