An Experimental and Theoretical Investigation of the Olefinic Carbon Chemical Shift Tensors intrans-Stilbene and Pt(η2-trans-stilbene)(PPh3)2

1998 ◽  
Vol 102 (18) ◽  
pp. 3184-3192 ◽  
Author(s):  
Guy M. Bernard ◽  
Gang Wu ◽  
Roderick E. Wasylishen
Keyword(s):  
Chemical Shift ◽  
Theoretical Investigation ◽  
Olefinic Carbon ◽  
Chemical Shift Tensors ◽  
Trans Stilbene ◽  
Carbon Chemical Shift

A solid-state 13C NMR and theoretical investigation of carbonyl and thiocarbonyl carbon chemical shift tensors

1995 ◽  
Vol 73 (4) ◽  
pp. 604-613 ◽  
Author(s):  
Christopher W. Kirby ◽  
Michael D. Lumsden ◽  
Roderick E. Wasylishen
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Ab Initio ◽  
Principal Axis ◽  
Comparative Investigation ◽  
Conclusive Evidence ◽  
Carbon Nucleus ◽  
Chemical Shift Tensors ◽  
Carbon Chemical Shift ◽  
C Nmr

The carbon chemical shift tensors of the carbonyl and thiocarbonyl groups of acetamide, thioacetamide, thioacetanilide, 4′-methoxyacetanilide, and 4′-methoxythioacetanilide have been experimentally determined using dipolar – chemical shift solid-state 13C NMR spectroscopy. The magnitudes of the three principal components of the carbon chemical shift tensors are found to exhibit marked variations between the carbonyl and thiocarbonyl functionalities. However, in contrast to the conclusions of an earlier comparative investigation involving benzophenone and thiobenzophenone, the orientations of the principal axis systems of these chemical shift tensors are found to be similar. These experimental results represent the first complete characterizations of the carbon chemical shift tensor in organic thiocarbonyls. The results of our ab initio GIAO and LORG calculations of carbon chemical shielding tensors in formaldehyde, thioformaldehyde, formamide, and thioformamide as well as in acetamide and thioacetamide are in qualitative agreement with experiment. The findings of the present investigation provide conclusive evidence that the well-known isotropic deshielding of the carbon nucleus in the C=S group relative to C=O is primarily attributable to the decreased energy associated with the σ ↔ π* excitation within the thiocarbonyl fragment. This result is in contrast with the conventional interpretation that the deshielding originates from a red shift in the C=S HOMO–UMO n → π* transition. Keywords: chemical shift tensors, solid-state 13C NMR, carbonyls, thiocarbonyls, ab initio calculations.

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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