Structures of Dimethyl Ether and Methyl Alcohol

Abstract

The molecular structures of dimethyl ether and methyl alcohol were determined in gaseous state by means of the sector-microphotometer method in electron diffraction. The structural information was derived from the resolution of radial distribution curves. It was confirmed that a dimethyl ether molecule exerts hindered internal rotation with a potential minimum at the C2v configuration. The most probable values for the bond distances and the bond angles are for dimethyl ether: C–O = 1.416±0.003 A, C–H = 1.094±0.006 A, ∠COC = 111.5°±1.5°; and for methyl alcohol: C–O = 1.428±0.003 A, C–H = 1.095±0.010 A, O–H = 0.960±0.015 A, ∠COH = 109°±3°. The results on methyl alcohol agree with those of microwave determinations. The observed values of vibrational amplitudes are in good agreement with those computed theoretically.