IMPORTANCE OF AN INTRAMOLECULAR 1,5-CH...O INTERACTION AND INTERMOLECULAR INTERACTIONS AS FACTORS DETERMINING CONFORMATIONAL EQUILIBRIA IN 1,2-DIMETHOXYETHANE - A MATRIX-ISOLATION INFRARED SPECTROSCOPIC STUDY

The infrared spectra of 1,2-dimethoxyethane in an argon matrix have been measured. Spectral analysis based on ab initio molecular orbital calculations and normal coordinate treatment has shown that the conformers TTT, TGT and TGG' (T: trans, G: gauche) coexist in the matrix, the TTT being the most stable. The experimental conformational stability agrees with the theoretical prediction from the molecular orbital calculations. The stability of the TGG' conformer is explained by an intramolecular 1,5-CH...O interaction. The stabilization of the TGT conformer in the liquid and crystalline states is shown to be caused by possible intermolecular interactions.