The structure of CO-OCS: A spectroscopic and theoretical investigation

The spectrum of the weakly bound complex CO-OCS has been measured in the infrared using direct absorption diode laser spectroscopy in a supersonic jet, and in the microwave region using a pulsed nozzle Fourier-transform instrument. In addition, microwave spectra of the two isotopomers (CO)-C-13-OCS and CO-(OCS)-S-34 were recorded. A T shaped structure has been determined with the carbon atom in CO closest to the OCS (RMS angle+/-20.5 degrees with respect to the intermolecular axis) and the sulphur end of OCS pointing away from CO (vibrationally averaged angle 105.7 degrees). The ground state centre of mass separation is 4.17 Angstrom. The effective structure is rationalized by a simple potential incorporating a distributed multipole analysis of the electrostatic charge distribution, distributed dispersion contribution and a cylindrical hard core repulsion, with discussion of the implications for the potential of including correlation effects in the CO multipole.