Nitrogen quadrupole coupling constants

The nitrogen quadrupole coupling (NQR) constants of (3) were determined and the dipole moment confirmed as / = 1.58 0.02D (78ZN(A)1518). The NQR spectra for three... 

Nitrogen quadrupole resonance studies have so far followed two major directions of investigation on the one hand, quadrupole coupling constants are interpreted in terms of the distribution of the bonding electrons, with many attempts to use the available molecular orbitals computed from models of various degrees of sophistication on the other hand, the effect of temperature on resonances yields information on the molecular motions and relaxation processes. 

The electric field gradient component produced along Oz by a pz electron is eqo and - eq0 along Ox and Oy. So, with the proposed orbitals and populations, the nitrogen atom quadrupole coupling constant in aC=N group is... 

Ab initio calculations of the nuclear quadrupole coupling constant suggest that the cyanate nitrogen atom is more ionic than that of the thiocyanate ion (118), but measurements show the latter to be more ionic than that in the selenocyanate ion (397). 

No N nuclear quadrupole resonance (NQR) studies have been reported for transition metal nitrosyl complexes. This technique is expected to show interesting differences between linear and bent nitro-syls since the values of the quadrupole coupling constant and the asymmetry parameter depend on the relative populations of the nitrogen s,p, py, andpz orbitals. NQR spectroscopy has been used to study organic and inorganic nitroso compounds, and it is found that both... 

Soper, P.D., Fegon, A.C., Read, W.G., and Flygare, W.H. (1982) The microwave rotational spectrum, molecular geometry,14N nuclear quadrupole coupling constants, and H-1S>F nuclear spin-nuclear spin coupling constant of the nitrogen-hydrogen fluoride dimer. J. Chem. Phys., 76, 292-300. 

The 14N quadrupole hyperfine structure was analyzed from the MW spectrum and the nitrogen nuclear quadrupole coupling constants (NQCC) for aniline-Hy are determined as follows xaa = 2.34, Xbb = 1-86 and Xcc = —4.20 MHz38. 

It should be noted that the CHj group and the nitrogen-bound carbon atom of the carbazole moiety ue subject to the same effect, arising from the dipolar coupling to the quadrupolar N nucleus. In this case, however, since the quadrupole coupling constant is much smaller than for the bromine isotopes (2.16 MHz for N-methyl pyrrole (29)) the interaction is much weaker and manifests itself only as a moderate broadening of the peaks with some ill-resolved structure. For these asymmetric resonances, the chemical shifts were measured at the center of gravity. 

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