Quantum Chemical Study on the Structures of CH3OCH3/H2O,CH3OCF3/H2O,CF3OCF3/H2O

Abstract

The study of intermolecular interactions is a useful step toward gaining a basic understanding of the dynamic behaviour of molecules in various environments. In the present study, high-level ab initio calculations [MP2] using correlation consistent basis sets of Dunning [aug-cc-pVDZ, aug-cc-pVTZ] were carried out to study the potential energy surfaces of CH3OCH3/H2O, CH3OCF3/H2O and CF3OCF3/H2O Van der Waals dimers and to clarify the stable structures of these clusters. For the calculation of interaction energies, the basis set superposition errors (BSSE) were estimated by counterpoise method. One stable structure for CH3OCH3/H2O dimer has been found. For the optimized structure, the H2O molecule is outside the C-O-C plane of the CH3OCH3, and the bond angle O(CH3OCH3)---H-O(H2O) is approximately 180°. For the structure of CH3OCF3/H2O, we have found two stable structures in which the H2O molecule exists in the C-O-C plane of the CH3OCH3/H2O molecule. For the stable structure of CF3OCF3/H2O, the H2O molecule are located in the direction of the lone pair of the CF3OCF3 moleclule. The details of the potential energy surfaces are discussed.