Quadrupolar couphng constants

The theoretical background for the quadrupole coupling constant was developed already in the 1950s . Direct calculation of quadrupolar couphng constants is stiU not straightforward and depends heavily on the basis set used The quadrupolar coupling constant is thus mainly used as an empirical parameter. Nevertheless, experimental trends can be reproduced quite well with available theoretical methods as shown in Section n.F. 

S. Kuroki, S. Ando, I. Ando, An MO smdy of nuclear quadrupolar coupHng constant and nuclear shielding of the carbonyl oxygen in soHd peptides with hydrogen bonds, Chem. Phys. 195 (1995) 107. 

SIMPSON for systematic variation of the nuclear electric quadrupolar coupUng constant Cq of the I-spins. Across the entire range of Cq-values, these REDOR curves calculated for dipolar couphng constants of different magnitudes (D=200 Hz, and D=600 Hz, open, and filled symbols) were found to be super-imposable, indicating that they represent universal curves. 

The first Co SNMR work appears to be the study of K3[Co(CN)6] at 4.2 K in 1959. The Co quadrupole couphng constant and the asymmetry parameter were determined to be 7.3 MHz and 0.75, respectively, for a pseudo-orthorhombic twin crystal. In a subsequent SNMR study of Cr-doped K3[Co(CN)6] at room temperature, the reported quadrupolar parameters were... 

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