13C satellites in the 19F NMR spectra of cis- and trans1,2-Difluoroethene partially oriented in nematic solvents
1975; Elsevier BV; Volume: 20; Issue: 1 Linguagem: Inglês
10.1016/0022-2364(75)90145-6
ISSN1557-8968
Autores Tópico(s)Fluorine in Organic Chemistry
ResumoA liquid crystal NMR study using the 13C satellites in the 19F spectra of cis- and trans-difluorethene is reported. The magnitudes and relative signs of the indirect HH, HF, FF and CF couplings have been determined and the anisotropies of the indirect couplings have been investigated. In agreement with the results of INDO calculations only JFFtrans contains large anisotropic parts. Assuming bond distances from other sources, we have found for trans-difluoroethene: ∠ CCH = 125.6° ± 0.6° and ∠ CCF = 119.0° ± 0.2°. For cis-difluoroethene the NMR parameters corrected for vibrational motions and combined with the experimental moments of inertia, lead to: rCF = 1.335 ± 0.003 Å, rcc = 1.330 ± 0.003 Å, rCH = 1.11 ± 0.01 Å, ∠ CCH = 122.9° ± 0.1° and∠ CCF = 122.0° ± 0.1°.
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