Author： Ernst Richard
Publisher： Taylor & Francis Ltd
ISSN： 1362-3028
Source： Molecular Physics, Vol.16, Iss.3, 1969-01, pp. : 241-255
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Abstract
The 19 F spectra of several substituted trifluorochlorocyclobutanes which commonly occur as mixtures of two cis-trans isomers have been investigated. Substituents of different bulkiness have been introduced to shift the conformational equilibrium of the puckering motion of the cyclobutane ring system. A complete assignment of the resonances of the two isomers was possible, based on chemical shifts and H-F coupling constants. Vicinal F-F coupling constants have been investigated for a possible dependence on the dihedral angle φ. It is found that the coupling constants change sign twice for 0 ≤ ğf ≤ 1>80°, being negative for small and large angles and positive for intermediate angles. The investigations were based on fluorine spectra with completely eliminated H-F couplings by means of noise decoupling.
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