Ítem


(4+2) and (2+2) Cycloadditions of Benzyne to C60 and Zig-Zag Single-Walled Carbon Nanotubes: The Effect of the Curvature

Addition of benzyne to carbon nanostructures can proceed via (4+2) (1,4-addition) or (2+2) (1,2-addition) cycloadditions depending on the species under consideration. In this work, we analyze by means of density functional theory calculations the reaction mechanisms for the (4+2) and (2+2) cycloadditions of benzyne to nanostructures of different curvature, namely, C60 and a series of zig-zag single-walled carbon nanotubes. Our DFT calculations reveal that, except for the concerted (4+2) cycloaddition of benzyne to zig-zag single-walled carbon nanotubes, all cycloadditions studied are stepwise processes with the initial formation of a biradical singly-bonded intermediate. From this intermediate, the rotation of the benzyne moiety determines the course of the reaction. The Gibbs energy profiles lead to the following conclusions: (i) except for the 1,4-addition of benzyne to a six-membered ring of C60, all 1,2- and 1,4-additions studied are exothermic processes; (ii) for C60, the (2+2) benzyne cycloaddition is the most favoured reaction pathway; (iii) for zig-zag single-walled carbon nanotubes, the (4+2) benzyne cycloaddition is preferred over the (2+2) reaction pathway; and (iv) there is a gradual decrease in the exothermicity of the reaction and an increase of energy barriers as the diameter of the nanostructure of carbon is increased. By making use of the activation strain model, it is found that the deformation of the initial reactants in the rate-determining transition state is the key factor determining the chemoselectivity of the cycloadditions with benzyne

The following organizations are thanked for financial support: the Spanish government (MINECO, projects number CTQ2014-54306-P, CTQ2014-59212-P, and CTQ2013-48252-P), the Generalitat de Catalunya (project number 2014SGR931, Xarxa de Referència en Química Teòrica i Computacional, and ICREA Academia 2014 prize to M. S.), and the FEDER fund (European Fund for Regional Development) for the grant UNGI10-4E-801

© Journal of Physical Chemistry C, 2016, vol. 120, núm. 3, p. 1716-1726

American Chemical Society (ACS)

Autor: Martínez, Juan Pablo
Langa, Fernando
Bickelhaupt, Friedrich Matthias
Osuna Oliveras, Sílvia
Solà i Puig, Miquel
Data: 2016
Resum: Addition of benzyne to carbon nanostructures can proceed via (4+2) (1,4-addition) or (2+2) (1,2-addition) cycloadditions depending on the species under consideration. In this work, we analyze by means of density functional theory calculations the reaction mechanisms for the (4+2) and (2+2) cycloadditions of benzyne to nanostructures of different curvature, namely, C60 and a series of zig-zag single-walled carbon nanotubes. Our DFT calculations reveal that, except for the concerted (4+2) cycloaddition of benzyne to zig-zag single-walled carbon nanotubes, all cycloadditions studied are stepwise processes with the initial formation of a biradical singly-bonded intermediate. From this intermediate, the rotation of the benzyne moiety determines the course of the reaction. The Gibbs energy profiles lead to the following conclusions: (i) except for the 1,4-addition of benzyne to a six-membered ring of C60, all 1,2- and 1,4-additions studied are exothermic processes; (ii) for C60, the (2+2) benzyne cycloaddition is the most favoured reaction pathway; (iii) for zig-zag single-walled carbon nanotubes, the (4+2) benzyne cycloaddition is preferred over the (2+2) reaction pathway; and (iv) there is a gradual decrease in the exothermicity of the reaction and an increase of energy barriers as the diameter of the nanostructure of carbon is increased. By making use of the activation strain model, it is found that the deformation of the initial reactants in the rate-determining transition state is the key factor determining the chemoselectivity of the cycloadditions with benzyne
The following organizations are thanked for financial support: the Spanish government (MINECO, projects number CTQ2014-54306-P, CTQ2014-59212-P, and CTQ2013-48252-P), the Generalitat de Catalunya (project number 2014SGR931, Xarxa de Referència en Química Teòrica i Computacional, and ICREA Academia 2014 prize to M. S.), and the FEDER fund (European Fund for Regional Development) for the grant UNGI10-4E-801
Format: application/pdf
ISSN: 1932-7447 (versió paper)
1932-7455 (versió electrònica)
Accés al document: http://hdl.handle.net/10256/12192
Llenguatge: eng
Editor: American Chemical Society (ACS)
Col·lecció: MINECO/PE 2015-2017/CTQ2014-54306-P
MINECO/PE 2015-2017/CTQ2014-59212-P
AGAUR/2014-2016/2014 SGR-931
Versió postprint del document publicat a: http://dx.doi.org/10.1021/acs.jpcc.5b11499
Articles publicats (D-Q)
info:eu-repo/grantAgreement/EC/FP7/630978
És part de: © Journal of Physical Chemistry C, 2016, vol. 120, núm. 3, p. 1716-1726
Drets: Tots els drets reservats
Matèria: Ciclització (Química)
Ring formation (Chemistry)
Títol: (4+2) and (2+2) Cycloadditions of Benzyne to C60 and Zig-Zag Single-Walled Carbon Nanotubes: The Effect of the Curvature
Tipus: info:eu-repo/semantics/article
Repositori: DUGiDocs

Matèries

Autors