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Issue 3, 2021
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Reversible dissociation of singly-bonded (C60)2 dimers in (MV˙+)2(C60)2·solvent salt containing paramagnetic methyl viologen MV˙+ radical cations

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Abstract

Methyl viologen (MV2+)(Cl)2 is reduced by cesium anthracene to form neutral MV0 whose interaction with C60 produces (MV˙+)2(C60)2·2.5C6H4Cl2·0.5C6H6 (1). X-ray diffraction analysis shows that C60˙ radical anions form singly-bonded (C60)2 dimers at 100 K and are arranged in zig-zag layers. According to EPR, the dimers dissociate in the 235–375 K range. Salt 1 contains two paramagnetic MV˙+ and C60˙ species in the monomeric phase with strong exchange interaction. This interaction is switched off at the dimerization of C60˙ and magnetically isolated MV˙+ pairs are formed. Spins of MV˙+ are strongly antiferromagnetically coupled in the pairs with the Weiss temperature of −32 K and J/kB = −20 K. MV˙+ shows narrow EPR signal with g = 2.0039 and the linewidth of about 0.2 mT (T <100 K). A plot of natural logarithm of the dimerization constant vs. reverse temperature (at 235–375 K) allows the estimation of the energy of single C–C bonds in the (C60)2 dimers as 38.2 ± 0.8 kJ mol−1.

Graphical abstract: Reversible dissociation of singly-bonded (C60−)2 dimers in (MV˙+)2(C60−)2·solvent salt containing paramagnetic methyl viologen MV˙+ radical cations

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Article information


Submitted
15 Oct 2020
Accepted
12 Nov 2020
First published
07 Dec 2020

New J. Chem., 2021,45, 1163-1167
Article type
Communication

Reversible dissociation of singly-bonded (C60)2 dimers in (MV˙+)2(C60)2·solvent salt containing paramagnetic methyl viologen MV˙+ radical cations

D. V. Konarev, S. S. Khasanov, O. A. Obraztsov, A. Otsuka, H. Yamochi, H. Kitagawa and R. N. Lyubovskaya, New J. Chem., 2021, 45, 1163
DOI: 10.1039/D0NJ05076H

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