A matrix-isolation infrared study of the adducts of triethyl phosphate with CCl₄, CHCl₃ and CH₂Cl₂

Abstract

An infrared spectroscopic study is reported of the adducts of triethyl phosphate (TEP) with CCl₄, CHCl₃ and CH₂Cl₂, isolated in a nitrogen matrix. The adduct formation is identified from a red shift in the phosphoryl (P=O) stretching vibration of triethyl phosphate. The experimental data are explained on the basis of adduct formation involving the interaction between the phosphoryl oxygen of the triethyl phosphate and the chlorine of the chloromethanes. The shift in the P=O frequencies as a result of the complex formation with the chloromethanes follows the order: CCl₄ < CHCl₃ <CH₂Cl₂, which is in keeping with the Lewis acidities of chlorine in these compounds. These complexes are similar to the van der Waals or anti-hydrogen-bonded complexes seen in the case of HF adducts with some bases. No evidence is observed for the formation of any hydrogen-bonded adduct of TEP with CHCl₃ and CH₂Cl₂.