Microwave spectrum, structure, dipole moment and internal rotation of ethyl fluorosilane

Abstract

Microwave spectra of the trans and gauche isomers of ethyl fluorosilane and their eleven isotopically substituted species have been measured. The r s structures of the two isomers were determined from the observed moments of inertia. The molecular structures found for the two isomers in the present study are compared with those of analogous molecules. Dipole moments of the two isomers were determined by Stark-effect measurements and are also compared with those of analogous molecules. The energy difference between the trans and gauche isomers was obtained from the relative intensity measurements of the spectra and the barrier to internal rotation of the methyl group for the gauche isomer was obtained from the A—E splittings of the spectra in the first excited methyl torsional state. The V 3 value was 2775 ± 25 cal mol −1.