Rotational spectrum, structure and modeling of the SO2–CS2SO2–CS2 complex

Abstract

The rotational spectra of seven isotopomers of the SO2–CS2SO2–CS2 van der Waals dimer have been observed with a Fourier transform microwave spectrometer. The rotational constants for the normal species were determined to be A = 2413.2000(3) MHz,A=2413.2000(3)MHz, B = 1105.3803(3) MHzB=1105.3803(3)MHz and C = 884.9885(2) MHz.C=884.9885(2)MHz. They are consistent with the SO2SO2 straddling the CS2CS2 molecule and CsCs symmetry for the complex. The centers of mass of the two monomers are separated by 3.4287(2) Å. Two structures were found that are consistent with this symmetry which differ in the relative tilt of the CS2CS2 and SO2.SO2. In both structures, the C2C2 axis of the SO2SO2 is aligned close to parallel to the CS2CS2 molecular axis with the oxygen end of the SO2SO2 tipped closer to the CS2.CS2. In one structure the deviation from parallel is 9.8(8)° while in the other it is 17.7(11)°. The dipole moment components have been determined to be μa = 0.0137(5) Dμa=0.0137(5)D and μb = 1.1961(9) D.μb=1.1961(9)D. A semi-empirical model employing electrostatic, dispersion and repulsion interactions was employed to analyze the system and resulted in a reasonable reproduction of the angular geometry. A comparison of the results for the SO2–CS2SO2–CS2 complex with the closely related SO2–CO2SO2–CO2 and SO2–OCSSO2–OCS complexes is presented. © 1999 American Institute of Physics.