Conformational Stability of 1,2-Dimethoxyethane in the Gas Phase Studied by Infrared Spectroscopy: Importance of an Intramolecular 1,5-CH···O Interaction

The gas-phase infrared spectra of 1,2-dimethoxyethane measured at various temperatures gave a value of 0.31 ± 0.04 kcal mol−1 for the energy difference between the trans–gauche–gauche′ and trans–trans–trans conformers, the latter being more stable. This value is in good agreement with the results of high-level ab initio calculations. The present experimental finding gives definitive evidence for the importance of an intramolecular 1,5-CH···O interaction in the stabilization of the trans–gauche–gauche′ conformer in the gas phase.