Molecular Complexes of Organometallic Molecules with Noble Gases: The Rotational Spectrum of Dimethylsilane-Argon

The rotational spectrum of the molecular complex dimethylsilane– argon was investigated by free-jet absorption millimeterwave and molecular-beam Fourier transform spectroscopy. The absolute energy minimum corresponds to a conformation in which the argon atom lies in the plane of symmetry of dimethylsilane, perpendicular to the CSiC plane. The distance of Ar from the center of mass of dimethylsilane is 3.90 B, and the Ar atom is tilted 148 away from the Si atom. The zero-point dissociation energy was estimated from the centrifugal distortion constant DJ to be 2.2 kJmol1. Small splitting, due to tunneling of the Ar atom and internal rotation of the two methyl groups, was observed, measured, and used to determine the potential energy surface for these motions.