The molecular structure of 1,1-dichloro-1-silacyclo-hexane and of 1,1-dimethoxy-1-silacyclohexane in the gas phase, an electron diffraction study

The molecular structure of 1,1-dichloro-1-silacyclohexane (DCSC) and of 1,1-dimethoxyl-silacyclohexane (DMSC) has been determined by gas phase electron diffraction. Starting values for the vibrational parameters were obtained from force field calculations.

Both molecules are in the chair conformation with a flattening in the vicinity of the silicon atom, which is most pronounced in the dichloro-compound. Disregarding the substituents the title compounds show C_s-symmetry. In DMSC the gem-dimethoxy grouping is in the sc, sc conformation in accordance with the anomeric effect.

A comparison is made between the experimentally found geometries with predictions of molecular mechanics calculations based on two available force fields.