Synchrotron-based far infrared study of the rotation-vibration-inversion spectrum of silacyclobutane below 500 cm{sup −1}: The ν{sub 29} and ν{sub 30} bands
Fourier transform spectra of the four-membered heterocycle silacyclobutane (c-C{sub 3}H{sub 8}Si) were recorded in the far infrared region from 100 to 500 cm{sup −1} with a maximum resolution of 0.000959 cm{sup −1} using synchrotron radiation from the Canadian Light Source. The two fundamental bands observed in this region correspond to motions best described as the out-of-plane modes related to ring puckering (ν{sub 30}) at ∼158 cm{sup −1} and SiH{sub 2} rocking (ν{sub 29}) at ∼410 cm{sup −1}. Both bands exhibit complex, dense spectral patterns that arise from ring inversion tunneling of the puckered SCB ring through a planar (C{sub 2v}) intermediate configuration. Analysis of these patterns revealed rotation-vibration transitions between states of the same inversion symmetry as well as rotation-vibration-inversion transitions that connect states of different inversion symmetry. Infrared ground state combination differences from 1871 pairs of P and R branch transitions were used to accurately determine the spectroscopic parameters for the tunneling-doubled ground state based on a broad range of quantum levels. With the ground state energy levels well-determined, 8255 infrared transitions were assigned and analyzed to derive the band centers, rotational and centrifugal distortion constants for the inversion split ν{sub 29} and ν{sub 30} vibrational states. Comparison with the band centers predicted via DFT (B3LYP) and MP2 calculations [6-311++G(2d,2p)] suggests that anharmonic corrections found via perturbation theory typically agree within 2% when compared with the observed spectrum of SCB.
- OSTI ID:
- 22253230
- Journal Information:
- Journal of Chemical Physics, Vol. 139, Issue 24; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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