NMR shift calculations

Ga NMR Shifts Calculated by DFT Methods and Geometrical Data for the Model Compounds"... 

Smith, S. G. Goodman, J. M. Assigning the stereochemistry of pairs of diastereoiso-mers using GIAO NMR shift calculation, J. Org. Chem. 2009, 74,4597-4607. 

The inclusion of aromatic guests in the hydrophobic pocket of the water-soluble calixarenes 7-9 (Fig. 11) was recently studied by H-NMR titration experiments in aqueous buffered solutions and molecular modeling studies combined with ab initio NMR shift calculations. ... 

Keywords silicon, cages, NMR spectroscopy. X-ray structures, NMR shift calculations... 

Fig. 3. Quantum chemical NMR shift calculations [HF/6-31G(d)//HF/6-311+G(2d,p), (GIAO method)] for acyclic compounds with a fixed CH2-Si-CH2 bond angle.

Table 4. Experimental NMR shifts, calculated deshieldings and calculated bond strength siuns at Na for crystalline silicates and aluminosilicates from Xue and Stebbins (1993). Deshieldings calculated using average Na-0 distances are given in parenlheses and those directly calculated from Na-centered clusters are given in bold (from Tossell 1999b).

Al NMR shifts calculated for various species, defined in terms of number of Al number of carboxylate and degree of protonation, were not consistent with the... 

QM MM/QM QM)-NMR Morokuma and co-workers have developed a layered approach to NMR shift calculations (ONIOM) where a higher level of theory (i.e. including electron correlation) is used for one part of the system which is combined with the shift calculation for the entire system at a lower level of theory.[65] Along similar lines, Qui and Karplus[66] have implemented a QM MM method to predict shifts in proteins. 

Figure 2-127. ChemDraw Ultra 7.0 can display eight different bond types. The H-NMR shift estimations for octamelhylcyclooctane are displayed in this example artificially the calculated spectrum is not shown here.

It has already been said that the merits of a method for charge calculation can be assessed mainly by its usefulness in modeling experimental data. Charges from the PEOE procedure have been correlated with Cls-ESCA shifts [28], dipole moments [33], and NMR shifts [34], to name but a few. 

Rotational equilibria of 2-carbonyl substituted thiophene and furan derivatives were calculated and show that the 2-substituent favors the anti-isomer in thiophene <96MI199>. NMR shifts of 35 alkyl 3-hydroxythiophene-2-carboxylates and 3-alkylamino-l-(3-thienyloxy)-2-propanols have been compiled and analyzed <96HC17>. 

NMR of solids is a very diverse collection of methods, and the practice of applying it to chemisorption is changing dramatically as a result of advances in theoretical chemistry including reliable chemical shift calculations. The wide application of NMR to solid state chemistry grew out of the revival of magic angle spinning in the mid 1970 s. This line... 

Spectra obtained by 1H NMR allowed the progress of the hydrogenolysis reaction to be followed quantitatively. The cyclopropyl protons in the polymer have an 1H NMR peak at 61.0 ppm, while the protons on the ring-opened, gem-dimethyl repeat unit (Equation A) have an XH NMR peak at 61.35 ppm. The gem-dimethyl peak assignment was based on chemical shift calculations (17). Also the dimethyl acetal of acetone has protons in a similar chemical environment to those on the gem-dimethyl ketal repeat unit and they have a chemical shift between 61.3 ppm and 61.A ppm (18). A proton NMR spectrum of partially hydrogenated polycyclopropanone is shown in Figure 7. 

Ga-Ga Distances, Force Constants, Charges, and NMR Shifts of the Calculated Model Compounds 8a, 8b, and 8c... 

Comparing the calculated NMR shifts to the observed signal of 11 shows that the methyl compound 11(11) comes closest to the experimentally observed signal of871Ga = -134 and therefore best matches the description of 11. 

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