Microwave spectrum, dipole moment, structure, and internal rotation of the cyclopropanehyphen;sulfur dioxide van der Waals complex

摘要

The rotational spectrum of the cyclopropanehyphen;sulfur dioxide complex was observed by Fourier transform microwave spectroscopy. The spectrum exhibitedahyphen; andchyphen;dipole selection rules with thechyphen;dipole transitions split into doublets of unequal intensity separated by about 150 kHz. The structure hasCssymmetry with the sulfur and carbon atoms all lying in theacplane; the oxygen and hydrogen atoms straddle the plane. The sulfur dioxide plane is nearly parallel to a Cndash;C bond edge. The distance from the center of mass of the SO2to the Cndash;C bond center is 3.295 Aring;. The dipole moment of the complex is 1.681(1) D, with components mgr;a=0.815(1) D and mgr;c=1.470(1) D. The splittings in the spectrum arise from an internal rotation of the cyclopropane subunit about its localC2axis which lies nearly along the line connecting the centers of mass.