Analysis of NMR lineshapes of rigid-lattice multispin systems II. Bond length and chemical shielding in CF 4

Abstract

The 19F NMR lineshape for the CF 4 molecule enclathrated in the heavy water clathrate hydrate was obtained in magnetic fields of 4 and 14 kG at low temperatures ( T ≤ 4.2K). A fit of the 4-spin lineshape by inclusion of chemical shielding anisotropy in a previously described computer program yielded 1.330 ± 0.005Åfor the C F bond length and 138 ± 4 ppm for the difference between chemical shifts parallel and perpendicular to the CF bond. Calculation of the spin-rotation tensor gave C av = − 6.83 ± 0.30 kHz and ( C ∥ − C ⊥) = 3.62 ± 0.15 kHz.