Molecular Structure and Conformation of Ethyl Methyl Ether as Studied by Gas Electron Diffraction

The bond distances (rg) and angles (rα) in ethyl methyl ether have been determined by gas electron diffraction as follows: average of C(methyl)–O and C(methylene)–O=1.418±0.002 Å, C–C=1.520±0.004 Å, C–H=1.118±0.004 Å, ∠C–O–C=111.9±0.5°, ∠O–C–C=109.4±0.3°, ∠H–C–H=109.0±0.4°, where uncertainties represent estimated limits of experimental error. The two rg(C–O) distances have been estimated independently with the aid of the rotational constants for the trans conformer reported by Hayashi et al.: C(methyl)–O=1.413±0.009 Å and C(methylene)–O=1.422±0.007 Å. The dihedral angle for the gauche conformer, 84±6°, and the relative abundance of the trans and gauche conformers in the gas phase at 20 °C, nt⁄(nt+ng)=0.80±0.08, have also been determined.