Crystal structures of silyl acetate at 150 K and methyl acetate at 145 K, and the molecular structure of silyl acetate in the gas phase

Abstract

The molecular structure of silyl acetate has been determined in the gas phase by electron diffraction and in the crystalline state by X-ray diffraction. The Si–O bond length is 1.685(3)Å in the gas and 1.696(4)Å in the solid. In both phases the heavy-atom skeleton is almost planar with the Si–O and CO bonds arranged cis to one another giving intramolecular Si ⋯ O (carbonyl) distances of 2.795(14)Å(gas) and 2.832(4)Å(solid). The crystal structure is distinguished by having unusually short Si ⋯ O (carbonyl) intermolecular contacts of length 2.721 (4)Å; these interactions exhibit the stereospecificity associated with secondary bonds. Solid methyl acetate, studied to provide a reference structure, has no short intermolecular contacts.