High-resolution rovibrational study of the Coriolis-coupled v₁₂ and v₁₅ modes of [1.1.1]propellane

Journal Article · Fri Jan 02 00:00:00 EST 2009 · Journal of Molecular Spectroscopy, 253(1):41-50

DOI:https://doi.org/10.1016/j.jms.2008.09.013· OSTI ID:949071

Kirkpatrick, Robynne W; Masiello, Tony; Jariyasopit, Narumol; Nibler, Joseph W; Maki, Arthur G; Blake, Thomas A; Weber, Alfons

Infrared spectra of the small strained cage molecule [1.1.1]propellane have been obtained at high resolution (0.0015 cm^-1) and the J and K, l rovibrational structure has been resolved for the first time. We recently used combination-differences to obtain ground state parameters for propellane; over 4,100 differences from five fundamental and four combination bands were used in this process. The combination-difference approach eliminated errors due to localized perturbations in the upper state levels of the transitions and gave well-determined ground state parameters. In the current work, these ground state parameters were used in a determination of the upper state parameters for the v₁₂(e') perpendicular and v₁₅(a₂") parallel bands. Over 4000 infrared transitions were fitted for each band, with J, K values ranging up to 71, 51 and 92, 90 respectively. While the transition frequencies for both bands can be fit nicely using separate analyses for each band, the strong intensity perturbations observed in the weaker v₁₂ band indicated that Coriolis coupling between the two modes was significant and should be included. Due to correlations with other parameters, the Coriolis coupling parameter ζ^y_15,12a for the v₁₅ and v₁₂ interaction is poorly determined by a transition frequency fit alone. However, by combining the frequency fit with a fit of experimental intensities, a value of -0.42 was obtained, quite close to that predicted from the ab initio calculation (-0.44). This intensity fit also yielded a (∂μ^z/∂Q₁₅)/(∂μ^x/∂Q_12a) dipole derivative ratio of 36.5, in reasonable agreement with a value of 29.2 predicted by Gaussian ab initio density functional calculations using a cc-pVTZ basis. This ratio is unusually high due to large charge movement as the novel central Caxial-Caxial bond is displaced along the symmetry axis of the molecule for the v₁₅ mode.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 949071
• Report Number(s): PNNL-SA-61274; 20907; KP1504020; TRN: US200907%%303
• Journal Information: Journal of Molecular Spectroscopy, 253(1):41-50, Vol. 253, Issue 1
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANIC COMPOUNDS
GROUND STATES
INFRARED SPECTRA
ROTATIONAL STATES
VIBRATIONAL STATES
CORIOLIS FORCE
DENSITY FUNCTIONAL METHOD
Corrected title. yh 3/9/09
Environmental Molecular Sciences Laboratory