Complexation Equilibria of Silver(I) Ions with N-Phenylthiourea in Aqueous Solutions

Complexation between silver(I) ions and N-phenylthiourea is studied over a wide range of silver(I) and N-phenylthiourea (L) concentrations at 25.0°C and ionic strength I = 0.11 M (0.01 M HNO3 + 0.1 M NaNO3) by potentiometric titration using a silver electrode. Mono- and binuclear complexes are present in the studied concentration range of Ag+ ions (1 × 10–5–1 × 10–3 mol/L). $${\text{A}}{{{\text{g}}}_{{\text{2}}}}{\text{L}}_{3}^{{2 + }}$$ is the dominant species. At CL/CAg > 1, the content of mononuclear species is much lower than that of binuclear ones. The calculated overall stability constants of the complexes are as follows: log β11 = 5.58, log β12 = 10.75, log β21 = 10.1, log β22 = 17.1, log β23 = 23.2, log β24 = 25.9, and log β25 = 29.2.