Hydrogen bonding and proton transfer in hydrido-bis-phenolate complexes in acetone

Abstract

The homoconjugation, (ArO)₂H^–, and heteroconjugation, Ar′O^–⋯HOAr, (where Ar is aromatic) with proton transfer have been determined in acetone at 298 K. Tetra-alkylammonium phenolates were titrated with a variety of phenols to given homocomplexes and heterocomplexes. Potentiometric data give the overall equilibria constants, K₀, proton-transfer constants, K_PT and formation constants, K_f. Two types of heterocomplexes were studied. When ArO^– is a weaker base than Ar′O^–, the complexation occurs without proton transfer, as confirmed by the low K₀ values for the reaction. The overall equilibrium constants, K₀, are large when ArO^– is a stronger base than Ar′O^–, as both the equilibrium proton-transfer constant (K_PT) and equilibrium formation constant (K_f) of the hydrogen bond are included in the measurement of K₀=K_fK_PT.