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Title: High-resolution rovibrational study of the Coriolis-coupled v 12 and v 15 modes of [1.1.1]propellane

Abstract

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 v 12(e') perpendicular and v 15(a 2") 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 v 12 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 v 15 and v 12 interaction is poorly determined bymore » 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/∂Q 15)/(∂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 v 15 mode.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
949071
Report Number(s):
PNNL-SA-61274
20907; KP1504020; TRN: US200907%%303
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Molecular Spectroscopy, 253(1):41-50; Journal Volume: 253; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Kirkpatrick, Robynne W, Masiello, Tony, Jariyasopit, Narumol, Nibler, Joseph W, Maki, Arthur G, Blake, Thomas A, and Weber, Alfons. High-resolution rovibrational study of the Coriolis-coupled v12 and v15 modes of [1.1.1]propellane. United States: N. p., 2009. Web. doi:10.1016/j.jms.2008.09.013.
Kirkpatrick, Robynne W, Masiello, Tony, Jariyasopit, Narumol, Nibler, Joseph W, Maki, Arthur G, Blake, Thomas A, & Weber, Alfons. High-resolution rovibrational study of the Coriolis-coupled v12 and v15 modes of [1.1.1]propellane. United States. doi:10.1016/j.jms.2008.09.013.
Kirkpatrick, Robynne W, Masiello, Tony, Jariyasopit, Narumol, Nibler, Joseph W, Maki, Arthur G, Blake, Thomas A, and Weber, Alfons. 2009. "High-resolution rovibrational study of the Coriolis-coupled v12 and v15 modes of [1.1.1]propellane". United States. doi:10.1016/j.jms.2008.09.013.
@article{osti_949071,
title = {High-resolution rovibrational study of the Coriolis-coupled v12 and v15 modes of [1.1.1]propellane},
author = {Kirkpatrick, Robynne W and Masiello, Tony and Jariyasopit, Narumol and Nibler, Joseph W and Maki, Arthur G and Blake, Thomas A and Weber, Alfons},
abstractNote = {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 ζy15,12a 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 (∂μz/∂Q15)/(∂μx/∂Q12a) 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.},
doi = {10.1016/j.jms.2008.09.013},
journal = {Journal of Molecular Spectroscopy, 253(1):41-50},
number = 1,
volume = 253,
place = {United States},
year = 2009,
month = 1
}
  • The infrared spectrum of [1.1.1]propellane has been recorded at high resolution (0.002 cm-1) with individual rovibrational lines resolved for the first time. This initial report presents the ground state constants for this molecule determined from the analysis of five of the eight infrared-allowed fundamentals v 9(e'), v 10(e'), v 12(e'), v 14(a 2''), v 15(a 2''), as well as of several combination bands. In nearly all cases it was found that the upper states of the transitions exhibit some degree of perturbation but, by use of the combination difference method, the assigned frequencies provided over 4000 consistent ground state differencemore » values. Analysis of these gave for the parameters of the ground state the following values, in cm -1: B 0 = 0.28755833(14), D J = 1.1313(5)x10 -7, D JK = -1.2633(7)x10 -7, H J = 0.72(4)x10 -13, H JK = -2.24(13)x10 -13, and H KJ = 2.25(15)x10 -13, where the numbers in parentheses indicate twice the uncertainties in the last quoted digit(s) of the parameters. Gaussian ab initio calculations, especially with the computed anharmonic corrections to some of the spectroscopic parameters, assisted in the assignments of the bands and also provided information on the electron distribution in the bridge-head carbon-carbon bond.« less
  • The region of the infrared-active band of the ν 9 CH2 bending mode [1.1.1]propellane has been recorded at a resolution (0.0025 cm -1) sufficient to distinguish individual rovibrational lines. This region includes the partially overlapping bands ν 9 (e') = 1459 cm -1, 2ν 18 (l = 2, E') = 1430 cm -1, ν 6 + ν 12 (E') = 1489 cm-1, and ν 4 + ν 15 (A 2") = 1518 cm -1. In addition, the difference band ν 4 - ν 15 (A2") was observed in the far infrared near 295 cm -1 and analyzed to give goodmore » constants for the upper ν 4 levels. The close proximities of the four bands in the ν 9 region suggest that Coriolis and Fermi resonance couplings could be significant and theoretical band parameters obtained from Gaussian ab initio calculations were helpful in guiding the band analyses. The analyses of all four bands were accomplished, based on our earlier report of ground state constants determined from combination differences involving more than 4000 pairs of transitions from five fundamental and four combination bands. This paper presents the analyses and the determination of the upper state constants of all four bands in the region of the ν 9 band. Complications were most evident in the 2ν 18 (l = 2, E') band, which showed significant perturbations due to mixing with the nearby 2ν 18 (l = 0, A 1') and ν 4 + ν 12 (E') levels which are either infrared inactive as transitions from the ground state, or, in the latter case, too weak to observe. Finally, these complications are discussed and a comparison of all molecular constants with those available from the ab initio calculations at the anharmonic level is presented.« less
  • This paper is a continuation of earlier work for which the high resolution infrared spectrum of [1.1.1]propellane was measured and its k and l structure resolved for the first time. Here we present results from an analysis of more than 16,000 transitions involving three fundamental bands v 10 (E'-A1'), v 11 (E'-A1'), v 14 (A2''-A1') and two difference bands (v 10- v 18) (E'-E'') and (v 11-v 18) (E'-E"). Additional information about v18 was also obtained from the difference band (v 15+v 18)-v 18 (E'-E") and the binary combination band (v 15+v 18) (E'-A1'). Through the use of the groundmore » state constants reported in an earlier paper [1], rovibrational constants have been determined for all the vibrational states involved in these bands. The rovibrational parameters for the v 18(E'') state were obtained from combination-differences and showed no need to include interactions with other states. The v 10(E') state analysis was also straight-forward, with only a weak Coriolis interaction with the levels of the v 14(A2'') state. The latter levels are much more affected by a strong Coriolis interaction with the levels of the nearby v 11(E') state and also by a small but significant interaction with another state, presumably the v16(E'') state, that is not directly observed. Gaussian calculations (B3LYP/cc-pVTZ) computed at the anharmonic level aided the analyses by providing initial values for many of the parameters. These theoretical results generally compare favorably with the final parameter values deduced from the spectral analyses. Finally, evidence was obtained for several level crossings between the rotational levels of the v 11 and v 14 states and, using a weak coupling term corresponding to a Δk = ±5, Δl = ∓1 matrix element, it was possible to find transitions from the ground state that, combined with transitions to the same upper state, give a value of C 0 = 0.1936519(4) cm -1. This result, combined with the value of B 0 = 0.28755833(14) cm-1 reported earlier [1], yields a value of 1.586282(3) Å for the length of the novel axial CC bond in propellane.« less
  • Infrared spectra of bicyclo[1.1.1]pentane (C5H8) have been recorded at a resolution (0.0015 cm-1) sufficient to resolve for the first time individual rovibrational lines. This initial report presents the ground state constants for this molecule determined from the detailed analysis of three of the ten infrared-allowed bands, v14(e') at 540 cm-1, v17(a2'') at 1220 cm-1, v18(a2'') at 832 cm-1, and a partial analysis of the v11(e') band at 1237 cm-1. The upper states of transitions involving the lowest frequency mode, v14(e'), show no evidence of rovibrational perturbations but those for the v17 and v18 (a2'') modes give clear indication of Coriolismore » coupling to nearby e' levels. Accordingly, ground state constants were determined by use of the combination-difference method for all three bands. The assigned frequencies provided over 3300 consistent ground state difference values, yielding the following constants for the ground state (in units of cm-1): B0 = 0.2399412(2), DJ = 6.024(6) x 10-8, DJK = -1.930(21) x 10-8. For the unperturbed v14(e') fundamental, more than 3500 transitions were analyzed and the band origin was found to be at 540.34225(2) cm-1. The numbers in parentheses are the uncertainties (two standard deviations) in the values of the constants. The results are compared with those obtained previously for [1.1.1]propellane and with those computed at the ab initio anharmonic level using the B3LYP density functional method with a cc-pVTZ basis set.« less
  • Fundamental T (..nu../sub 3/) type high-J rovibrational fine structure is derived for a range of values of the Coriolis and (2 x 2)/sup 4/ centrifugal constants. The theory of level clusters is developed further. Correlations are made between cluster states corresponding to well separated P/sup +/, Q/sup 0/, and R/sup -/ branches, and the opposite case in which Pi/sub plus-or-minus/ and ..sigma../sub 0/ labels are appropriate.