ISSN:
0749-1581
Schlagwort(e):
NMR
;
31P NMR
;
solid state
;
CP/MAS
;
crystallographically equivalent nuclei
;
2J(31P, 31P)
;
1J(109/107Ag, 31P)
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Solid-state 31P magic angle spinning (MAS) NMR spectra of Ag[P(m-tolyl)3]2NO3 were investigated as a function of the magic angle spinning frequency. Examination of the 31P MAS NMR spectra obtained at 4.70 and 9.40 T indicates that the two phosphorus nuclei have identical isotropic chemical shifts, that is, they are crystallo-graphically equivalent, δ = 11.2 ppm. However, since the orientation of their respective chemical shift tensors is not coincident, the two phosphorus nuclei are magnetically non-equivalent and exhibit spinning-frequency dependent 31P NMR lineshapes. Analysis of the spinning-frequency dependent 31P MAS NMR spectra at 4.70 and 9.40 T indicates that 2J(31P, 31P) = 140 Hz. This value was confirmed by 2D J-resolved spectroscopy. The determination of an indirect spin-spin coupling constant between two nuclei which constitute an ‘isolated’ spin pair with identical isotropic chemical shifts is not possible in conventional solution-state NMR studies unless a third spin is introduced. The 31P MAS NMR spectra of Ag[P(m-tolyl)3]2NO3 also exhibit resolvable splittings due to 109Ag and 107Ag; 1J(109Ag, 31P) = 517±5 Hz and 1J(107Ag, 31P) = 453 ± 5 Hz. In solution NMR studies these couplings are not always observed because of rapid metal-ligand exchange.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1260330908
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