Synthesis and Characterization of Fe(III) and Pb(II) Complexes with 3-Hydroxypyridine-2(1H)-Thiones

Abstract

Two kinds of 3-hydroxypyridine-2(1H)-thiones were synthesized. The visible (VIS) spectroscopic analysis indicated that 3-hydroxy-1-methylpyridine-2(1H)-thione (4a) and 3-hydroxy-1-(2-hydroxyethyl)pyridine-2(1H)-thione (4b) formed stable 3:1 Fe(III) complexes. The stability constant of the 4b-Fe(III) complex was estimated from the competitive reaction with EDTA and was found to be 36.7 in logβ₃. Treatment of compound 4b with Ga(acac)₃ in D₂O:CD₃OD (9:1) solution afforded 3:1 Ga(III) complex, which was assigned by means of ¹H nuclear magnetic resonance (¹H NMR) spectroscopy. Treatment of compound 4b with Pb(NO₃)₂ gave 4b-Pb(II) complex. The Pb(II) selectivity over biologically relevant Mg(II) and Ca(II) was remarkably improved by adopting N-hydroxyethyl functionality instead of N-methyl group.

Keywords:

• Bidentate ligand
• 3-Hydroxypyridine-2(1H)-thione
• Fe(III) complex
• Ga(III) complex
• Pb(II) complex