scholarly journals Conformation analysis of three germacranolides by the PM3 semi-empirical method

2003 ◽  
Vol 68 (4-5) ◽  
pp. 281-289 ◽  
Author(s):  
Slobodan Milosavljevic ◽  
Ivan Juranic ◽  
Ivana Aljancic ◽  
Vlatka Vajs ◽  
Nina Todorovic
Keyword(s):  
Low Temperature ◽  
Quantum Chemical Calculations ◽  
1H Nmr ◽  
Quantum Chemical ◽  
Nmr Spectra ◽  
Sesquiterpene Lactones ◽  
Empirical Method ◽  
Conformation Analysis ◽  
Karplus Equation ◽  
Semi Empirical

The conformations of the C-6 lactonized germacranolides 1?3 were calculated by applying the PM3 semi-empirical method. The low-temperature 1H-NMR spectra of parthenolide (1) were also measured. The relations between the calculated and the experimentally determined geometries were established using a modified Karplus equation. The applied quantum-chemical calculations proved to be an efficient and easy-to-use tool for the elucidation and prediction of the properties of germacranolide-type sesquiterpene lactones.

Conformational study of blocked pentofuranoses and their 1,5-anhydro derivatives by 1H NMR spectroscopy

1984 ◽  
Vol 49 (1) ◽  
pp. 235-243
Author(s):  
Jaroslav Zajíček ◽  
Miloš Buděšínský ◽  
Jiří Farkaš
Keyword(s):  
Spectral Analysis ◽  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
1H Nmr ◽  
Quantum Chemical ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Conformational Study ◽  
H Nmr

Preferred conformations of the furanose ring and conformer population about the C(5)-C(4) bond in a series of benzoylated pentofuranosyl cyanides have been determined from their 1H NMR spectra. For the 1,5-anhydropentofuranose derivatives the results of the 1H NMR spectral analysis have been compared with the quantum chemical calculations.

Molecular Screening in Helium Molecular Ion

1971 ◽  
Vol 49 (20) ◽  
pp. 3406-3408 ◽  
Author(s):  
C. M. Wang ◽  
B. Musulin
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Empirical Method ◽  
Molecular Screening ◽  
Energy Calculations ◽  
Molecular Ion ◽  
Semi Empirical ◽  
Orbital Exponents

Variational energy calculations for He2+ were performed and the results were used to evaluate a semi-empirical method for choosing orbital exponents in quantum chemical calculations.

Can fluorosyl hydride be formed or even prepared?

1990 ◽  
Vol 55 (4) ◽  
pp. 890-895
Author(s):  
Rudolf Zahradník ◽  
B. Andes Hess
Keyword(s):  
Low Temperature ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Solid Matrix ◽  
Vibrational Characteristics ◽  
Very Low Temperature

HFO and HClO (fluorosyl and chlorosyl hydrides) and isomeric molecules HOF and HOCl (hypofluorous and hypochlorous acids) have been studied theoretically. On the basis of nonempiracal quantum chemical calculations (MP2, MP4 and CCD/6-311G**) geometry, energy and vibrational characteristics are analyzed and it is concluded that there is a poor chance to observe formation of HFO. Possibly, bombardment of HF in a solid matrix by 16O could lead at very low temperature to HFO.

scholarly journals Conformational properties of 1-cyano-1-silacyclohexane, C5H10SiHCN: Gas electron diffraction, low-temperature NMR and quantum chemical calculations

2017 ◽  
Vol 1132 ◽  
pp. 149-156 ◽  
Author(s):  
Alexander V. Belyakov ◽  
Yrii F. Sigolaev ◽  
Sergey A. Shlykov ◽  
Sunna Ó. Wallevik ◽  
Nanna R. Jonsdottir ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Low Temperature ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Gas Electron Diffraction ◽  
Conformational Properties
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