A new class of organosilicon compounds containing a pentacoordinatesilicon atom, (aroyloxymethyl)trifluorosilanes (AFS), has been prepared. The presence of an intramolecular coordinate F3Si ← OC bond is supported by X-ray diffraction, IR spectroscopy and dipole moment data. Si ← O coordination in AFS has been shown to remain intact in the gaseous and liquid states below 420 K as well as in solution