Anisotropic chemical shifts and spin rotation constants of 15N from liquid and solid state NMR: Nitrobenzene
1974; Elsevier BV; Volume: 16; Issue: 2 Linguagem: Inglês
10.1016/0022-2364(74)90048-1
ISSN1557-8968
Autores Tópico(s)Electron Spin Resonance Studies
ResumoThe study of the 15N spin-lattice relaxation time Tl in nitrobenzene at 14 and 32 MHz from -10 to 60°C showed that at 32 MHz relaxation due to anisotropic chemical shift is predominant. At low frequencies, the relaxation is caused mainly by spin rotation and at low temperature also by intermolecular dipole-dipole inter action. From the powder spectrum in solid nitrobenzene, the principal elements of the shielding tensor a were obtained: xx = -273 ± 10 ppm, 0' = +94 ± 10 ppm, and O'zz = + 156 ± 10 ppm relative to liquid nitrobenzene, .dO' = O'xx - t(O' + O'zz) = -398 ± 20 ppm. From the almost axially symmetric a-tensor, the spin rotation constants were calculated: CII = 11.4 ± 1.5 kHz and C.L = 1.35 ± 0.5 kHz, where ell is the component parallel to the twofold axis of the molecule. These values for Au and the spin rotation constants are in excellent agreement with those obtained by analysis of the relaxation data. A comparison of anisotropic chemical shifts and spin rotation constants for IsN and 13C in isoelectronic compounds is given.
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