Abstract

High resolution rovibrational spectra of the weakly bonded CO−C1₂ complex have been recorded in the 2143 cm^-1 region by exciting the CO chromophore with a tunable diode laser. The spectra indicate that CO−C1₂ is linear and semi-rigid. By fitting the data to a linear molecule Hamiltonian, the following constants (in cm^-1) were obtained: ν_O= 2149.5424(4), B″= 0.0315823(39), B′ = 0.0314867(52), D_J″ = 4.37(25) × 10⁻⁸, and D_J′ = 4.58(35) × 10⁻⁸. The distance between the CO and Cl₂ centers of mass is approximately 4.78 Å. The orientation of CO is not determined experimentally. However, Cl₂ appears to act as a classical six-electron acceptor, while CO behaves like a weak Lewis base, donating charge from the carbon side via the weakly antibonding 5σ orbital, thereby raising the CO vibrational frequency.

© 1992 Optical Society of America