Chemistry Reference
In-Depth Information
Fig. 4.10
Energy profile (in kcal mol
−
1
) corresponding to the Diels-Alder reaction of C
60
with
cyclopentadiene computed at B3LYP/6-31G(d) (represented in
orange
and
continuous line
),
B3LYP-D/6-31G(d) (in
orange
,
discontinuous line
), ONIOM2(B3LYP/6-31G(d):SVWN/STO-3G)
(in
blue
,
continuous line
), ONIOM2-D(B3LYP/6-31G(d):SVWN/STO-3G) (in
blue
,
discontinuous
line
) and ONIOM2(M06-2X/6-31G(d):SVWN/STO-3G) (in
cyan
,
continuous line
). Comparison
between the reaction energies
H
R
and activation barriers
H
‡
(in kcal mol
−
1
.
H
‡
corresponds to
the activation barrier calculated with respect to isolated reactants (i.e H
TS
(H
C60
H
diene
)) whereas
−
+
H
‡
I
is referred to the optimized reactant complex (i.e H
TS
H
int
). The difference between the
computed energies and the experimental values is also indicated (the experimental reaction energy
is
−
2.2 kcal mol
−
1
and the activation barrier is 6.9 kcal mol
−
1
). In parentheses are given
the relative enthalpies including solvent effects (PCM and toluene as the solvent)
−
19.8
±
indicate that inclusion of dispersion corrections is compulsory to accurately repro-
duce the experimental reaction and activation energies for the study of the chemical
reactivity of fullerenes and nanotubes.
4.3.2
The Diels-Alder Regioselectivity and Different
Product Stability of La@C
2v
-C
82
(1,2,3,4,5-Pentamethyl)cyclopentadiene
In the DA addition of cyclopentadiene (Cp) on La@
C
2v
-C
82
the attack of Cp on
bond
19
(see Fig.
4.11
a) was proposed to be the major product of the reaction
