Spectra and structure of small ring molecules. XLVII. Rotational and vibrational spectra and conformational stability of cyclobutylcarboxylic acid fluoride

1986 ◽  
Vol 85 (10) ◽  
pp. 5446-5456 ◽  
Author(s):  
J. R. Durig ◽  
H. M. Badawi ◽  
H. D. Bist ◽  
T. S. Little
Keyword(s):  
Vibrational Spectra ◽  
Conformational Stability ◽  
Small Ring ◽  
Acid Fluoride ◽  
Ring Molecules

Conformational stability, vibrational spectra and ab initio calculations for chloromethyl methyl silane and chloromethyl methyl difluorosilane

1999 ◽  
Vol 480-481 ◽  
pp. 147-151 ◽  
Author(s):  
Gamil A. Guirgis ◽  
Yasser E. Nashed ◽  
James B. Robb II ◽  
Peter Klaeboe ◽  
Pengqian Zhen ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Vibrational Spectra ◽  
Conformational Stability

Comparison of the Conformational Stability for Several Vinylhalomethanes and Silanes with Experiment Using MP2 Perturbation Theory and DFT

2007 ◽  
Vol 72 (1) ◽  
pp. 15-50 ◽  
Author(s):  
Wolfgang Förner ◽  
Hassan M. Badawi
Keyword(s):  
Experimental Data ◽  
Vibrational Spectra ◽  
Recent Literature ◽  
Conformational Stability ◽  
Basis Set ◽  
Major Conclusion ◽  
Stable Conformer ◽  
Polarization Functions ◽  
Complete Series ◽  
Triple Zeta

In recent literature it was reported that the valence triple zeta basis set augmented by polarization functions is not too reliable for vinyl monohalo- and dihalomethanes and -silanes, the halogen being fluorine and chlorine. The major conclusion was that a valence triple zeta basis is too small to be augmented by polarization functions in a balanced way, at least on vinylmonofluoromethane. Thus we decided to apply the 6-311++G** basis set to the complete series of methanes, silanes and germanes (the latter ones are just added for completeness because no experimental data are available for them and, moreover, we published them already previously) and to compare the results to experimental data available in the literature to see whether the failures of this basis set show up in the complete series of molecules. In the literature we found five such molecules and the information which of the conformers is the most stable. Indeed we found that predictions on the relative stability of conformers in those systems with this basis set and MP2 as well as DFT are with a 60:40 chance, three being correct predictions and two being incorrect ones out of the five. However, since the energy differences are rather small in these systems and due to the fact that - as a consequence of twofold degeneracy of the gauche conformer on the potential curve of the torsional vibration - the abundances of the conformers in equilibrium do not change too much, we decided to calculate also vibrational spectra for three examples and to compare them also to experiment. It is reported that besides the failures in total energy (we have chosen two examples where predictions of the nature of the stable conformer are correct, and one where it is not), the vibrational spectra are rather well reproduced, especially when experimental energies are used to calculate abundances in equilibrium in the case where the prediction of the stable conformer failed.

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