Quadrupolar metals

Recent applications of X/Y correlation techniques to measure chemical shifts of low- , spin-1/2 transition metal nuclei other than rhodium focused mainly on the analysis of silver and tungsten complexes in addition, the use of 13C-relayed H/195Pt correlations for the stereochemical analysis of some platinum complexes was explored.44 A report on the application of 31P/51V correlation spectroscopy demonstrated further the possibility of indirect detection of rapidly relaxing quadrupolar metal nuclei and the feasibility of the... 

Aramini, J. M. and Vogel, H.J. (1998) Quadrupolar metal ion NMR studies of metalloproteins, Biochemistry and Cell Biology 76, 210-222. 

Table 1 Classification of quadrupolar metal nuclei according to NMR sensitivity and...

Examples Involving Quadrupolar Metals. The quadrupolar metals are grouped in Table II, again with an indication of their ease of detection. The classification is considerably more arbitrary than for the dipolar metals since the ease of detection will depend markedly on the degree of symmetry around the metal and the magnitude of the quadrupole coupling constant. Where a choice exists, the most likely preferred isotope is indicated. 

As is the case for the dipolar metals, the number of applications involving quadrupolar metals is far too great to cover in a short review such as this. Dechter s coverage (10) of the literature from 1978 through September, 1983 is particularly timely in updating earlier reviews, and selected references which are thought to be currently representative will simply be mentioned here. 

In favorable cases, aspects normally associated with spin-1/2 systems can feature in the study of quadrupolar metals. For example, variable temperature 4i>Sc NMR spectra provided evidence... 

F.H. Larsen, J. Skibsted, H.J. Jakobsen, N.C. Nielsen, Solid-state QCPMG NMR of low-y quadrupolar metal nuclei in natural abundance, J. Am. Chem. Soc. 122 (2000) 7080-7086. 

Finally, cases involving coupled to metals should be mentioned. Spectra which involve coupling of to several quadrupolar metals, e.g. 63,65Cu (S = 3/2), 35Mn (S = 5/2), (S = 7/2) and 3Nb (S = 9/2) have been found to consist of dis-tort-ed /-multiplets, as expected from Equation [6]. The pair 3iPj extensively studied in a... 

Although C NMR is a powerful technique for the study of metal carbonyl complexes, its utility is marginal when quadrupo-lar metal nuclei are involved due to metal-carbon spin-spin coupling which broadens resonances and distorts their intensities. Since two bond metal-oxygen couplings do not interfere in a similar fashion, 0 NMR alone can provide definitive structural and dynamic information for many quadrupolar metal carbonyls (17-21). The most complex molecule of this type which has been studied to date is the 03 HFeCo3(C0)j 2 cluster (20), 9. At... 

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