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Shiotani, Masaru
Publications (4 of 4) Show all publications
Shiotani, M., Lund, A., Lunell, S. & Williams, F. (2007). Structures of the hexafluorocyclopropane, octafluorocyclobutane, and decafluorocyclopentane radical anions probed by experimental and computational studies of anisotropic electron spin resonance (ESR) spectra. Journal of Physical Chemistry A, 111(2), 321-338
Open this publication in new window or tab >>Structures of the hexafluorocyclopropane, octafluorocyclobutane, and decafluorocyclopentane radical anions probed by experimental and computational studies of anisotropic electron spin resonance (ESR) spectra
2007 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, no 2, p. 321-338Article in journal (Refereed) Published
Abstract [en]

Anisotropic electron spin resonance (ESR) spectra are reported for the radical anions of hexafluorocyclopropane (c-C3F6-), octafluorocyclobutane (c-C4F8-), and decafluorocyclopentane (c-C5F10-) generated via gamma-irradiation in plastically crystalline tetramethylsilane (TMS) and rigid 2-methyltetrahydrofuran (MTHF) matrices. By combining the analysis of these experimental ESR spectra involving anisotropic hyperfine (hf) couplings with a series of quantum chemical computations, the geometrical and electronic structure of these unusual perfluorocycloalkane radical anions have been characterized more fully than in previous studies that considered only the isotropic couplings. Unrestricted Hartree-Fock (UHF) computations with the 6-311+G(d,p) basis set predict planar ring structures for all three radical anions, the ground electronic states being (2)A(2)" for c-C3F6- (D-3h symmetry), (2)A(2u) for c-C4F8- (D-4h), and (2)A(2)" for c-C5F10- (D-5h), in which the respective six, eight, and ten F-19-atoms are equivalent by symmetry. A successful test of the theoretical computation is indicated by the fact that the isotropic F-19 hf couplings computed by the B3LYP method with the 6-311+G(2df,p) basis set for the optimized geometries are in almost perfect agreement with the experimental values: viz., 19.8 mT (exp) vs 19.78 mT (calc) for c-C3F6-; 14.85 mT (exp) vs 14.84 mT (calc) for c-C4F8-; 11.6 mT (exp) vs 11.65 mT (calc) for c-C5F10-. Consequently, the same computation method has been applied to calculate the almost axially symmetric anisotropic F-19 hf couplings for the magnetically equivalent F-19 atoms: (-4.90 mT, -4.84 mT, 9.75 mT) for c-C3F6-, (-3.54 mT, -3.48 mT, 7.02 mT) for c-C4F8-, and (-2.62 mT, -2.56 mT, 5.18 mT) for c-C5F10-. ESR spectral simulations performed using the computed principal values of the hf couplings and the spatial orientations of the F-19 nuclei as input parameters reveal an excellent fit to the experimental anisotropic ESR spectra of c-C3F6-, c-C4F8-, and c-C5F10-, thereby providing a convincing proof of the highly symmetric D-nh structures that are predicted for these negative ions. Furthermore, using the computed F-19 principal values and their orientations, the effective F-19 anisotropic hf couplings along the molecular symmetry axes were evaluated for c-C3F6- and c-C4F8- and successfully correlated with the positions of the characteristic outermost features in both the experimental and calculated anisotropic spectra. In addition, the electronic excitation energies and oscillator strengths for the c-C3F6-, c-C4F8-, and c-C5F10- radical anions were computed for the first time using time-dependent density functional theory (TD-DFT) methods.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-25008 (URN)10.1021/jp064891u (DOI)000243388500018 ()
Available from: 2007-02-08 Created: 2007-02-08 Last updated: 2017-12-07Bibliographically approved
Komaguchi, K., Nomura, K., Shiotani, M., Lund, A., Jansson, M. & Lunell, S. (2006). ESR and theoretical studies of trimer radical cations of coronene. Spectrochimica Acta A, 63, 76
Open this publication in new window or tab >>ESR and theoretical studies of trimer radical cations of coronene
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2006 (Swedish)In: Spectrochimica Acta A, Vol. 63, p. 76-Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-24799 (URN)
Available from: 2007-02-07 Created: 2007-02-07 Last updated: 2011-01-11
Shiotani, M., Persson, P., Lunell, S., Lund, A. & Williams, F. (2006). Structures of Tetrafluorocyclopropene, Hexafluorocyclobutene, Octafluorocyclopentene and Related Perfluoroalkene Radical Anions Revealed by ESR Spectroscopic and Computational Studies. Journal of Physical Chemistry A, 110, 6307
Open this publication in new window or tab >>Structures of Tetrafluorocyclopropene, Hexafluorocyclobutene, Octafluorocyclopentene and Related Perfluoroalkene Radical Anions Revealed by ESR Spectroscopic and Computational Studies
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2006 (English)In: Journal of Physical Chemistry A, Vol. 110, p. 6307-Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-24802 (URN)
Available from: 2007-02-07 Created: 2007-02-07 Last updated: 2011-01-11
Komaguchi, K., Norberg, D., Nakazawa, N., Shiotani, M., Persson, P. & Lunell, S. (2005). Direct ESR evidence for SH2 type reaction of methyl radical with methylsilane and methylgermane in a low temperature solid: A deuterium labeling study. Chemical Physics Letters, 410(1-3), 1-5
Open this publication in new window or tab >>Direct ESR evidence for SH2 type reaction of methyl radical with methylsilane and methylgermane in a low temperature solid: A deuterium labeling study
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2005 (English)In: Chemical Physics Letters, Vol. 410, no 1-3, p. 1-5Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-73838 (URN)doi:10.1016/j.cplett.2005.04.091 (DOI)
Available from: 2007-08-06 Created: 2007-08-06 Last updated: 2011-01-11
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