Electrochemically Induced Dimerization of p⁹mp-C₇₀(CF₃)₁₂ Trifluoromethylated Fullerene

Abstract

We report a comprehensive study of a novel isomer of C 70 (CF 3 ) 12 , p 9 mp-C 70 (CF 3 ) 12 , whose electrochemical behavior differs from most of the other trifluoromethylated fullerenes. The addition pattern of p 9 mp-C 70 (CF 3 ) 12 is established by means of 19 F− 19 F COSY NMR spectroscopy and DFT calculations. Like p 7 mp-C 70 (CF 3 ) 10 , the new isomer p 9 mp-C 70 (CF 3 ) 12 undergoes dimerization to the [C 70 (CF 3 ) 12 ] 2 2− upon single-electron reduction. The electrochemical observations are supported by the DFT calculations of dimerization energy and the temperature dependence of the CW X-band EPR spectroscopy data. Experimentally determined dimerization energies of p 9 mp-C 70 (CF 3 ) 12 −• and p 7 mp-C 70 (CF 3 ) 10 −• in solution are ca −8 and −26 kJ mol −1 , respectively, in good correspondence with DFT data.

Reversibly switchable methanofullerene by photoexcitation and reduction

“…The ESR spectrum of initial C s -C 70 (CF 3 ) 8 demonstrates the only unfeatured singlet with a 0.9 AE 0.2 G linewidth and the same g-factor. 17 In the unmodified C 70 (CF 3 ) n molecules, splitting of comparable magnitude is due to the fluorine atoms, correlated with the distance from the respective CF 3 groups to the [5,6]-bond. 17 The rapid rotation of the symmetrypaired CF 3 groups in C 70 (CF 3 ) 8 [DPM] À should produce septet subpatterns, not apparently visible due to the complexity of the spectrum.…”

“…17 In the unmodified C 70 (CF 3 ) n molecules, splitting of comparable magnitude is due to the fluorine atoms, correlated with the distance from the respective CF 3 groups to the [5,6]-bond. 17 The rapid rotation of the symmetrypaired CF 3 groups in C 70 (CF 3 ) 8 [DPM] À should produce septet subpatterns, not apparently visible due to the complexity of the spectrum. The phenyl protons in DPM can give rise to hyperfine interactions as well.…”