The Molecular Structure and Tautomer Equilibrium of Gaseous 1,2,3-Triazole Studied by Microwave Spectroscopy, Electron Diffraction and Ab Initio Calculations.

Begtrup, Mikael; Nielsen, Claus J.; Nygaard, Lise; Samdal, Svein; Sjøgren, Carl E.; Sørensen, Georg; Khan, S. I.; Vilkov, L. V.; Rypdal, Kristian

doi:10.3891/acta.chem.scand.42a-0500

Cited by 70 publications

(46 citation statements)

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“…In terms of tautomerism between neutral species, 1b is 17.5 kJ mol Ϫ1 more stable than 1a. Other theoretical calculations have arrived at the same conclusion: 20.5 (HF/6-31G*), [33] 14.7 (HF/ DZ), [37] 19.7 (HF/6-31G**//HF/6-31G*), [34] 14.8 (MP2/6- [38] 20.9 kJ mol Ϫ1 (MP2/6-31G*). [39,40] The case of phenyl-v-triazole 4 had not been studied previously.…”

Section: Equilibria Involved and Theoretical Considerationsmentioning

confidence: 59%

Basicity of N-H- and N-Methyl-1,2,3-triazoles in the Gas Phase, in Solution, and in the Solid State − An Experimental and Theoretical Study

et al. 2001

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Keywords: Ab initio calculations / Crystal structure / FT-ICR basicity / Tautomerism / 1,2,3-TriazolesThe gas-phase and aqueous basicities of six 1,2,3-triazoles have been determined, the former by FT-ICR and the latter by spectrophotometry and 1 H NMR. The gas-phase experiments agree very well with the Gibbs free energies calculated at the B3LYP/6-31G* level. In contrast, only semiquantitative ascertainments are possible when basicities in the gas phase and in solution are compared. It is possible, with the aid of calculations, to obtain a complete picture of the complex equilibria involved in C-substituted N-H-1,2,3-tria-

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Section: Equilibria Involved and Theoretical Considerationsmentioning

confidence: 59%

Basicity of N-H- and N-Methyl-1,2,3-triazoles in the Gas Phase, in Solution, and in the Solid State − An Experimental and Theoretical Study

et al. 2001

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“…25 The ratio of 2H:1H was determined to be approximately 1000:1. 24,25 This predominance of the 2H form was supported by the UPS comparison 26,27 of the tautomeric mixture with the "blocked" pair of N-methyl compounds (Fig. 1, compounds 1Me and 2Me).…”

Section: A Structural Issuesmentioning

confidence: 99%

“…An early ultraviolet photoelectron spectroscopy (UPS) study 23 adopted the structure of the 1H form, which at that time was the only tautomer known. Both the 1H and 2H tautomers were later identified in the gas phase by microwave spectroscopy 24,25 and the 2H tautomer by electron diffraction. 25 The ratio of 2H:1H was determined to be approximately 1000:1.…”

Section: A Structural Issuesmentioning

confidence: 99%

“…Both the 1H and 2H tautomers were later identified in the gas phase by microwave spectroscopy 24,25 and the 2H tautomer by electron diffraction. 25 The ratio of 2H:1H was determined to be approximately 1000:1. 24,25 This predominance of the 2H form was supported by the UPS comparison 26,27 of the tautomeric mixture with the "blocked" pair of N-methyl compounds (Fig.…”

Section: A Structural Issuesmentioning

confidence: 99%

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The electronic states of 1,2,3-triazole studied by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy, and a comparison with ab initio configuration interaction methods

Palmer¹,

Hoffmann

Jones

et al. 2011

The Journal of Chemical Physics

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The electronic states of 1,2,3-triazole studied by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy, and a comparison with ab initio configuration interaction methods Citation for published version:Palmer, MH, Hoffmann, SV, Jones, NC, Head, AR & Lichtenberger, DL 2011, 'The electronic states of 1,2,3-triazole studied by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy, and a comparison with ab initio configuration interaction methods' The Journal of Chemical Physics, vol. 134 General rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately and investigate your claim.

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“…Experimental results concerning the tautomerism of 1,2,3-triazole are controversial. Early gas phase IR spectra were interpreted in terms of a predominance of the 1 H-tautomer 4 a [39], Based on more recent gas phase experiments [22,23,32,40], however, there seems now consensus that 2H-triazole 4 b is greatly favoured in the gas phase. Especially, from intensity measurements of microwave spectra at room temperature a tautomeric ratio 4 a: 4 b «1:1000, corresponding to A G % 4.0 kcal mol -1 was estimated [32].…”

Section: Tautomerization Energiesmentioning

confidence: 99%

Tautomerism in Five-membered Nitrogen Heterocycles. A Test of the Reliability of Semiempirical (AMI, PM3, MNDO) Quantum Chemical Methods

Fabian

1990

Zeitschrift Für Naturforschung A

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The reliability of three popular semiempirical quantum chemical methods (AMI, PM3, MNDO) for the treatment of tautomeric equilibria is tested in a series of five-membered nitrogen heterocycles. The known flaw of MNDO to overestimate the stability of compounds with two or more adjacent pyridine-like lone pairs is also present in AMI and to a somewhat lesser extent in PM3. Tautomeric species differing in the number of adjacent pyridine-like lone pairs, thus, cannot be adequately treated by these semiempirical methods. Both AMI as well as PM3, however, represent major improvements over MNDO in the case of lactam-lactim tautomerism. The stability of N-oxides as compared to N-hydroxy tautomers seems to be overestimated by the PM3 method. All three semiempirical methods yield quite reliable ionization potentials and dipole moments.

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The Molecular Structure and Tautomer Equilibrium of Gaseous 1,2,3-Triazole Studied by Microwave Spectroscopy, Electron Diffraction and Ab Initio Calculations.

Cited by 70 publications

References 0 publications

Basicity of N-H- and N-Methyl-1,2,3-triazoles in the Gas Phase, in Solution, and in the Solid State − An Experimental and Theoretical Study

Basicity of N-H- and N-Methyl-1,2,3-triazoles in the Gas Phase, in Solution, and in the Solid State − An Experimental and Theoretical Study

The electronic states of 1,2,3-triazole studied by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy, and a comparison with ab initio configuration interaction methods

Tautomerism in Five-membered Nitrogen Heterocycles. A Test of the Reliability of Semiempirical (AMI, PM3, MNDO) Quantum Chemical Methods

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