Cyclosulfurization of CSubscript60/Subscript a

Authors: Maryam Anafcheh Fatemeh Ektefa

Publish Date: 2015/02/11

Volume: 26, Issue: 4, Pages: 1115-1124

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Abstract

We have applied DFT calculations to investigate the cyclosulfurization of the hexagon–hexagon h–h C–C bonds of C60 and C70 fullerenes Pentathiepin rings formed on the fullerene surfaces show chairlike structure and a high energy barrier 37 kcal mol−1 during ring inversion The carbon atoms relax outwardly from the surface of the fullerene in the attached sites This leads to the flattened polar caps and polygonal cross section at the equatorial belt of C70 when all the h–h C–C bonds at the polar caps are functionalized Reaction energies E r are obtained to be negative which indicate the exothermic character of the cyclosulfurization processes Generally the cyclosulfurization reaction of h–h bonds of C60 and h–h bonds at the polar caps of C70 is more energetically favorable due to the higher curvature of carbon sites facilitating the formation of pentathiepin rings on the fullerene surface For the successive cyclosulfurization of fullerenes the E r per addend show no considerable change in the C60 derivatives while because of steric repulsion between addends the E r per addend increase in the C70 derivatives with two pentathiepin rings The cyclosulfurization leads to an increase in the electrophilicity of the functionalized fullerenes Moreover the electrophilicity of the C70 derivatives in which pentathiepin rings are bound to the equatorial h–h bonds is always greater than those at the polar caps

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