Preview

Fine Chemical Technologies

Advanced search

Dynamics of hindered CF3-rotor in 2,5-bis (trifl uoromethyl )-nitroben zene radical -anion in anhydro us DMF. A temperature - activation theory of reversible HFS transformations of EPR spectrum

https://doi.org/10.32362/2410-6593-2016-11-3-31-38

Full Text:

Abstract

The temperature dependence of EPR spectrum of 2,5-bis(trifluoromethyl)nitrobenzene radical anion in anhydrous DMF was investigated. Internal dynamics of hindered rotation of the CF3-group in ortho-position to NO2-group causes HFS modulation. The spectrum changes are reversible and temperature-dependent. An original temperature-activation representation of complex spectral density was proposed instead of the traditional spectral-kinetics representation to explain the observed transformation. The change resulted in a new convenient phenomenological reconstruction model, which allowed simulating the spectra in the whole temperature range. Splitting constants and contributions to the spectral widths of the spectral lines were found. The activation energy of the CF3-group hindered rotation is significant and amounts to 37 kJ/mol.

About the Authors

E. A. Polenov
Moscow Technological University (Institute of Fine Chemical Technologies)
Russian Federation
Moscow, 119571 Russia


P. V. Melnikov
Moscow Technological University (Institute of Fine Chemical Technologies)
Russian Federation
Moscow, 119571 Russia


References

1. Polenov E.A., Bozhenko K.V., Shundrin L.A., Smekalkin D.M. // Bull. Rus. Acad. Sci.: Physics. 2004. V. 68. № 7. P. 1206.

2. Smekalkin D.M., Novosadov B.K., Polenov E.A. // Vestnik MITKHT. 2007. V. 2. № 5. P. 21–27. (in Russ.)

3. Polenov E.A., Melnikov P.V., Shundrin L.A., Bozhenko K.V. // Bull. Rus. Acad. Sci.: Physics. 2006. V. 70. № 8. P. 1268–1273.

4. Polenov E.A., Shundrin L.A., Melnikov P.V. // Rus. Chem. Bull. 2006. V. 55. № 6. P. 961–967.

5. Polenov E.A., Melnikov P.V., Platonov D.V., Shundrin L.A. // J. Struct. Chem. 2007. V. 48. № 2. P. 245–252.

6. Shundrin L.A., Melnikov P.V., Polenov E.A. // J. Struct. Chem. 2010. V. 50. № 6. P. 1071–1081.

7. Janzen E.G., Gerlock J.L // J. Am. Chem. Soc. 1967. V. 89. № 19. P. 4902–4910.

8. Rogers J.W., Watson W.H. // J. Phys. Chem. 1968. V. 72. № 1. P. 68–74.

9. Melnikov P.V., Polenov E.A. Analizator spektrov. Rekonstrukcija: Gosudarstvennaja registracija programmy dlja JeVM [Spectra analyzer. Reconstruction. State registration of the computer program] № 2014610483. Date 10.01.2014. (in Russ.)


For citation:


Polenov E.A., Melnikov P.V. Dynamics of hindered CF3-rotor in 2,5-bis (trifl uoromethyl )-nitroben zene radical -anion in anhydro us DMF. A temperature - activation theory of reversible HFS transformations of EPR spectrum. Fine Chemical Technologies. 2016;11(3):31-38. https://doi.org/10.32362/2410-6593-2016-11-3-31-38

Views: 120


ISSN 2410-6593 (Print)
ISSN 2686-7575 (Online)