Effect of tetraphenylphosphonium and tetraphenylborate ions on the water structure in aqueous solutions; FTIR studies of HDO spectra

Abstract

FTIR spectroscopy has been used to study interactions of Ph₄B^- and Ph₄P⁺ ions with water in aqueous solutions. The effect of Ph₄BNa and Ph₄PCl on the HDO vibration band in the fundamental region has been investigated. A new modification of the difference spectra method has been applied for the analysis of the spectral data. The results have revealed distinct differences in hydration of Ph₄B^- and Ph₄P⁺ ions: Ph₄B^- ion strongly decreases the hydrogen-bond energy of surrounding water molecules, while Ph₄P⁺ ion changes it slightly. The effect of Ph₄B^- is determined by anion–water interactions, while the effect of Ph₄P⁺ is determined by water–water interactions around the cation. The changes in the energy of water hydrogen bonds upon the ions have been evaluated.