The Structure and Internal Dynamics of R6-p-C6H4-R6 Biradical: EPR, X-ray Crystallography and DFT Calculations


A purposefully synthesized nitroxide biradical R6-p-C6H4-R6 (B1), where R6 is the 1-oxyl-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine group with a relatively short distance between the two radical sites, has been studied by X-band electron paramagnetic resonance (EPR) spectroscopy. Hyperfine splitting (hfs) constants on the 14N atoms, electron spin exchange integral |J|, and the distance between the two N–O fragments rNO–NO were experimentally measured. Density functional theory, DFT, calculations were performed using the ORCA program package. The optimized geometry was compared with X-ray crystallographic data and theoretical hfs constants were compared with the respective experimental EPR values. It is concluded that the current quantum chemical approaches provide good results in calculating hfs constants as well as some other EPR parameters. It is confirmed that the intramolecular electron spin exchange in biradicals analogous to B1 is realized by the indirect mechanism rather than direct collision of the N–O· groups. It is also shown that one can calculate and predict values of |J| in other similar biradicals based on the principle of “attenuation coefficients.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9


  1. 1.

    A 1-oxyl-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine moiety is formed roughly by two planes: N1–C2–C3–C4–C5 (by IUPAC nomenclature) or N1–C6–C5–C4–C8 (X-ray pattern, Fig. 2) plane (colored in light gray in Fig. 9a), and N1–C5–C6 (by IUPAC nomenclature) or N1–C7–C8 (X-ray pattern, Fig. 2) plane (colored in dark gray in Fig. 9).


  1. 1.

    E.G. Rozantsev, Free Nitroxyl Radicals (Plenum Press, New York, 1970)

    Google Scholar 

  2. 2.

    V.N. Parmon, A.I. Kokorin, G.M. Zhidomirov, Stable Biradicals (Nauka, Moscow, 1980)

    Google Scholar 

  3. 3.

    E.G. Rozantsev, R.I. Zhdanov (eds.), Nitroxide Radicals. Synthesis, Chemistry, Applications (Nauka, Nauka, 1987)

    Google Scholar 

  4. 4.

    L.B. Volodarsky (ed.), Nitroxide. Synthesis, Properties, Applications, vol. 1, 2 (CRC Press, Boca Raton, 1988)

    Google Scholar 

  5. 5.

    A. Rassat, Pure Appl. Chern. 62, 223 (1990)

    Article  Google Scholar 

  6. 6.

    A.I. Kokorin, Appl. Magn. Reson. 26, 253 (2004)

    Article  Google Scholar 

  7. 7.

    M.T. Lemaire, Pure Appl. Chem. 76, 277 (2004)

    Article  Google Scholar 

  8. 8.

    M. Baumgarten, in: World Scientific Reference on Spin in Organics, vol. 4, ed. by J.S. Miller (World Scientific Publishing Co Pte Ltd., Singapore, 2017), pp. 1–93

    Google Scholar 

  9. 9.

    M. Abe, Chem. Rev. 113, 7011 (2013)

    Article  Google Scholar 

  10. 10.

    A.B. Shapiro, M.G. Goldfield, E.G. Rozantsev, Tetrahedron Lett. 14, 2183 (1973)

    Article  Google Scholar 

  11. 11.

    V.V. Pavlikov, A.B. Shapiro, E.G. Rozantsev, Izv. AN SSSR, Ser. Khim. No. 1, 128 (1980)

  12. 12.

    V.V. Pavlikov, V.V. Muraviev, A.B. Shapiro, Izv. AN SSSR, Ser. Khim. No. 5, 1200 (1980)

  13. 13.

    S. Torii, T. Hase, M. Kuroboshi, C. Amatore, A. Jutand, H. Kawafuchi, Tetrahedron Lett. 38, 7391 (1997)

    Article  Google Scholar 

  14. 14.

    E.G. Rozantsev, O.A. Ozhogina, R.R. Rakhimov, A.I. Prokof’ev, Mol. Phys. 76, 1009 (1992)

    ADS  Article  Google Scholar 

  15. 15.

    A.I. Kokorin, V.V. Pavlikov, A.B. Shapiro, Proc. Acad. Sci. USSR, Doklady Phys. Chem. 253, 147 (1980)

    Google Scholar 

  16. 16.

    A.B. Shapiro, V.N. Parmon, V.V. Pavlikov, V.I. Rubtsov, E.G. Rozantsev, Izv. AN SSSR, Ser. Khim. No. 2, 449 (1980)

  17. 17.

    A.I. Kokorin, V.A. Tran, K. Rasmussen, G. Grampp, Appl. Magn. Reson. 30, 35 (2006)

    Article  Google Scholar 

  18. 18.

    V.A. Tran, A.I. Kokorin, G. Grampp, K. Rasmussen, Appl. Magn. Reson. 35, 389 (2009)

    Article  Google Scholar 

  19. 19.

    A.I. Kokorin, E.N. Golubeva, B. Mladenova, V.A. Tran, T. Kalai, K. Hideg, G. Grampp, Appl. Magn. Reson. 44, 1041 (2013)

    Article  Google Scholar 

  20. 20.

    A.I. Kokorin, S. Landgraf, A.B. Shapiro, G. Grampp, Appl. Magn. Reson. 45, 125 (2014)

    Article  Google Scholar 

  21. 21.

    O.I. Gromov, E.N. Golubeva, V.N. Khrustalev, T. Kálai, K. Hideg, A.I. Kokorin, Appl. Magn. Reson. 45, 981 (2014)

    Article  Google Scholar 

  22. 22.

    A.I. Kokorin, O.I. Gromov, T. Kálai, K. Hideg, Appl. Magn. Reson. 47, 1283 (2016)

    Article  Google Scholar 

  23. 23.

    A.I. Kokorin, R.B. Zaripov, O.I. Gromov, A.A. Sukhanov, T. Kálai, E. Lamperth, K. Hideg, Appl. Magn. Reson. 47, 1057 (2016)

    Article  Google Scholar 

  24. 24.

    A.I. Kokorin, R.B. Zaripov, O.I. Gromov, K. Hideg, T. Kálai, Appl. Magn. Reson. 49, 137 (2018)

    Article  Google Scholar 

  25. 25.

    T. Kálai, J. Jekő, Z. Berente, K. Hideg, Synthesis 38, 439 (2006)

    Google Scholar 

  26. 26.

    J.A. Riddick, W.B. Bunger, K.T. Sakano, in: Techniques of Chemistry. Vol. II: Organic Solvents, Physical Chemistry and Methods of Purification (Wiley, New York, 1986). p. 785

  27. 27.

    Yu.N. Molin, K.M. Salikhov, K.I. Zamaraev, Spin Exchange (Springer, Berlin, 1980)

    Google Scholar 

  28. 28.

    A.I. Kokorin, V.N. Parmon, A.A. Shubin, Atlas of Anisotropic EPR Spectra of Nitroxide Biradicals (Nauka, Moscow, 1984)

    Google Scholar 

  29. 29.

    S.H. Glarum, J.H. Marshall, J. Chem. Phys. 47, 1374 (1967)

    ADS  Article  Google Scholar 

  30. 30.

    H. Lemaire, J. Chim. Phys. 64, 559 (1967)

    Article  Google Scholar 

  31. 31.

    V.N. Parmon, G.M. Zhidomirov, Mol. Phys. 27, 367 (1974)

    ADS  Article  Google Scholar 

  32. 32.

    Ya.S. Lebedev, O.Ya. Grinberg, A.A. Dubinsky, O.G. Poluektov, in Bioactive Spin Labels, ed. by R.I. Zhdanov (Springer, Berlin, 1992), pp. 228–254

    Google Scholar 

  33. 33.

    T.G.G. Battye, L. Kontogiannis, O. Johnson, H.R. Powell, A.G.W. Leslie, Acta Cryst. D67, 271 (2011)

    Google Scholar 

  34. 34.

    P.R. Evans, Acta Cryst. D62, 72 (2006)

    Google Scholar 

  35. 35.

    G.M. Sheldrick, Acta Cryst. C71, 3 (2015)

    Google Scholar 

  36. 36.

    T.H. Dunning Jr., J. Chem. Phys. 90, 1007 (1989)

    ADS  Article  Google Scholar 

  37. 37.

    F. Neese, J. Chem. Phys. 127, 164112 (2007)

    ADS  Article  Google Scholar 

  38. 38.

    V. Barone, P. Cimino, E. Stendardo, J. Chem. Theory Comput. 4, 751 (2008)

    Article  Google Scholar 

  39. 39.

    F. Neese, Software Update: The ORCA Program System, Version 4.0, Wiley Interdiscip. Rev. Comput. Mol. Sci. e1327, IF 8.836 (2017).

  40. 40.

    V.E. Shklover, I.A. Zamaev, YuT Struchkov, T.V. Medvedeva, YuV Korshak, A.A. Ovchinnikov, V.N. Spector, Z. Kristallogr. 191, 9 (1990)

    Article  Google Scholar 

  41. 41.

    V.A. Igonin, V.E. Shklover, YuT Struchkov, O.L. Lazareva, G.A. Vinogradov, Acta Cryst. C46, 776 (1990)

    Google Scholar 

  42. 42.

    D.W. Wiley, J.C. Calabrese, R.L. Harlow, J.S. Miller, Angew. Chem. 30, 450 (1991)

    Article  Google Scholar 

  43. 43.

    J.W. Bats, O. Frolow, J.W. Engels, Acta Cryst. E65, o529 (2009)

    Google Scholar 

  44. 44.

    A.V. Bogdanov, AKh Vorobiev, PhysChemChemPhys. 18, 31144 (2016)

    Google Scholar 

  45. 45.

    V. Sadovnichy, A. Tikhonravov, Vl. Voevodin, V. Opanasenko, in Contemporary High Performance Computing: From Petascale toward Exascale (Chapman & Hall/CRC Computational Science, CRC Press, Boca Raton, USA, 2013), pp. 283–307

    Google Scholar 

Download references


This work was supported in part by the RUDN University Program “5-100”. Synchrotron radiation-based single-crystal X-ray diffraction measurements were performed at the unique scientific facility Kurchatov Synchrotron Radiation Source supported by the Ministry of Education and Science of the Russian Federation (project code RFMEFI61917X0007). The study was also supported in part by Russian Foundation for Basic Research (Grant No 18-33-00866-mol-a), the Supercomputing Center of M. V. Lomonosov Moscow State University [45], and through the Program of Fundamental Research of the Presidium of RAS (No. 1.26П). The work was supported in part by Hungarian National Research Development and Innovation Office (OTKA FK 124331). AIK thanks Dr. A. A. Shubin (Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk) who provided us with his computer program package of EPR spectra simulation.

Author information



Corresponding author

Correspondence to A. I. Kokorin.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kokorin, A.I., Gromov, O.I., Dorovatovskii, P.V. et al. The Structure and Internal Dynamics of R6-p-C6H4-R6 Biradical: EPR, X-ray Crystallography and DFT Calculations. Appl Magn Reson 50, 425–439 (2019).

Download citation