CONTACT VERSUS DIPOLAR NMR SHIFTS IN ION-PAIRED SYSTEMS
- 1 January 1976
- journal article
- research article
- Published by Taylor & Francis in Journal of Coordination Chemistry
- Vol. 5 (2) , 77-83
- https://doi.org/10.1080/00958977608075925
Abstract
Proton NMR data for a series of unsymmetrically substituted ammonium and phosphonium cations in ion pairs with tetrahalocobaltate(II) and nickelate anions are compared with similar data for lanthanide containing systems. The data suggest that the dominant shift mechanism is the axial (through space) dipolar interaction in the cobalt complexes, and not the Fermi-Contact mechanism postulated in previous articles. The structural parameters for the ion-pairs which are obtained by comparison of theory and experiment are used to infer that the cation orientation with respect to the principal axis of magnetic susceptibility of the anion is roughly the same in both sets of complexes, as is the interionic distance, A.Keywords
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