GIAO-HF/DFT calculation of13C and15N chemical shifts for studying tautomerism and intramolecular hydrogen bonding in 2,3-disubstituted quinoxalines

Kleinpeter, Erich; Hilfert, Liane; Koch, Andreas

doi:10.1002/1099-1395(200008)13:8<473::aid-poc260>3.0.co;2-e

Cited by 7 publications

(1 citation statement)

References 16 publications

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“…As a result of increasing computer power and software implementations, the ab initio computation of chemical shifts is becoming increasingly common. 1,[3][4][5][6][7][8][9][10][11][12][13][14] With the technique becoming commonly used, it is important to know which methods perform well and which methods perform poorly. Much work has been done to show that shifts can be accurately calculated using very high levels of theory.…”

Section: Introductionmentioning

confidence: 99%

A hybrid quantum mechanical and empirical model for the prediction of isotropic¹³C shielding constants of organic molecules

Giesen

Zumbulyadis

2002

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 99%

A hybrid quantum mechanical and empirical model for the prediction of isotropic¹³C shielding constants of organic molecules

Giesen

Zumbulyadis

2002

Phys. Chem. Chem. Phys.

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NMR Spectroscopic Study of Tautomerism in Solution and in the Solid State

Kleinpeter

2013

Tautomerism

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Tautomerism in 4‐substituted 1‐phenyl‐3‐methyl‐pyrazolin‐5‐ones—a theoretical ab initio and ¹³C NMR study

Kleinpeter

Koch

2001

J of Physical Organic Chem

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The tautomeric equilibria between the CH, OH and NH forms in a series of 4‐substituted 1‐phenyl‐3‐methyl‐pyrazolin‐5‐ones have been studied using ab initio calculations at various levels of theory and comparison made with the experimental results obtained from NMR measurements. Quantitative comparison of both the relative energies and the 13C chemical shifts of the tautomers constituting the tautomeric equilibria were made by calculation of both sets of parameters. The influence of the solvent was included by employing various models of the self‐consistent reaction field theory. Initially, the solvent was included in the calculations by applying a continuum of differing polarity over the surface of isolated tautomers (self‐consistent isodensity polarized continuum model method), then later by assuming formation of an adduct between the solute and the solvent (thereby simulating effectively the hydrogen bonding in the OH and NH tautomers) and finally by calculating dimer or trimer complexes of the various tautomers. In this manner, the agreement between the theoretically calculated and the experimentally determined tautomeric equilibria was improved significantly. The theoretically calculated 13C chemical shifts of the tautomers were found to be viable for the assignment of the tautomers, particularly the preferred tautomer in the OH/NH equilibrium, which remains fast on the NMR time scale even at low temperatures. Copyright © 2001 John Wiley & Sons, Ltd.

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GIAO-HF/DFT calculation of13C and15N chemical shifts for studying tautomerism and intramolecular hydrogen bonding in 2,3-disubstituted quinoxalines

Cited by 7 publications

References 16 publications

A hybrid quantum mechanical and empirical model for the prediction of isotropic¹³C shielding constants of organic molecules

A hybrid quantum mechanical and empirical model for the prediction of isotropic¹³C shielding constants of organic molecules

NMR Spectroscopic Study of Tautomerism in Solution and in the Solid State

Tautomerism in 4‐substituted 1‐phenyl‐3‐methyl‐pyrazolin‐5‐ones—a theoretical ab initio and ¹³C NMR study

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GIAO-HF/DFT calculation of13C and15N chemical shifts for studying tautomerism and intramolecular hydrogen bonding in 2,3-disubstituted quinoxalines

Cited by 7 publications

References 16 publications

A hybrid quantum mechanical and empirical model for the prediction of isotropic13C shielding constants of organic molecules

A hybrid quantum mechanical and empirical model for the prediction of isotropic13C shielding constants of organic molecules

NMR Spectroscopic Study of Tautomerism in Solution and in the Solid State

Tautomerism in 4‐substituted 1‐phenyl‐3‐methyl‐pyrazolin‐5‐ones—a theoretical ab initio and 13C NMR study

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Product

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A hybrid quantum mechanical and empirical model for the prediction of isotropic¹³C shielding constants of organic molecules

A hybrid quantum mechanical and empirical model for the prediction of isotropic¹³C shielding constants of organic molecules

Tautomerism in 4‐substituted 1‐phenyl‐3‐methyl‐pyrazolin‐5‐ones—a theoretical ab initio and ¹³C NMR study