NMR Parameters Experimental and Theoretical Studies

An approach to the determination of the orientation of the carbonyl CSA tensor in a dipolar coupled spin network has been proposed. The 

A solid-state NMR study of [a- C, 0]benzamide has been presented. The orientations of the e.f.g. and chemical shift tensors have been determined from the analysis of MAS and static NMR spectra. It has been shown that the principal component of the chemical shift tensor with the least shielding is approximately 18° off the C=0 bond and that the component with the most shielding is perpendicular to the amide plane. 

The paramagnetic effects of oxygen molecules on the sodium cations in zeolite LiNaX (approximate to 70% Li 30% Na) have been investigated using VT Na MAS NMR and Na MQ MAS NMR. 23 jyjg been used to calculate the isotropic chemical shifts, quadrupolar shifts, and the quadrupolar coupling constants. 

Correlation and relativistic effects on Pb-Pb and Pb-O interactions in P-PbO have been examined using ab initio calculations and Pb NMR CSA tensor analysis. It has been shown that a covalent-like Pb -Pb interaction accounts for many facets of the NMR and the X-ray absorption near-edge structure, as well as other spectroscopic properties. 

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NMR parameters experimental and theoretical studies 4.1 Spin I nuclei... 

Finally there is a desperate need for greater correlations of these structural and theoretical studies of the nature of the mctal-unsaturated molecule interaction with other experimentally derived quantities. We have in mind correlations with spectroscopically derived quantities, such as stretching frequencies and NMR shielding parameters. But we also have in mind the most important problem of the correlation of the metrical details of the bonding with the reaction chemistry. If the discovery and... 

Three cis-dioxovanadium(V) complexes with similar N-salicylidenehy-drazide ligands modeling hydrogen bonding interactions of vanadate relevant for vanadium haloperoxidases are studied by solid-state NMR spectroscopy. Their parameters describing the quadrupolar and chemical shift anisotropy interactions are determined both experimentally and theoretically using DFT methods. 

The value of a coupled experimental and theoretical approach of the NMR parameters is illustrated on F and Al. It demonstrates the advantages of the use of DFT calculations to correlate these parameters to structural features. The current increase of computational power is likely to make the use of these ab initio calculations more popular to assist the study of complex disordered or amorphous material. 

High resolution NMR parameters are reeognized as invaluable probes to detect fine details of the electronic molecular structure of different types of compounds when adequate combinations of theoretical and experimental approaches are adopted. Pioneer works of Professor Oddershede on the study of high resolution NMR parameters are very well recognized in the literature [1-6], For this reason and for this occasion, the authors thought it pertinent to present a contribution... 

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