Spectroscopic studies on the complex formation of triphenyl-phosphine sulfide and triphenylphosphine selenide with various OH proton donors

Abstract

The hydrogen-bonded complexes of triphenylphosphine sulfide and triphenylphosphine selenide with phenol, 1-naphthol, 2-naphthol, 2,2,2-trifluoroethanol, 2,2,2-trichloroethanol and 2,2,2-tribromoethanol have been studied by near i.r. spectroscopy in carbon tetrachloride solution at 288.15, 298.15, 308.15 and 318.15 K. The equilibrium constants ( K) at different temperatures have been determined from the changes in the intensity of the free OH-stretching band of the proton donor. Thermodynamic quantities have been calculated from the temperature dependence of the K values. The results show that triphenylphosphine sulfide and triphenylphosphine selenide form weak molecular complexes with these OH proton donors and there is no marked difference in their hydrogen-bonding abilities. The proton donating power of the OH proton donors decreases in the order 1-naphthol ∼ 2-naphthol > phenol ∼ 2,2,2-trifluoroethanol > 2,2,2-trichloroethanol > 2,2,2-tribromoethanol.