THE MICROWAVE SPECTRUM OF SILYL METHYL ETHER

Abstract

The microwave spectrum of silyl methyl ether ($SiH_{3}OCH_{3}$) has been studied in the region 8--40 GHz. Generally, the lines were observed to be split into five components as predicted by the symmetry group of the molecule. Several a-type R branch and several b-type Q branch lines of the series $J_{OJ}\rightarrow{J}{1, {J}+1}$, have been observed and assigned. The splittings between the doublet (AA, AE) and the triplet (EA, $(EE){+}$, $(EE){-}$) of the b-type Q branches are quite large ($\sim$500 MHz). The AA to AE splitting of these lines is $\sim$ 26 MHz. A preliminary calculation of the barriers assuming the large splittings are associated with the methyl group and the smaller splittings with the silyl group yields $V{3}$ (methyl) = 600 cal/mole, $V_{3}$ (silyl) = 1150 cal/mole. The dipole moment has been measured from Stark splittings and has been found to be $\mu_{a} = 0.647 \pm 0.006$ debye, $\mu_{b} = 0.95 \pm 0.02$ debye, $\mu_{total} = 1.15 \pm 0.02$ debye.