Theory lanthanide-induced shifts

Quantitative separation of the n contact and pseudocontact contributions to the lanthanide induced shifts (LIS) in aniline and m-and p-toluidines has been reported. (395, 396) The contact shift patterns are estimated from the rr-spin density distribution of the appropriate cation radical or from the Ni(acac)2 induced shifts. The separation of the shifts was checked by comparing the relative contact shift contribution with the <5 ) value of Golding and Halton (389) and the remaining pseudocontact contribution with the calculated values of Bleaney s theory. (380)... 

The induced shifts of nuclei not directly adjacent to lanthanide ions have been known for many years to be predominantly dipolar in nature. However, a fully satisfactory theory to account for the variation in these induced shifts across the lanthanide series has been difficult to achieve. Theoretical treatments have been developed independently by Bleaney, (380) Golding and Pyykko, (381) and Horrocks et al. (382) Bleaney s approach involves the following power series expansion in temperature for the susceptibility anisotropy, assuming axial symmetry ... 

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