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Full Exploration of the Diels–Alder Cycloaddition on Metallofullerenes M 3 N@C 80 (M=Sc, Lu, Gd): The D 5 h versus I h Isomer and the Influence of the Metal Cluster
Author(s) -
Osuna Sílvia,
Valencia Ramón,
RodríguezFortea Antonio,
Swart Marcel,
Solà Miquel,
Poblet Josep M.
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200940
Subject(s) - metallofullerene , cycloaddition , chemistry , lutetium , reactivity (psychology) , fullerene , regioselectivity , endohedral fullerene , crystallography , icosahedral symmetry , double bond , single bond , stereochemistry , computational chemistry , group (periodic table) , organic chemistry , catalysis , medicine , alternative medicine , pathology , oxide , yttrium
In this work a detailed investigation of the exohedral reactivity of the most important and abundant endohedral metallofullerene (EMF) is provided, that is, Sc 3 N@ I h ‐C 80 and its D 5 h counterpart Sc 3 N@ D 5 h ‐C 80 , and the (bio)chemically relevant lutetium‐ and gadolinium‐based M 3 N@ I h / D 5 h ‐C 80 EMFs (M=Sc, Lu, Gd). In particular, we analyze the thermodynamics and kinetics of the Diels–Alder cycloaddition of s ‐cis ‐1,3‐butadiene on all the different bonds of the I h ‐C 80 and D 5 h ‐C 80 cages and their endohedral derivatives. First, we discuss the thermodynamic and kinetic aspects of the cycloaddition reaction on the hollow fullerenes and the two isomers of Sc 3 N@C 80 . Afterwards, the effect of the nature of the metal nitride is analyzed in detail. In general, our BP86/TZP//BP86/DZP calculations indicate that [5,6] bonds are more reactive than [6,6] bonds for the two isomers. The [5,6] bond D 5 h ‐b , which is the most similar to the unique [5,6] bond type in the icosahedral cage, Ih ‐a , is the most reactive bond in M 3 N@ D 5 h ‐C 80 regardless of M. Sc 3 N@C 80 and Lu 3 N@C 80 give similar results; the regioselectivity is, however, significantly reduced for the larger and more electropositive M=Gd, as previously found in similar metallofullerenes. Calculations also show that the D 5 h isomer is more reactive from the kinetic point of view than the I h one in all cases which is in good agreement with experiments.