THE MICROWAVE SPECTRA AND RING-PUCKERING VIBRATIONS IN THIETANONE-3 AND 1, 2 DIMETHYLENECYCLOBUTANE

$^{1}$C. S. Blackwell, Ph.D. dissertation, Massachusetts Institute of Technology, June, 1971. $^{2}$F. A. Miller, ``Advances in Raman Spectroscopy'', ed. J. P, Mathieu, v. 1, pp. 533-534, Heyden and Son Ltd., N. Y. (1972).Author Institution: Department of Physics and Department of Chemistry, Mississippi State UniversityThe microwave spectra of thietanone-3 (I) and 1, 2 Dimethylene-cyclobutane (II) have been studied in the range 26.5 - 40.0 GHz. The rotational constants of (I) have been derived [FIGURE] by fitting a-type low-J R-branch transitions in the ground vibrational state (in MHz: A = 10 205.00; B = 3266.63; C = 2559.70) and 10 excited states of the ring-puckering mode. Analysis of these yields a single minimum potential function which implies a planar ring skeleton in agreement with a previous far-infrared $study.^{1}$ Analysis of the Stark effect yielded the dipole moment in the ground state ($\mu_{a} = 0.999 \pm 0.003D)$ and 5 vibrationally excited states. The rotational constants of (II) in the ground state (in MHz: A = 4925.21; B = 4089.88; C = 2301.67) and 4 excited states of the ring-puckering vibration have been derived from fitting b-type low-J R-branch transitions. Stark effect measurements yield $\mu+b = 0.457 \pm 0.002D$. The data are not sufficient to determine the value of the potential constants for the ring-puckering vibration, but the value of $I_{c}-I_{a}-I_{b}$ in the ground state and the smooth variation of rotational constants with vibrational state are sufficient to rule out the possibility of a non-planar ring $skeleton.^{2}

THE MICROWAVE SPECTRUM OF 1,3-CYCLOHEPTADIENE

$^{1}$ J.F. Chiang and S. H. Bauer, J. Am. Chem. Soc. 88, 420 (1966).""Author Institution: Department of Physics and Department of Chemistry, Mississippi State UniversityThe microwave spectrum of 1,3-cycioheptadiene has been studied in the X-band [FIGURE] and R-band frequency regions. Preliminary analysis gives A = 3419.25, B = 3297.15, and C = 1799.93 MHz for the ground vibrational state rotational constants. These rotational constants are reasonably consistent with the electron diffraction $structure,^{1}$ where the carbon skeleton is coplanar except for the $C_{6}$ atom which is out of the plane. Further confirmation of the structure should come from the dipole components in the principal axis system. Stark effect measurements are in progress

THE MTCROWAVE SPECTRUM OF 1,2,3,6 TETRAHYDROPYRIDINE

Author Institution: Department of Physics and Department of Chemistry, Mississippi State UniversityThe microwave spectrum of 1,2,3,6 tetrahydropyridine has been studied with a Hewlett-Packard Model 8400C microwave spectrometer in both the X-band (8.0-12.4 GHz) and R-band regions (26.5-40.0 GHz)[FIGURE]. a-, b-, and c-type transitions have been assigned for two different conformations. A study of the N-deutero derivative has allowed identification of the conformers as twist-axial and twist-equatorial respectively, where twist refers to the conformation of the ring skeleton and axial equatorial to the orientation of the hydrogen on the nitrogen atom. Stark effect measurements are in progress

MICROWAVE STUDIES OF 2-CHLOROACRYLONITRILE AND METHYLENE CYANIDE

Author Institution: Department of Physics and Department of Chemistry, Mississippi State UniversityThe microwave spectrum of 2-chloroacrylonitrile has been studied in the 26.5 - 40.0 GHz region. Both a- and b-type rotational transitions have been measured and assigned for both chlorine isotopes. The ground state rotational constants for $CH_{2} = C^{35}$Cl(CN) are (in MHz) $A = 6973.25$, $B = 3148.15$ and $C = 2165.94$. The rotational constants compare exceptionally well with those calculated from the structures of vinyl cyanide$^{1}$ and vinyl $chloride.^{2}$ The microwave spectrum of mathylene cyanide$^{3}$ has been reinvestigated and the distortion effects of $CH_{2}$(CN)$_{2}$ and $CH_{2} =$C Cl(CN) have been studied. For $CH_{2}$(CN)$_{2}$ transitions up to $J = 62$ have been measured. The quartic distortion constants for $CH_{2}$(CN)$_{2}$ are (In MHz): $\Delta J = (1.855455 \pm 0.014) \times 10^{-3}$, $\Delta JK = (-6.79218 \pm 0.027) \times 10^{-2}$, $\Delta K = (8.621623 \pm 0.013) \times 10^{-1}$, $\delta J = (4.892607 \pm 0.016) \times 10^{-4}$ and $\delta_{k} = (6.7501 \pm 0.29) \times 10^{-3}$, Quoted errors are twice the standard deviations