A MATRIX-ISOLATION INFRARED STUDY OF THE ADDUCTS OF TRIETHYL PHOSPHATE WITH CCL4, CHCL3 AND CH2CL2

An infrared spectroscopic study is reported of the adducts of triethyl phosphate (TEP) with CCl4, CHCl3 and CH2Cl2, isolated in a nitrogen m atrix. The adduct formation is identified from a red shift in the phos phoryl (P=O) stretching vibration of triethyl phosphate. The experimen tal data are explained on the basis of adduct formation involving the interaction between the phosphoryl oxygen of the triethyl phosphate an d 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 much less than CH2Cl2, which is in keeping with the Lewis acidities of chlorine in these compounds. These complexes a re 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 fo r the formation of any hydrogen-bonded adduct of TEP with CHCl3 and CH 2Cl2.