MICROWAVE SPECTRUM AND STRUCTURE OF 1,1-DIFLUOROETHYLENE OZONIDE
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Date
1981
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Ohio State University
Abstract
The microwave spectra of seven isotopic species of 1,1-difluoroethylene ozonide (3,3-difluoro-1,2,4-trioxolane, FCFOOHCHO) have been assigned, including the $parent^{1}$, both $D_{1}$, species, two singly-substituted and the doubly-substituted $^{18}O$(peroxy) species, and the $^{18}O_{3}$ species. The rotational constants show that, unlike all ozonides previously studied by microwave $spectroscopy^{2,3,4}$, the preferred conformation is an $O_{p}(CH_{2})$ envelope. The structural analysis is based on a predicate observables method, in which the assumed structural parameters are allowed to vary over a small range to give the best least-squares fit to the experimental data; this tends to reduce the possible effects of a poorly chosen assumed parameter. The results suggest an anomeric interaction to be operative, i.e., a C-F (cis to the envelope flap) bond slightly longer than the C-F (trans to flap) bond with the adjacent C-0 bonds much shorter than the C(H)-0 bonds, and a F(cis)-C-O-O dihedral angle close to $90^{\circ}$. A clear conformational trend of twist: partial Op envelope: full $O_{p}$ envelope is seen in the series of ozonides of ethylene, 1-fluoroethylene, and 1,1-difluoroethylene.
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$^{1}$C. W. Gillies, S.P. Sponseller, and R.L. Kuczkowski, J. Phys. Chem. 83, 1545 (1979). $^{2}C$. W. Gillies and R.L, Kuczkowski, JACS 94, 6337 (1972). $^{3}R$. P. Lattimer, R.L. Kuczkowski, and C.W. Gillies, JACS 96, 348 (1974). $^{4}K$. W. Hillig II, PhD Thesis, Department of Chemistry, Univ. of Michigan, Ann Arbor, MI 48109 (1981). KUCZKOWSKI, R.L.
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