Reactivity and regioselectivity in Diels-Alder reactions of anion encapsulated fullerenes.
Phys Chem Chem Phys
; 19(45): 30393-30401, 2017 Nov 22.
Article
em En
| MEDLINE
| ID: mdl-29119190
ABSTRACT
Encapsulation and surface chemical modification are methodologies to enhance the properties of fullerenes for various applications. Herein, density functional theory calculations are performed to study the Diels-Alder (DA) reactivity of anion encapsulated C60, including [X@C60]- (X = F, Cl, Br, or I), [S@C60]2-, and [N@C60]3-. Computational results reveal that encapsulated Cl-, Br-, I-, or S2- anions are located close to the center of the C60 molecule; however, encapsulated F- is displaced from the center. Encapsulated N3- bonds to the inner surface of the carbon cage, which leads to a negative charge transfer to the C60. In [N@C60]3-, C-C bonds near to the encapsulated N atom are more reactive. Our calculations reveal that encapsulated halogen or S anions decrease the DA reactivity because of the stronger closed-shell repulsion of the encapsulated anion. However, encapsulated N3- increases the DA reactivity. The higher distortion energy of the halogen- or S2--anion encapsulated C60 leads to lower reactivity of the 6-5 bond. Opposite regioselectivity of the DA reaction with [N@C60]3- is attributed to distortion energy of the cyclopentadiene (CPD) moiety. The asymmetrical transition state geometry leads to a lower distortion energy of the CPD moiety.
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MEDLINE
Idioma:
En
Revista:
Phys Chem Chem Phys
Assunto da revista:
BIOFISICA
/
QUIMICA
Ano de publicação:
2017
Tipo de documento:
Article