ESR studies of paramagnetic derivatives of C{sub 60}

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:143989

Krusic, P J; Wasserman, E ^[1]; Morton, J R; Preston, K F ^[2]

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1. Du Pont Company, Wilmington, DE (United States)
2. National Research Council of Canada, Ottawa, Ontario, (Canada)

Alkyl radicals add readily to C{sub 60} to afford mixtures of diamagnetic and paramagnetic derivatives R{sub n}C{sub 60}. The information obtained by electron spin resonance for the radical adducts with n = 1, 3 and 5 will be discussed. In the monoalkyl adducts RC{sub 60}{sup {sm_bullet}} (R =(CH{sub 3}){sub 3}C, (CH{sub 3}){sub 2}CH, CH{sub 3}, CH{sub 2}, CH{sub 3} C{sub 6}H{sub 5}CH{sub 2} etc) the unpaired electron is mostly confined to two fused six-membered rings on the surface of C{sub 60} having the substituent R at one of the points of fusion. Rotation about the bond connecting the alkyl substituent to C{sub 60} is strongly hindered so that the substituents adopt preferred conformations relative to the C{sub 60} framework. An analysis of the temperature dependent shape of the spectrum of the tert-butyl adduct yielded an activation energy for internal rotation of 8.2 kcal/mol. The monoalkyl radical adducts exist in equilibrium with their diamagnetic dumbbell-shaped dimers RC{sub 60}-C{sub 60}R. The strength of the bond uniting the two halves of the dimer depends strongly on the size of R. A structure for the dimers consistent with the ESR data is proposed. The ESR spectra of the radical adducts with n = 3 and 5 will also be discussed.

• OSTI ID: 143989
• Report Number(s): CONF-930304--
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
ADDUCTS
ALKYL RADICALS
CHEMICAL REACTIONS
DERIVATIZATION
DIAMAGNETISM
ELECTRON SPIN RESONANCE
FULLERENES
PARAMAGNETISM
STEREOCHEMISTRY