Sodium quadrupole coupling constants

S nuclear quadrupole coupling constants have been determined from line width values in some 3- and 4-substituted sodium benzenesulphonates33 63 and in 2-substituted sodium ethanesulphonates.35 Reasonably, in sulphonates R — SO3, (i) t] is near zero due to the tetrahedral symmetry of the electronic distribution at the 33S nucleus, and (ii) qzz is the component of the electric field gradient along the C-S axis. In the benzenesulphonate anion, the correlation time has been obtained from 13C spin-lattice relaxation time and NOE measurements. In substituted benzenesulphonates, it has been obtained by the Debye-Stokes-Einstein relationship, corrected by an empirically determined microviscosity factor. In 2-substituted ethanesulphonates, the molecular correlation time of the sphere having a volume equal to the molecular volume has been considered. 

A linear relationship has been demonstrated by Clayden and Pugh (1998) between the quadrupole coupling constant Xq and the ionic radius r (in nm) of the M ions in the small group of sodium metal(IV) phosphates NaM2(P04)3 where M = Sn, Ge, Ti and Zr. The two resolvable Na sites of NaSn2(P04)3 straddle the line for these compounds, defined by ... 

Table 3. Quadrupole coupling constants, Cq, asymmetry parameters, 7]q, and isotropic chemical shifts, 5, (referenced to solid NaCl) of sodium cations in dehydrated zeolites NaY and NaX calculated by a point charge model (see text) and experimentally derived by solid-state Na MAS NMR spectroscopy [194,201,203] ...

Na Quadrupole Coupling Constants in Different Coordination Shells from 23Na and C Fourier Transform NMR Measurements on Sodium Cryp-tates, J. P. Kintzinger and J. M. Lehn, J. Amer. Chem. Soc., 96, 3313 (1974). 

In order to observe the whole spectrum from a molecule in which the quadrupole coupling constant is on the order of a few MHz, a weak alignment degree with respect to the magnetic field is mandatory. Therefore, dilute lyotropic liquid crystals, namely sodium dodecylsulphate (SDS)/... 

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