2018. 59, 5 – . 1089 – 1096
ANALYSIS OF THE INTERACTION BETWEEN THE C
20
CAGE AND cis-PtCl
2
(NH
3
)
2
:
A DFT INVESTIGATION OF THE SOLVENT EFFECT, STRUCTURES,
PROPERTIES, AND TOPOLOGIES
Z. Kazemi
1
, R. Ghiasi
2
, S. Jamehbozorgi
3
1
Department of Chemistry, Faculty of Science, Arak Branch, Islamic Azad University, Arak, Iran
2
Department of Chemistry, East Tehran Branch, Islamic Azad University, Tehran, Iran
E-mail: rezaghiasi1353@yahoo.com
3
Department of Chemistry, Faculty of Science, Hamedan Branch, Islamic Azad University, Hamedan, Iran
Received October, 10, 2017
This study investigates the interaction between C
20
and the cis-PtCl
2
(NH
3
)
2
complex using
MPW1PW91 quantum chemical calculations in gas and solution phases. Two interaction
modes between C
20
and the cis-PtCl
2
(NH
3
)
2
complex are considered: I-isomer (
2
-C
20
) and
II-isomer (
1
-C
20
). It also determines the effects of the solvent polarity on the dipole moment,
electronic spatial extent (ESE), structural parameters, and frontier orbital energies of two pos-
sible isomers of the C
20
…cis-PtCl
2
(NH
3
)
2
complex. The bonding interaction between C
20
and
the cis-PtCl
2
(NH
3
)
2
complex was examined through energy decomposition analysis (EDA).
The metal—ligand bonds are evaluated using the percentage composition of the specific
groups of frontier orbitals. The quantum theory of atoms in molecules (QTAIM) analysis is
applied to assess the Pt—C bonds within the complex. Finally, the Pt—C spin-spin coupling
constants are calculated using the gauge independent atomic orbital (GIAO) method.
DOI: 10.26902/JSC20180505
K e y w o r d s: C
20
cage, cisplatin, energy decomposition analysis (EDA), solvent effect, quan-
tum theory of atoms in molecules (QTAIM).
INTRODUCTION
The structure and properties of the C
20
molecule have been studied in several theoretical and ex-
perimental studies [ 1—6 ]. The C
20
molecule is considered as the smallest member of the fullerene
family. It has been synthesized and characterized in the gas phase [ 7—9 ]. Due to their potential cha-
racteristics, fullerenes have been experimentally and theoretically used as basic elements in research
on nanoscale devices [ 10, 11 ]. Experimentalists and theoreticians are also paying increasing attention
to the structural and electronic properties of C
20
. Previous researches have highlighted the significant
aromaticity of the most stable fullerene C
20
and its derivatives, including C
20
(C
2
H
2
)
n
and C
20
(C
2
H
4
)
n
(n = 1—3) [ 11 ]. However, according to available studies, C
20
(C
2
H
2
)
4
and C
20
(C
2
H
4
)
4
are not aromatic.
A number of studies have been focused on the heteroatom effects on the structure, stability, and aro-
maticity of X
n
C
20–n
fullerenes [ 12 ]. Theoretical studies have also examined the interactions between
C
20
and N
2
X
2
(X = H, F, Cl, Br, Me) [ 13 ] and the effects of solvents in the interaction between C
20
and N
2
H
2
[ 14 ]. The formation and electronic structure of C
20
fullerene transition metal clusters have
also been evaluated using density functional theory [ 15 ].
It is now known that among the several probable C
20
isomers, the ring, bowl, and cage have the
lowest levels of energy. Although the spectroscopic support for the existence of these three isomers as
stable species under isolated molecule conditions has been reported [ 16 ], yet the one isomer with the
© Kazemi Z., Ghiasi R., Jamehbozorgi S., 2018