1. Torsional splitting and the four-fold barrier to internal rotation: The rotational spectra of vinylsulfur pentafluoride.
- Author
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Orellana, W., Stephens, Susanna L., Pringle, Wallace C., Groner, Peter, Novick, Stewart E., and Cooke, S. A.
- Subjects
TORSION ,FOURIER transform spectroscopy ,FOURIER transform optics ,DEFORMATIONS (Mechanics) ,ROTORS - Abstract
Vinylsulfur pentafluoride (VSPF), a molecule with a four-fold internal rotor, —SF
4 , has been studied with high resolution Fourier transform microwave spectroscopy. We believe that this is the first report of resolved four-fold internal rotation. As such, we have presented the tools needed to understand and analyze such a problem. These include debugging the ERHAM computer program necessary to fit the spectra and the free rotor to high barrier correlation diagram necessary to understand the torsional states of the four-fold rotor. The A, E, and B torsional state rotational transitions are well resolved and assigned. Spectroscopic transitions of four isotopologues of VSPF, H2 C=CH—SF5 , the normal isotopologue, and the singly substituted34 S and13 C isotopologues were measured and assigned. Contrary to expectation, the A torsional state could not be fit with only a semi-rigid Hamiltonian. The barrier to internal rotation, V4 , is found to be 227 cm−1 . Ab initio calculations at the MP2 aug-cc-pVQZ level of theory and basis set were performed and the results of this calculation are compared to our experimental results. [ABSTRACT FROM AUTHOR]- Published
- 2018
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