# A COMPLETE STRUCTURE OF TRANS-3,4-DIFLUOROCYCLOBUTENE FROM MICROWAVE SPECTROSCOPY

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 Title: A COMPLETE STRUCTURE OF TRANS-3,4-DIFLUOROCYCLOBUTENE FROM MICROWAVE SPECTROSCOPY Creators: Craig, Norman C.; McCarty, Lewis V.; Lingenfelter, Peter T.; Osmani, A. Sonan; Rathore, Osman; Tubergen, Michael J.; Kuczkowski, R. L. Issue Date: 2002 Publisher: Ohio State University Abstract: Microwave spectra have been observed in the 6-17-GHz region for trans-3,4-difluorocyclobutene, two $^{13}C_{1}$ modifications, two $d_{1}$ modifications, and the perdeutero species. Watson-type Hamiltonians have been fit with a full set of quartic centrifugal distortion constants for all species except for the $d_{4}$ species. Rotational constants for the normal species in MHz are $A = 5664.02410(29), B = 3366.07000(19)$, and $C = 2345.58058(16)$. Complete structures fit with an $r_{s}/ r_{0}$ treatment and an $r_{0}$ treatment are in satisfactory agreement. Preferred $r_{s}/ r_{0}$ results with Costain uncertainties in parentheses are $1.349(4) {\AA}$ for the $C=C$ bond, $1.503(9) {\AA}$ for the contiguous $C-C$ bonds, $1.534(4) {\AA}$ for the unique $C-C$ bond, $1.398(6) {\AA}$ for the $C-F$ bond, $1.081(3) {\AA}$ for the $=C-H$ bond, and $1.102(5) {\AA}$ for the $-C-H$ bond. Consistent with $C_{2}$ symmetry, the ring is slightly puckered. Compared with cyclobutene, the $C=C$ bond is slightly longer and the $C-C$ bonds are shorter, adjustments which are familiar consequences of fluorine substitution on small rings. Description: Author Institution: Department of Chemistry, Oberlin College; Department of Chemistry, Kent, State University; Department of Partment of Chemistry, University of Michigan URI: http://hdl.handle.net/1811/20567 Other Identifiers: 2002-TB-13