High-level ab initio predictions of CO2•••N2O structure

Ab initio calculations using MPn, QCISD, QCISD(T), and CCSD(T) methodologies and cc-pVDZ, aug-cc-pVDZ, and cc-pVTZ correlation-consistrnt basis sets were carried out to determine the most stable structure of the CO2. . .N2O van der Waals system. Rovibrational absorption and microwave spectroscopic constants are consistent with an approximately slipped parallel structure, but the experimental data cannot determine the orientation of N2O in the dimer. MPn and QCI methods lead to contradictory predictions. The QCI most stable structure, with the oxygen atom of N2O nearly over the carbon atom of CO2, is consistent with the experimental data. (C) 2001 John Wiley & Sons, Inc.