Experimental and Theoretical Investigation of the13C and15N Chemical Shift Tensors in MelanostatinExploring the Chemical Shift Tensor as a Structural Probe

2004 ◽  
Vol 126 (3) ◽  
pp. 966-977 ◽  
Author(s):  
Mark Strohmeier ◽  
David M. Grant
Keyword(s):  
Chemical Shift ◽  
Theoretical Investigation ◽  
Chemical Shift Tensor ◽  
Chemical Shift Tensors ◽  
Structural Probe

Phosphorus-31 NMR studies of several phosphines in the solid state

1989 ◽  
Vol 67 (11) ◽  
pp. 1909-1913 ◽  
Author(s):  
Glenn H. Penner ◽  
Roderick E. Wasylishen
Keyword(s):  
Chemical Shift ◽  
Principal Components ◽  
Chemical Shift Tensor ◽  
Cross Polarization ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Chemical Shift Tensors ◽  
X Ray ◽  
Cp Mas Nmr ◽  
Proton Decoupling

Phosphorus-31 NMR powder spectra and high resolution MAS spectra have been obtained for a number of solid phosphines under conditions of high-power proton decoupling and cross-polarization. The principal components of the 31P chemical shift tensor obtained from static powder spectra or slow MAS spectra are discussed in terms of the known structures of many of the phosphines. The CP/MAS 31PNMR spectra are used to determine the number of crystallographically nonequivalent molecules in the unit cell. The NMR results are consistent with data available from X-ray diffraction. In one case there is evidence of polymorphism. Keywords: 31P NMR of solid phosphines, principal components of 31P chemical shift tensors, crystallographic nonequivalence from 31P CP/MAS NMR.

scholarly journals A phosphorus-31 NMR study of solid carbonylhydridotris(triphenylphosphine)rhodium(I). Unusual MAS sideband intensities in second-order NMR spin systems

1992 ◽  
Vol 70 (3) ◽  
pp. 863-869 ◽  
Author(s):  
Gang Wu ◽  
Roderick E. Wasylishen ◽  
Ronald D. Curtis
Keyword(s):  
Chemical Shift ◽  
Spin System ◽  
Principal Components ◽  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Chemical Shift Tensor ◽  
Magic Angle ◽  
Nmr Spectrum ◽  
Chemical Shift Tensors ◽  
Nmr Study

The CP/MAS 31P NMR spectrum of carbonylhydridotris(triphenylphosphine)rhodium(I), RhH(CO)(PPh3)3 (1), can be described as a tightly coupled ABMX spin system (X = 103Rh). In contrast to the solution 31P NMR spectrum, the three equatorial phosphorus nuclei are nonequivalent in the solid state and this structural feature allows us to measure the two-bond spin–spin couplings, 2J(31P,31P). A new method is proposed for extracting the principal components of the chemical shift tensor from slow MAS NMR spectra in a tightly J-coupled two-spin system. For compound 1, the principal components of the 31P chemical shift tensors calculated using this method are in good agreement with those obtained from NMR spectra of a static sample. The principal components of the 31P chemical shift tensors determined for 1 are compared with those reported previously for Wilkinson's catalyst, RhCl(PPh3)3. The δ22 component of the 31P chemical shift tensors in 1 shows the largest variation with structure. This is ascribed to differences in the orientation of the P—Cipso bond about the equatorial plane of the trigonal bipyramidal structure. Keywords: rhodium–phosphine compounds, AB spin system, 31P chemical shift tensor, magic-angle spinning, molecular structure.

207Pb and 205Tl NMR on Perovskite Type Crystals APbX3 (A = Cs, Tl, X = Br, I)

1987 ◽  
Vol 42 (11) ◽  
pp. 1313-1320 ◽  
Author(s):  
Surendra Sharma ◽  
Norbert Weiden ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Chemical Shift ◽  
Single Crystals ◽  
Room Temperature ◽  
Saturated Aqueous Solution ◽  
Chemical Shift Tensor ◽  
Chemical Shift Tensors ◽  
Perovskite Type

By 205Tl and 207Pb NM R the chemical shift in polycrystalline samples of binary halides AX, BX2 and ternary halides ABX3 (A = Cs, Tl; B = Pb; X = Br, I) was studied at room temperature. The chemical shift tensors δ ( 205Tl) and δ (207Pb) were determined in magnitude and orientation on single crystals of the orthorhombic TlPbI3. The components of the δ(205Tl) tensor are δx (205Tl) || a = 611ppm; δy (205Tl) || b = 680 ppm; δZ(205Tl) || c = 1329 ppm; δiso(205Tl) = 873.3 ppm (with respect to 3.4 molar aqueous solution of TlOOCCH3). The chemical shift tensor of 207Pb in TlPbI3 shows two orientations. One of them is: δx (207Pb) = 3760 ppm, inclined 30° from b towards c, δy(207Pb) || a = 3485 ppm, δz(207Pb) = 2639 ppm inclined 120° from b towards c. δiso(207Pb) = 3295 ppm (with respect to saturated aqueous solution of Pb(NO3)2). The results are discussed with respect to the crystal structure and a model to explain orientation and anisotropy of the tensors δ(205Tl) and δ(207Pb) in TlPbI3 is proposed.In the system CsPbBr3-x Ix δ(207Pb) was studied on polycrystalline samples. The chemical shift increases with increasing x and negative excess shift is observed.

scholarly journals Modeling Small Structural and Environmental Differences in Solids with 15 N NMR Chemical Shift Tensors

ChemPhysChem ◽  
2021 ◽  
Author(s):  
Luther Wang ◽  
Alexander B. Elliott ◽  
Sean D. Moore ◽  
Gregory J. O. Beran ◽  
Joshua D. Hartman ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Nmr Chemical Shift ◽  
Chemical Shift Tensors

scholarly journals Chemical-shift tensors of heavy nuclei in network solids: a DFT/ZORA investigation of 207Pb chemical-shift tensors using the bond-valence method

2015 ◽  
Vol 17 (38) ◽  
pp. 25014-25026 ◽  
Author(s):  
Fahri Alkan ◽  
C. Dybowski
Keyword(s):  
Chemical Shift ◽  
Quantum Chemistry ◽  
Principal Components ◽  
Bond Valence ◽  
Cluster Models ◽  
Magnetic Shielding ◽  
Heavy Nuclei ◽  
Chemical Shift Tensors ◽  
Accurate Computation ◽  
Bond Valence Model

Accurate computation of 207Pb magnetic shielding principal components is within the reach of quantum chemistry methods by employing relativistic ZORA/DFT and cluster models adapted from the bond valence model.

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