K-39 quadrupolar and chemical shift tensors for organic potassium complexes and diatomic molecules.
Solid-state potassium-39 NMR spectra of two potassium complexes of crown-ether-based organic ligands (1.KI and 2) have been acquired at 11.75 and 21.1 T and interpreted to provide information on the 39K quadrupolar and chemical shift tensors. The analyses reveal a large potassium chemical shift tensor span of 75+/-20 ppm for 1.KI. This appears to be the first such measurement for potassium in an organic complex, thereby suggesting the utility of potassium chemical shift tensors for characterizing organic and biomolecular K+ binding environments. Compound 2 exhibits a cation-pi interaction between K+ and a phenyl group, and therefore, the 39K NMR tensors obtained for this compound must be partly representative of this interaction. Analyses of potassium-39 spin-rotation data for gaseous 39K19F and 39K35Cl available from molecular beam experiments performed by Cederberg and co-workers reveal the largest potassium CS tensor spans known to date, 84.39 and 141 ppm, respectively. Collectively, the results obtained highlight the potential of ultrahigh-field potassium-39 solid-state NMR spectroscopy and, in particular, the wide range of the anisotropy of the potassium CS tensor when organic and diatomic systems are considered.
Lee
Philip K
PK
Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario K1N6N5, Canada.
Chapman
Rebecca P
RP
Zhang
Lei
L
Hu
Jiaxin
J
Barbour
Leonard J
LJ
Elliott
Elizabeth K
EK
Gokel
George W
GW
Bryce
David L
DL
D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011188:Potassium / Q000737:chemistry*
D011188:Potassium