INFRARED SPECTROSCOPY OF THE WEAKLY BONDED CO-$Cl_{2}$ COMPLEX

Abstract

Author Institution: U.S. Army Ballistic Research Laboratory, SLCRR-IB-I; Department of Chemical Engineering, University of Florida; Department of Chemistry, Denison University; Department de Quimica-Fisica, Facultad de Quimica; Department of Chemistry, University of Southern CaliforniaHigh-resolution rovibrational absorption spectra of the weakly bonded CO-$Cl_{2}$ complex have been recorded in the $2143 cm^{-1}$ region by existing the CO chromophore with a tunable diode laser. The spectra indicate that CO-$Cl_{2}$ is linear and semi-rigid. By fitting the data to a linear-molecule Hamiltonian, the following constants (in $cm^{-1}$) were obtained; $v_{0}= 2149.5424(4), B^{\prime} =0.031582339), B^{\prime} = 0.0314867(52), D_{J}^{\prime} = 4.37(25) \times 10^{-8}$, and $D_{J}^{\prime} = 4.58(35)\times 10^{-8}$. The distance between the CO and $Cl_{2}$ centers of mass is approximately 4.78 \AA. The orientation of CO is not determined experimentally. However, $Cl_{2}$ appears to act as a classical $\sigma$-electron acceptor, while CO behaves like a weak Lewis base, donating charge from the carbon side via the weakly antibonding 5$\sigma$ orbital, thereby raising the CO vibrational frequency."