Potentiometric studies on complexes of silver(I) in solutions. Part 2. Correlation between the stability of the silver(I)–azole complexes and the ligand basicity

Abstract

Stability constants of Ag^I complexes with pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 1,2,4-triazole, 4-amino-1,2,4-triazole, thiazole, 4-methylthiazole, and 2-aminothiazole have been determined potentiometrically by simultaneous measurement of [Ag⁺] and [H₃O⁺]. All measurements were run at 25 ± 0.1 °C at a ionic strength I= 0.5 mol dm^–3 adjusted with KNO₃. Linear correlations have been found between logβ₁, logβ₂, and pK_a for these complexes. The contribution of π_{M → L}bonding to the co-ordination bonds is discussed. The π-electron-acceptor strength of unsubstituted azoles has been found to follow the sequence 1,2,4-triazole > pyrazole > thiazole imidazole.