THE RING PUCKERING VIBRATION OF 2,5-DIHYDROTHIOPHENE
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Date
1968
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Ohio State University
Abstract
The infrared spectrum of 2,5-dihydrothiophene has been measured from 80 to $4000 cm^{-1}$. The far infrared region contained sharp Q branches at $87.0, 95.5, 102.0, 107.0, 111.2, 114.8, 118.1, 120.7, 123.2, 125.2$, and $127.0 cm^{-1}$ which have been assigned to single quantum transitions between the first 12 levels of the ring puckering vibration. A mixed harmonic-quartic potential energy function has been fitted to the observed frequencies and is described by the following relation in reduced coordinates: $V(cm^{-1}) = 16.86 (x^{4}+5.93x^{2})$. Such a potential function can be rationalized only in terms of a planar ring skeleton with no barrier to inversion. Two combination and one difference band series of the ring puckering transitions with fundamentals centered near 3064, 670, and $2865 cm^{-1}$, respectively, have also been studied. The ring puckering transitions obtained from the $670 cm^{-1}$ band series agree favorably with the far infrared frequencies; however, those in reference to the two carbon-hydrogen stretching fundamentals exhibit significant deviations which are corrected by an anharmonicity cross term.
Description
W.H. Green is an NAS-NRC Postdoctoral Research Fellow.
Author Institution: U. S. Naval Research Laboratory, Washington D.C.
Author Institution: U. S. Naval Research Laboratory, Washington D.C.