A matrix-isolation infrared study of the adducts of triethyl phosphate with CCl<SUB>4</SUB>, CHCl<SUB>3</SUB> and CH<SUB>2</SUB>Cl<SUB>2</SUB>

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 &lt; CHCl3 &lt;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