Journal ArticleDOI
Puckering structure in the infra-red spectrum of cyclobutane
J.M.R. Stone,Ian Mills +1 more
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The theory of rotational-pucker-vibrational transitions in the vibrational spectrum of cyclobutane is reviewed in this article, in terms of two slightly different puckering potential functions for the ground and the excited vibrational states.Abstract:
The theory of rotational-pucker-vibrational transitions in the vibrational spectrum of cyclobutane is reviewed. Puckering sideband structure on the 1453 cm-1 v 14 infra-red fundamental of C4H8 has been observed and analysed, in terms of two slightly different puckering potential functions for the ground and the excited vibrational states. The results have been fitted to quartic-quadratic potential functions in the puckering coordinate, with a barrier to inversion of 503 cm-1 (1·44 kcal mole-1 = 6·02 kJ mole-1) in the ground state and 491 cm-1 in the excited state ν 14 = 1. For reasonable assumptions about the reduced mass, the equilibrium dihedral angle of the C4 ring is determined to be about 35°, in agreement with previous estimates. Ueda and Shimanouchi's observations on the 2878 cm-1 C4H8 band have been re-analysed, and puckering sidebands have also been observed and analysed for the 1083 cm-1 v 14 infra-red fundamental of C4D8. Pure puckering transitions have been observed in the Raman spectrum of C4...read more
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Journal ArticleDOI
Far-infrared spectra of ring compounds: A semi-rigid model for the ring-puckering vibration in some pseudo-four-membered ring molecules☆
TL;DR: In this paper, a three-parameter Hamiltonian appropriate to ring-puckering vibration of the form H = 1 2 g 0 44 P 2 + cPx 2 P + ax 4 + bx 2, where a, b, c are adjustable parameters.
Journal ArticleDOI
Raman spectra of gases. VII. Barriers to planarity in 1,4‐ and 1,3‐cyclohexadiene
TL;DR: In this article, the authors assign a band at 216 cm−1 in the 1,4-cyclohexadiene spectrum to ring-puckering mode, which is consistent with D 2h configuration.
Journal ArticleDOI
Ab inttio structural analysis of some saturated 3- and 4-membered rings
TL;DR: In this article, the ground states of ten 3- and 4-membered ring compounds have been optimized using the gradient method at the 4-21 level, and an optimized 3-3-21 basis has been constructed, and the importance of including d-functions is demonstrated.
Journal ArticleDOI
Theoretical determination of molecular structure and conformation: Part X. Geometry and puckering potential of azetidine, (CH2)3NH, combination of electron diffraction and ab initio studies
TL;DR: In this paper, the puckering potential of azetidine is explored over the range −40° < o (puckering angle) < 40°, for both sp3 and sp2 hybridization of the nitrogen atom.
Journal ArticleDOI
Conformations of cyclobutane
F. Albert Cotton,B.A. Frenz +1 more
TL;DR: The literature concerning the structures of compounds containing saturated, 4-carbon rings is reviewed in this article, and the variety of conformations (dihedral angles of 0° to 30° ± 6°) of the cyclobutane ring are tabulated and discussed.
References
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Journal ArticleDOI
The symmetry groups of non-rigid molecules
TL;DR: In this article, the concept of molecular symmetry is extended to molecules such as ethane and hydrazine, which can pass from one conformation to another, and examples are given to illustrate the use of this concept in determining the statistical weights of individual levels and selection rules for electric dipole transitions between them.
Journal ArticleDOI
Report on Notation for the Spectra of Polyatomic Molecules
TL;DR: A SATISFACTORY standardization of notation for diatomic molecules and their spectra already eXIsts. as mentioned in this paper has been proposed for the entire range of polyatomic spectroscopy from ultraviolet to microwave and magnetic resonanc spectra.
Journal ArticleDOI
Microwave Spectrum, Vibration—Rotation Interaction, and Potential Function for the Ring‐Puckering Vibration of Trimethylene Sulfide
TL;DR: The microwave spectrum of the ground and first four excited states of the ring-puckering mode of trimethylene sulfide has been observed and assigned as mentioned in this paper, and the potential function governing the vibration has been determined to be 7.0207Q4−87.7581Q2 cm−1, where Q is the coordinate describing the vibration.
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