Quadrupole Coupling and Anisotropic Chemical Shift in Re2(CO)10, Mn2(CO)10, and ReMn(CO)10

1972 ◽  
Vol 57 (2) ◽  
pp. 813-821 ◽  
Author(s):  
E. S. Mooberry ◽  
H. W. Spiess ◽  
R. K. Sheline
Keyword(s):  
Chemical Shift ◽  
Quadrupole Coupling ◽  
Anisotropic Chemical Shift

ChemInform Abstract: Solid-state27Al NMR Chemical Shift and Quadrupole Coupling Data for Condensed AlO4Tetrahedra

1986 ◽  
Vol 17 (37) ◽  
Author(s):  
D. MUELLER ◽  
W. GESSNER ◽  
A. SAMOSON ◽  
E. LIPPMAA ◽  
G. SCHELER
Keyword(s):  
Chemical Shift ◽  
Nmr Chemical Shift ◽  
Quadrupole Coupling

Are the amide bonds in N-acyl imidazoles twisted? A combined solid-state 17O NMR, crystallographic, and computational study

2015 ◽  
Vol 93 (4) ◽  
pp. 451-458 ◽  
Author(s):  
Xianqi Kong ◽  
Aaron Tang ◽  
Ruiyao Wang ◽  
Eric Ye ◽  
Victor Terskikh ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Crystal Structures ◽  
Computational Study ◽  
Chemical Shifts ◽  
Amide Bond ◽  
Chemical Shift Tensors ◽  
Amide Bonds ◽  
Bond Rotation ◽  
Quadrupole Coupling

We report synthesis of 17O-labeling and solid-state 17O NMR measurements of three N-acyl imidazoles of the type R-C(17O)-Im: R = p-methoxycinnamoyl (MCA-Im), R = 4-(dimethylamino)benzoyl (DAB-Im), and R = 2,4,6-trimethylbenzoyl (TMB-Im). Solid-state 17O NMR experiments allowed us to determine for the first time the 17O quadrupole coupling and chemical shift tensors in this class of organic compounds. We also determined the crystal structures of these compounds using single-crystal X-ray diffraction. The crystal structures show that, while the C(O)–N amide bond in DAB-Im exhibits a small twist, those in MCA-Im and TMB-Im are essentially planar. We found that, in these N-acyl imidazoles, the 17O quadrupole coupling and chemical shift tensors depend critically on the torsion angle between the conjugated acyl group and the C(O)–N amide plane. The computational results from a plane-wave DFT approach, which takes into consideration the entire crystal lattice, are in excellent agreement with the experimental solid-state 17O NMR results. Quantum chemical computations also show that the dependence of 17O NMR parameters on the Ar–C(O) bond rotation is very similar to that previously observed for the C(O)–N bond rotation in twisted amides. We conclude that one should be cautious in linking the observed NMR chemical shifts only to the twist of the C(O)–N amide bond.

scholarly journals On the preparation and NMR spectroscopic characterization of potassium aluminium tetrahydride KAlH4

2019 ◽  
Vol 21 (23) ◽  
pp. 12576-12584 ◽  
Author(s):  
Bodo Zibrowius ◽  
Michael Felderhoff
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Spectroscopic Characterization ◽  
Mas Nmr ◽  
Isotropic Chemical Shift ◽  
Quadrupole Coupling ◽  
Coupling Parameters

Conventional 1D 27Al MAS NMR spectroscopy allows the isotropic chemical shift and the quadrupole coupling parameters of Pnma KAlH4 to be determined precisely.

The 59Co nuclear magnetic resonance spectra of polycrystalline complexes

1987 ◽  
Vol 65 (6) ◽  
pp. 1332-1335 ◽  
Author(s):  
Donald R. Eaton ◽  
Richard J. Buist ◽  
Brian G. Sayer
Keyword(s):  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
X Ray ◽  
Low Field ◽  
Nmr Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
Quadrupole Coupling ◽  
Low Field Nmr

The solid state 59Co nmr spectra of a number of octahedral complexes are reported. In the case of sodium hexanitrocobaltate(III) the spectra have been obtained at several different field strengths and the results are analysed to give a quadrupole coupling constant of 9.4 MHz, an asymmetry parameter of zero and an axial chemical shift tensor with an anisotropy of 180 ppm. Several other complexes have been examined at high field (11.8 T) to minimize the effects of quadrupole coupling and maximize the influence of chemical shift anisotropy. The results are, where possible, compared with single crystal X-ray and low field nmr data. It is concluded that high fields are necessary to obtain reliable chemical shift anisotropy values. The conditions necessary for obtaining reasonable quality spectra from polycrystalline samples containing quadrupolar nuclei are discussed.

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