Free jet rotational spectrum of propylene oxide–krypton and modelling and ab initio calculations for propylene oxide–rare gas dimers

Abstract

The rotational spectra of propylene oxide-⁸⁴Kr and propylene oxide-⁸⁶Kr have been measured by free jet millimetre-wave absorption spectroscopy. The preferred experimentally derived conformation of the complex is supported by results obtained with a simple distributed polarisability model and by ab initio calculations. The dissociation energy of the complex has been estimated, from the D_J centrifugal distortion constant, to be ca. 3.7 kJ mol⁻¹, which compares with 3.3 kJ mol⁻¹ from the model. Modelling and ab initio calculations have also been performed for the related propylene oxide–Ne and propylene oxide–Ar complexes, and led to a re-assignment of their absolute energy minima. The results obtained for the three propylene oxide–rare gas atom dimers are compared.