Complete Structure of trans-3,4-Difluorocyclobutene from Microwave Spectroscopy

Title:
Complete Structure of trans-3,4-Difluorocyclobutene from Microwave Spectroscopy
Authors:
Craig, Norman C.; McCarty, Lewis V.; Lingenfelter, Peter T.; Osmani, A. Sonan; Rathore, Osman
Abstract:
Microwave spectra have been observed with Fourier transform and cold jet expansion techniques in the 6−17 GHz range for trans-3,4-difluorocyclobutene, its two 13C1 modifications, two d1 modifications, and the perdeutero species. Watson-type Hamiltonians have been fit with a full set of quartic centrifugal distortion constants for all species except the d4 species. Complete structures fit with an rs/r0 treatment and an r0 treatment are in satisfactory agreement. Preferred rs/r0 results with Costain uncertainties in parentheses are 1.349(4) Å for the CC bond, 1.503(9) Å for the contiguous C−C bonds, 1.534(4) Å for the distant C−C bond, 1.398(6) Å for the C−F bond, 1.081(3) Å for the C−H bond, and 1.102(5) Å for the −C−H bond. Consistent with its C2 symmetry, the ring is slightly puckered, and the C−F bonds are roughly equatorial. Compared with the structure of cyclobutene, the structure of trans-3,4-difluorocyclobutene shows a modest lengthening of the CC bond and more significant decreases in the C−C bond lengths. These effects are consistent with observations for other fluorine-substituted rings in which contiguous fluorine atom substitution causes CC bond shortening and distant fluorine atom substitution causes CC bond lengthening. The CC bond adjustments in trans-3,4-difluorocyclobutene are, however, surprisingly similar to the adjustments observed for 3,3,4,4-tetrafluorocyclobutene.
Citation:
Craig, Norman C., Lewis V. McCarty, Peter T. Lingenfelter, A. Sonan Osmani, and Osman Rathore. 2002. "Complete Structure of trans-3,4-Difluorocyclobutene from Microwave Spectroscopy." Journal of Physical Chemistry A 106(28): 6637-6642.
Publisher:
American Chemical Society
DATE ISSUED:
2002
Department:
Chemistry
Type:
Article
PUBLISHED VERSION:
10.1021/jp020504e
PERMANENT LINK:
http://hdl.handle.net/11282/334011

Full metadata record

DC FieldValue Language
dc.contributor.authorCraig, Norman C.en
dc.contributor.authorMcCarty, Lewis V.en
dc.contributor.authorLingenfelter, Peter T.en
dc.contributor.authorOsmani, A. Sonanen
dc.contributor.authorRathore, Osmanen
dc.date.accessioned2014-11-10T14:12:26Z-
dc.date.available2014-11-10T14:12:26Z-
dc.date.issued2002en
dc.identifier.citationCraig, Norman C., Lewis V. McCarty, Peter T. Lingenfelter, A. Sonan Osmani, and Osman Rathore. 2002. "Complete Structure of trans-3,4-Difluorocyclobutene from Microwave Spectroscopy." Journal of Physical Chemistry A 106(28): 6637-6642.en
dc.identifier.issn1089-5639en
dc.identifier.urihttp://hdl.handle.net/11282/334011-
dc.description.abstractMicrowave spectra have been observed with Fourier transform and cold jet expansion techniques in the 6−17 GHz range for trans-3,4-difluorocyclobutene, its two 13C1 modifications, two d1 modifications, and the perdeutero species. Watson-type Hamiltonians have been fit with a full set of quartic centrifugal distortion constants for all species except the d4 species. Complete structures fit with an rs/r0 treatment and an r0 treatment are in satisfactory agreement. Preferred rs/r0 results with Costain uncertainties in parentheses are 1.349(4) Å for the CC bond, 1.503(9) Å for the contiguous C−C bonds, 1.534(4) Å for the distant C−C bond, 1.398(6) Å for the C−F bond, 1.081(3) Å for the C−H bond, and 1.102(5) Å for the −C−H bond. Consistent with its C2 symmetry, the ring is slightly puckered, and the C−F bonds are roughly equatorial. Compared with the structure of cyclobutene, the structure of trans-3,4-difluorocyclobutene shows a modest lengthening of the CC bond and more significant decreases in the C−C bond lengths. These effects are consistent with observations for other fluorine-substituted rings in which contiguous fluorine atom substitution causes CC bond shortening and distant fluorine atom substitution causes CC bond lengthening. The CC bond adjustments in trans-3,4-difluorocyclobutene are, however, surprisingly similar to the adjustments observed for 3,3,4,4-tetrafluorocyclobutene.en
dc.language.isoen_USen
dc.publisherAmerican Chemical Societyen
dc.identifier.doi10.1021/jp020504een
dc.subject.departmentChemistryen
dc.titleComplete Structure of trans-3,4-Difluorocyclobutene from Microwave Spectroscopyen
dc.typeArticleen
dc.identifier.journalJournal of Physical Chemistryen
dc.identifier.volume106en
dc.identifier.issue28en
dc.identifier.startpage6637en
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