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.

Stability constants of AgI 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 pKa for these complexes. The contribution of πM → Lbonding 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.