Exohedral Reactivity of Trimetallic Nitride Template (TNT) Endohedral Metallofullerenes Josep M. Campanera,‡ Carles Bo,‡ and Josep M. Poblet*,† Departament de Quı´mica Fı´sica i Inorga` nica, UniVersitat RoVira i Virgili, c/Marcel lı´ Domingo, s/n, Campus Sescelades, 43007 Tarragona, Catalonia, Spain, and ICIQ-Institut Catala` d’InVestigacio´ Quı´mica, AVda. Paı¨sos Catalans, 16, 43007 Tarragona, Catalonia, Spain
[email protected] ReceiVed August 8, 2005
Fullerenes containing a trimetallic nitride template (TNT) within the cage are a particularly interesting class of endohedral metallofullerenes. Recently two exohedral derivatives of the Sc3N@C80 fullerene have been synthesized: a Diels-Alder and a fulleropyrrolidine cycloadduct. The successful isolation, purification, and structural elucidation of these metallofullerenes derivatives have encouraged us to understand how the chemical reactivity is affected by TNT encapsulation. First of all, we predicted the most reactive exohedral sites, taking into account the double bond character and the pyramidalization angle of the C-C bonds. For this purpose, a full characterization of all different types of C-C bonds of the following fullerenes was carried out: Ih-C60:1, D3-C68:6140, D3-Sc3N@C68, D5h-C70:1, D3h′-C78:5, D3h-Sc3N@C78, Ih-C80:7 and several isomers of Sc3N@C80. Finally the exohedral reactivity of these TNT endohedral metallofullerenes, via [4 + 2] cycloaddition reactions of 1,3-butadiene, was corroborated by means of DFT calculations.
Introduction Many fullerenes with encapsulated metals and nonmetals have been reported, but they are typically formed in low yields (
