A Combined Structural Study Using NMR Chemical-Shielding-Tensor Correlation and Neutron Diffraction in Polycrystalline Methanol

1994 ◽  
Vol 116 (12) ◽  
pp. 5315-5323 ◽  
Author(s):  
P. Robyr ◽  
B. H. Meier ◽  
P. Fischer ◽  
R. R. Ernst
Keyword(s):  
Neutron Diffraction ◽  
Structural Study ◽  
Chemical Shielding ◽  
Tensor Correlation ◽  
Shielding Tensor

31P NMR chemical shielding tensor of 2‐aminoethylphosphonic acid

1987 ◽  
Vol 86 (10) ◽  
pp. 5405-5410 ◽  
Author(s):  
Marie‐Rose Van Calsteren ◽  
George I. Birnbaum ◽  
Ian C. P. Smith
Keyword(s):  
31P Nmr ◽  
Chemical Shielding ◽  
Shielding Tensor

13C chemical shielding tensor orientations in a phosphoenolpyruvate moiety from 13C rotational-resonance MAS NMR lineshapes

2004 ◽  
Vol 6 (10) ◽  
pp. 1097-1105 ◽  
Author(s):  
M. Bechmann ◽  
S. Dusold ◽  
A. Sebald ◽  
W.A. Shuttleworth ◽  
D.L. Jakeman ◽  
...  
Keyword(s):  
Mas Nmr ◽  
Chemical Shielding ◽  
Rotational Resonance ◽  
Shielding Tensor

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1962-1972
Author(s):  
Scott Kroeker ◽  
Roderick E Wasylishen
Keyword(s):  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Spin Coupling ◽  
Group Symmetry ◽  
Magic Angle ◽  
Chemical Shielding ◽  
Shielding Tensor ◽  
Angle Spinning ◽  
Spin Spin Coupling

Direct NMR observation of copper-63/65 nuclei in solid K3Cu(CN)4 provides the first experimental example of anisotropic copper chemical shielding. Axially symmetric by virtue of the space group symmetry, the shielding tensor spans 42 ppm, with the greatest shielding when the unique axis is perpendicular to the applied magnetic field. The nuclear quadrupole coupling constant is also appreciable, CQ(63Cu) = -1.125 MHz, reflecting a deviation of the Cu(CN)43- anion from pure tetrahedral symmetry. Spin-spin coupling to 13C nuclei in an isotopically enriched sample is quantified by line-shape simulations of both 13C and 63/65Cu magic-angle spinning (MAS) NMR spectra to be 300 Hz. It is shown that this information is also directly available by 63/65Cu triple-quantum (3Q) MAS NMR. The relative merits of these three approaches to characterizing spin-spin couplings involving half-integer quadrupolar nuclei are discussed. Chemical shielding tensors for nitrogen-15 and carbon-13 are obtained from NMR spectra of non-spinning samples, and are compared to those of tetrahedral group 12 tetracyanometallates. Finally, 2J(63/65Cu,15N) detected in 15N MAS experiments are found to be 19 and 20 Hz for the two crystallographically distinct cyanide ligands.Key words: NMR, quadrupolar nucleus, chemical shielding tensor, multiple-quantum magic-angle spinning, metal cyanide, spin-spin coupling.

Structural study of the cesium oxypentafluorouranate (VI) CsUOF5

1978 ◽  
Vol 56 (19) ◽  
pp. 2546-2549 ◽  
Author(s):  
Philippe Joubert ◽  
Jean-Marc Weulersse ◽  
Roland Bougon ◽  
Bernard Gaudreau
Keyword(s):  
Neutron Diffraction ◽  
Structural Study ◽  
Characteristic Time ◽  
The Other ◽  
Point Symmetry ◽  
Space Group ◽  
Dynamic Type ◽  
Nmr Study ◽  
Powder Samples ◽  
Occupation Rate

Powder samples of cesium oxypentafluorouranate(VI) were studied by both neutron diffraction and 19F broad Une nuclear magnetic resonance.CsUOF5 crystallises with the [Formula: see text] space group, with the parameters a = 5.41 ± 0.01 Ǻ; α = 95°34′ ± 5′. The structure, which was found to be unchanged at temperatures as low as 4.2 K, was interpreted by a statistical occupation of six-fold equivalents sites, the occupation rate being 1/6 and 5/6 for oxygen and fluorine, respectively. The nmr study showed that the disorder corresponding to this structure was of dynamic type, and that the UOF5− ions were in isotropical rotation. The motion is observable at temperatures as low as 223 K with a characteristic time τ equal to3 × 10-5 s at 266 K. On the other hand, it was also shown through this nmr study that the point symmetry of the UOF5− ion corresponds to the C4v group, with the axial fluorine being more covalent than the equatorial ones. Consistency of the diffraction and nmr results is discussed.

Revealing Successive Steps of Deprotonation ofl- Phosphoserine through13C and31P Chemical Shielding Tensor Fingerprints

2006 ◽  
Vol 110 (29) ◽  
pp. 9137-9144 ◽  
Author(s):  
Carole Gardiennet-Doucet ◽  
Xavier Assfeld ◽  
Bernard Henry ◽  
Piotr Tekely
Keyword(s):  
Chemical Shielding ◽  
Shielding Tensor
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