A comparative study on interaction capacity of CO2 CPL 2014

Chemical Physics Letters 598 (2014) 75–80

Contents lists available at ScienceDirect

Chemical Physics Letters
journal homepage: www.elsevier.com/locate/cplett

A comparative study on interaction capacity of CO2 with the >S@O
and >S@S groups in some doubly methylated and halogenated
derivatives of CH3SOCH3 and CH3SSCH3
Vo Thuy Phuong a, Nguyen Thi Thu Trang b,c, Vien Vo a, Nguyen Tien Trung a,⇑
a
b
c

Faculty of Chemistry, and Laboratory of Computational Chemistry, Quy Nhon University, Quy Nhon, Viet Nam
Faculty of Science, Hai Phong University, Hai Phong, Viet Nam
Faculty of Chemistry, Ha Noi National University of Education, Ha Noi, Viet Nam

a r t i c l e

i n f o

Article history:
Received 28 November 2013
In final form 4 March 2014
Available online 12 March 2014

a b s t r a c t
Interactions of CO2 with CH3SZCHX2 (Z@O, S; X@H, CH3, F, Cl, Br) induce significantly stable complexes
with interaction energies from À13.7 to À16.4 kJ molÀ1 (MP2/aug-cc-pVTZ//MP2/6-311++G(2d,2p)).

Remarkably, some stable shapes of CH3SZCH3Á Á ÁCO2 are revealed for the first time. Substitution of two
H atoms in a CH3 of CH3SZCH3 by two X alike groups makes CH3SZCHX2Á Á ÁCO2 more stable than
CH3SZCH3Á Á ÁCO2, and their stability increases in the order F < Cl < Br < CH3. The >S@O is stronger than
the >S@S in interacting with CO2, and they both can be valuable candidates in the design of CO2-philic
materials and in the findings of materials to adsorb CO2.
Ó 2014 Elsevier B.V. All rights reserved.

1. Introduction
Supercritical fluid technology is considered as an attractive option for separation of fine chemicals from liquid solvents, and
supercritical carbon dioxide (scCO2) has become of interest as a
promising alterative to organic solvents for extractions, separations, chemical reactions, and material processes [1–4]. ScCO2 is
convenient to use as it possesses a lot of desirable properties. Nevertheless, the limitation in the applications of scCO2 is its restrictive
capacity of solvation for polar and high molecular weight compounds. It is required to unravel the factors for controlling the solubility of compounds in scCO2 and to design CO2-philic materials in
order to enhance more applications of scCO2. A large number of
experimental and theoretical studies on solute–solvent interactions
have been performed to gain understanding on solubility and structures of solutes in scCO2 [5–14]. In general, naked or substituted
hydrocarbons along with compounds functionalized by hydroxyl,
carbonyl, thiocarbonyl, carboxyl and amide groups have been paid
much attention as CO2-philic compounds [7,8,11–16]. The obtained
results showed that the carbonyl and thiocarbonyl compounds
have presented a higher stability, as compared to other functionalized ones, when they interact with CO2. This durability has been
assigned to a main contribution of the >C@ZÁ Á ÁC (Z@O, S) Lewis
acid–base interaction and/or an additional cooperation of the
C–HÁ Á ÁO hydrogen bonded interaction, except for a crucial role of
⇑ Corresponding author. Fax: +84 563846089.
E-mail address: (N.T. Trung).
/>0009-2614/Ó 2014 Elsevier B.V. All rights reserved.

the O–HÁ Á ÁO hydrogen bond predominating over the >C@OÁ Á ÁC Lewis acid–base interaction for the HCOOHÁ Á ÁCO2 complex in our previous study [14]. Nevertheless, the role of the C–HÁ Á ÁO hydrogen
bond in increasing soluble capacity of compounds in scCO2 remains

in debate. In addition, the finding of a specific scheme that can
rationalize the origin of blue shifting hydrogen bond is still an
objective of both theoretical and experimental works despite the
fact that in previous studies several rationalizations have been offered [17–21]. It is more appropriate if one considers the origin of
blue shifting hydrogen bond based on inherent properties of isolated isomers that are proton donors and proton acceptors [11,21].
Dimethyl sulfoxide (DMSO) is often used in biological and physicochemical studies, and is a common solvent in supercritical antisolvent processes [22–24].Many important applications have been
obtained such as micronization of pharmaceutical compounds,
polymers, catalysts, superconductors and coloring materials [25].
The phase equilibrium between the components including solute,
solvent and sometimes a cosolvent plays an important role in the
proper technological choice for the micronization process [26].
Hence, the experimental investigations into the phase equilibria
of DMSO with CO2, with both CO2 and H2O were performed [27].
A detailed study on the interaction of DMSO with H2O was reported
in ref. [23]. There is hardly any information relating to the complex
between DMSO and CO2 except what mentioned in ref. [28]. The
authors suggested that DMSO interacts strongly with CO2, and the
complex strength is contributed by a >S@OÁ Á ÁC (CO2) Lewis acid–
base interaction and two C–HÁ Á ÁO hydrogen bonded interactions.
However, a thorough theoretical investigation into existence and


76

V.T. Phuong et al. / Chemical Physics Letters 598 (2014) 75–80

role of interactions of DMSO with CO2 at the molecular level has not
been put forth yet. On the other hand, the interaction of dimethyl
thiosulfoxide (CH3SSCH3) with CO2 has not yet been investigated
although the CH3SSCH3 was synthesized experimentally [29] and

discussed theoretically [30]. To the best of our knowledge, a comparative study on the interaction capacity of >S@O and >S@S functionalized compounds including CH3SOCH3 and CH3SSCH3, and
their doubly methylated and halogenated derivatives (denoted by
CH3CZCHX2, with X@CH3, F, Cl, Br; Z@O, S), with CO2 has not been
reported in the literature. More remarkably, our objective in this
work is also to have a closer look at the origin of the C–HÁÁÁO hydrogen bond based on different polarization of C–H covalent bond acting as the proton donor in the isolated monomer.
2. Computational methods
Geometry optimizations for monomers and complexes of CH3
SZCHX2 (X@H, CH3, F, Cl, Br; and Z@O, S) and CO2 were carried out
at MP2/6-311++G(2d,2p). Harmonic vibrational frequencies at the
same level of theory were determined to ensure that the optimized
structures were all energy minima on potential energy surface, and
to estimate zero-point energy (ZPE). To avoid vibrational couplings
between the CH3 stretching modes of CH3SZCH3, CH3SZCH(CH3)2
(Z@O, S), the harmonic frequencies in these monomers and relevant
complexes were calculated by means of the deuterium isotope effect. Single point energy calculations were done in all cases using
MP2/aug-cc-pVTZ//MP2/6-311++G(2d,2p) and in some specific
cases using CCSD(T)/6-311++G(3df,2pd)//MP2/6-311++G(2d,2p)
for test purposes. Basis set superposition errors (BSSE) were calculated by using the counterpoise method of Boys and Bernadi [31].
The interaction energies were obtained as the difference in total energy between each complex and the sum of isolated monomers, corrected for ZPE only (DE) or for both ZPE and BSSE (DE⁄). All of the
calculations were carried out using the GAUSSIAN 09 program [32].
Topological parameters of the complexes were estimated by
AIM2000 software [33] based on Bader’s Atoms in Molecules theory
[34,35]. Finally, the electronic properties of the monomers and complexes were examined through a natural bond orbital (NBO) analysis
using GENNBO 5.G program [36] at the MP2/6-311++G(2d,2p) level.
3. Result and discussion
3.1. Interactions of CO2 with CH3SZCH3 (Z@O, S)
Three stable shapes of the optimized structures of complexes
CH3SZCH3Á Á ÁCO2 (Z@O, S) at MP2/6-311++G(2d,2p) are presented

in Figure 1, which are denoted hereafter by T1, T2 and T3. Their

topological geometries are shown in Figure S1 of Supplementary
information (SI). The selected parameters including intermolecular
distance, electron density (q(r)) and Laplacian (r2(q(r))) of bond
critical points (BCP) are gathered in Table 1. For test purpose, interaction energies of complexes at two different levels of theory are
also given in the Table 1. Generally, all OÁÁÁC (CO2), SÁÁÁC (CO2), HÁÁÁO
(CO2) and SÁÁÁO (CO2) contact distances are close to or smaller than
the sums of van der Waals radii of two relevant atoms (3.22 Å for
OÁÁÁC, 3.50 Å for SÁÁÁC, 2.72 Å for HÁÁÁO and 3.32 Å for SÁÁÁO). In addition, the q(r) and r2(q(r)) values of bond critical points of ZÁ Á ÁC,
OÁ Á ÁS and OÁ Á ÁH intermolecular contacts fall within the critical
limit for formation of non-covalent interactions (0.002–0.035 au
for q(r) and 0.02–0.15 au for r2(q(r))) [37]. Accordingly, these
intermolecular contacts are the Lewis acid–base, chalcogen–chalcogen and hydrogen bonded interactions in the relevant complexes, respectively. In particular, the strength of the T1 and T3
shapes is contributed by both the S@ZÁ Á ÁC (CO2) Lewis acid–base
and C–HÁ Á ÁO (CO2) hydrogen bonded interactions, while the contributions to the strength of T2 shape arise from the S@ZÁ Á ÁC (CO2)
Lewis acid–base and OÁ Á ÁS@Z chalcogen–chalcogen interactions
(cf. Figure 1).
The obtained results point out that there is a slight difference of
the interaction energies in two levels of theory applied. Thus, the
interaction energies of complexes examined range from À13.8 to
À17.2 kJ molÀ1 and À9.8 to À14.4 kJ molÀ1 (at MP2/aug-ccpVTZ//MP2/6-311++G(2d,2p)), and À13.6 to À17.7 kJ molÀ1 and
À9.6 to À14.5 kJ molÀ1 (at CCSD(T)/6-311++G(3df,2pd)//MP2/
6-311++G(2d,2p)) for only ZPE correction and both ZPE and BSSE
corrections, respectively (cf. Table 1). The results indicate that
the formed complexes are significantly stable, and more stable
than the complexes of the >C@O and >C@S functionalized compounds and CO2 reported in refs. [11,14,28]. This presents a stronger interaction of CO2 with the >S@O and >S@S counterparts
relative to the >C@O and >C@S ones. The reason for this is that
the O and S atoms in the >C@O and >C@S groups are sp2-hybridized making their lone pairs in plane, while both of them in the>
S@O and >S@S groups have a higher p-character hybridization.
Unlike in the carbonyl and thiocarbonyl compounds, the S–Z–
C–O (Z@O, S) dihedrals is indeed nonzero (cf. Figure 1).

The strength of the CH3SZCH3Á Á ÁCO2 (Z@O, S) complexes
decreases in the order of T1 = T3 > T2, and the CH3SOCH3Á Á ÁCO2
complexes are more stable than the corresponding CH3SSCH3
Á Á ÁCO2 ones. Both the larger proton affinity (PA) of 907.1 kJ molÀ1
at S site and the smaller deprotonation enthalpy (DPE) of
1578.4 kJ molÀ1 of C–H bond for CH3SSCH3 should be more

Figure 1. The stable shapes of complexes between CH3SZCH3 (Z@O, S) and CO2.


77

V.T. Phuong et al. / Chemical Physics Letters 598 (2014) 75–80
Table 1
Some selected parameters of the CH3SZCH3Á Á ÁCO2 complexes (interaction energies in kJ.mol-1, contact distances in Å, electron density and Laplacian in au).
Structures

DE a
DE b
DE⁄a
DE⁄b
R1 or R3
R2
q(ZÁ Á ÁC) or q(OÁ Á ÁS)
q(OÁ Á ÁH)
r2(q(ZÁ Á ÁC) or q(OÁ Á ÁS))
r2(q(OÁ Á ÁH))
a
b

Z@O

Z@S

T1

T2

T3

T1

T2

T3

À17.2
À17.6
À14.4
À14.5
2.63
2.77
0.0119
0.0064
0.0468
0.0228

À14.3
À14.8
À10.9

À11.3
3.49
2.69
0.0143
0.0139
0.0556
0.0359

À17.4
À17.7
À13.7
À14.0
2.65
2.70
0.0140
0.0062
0.0536
0.0209

À17.1
À16.8
À14.2
À13.5
2.59
3.33
0.0079
0.0073
0.0272
0.0258

À13.8
À13.6
À9.8
À9.6
3.37
3.30
0.0085
0.0059
0.0296
0.0224

À16.9
À16.4
À13.2
À12.0
2.54
3.30
0.0085
0.0075
0.0291
0.0248

Taken from MP2/aug-cc-pVTZ//MP2/6-311++G(2d,2p).
Taken from CCSD(T)/6-311++G(3df,2pd)//MP2/6-311++G(2d,2p).

advantageous to durable enhancement of complexes CH3SSCH3
Á Á ÁCO2 relative to CH3SOCH3Á Á ÁCO2 (PA at O site being 900.1 kJ molÀ1
and DPE of C–H bond being 1610.1 kJ molÀ1 at CCSD(T)/
6-311++G(3df,2pd)//MP2/6-311++G(2d,2p)). However, a reverse
tendency of the strength is observed (cf. Table 1). The larger

magnitude in strength of the CH3SOCH3Á Á ÁCO2 ones compared to
the CH3SSCH3Á Á ÁCO2 ones might be due to a larger contribution of
attractive electrostatic interaction to the overall interaction energy.
Thus, as shown in Table 1, each R2 value, and R1 and R3 values are
smaller and larger, respectively, for CH3SOCH3Á Á ÁCO2 than for
CH3SSCH3Á Á ÁCO2. This result suggests a stronger interaction of CO2
with the >S@O moiety compared to the >S@S moiety. This trend is
different from the reported results on substitution of O atom in
>C@O by S atom (>C@S) in the carbonyl compounds interacting with
CO2 [11], in which the former is weaker than the latter. Remarkably,
it should be emphasized that the two stable T2 and T3 structures of
CH3SOCH3Á Á ÁCO2, and the three stable shapes of CH3SSCH3Á Á ÁCO2 are
revealed for the first time. For the CH3SOCH3Á Á ÁCO2 complexes, the
strength of T3 is close to that of T1 reported by Wallen et al. [28].
Thus, the interaction energies of T1 in this work are À14.4 kJ molÀ1
at MP2/aug-cc-pVTZ//MP2/6-311++G(2d,2p) and À14.5 kJ molÀ1
at CCSD(T)/6-311++G(3df,2pd)//MP2/6-311++G(2d,2p), which are
appropriate to the value of À14.3 kJ molÀ1 at MP2/aug-cc-pVDZ//
MP2/6-31+G(d) reported in ref. [28].
In summary, the CH3SZCH3Á Á ÁCO2 (Z@O, S) complexes are in
general stabilized by the Lewis acid–base, chalcogen–chalcogen
and hydrogen bonded interactions, nevertheless a crucial role
contributing to the overall stabilization energy should be
suggested to be the Lewis acid–base interaction.
3.2. Interactions of CO2 with CH3SZCHX2 (X@H, CH3, F, Cl, Br; Z@O, S)
Apart from the most stable T1 shape in the CH3SZCH3Á Á ÁCO2
complexes and the demands of evaluating the role of Lewis acid–
base and hydrogen bonded interactions in stabilizing the complexes as well as pursuing the issue of the C–HÁ Á ÁO blue shifting
hydrogen bond based on various polarity of the C–H covalent bond,
we replaced two H atoms in a CH3 group of CH3SZCH3 by two CH3,

F, Cl and Br alike groups, and investigated the effects of gas phase
basicity at Z site and of polarity of the C–H bond in the isolated
monomers on the strength of complexes of CO2 and CH3SZCHX2
(X@CH3, F, Cl, Br; Z@O, S). The stable shapes of the F, Cl and Br
derivatives and CO2 are virtually similar to the T1 shape, while a
slight difference in geometry is observed for CH3SZCH(CH3)3Á Á ÁCO2.
All of them are presented in Figure 2, and some selected geometric
parameters of CH3SZCHX2Á Á ÁCO2 are gathered in Table S1 of SI.
All OÁÁÁC (CO2), SÁÁÁC (CO2) and HÁÁÁO (CO2) contact distances are
smaller than the sums of van der Waals radii of two relevant atoms

(3.22 Å for OÁÁÁC, 3.50 Å for SÁÁÁC and 2.72 Å for HÁÁÁO). They are indeed in the ranges of 2.76–2.80 Å for OÁÁÁC, 3.33–3.40 Å for OÁÁÁC,
and 2.30–2.63 Å for OÁÁÁH contacts (cf. Table S1). Consequently,
these interactions are the Lewis acid–base type and the hydrogen
bond. The evidence for the interactions is also based on the deviation of the carbon atom of CO2 from sp-hybridization (a3 < 180°).
The AIM analyses performed to lend further support for the presence of interactions and their contribution to complex strength
are presented in Figure S2 and Table 2 of SI. All q(r) and r2(q(r))
values of BCPs in the examined complexes belong to the limitation
criteria for the formation of weak intermolecular interactions [37].
The a1 values are larger for CH3SSCHX2Á Á ÁCO2 than for CH3SOCHX2
Á Á ÁCO2, indicating the stronger C–HÁ Á ÁO hydrogen bonded interaction for the former than the latter. On the contrary, the Lewis
acid–base interaction is stronger for CH3SSCHX2Á Á ÁCO2 than for
CH3SOCHX2Á Á ÁCO2, which arises from the smaller a2 values of ca.
20° for the former. Thus, as shown in Table S1, intermolecular contact distances also confirm this point.
The interaction energies, proton affinities and deprotonation
enthalpies in the monomers and the complexes CH3SSCHX2Á Á ÁCO2
are tabulated in Table 2. The interaction energies are significantly
negative, implying the very stable complexes of CO2 and
CH3SSCHX2. They are indeed from À14.4 to À16.4 kJ molÀ1 and
from À13.7 to À15.5 kJ molÀ1 (including ZPE and BSSE) for

CH3SOCHX2Á Á ÁCO2 and CH3SSCHX2Á Á ÁCO2, respectively. In general,
the CH3SOCHX2Á Á ÁCO2 complexes are more stable than the
CH3SSCHX2Á Á ÁCO2 complexes. This firmly indicates that the >S@O,
as compared to the >S@S, has a stronger interaction with CO2, which
originates from a contribution of attractive electrostatic interaction
larger for the former than for the latter in stabilizing the complexes
examined.
For the CH3SOCHX2Á Á ÁCO2 complexes, the strength is enhanced
in the order of X from H via F to Cl to Br and finally to CH3 (cf. Table 2). Accordingly, the substitution of two H atoms in a CH3 group
of CH3SOCH3 by two X alike groups makes the formed complexes
more stable, as compared to CH3SOCH3Á Á ÁCO2. The replacement
also leads to a slight enhancement of stability of the CH3SSCHX2
Á Á ÁCO2 complexes in the sequence from F, H, Cl, Br to CH3
(cf. Table 2). Coming back to the estimated values of PA at the O
and S sites and DPE of the C–H bond involved in hydrogen bond
for the isolated monomers, one can see that the gas phase basicity
at the O and S sites increases from F via Cl to Br to H and to CH3,
and the polarity of the C–H bonds decreases in the sequence from
Br, Cl, H, F to CH3. Accordingly, the overall stabilization energy for
the CH3SZCHX2Á Á ÁCO2 complexes is contributed by a main role of
the >S@ZÁ Á ÁC interaction and an additional cooperation of the
C–HÁ Á ÁO hydrogen bond, in which an enhanced contribution of
the hydrogen bond should be suggested for the complexes from


78

V.T. Phuong et al. / Chemical Physics Letters 598 (2014) 75–80

Figure 2. The stable shapes of interactions of CH3SZCH(CH3)2 and CH3SZCHX2 (X@H, F, Cl, Br; Z@O, S) with CO2 at MP2/6-311++G(2d,2p).

Table 2
Interaction energies using MP2/aug-cc-pVTZ//MP2/6-311++G(2d,2p), and proton affinities (PA) at the O and S sites and deprotonation enthalpies (DPE) of the C–H bonds involved
in hydrogen bond for the isolated monomers using CCSD(T)/6-311++G(3df,2pd)//MP2/6-311++G(2d,2p) (all in kJ molÀ1).
Z@O

a

Z@S

X

H

CH3

F

Cl

Br

H

CH3

F

Cl

Br

DE ⁄
PA
DPEa

À14.4
900.1
1610.1

À16.4
904.8
1711.9

À14.7
876.2
1619.5

À15.0
876.7
1560.8

À16.3
884.9
1540.6

À14.2
907.1
1578.4

À15.5
911.0
1704.7

À13.7
883.8
1606.0

À14.3
891.0
1540.4

À15.4
896.0
1522.0

Single point energies of CH3SZCX2 anions calculated at the respective geometry of isolated monomer without optimization.

H via F to Cl and finally to Br derivative. In short, the obtained results
indicate that the >S@O and >S@S counterparts should be valuable candidates in the design of CO2-philic materials and in the findings of
materials to adsorb CO2 in the near future.
Interactions of CO2 with CH3SZCHX2 cause the length changes of
the C–H bond involved in hydrogen bond, and its stretching frequency, and the results are listed in Table 3. All values indicate that
the C–HÁ Á ÁO interaction in all the examined complexes belongs to
the blue shifting hydrogen bond. Following complexation, a contraction of the C–H bond length and an increase in its corresponding stretching frequency are indeed observed in all complexes,
which are in the range of 0.5–2.0 mÅ and of 8.3–27.8 cmÀ1, respectively. The C–H bond length is shortened by 0.5 mÅ for CH3SOCH3
Á Á ÁCO2 at MP2/6-311++G(2d,2p), comparable to the reported value
of by 0.3 mÅ at MP2/6-31 + G(d) by Wallen et al. [28]. Increasing
magnitude of the C–H bond length contraction and its stretching
frequency blue shift for each CH3SZCHX2Á Á ÁCO2 is in the order of

X from Br via Cl and to F. This trend is consistent with a decrease
of the C–H polarization in the CH3SZCHX2 monomers. In other
words, the smaller the polarity of the C–H bond involved in hydrogen bond is, the larger the contraction and the stretching frequency

blue shift of the C–H bond as a result of complexation are, and vice
versa. Nevertheless, there is a different tendency in the changes of
the C–H bond length and its stretching frequency for CH3SZCHX2
Á Á ÁCO2, with X@H, CH3, and Z@O, S (cf. Table 3). Therefore, it might
be mentioned that the origin of blue shift hydrogen bond should be
slightly affected by the complex shape and the neighbouring intermolecular interactions, besides the crucial dependence on the
polarity of covalent bond acting as the isolated proton donor.
NBO analyses are applied to support for the evidence of the
interactions and the origin of the C–HÁ Á ÁO hydrogen bond upon
complexation, and the typical results are tabulated in Table 4. All
positive values of EDT (electron density transfer) imply a stronger
transfer of electron density from CH3SZCHX2 to CO2. In other
words, the electron transfer interaction from the n(Z) lone pairs
to the p⁄(C@O) orbital dominates rather than the electron transfer
from the n(O) lone pairs to r⁄(C–H) orbital in the complex stabilization. The EDT values are larger for CH3SOCHX2Á Á ÁCO2 than for
CH3SSCHX2Á Á ÁCO2, indicating that the >S@OÁ Á ÁC interaction is more
stable than the >S@SÁ Á ÁC interaction. The values of intermolecular
hyperconjugation energies transferring electron density from the
n(Z) to the p⁄(C@O) (denoted by Einter(n(Z10) ? p⁄(C11@O13))),

Table 3
The variation of the C5–H6 bond length (Dr, mÅ), its stretching frequencies (Dm, cmÀ1) at MP2/6-311++G(2d,2p).
Z@O

⁄

Z@S

X

H

CH3

F

Cl

Br

H

CH3

F

Cl

Br

Dr
Dm

À0.5
8.3

À1.2 (À0.2)
17.6 (1.6)

À2.0
27.8

À1.1
19.2

À1.0
17.5

À0.5
9.1

À1.2 (À0.4)
17.4 (1.8)

À1.6
24.6

À1.3
22.6

À1.0
18.7

The values given in brackets for the C7–H14 covalent bond.

79

V.T. Phuong et al. / Chemical Physics Letters 598 (2014) 75–80
Table 4
NBO analyses of the CH3SZCHX2Á Á ÁCO2 complexes at MP2/6-311++G(2d,2p).

Z@O

Z@S

a

X

EDT/electron

Dr⁄(C5–H6)
.103/electron

D%s (C5)
electron

E(n(O12) ? r⁄(C5–H6))
kJ molÀ1

E(n(Z10) ? r⁄(C11@O13))
kJ molÀ1

H
CH3

5.3
4.1
3.1
3.2
3.0

0.4
0.4
0.2a
0.6
0.6
0.7

1.34
0.46
0.11a
2.64
3.1
3.14

14.1
3.31

F
Cl
Br

0.2
0.3

0.3a
À1.3
À1.4
À1.1

H
CH3

5.1
3.2
2.0
1.6
1.3

0.4
0.4
0.3a
0.5
0.7
0.9

2.51
0.62
0.21a
5.19
6.61
7.91

6.7
1.37

F
Cl
Br

0.7
0.2
0.2a
À0.8
À1.3
À1.0

11.7
11.6
11.8

6.15
5.52
6.4

For C7–H14 covalent bond.

and from the n(O) to the r⁄(C–H) (denoted by Einter(n(O12) ?
r⁄(C5–H6))) listed in Table 4 indeed confirm this observation.
Hence, the corresponding intermolecular distances of >S@OÁ Á ÁC
for CH3SOCHX2Á Á ÁCO2 are shorter than those of >S@SÁ Á ÁC for
CH3SSCHX2Á Á ÁCO2, while a shorter contact distances of OÁ Á ÁH are
obtained for the latters relative to the formers (cf. Table S1).
Upon complexation, a small increase in s-character percentage
of the C hybrid orbitals is observed for all complexes. They are in

the range of ca. 0.2–0.7%. Such a gain in s-character partly contributes to a contraction of the C–H bond lengths. However, there are
different variations of electron density in the r⁄(C–H) orbitals. In
particular, a decrease of electron density in the r⁄(C–H) orbitals
by ca. 0.0008–0.0014 electron is obtained for CH3SZCHX2Á Á ÁCO2
(X@F, Cl, Br), while an increase of electron density by ca. 0.0002–
0.0007 electron is predicted for CH3SZCHX2Á Á ÁCO2 (X@H, CH3). As
a consequence, a contraction of the C–H bond involved in hydrogen
bond along with a blue shift of its stretching frequency for
CH3SZCHX2Á Á ÁCO2 (X@F, Cl, Br) arises from both a decrease of the
r⁄(C–H) electron density and an increase in the s-character
percentage of the C hybrid orbital. On the other hand, for
CH3SZCHX2Á Á ÁCO2 (X@H, CH3), a C–H bond length contraction
and its stretching frequency blue shift are determined by an
increase in the s-character percentage of the C hybrid orbital overriding an increase in the occupation of the r⁄(C–H) orbitals.
4. Concluding remarks

Acknowledgments
This research is funded by the Vietnam National Foundation for
Science and Technology Development (NAFOSTED) under grant
number 104.03-2012.12. NTT and VV also thanks Katholieke Universiteit Leuven for extending computational facilities through
the VLIR project ZEIN2012Z129.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at />005.
References
[1]
[2]
[3]
[4]
[5]

[6]
[7]
[8]
[9]
[10]
[11]

Interactions of CO2 with CH3SOCH3 and CH3SSCH3 induce three
quite stable shapes with interaction energies from À9.6 to
À14.5 kJ molÀ1 for both ZPE and BSSE corrections at CCSD(T)/6311++G(3df,2pd)//MP2/6-311++G(2d,2p). Remarkably, two quite
stable shapes of the CH3SZCH3Á Á ÁCO2 (Z@O, S) complexes are
revealed for the first time. The interaction energies of the
CH3SZCHX2Á Á ÁCO2 complexes range from À13.7 to À16.4 kJ molÀ1
for both ZPE and BSSE corrections (MP2/aug-cc-pVTZ//MP2/
6-311++G(2d,2p)). Their strength is mainly determined by the
> S@ZÁ Á ÁC Lewis acid–base interaction, and an additional contribution of the C–HÁ Á ÁO hydrogen bonded interaction with an enhanced
role in the sequence from H to F to Cl to Br derivative. The
CH3SOCHX2Á Á ÁCO2 complexes are more stable than the
CH3SSCHX2Á Á ÁCO2 complexes, which result from a large contribution of attractive electrostatic interaction of the >S@O relative to
the >S@S to the overall stabilization energy. The substitution of
two H atoms in a CH3 group of CH3SZCH3 by two F, Cl, Br and
CH3 alike groups makes the CH3SZCHX2Á Á ÁCO2 complexes more
stable, as compared to the CH3SZCH3Á Á ÁCO2 complexes, in going
from F via Cl, Br and finally to CH3 derivative.

[12]
[13]
[14]
[15]
[16]

[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
[30]

E.J. Beckman, J. Supercrit. Fluids 28 (2004) 121.
O. Kajimoto, Chem. Rev. 99 (1999) 475.
C.A. Eckert, B.L. Knutson, P.G. Debenedetii, Nature 383 (1996) 313.
K.P. Johnston, P.S. Shah, Science 303 (2004) 482.
T.W. Zerda, B. Wiegand, J. Jonas, J. Chem. Eng. Data 31 (1986) 274.
Y. Kachi, T. Tsukahara, Y. Kayaki, T. Ikariya, J. Sao, Y. Ikea, J. Supercrit. Fluids 40
(2007) 20.
P. Diep, K.D. Jordan, J.K. Johnson, E.J. Beckman, J. Phys. Chem. A 102 (1998)
2231.
R. Sui, J.M.H. Lo, P.A. Charpentier, J. Phys. Chem. C 113 (2009) 21022.
Y. Wang et al., J. Phys. Chem. B 113 (2009) 14971.
M.A. Blatchford, P. Raveendran, S.L. Wallen, J. Phys. Chem. A 107 (2003)
10311.
N.T. Trung, N.P. Hung, T.T. Hue, M.T. Nguyen, Phys. Chem. Chem. Phys. 13
(2011) 14033.

P. Lalanne, T. Tassaing, Y. Danten, F. Cansell, S.C. Tucker, M. Besnard, J. Phys.
Chem. A 108 (2004) 2617.
P. Raveendran, S.L. Wallen, J. Am. Chem. Soc. 124 (25) (2002) 7274.
N.T. Trung, M.T. Nguyen, Chem. Phys. Lett. 581 (2013) 10.
M. Altarsha, F. Ingrosso, M.F. Ruiz-Lopez, ChemPhysChem 13 (2012) 3397.
L.M. Azofra, M. Altarsha, M.F. Ruiz-Lopez, F. Ingrosso, Theor. Chem. Acc. (2013)
132.
V. Alabugin, M. Manoharan, S. Peabody, F. Weinhold, J. Am. Chem. Soc. 125
(2003) 597.
J. Joseph, E.D. Jemmis, J. Am. Chem. Soc. 127 (2007) 4620.
K. Hermansson, J. Phys. Chem. A 106 (2002) 4695.
P. Hobza, Z. Havlas, Chem. Rev. 100 (2000) 4253 (and references here).
N.T. Trung, T.T. Hue, M.T. Nguyen, J. Chem. Phys. A 113 (2009) 3245.
E. Reverchon, J. Supercrit. Fulids 15 (1999) 1.
Q. Li, X. An, B. Gong, J. Cheng, Spectrochim. Acta 69 (2008) 211.
J. Vieceli, I. Benjamin, Langmuir 19 (2003) 5383.
E. Reverchon, R. Adami, J. Supercrit. Fluids 37 (2006) 1.
A.V. Gonzalez, R. Tufeu, P. Subra, J. Chem. Eng. Data 47 (2002) 492.
A.E. Andreatta, L.J. Florusse, S.B. Bottini, C.J. Peters, J. Supercrit. Fluids 42 (2007)
60.
P. Raveendran, S. Wallen, J. Am. Chem. Soc. 124 (2002) 12590.
P. Gerbaux, J.-Y. Salpin, G. Bouchoux, R. Flammang, Int. J. Mass Spectrom. 195
(196) (2000) 239.
R. Steudel, Y. Drozdova, K. Miaskiewicz, R.H. Hertwig, W. Koch, J. Am. Chem.
Soc. 119 (1997) 1990.


80

V.T. Phuong et al. / Chemical Physics Letters 598 (2014) 75–80

[31] S.F. Boys, F. Bernadi, Mol. Phys. 19 (1970) 553.
[32] M.J. Frisch et al., GAUSSIAN 09 (version A.02) Inc., Wallingford, CT, 2009.
[33] AIM 2000, Designed by Friedrich Biegler-König, University of Applied Sciences,
Bielefeld, Germany, 2000.
[34] R.F.W. Bader, Chem. Rev. 91 (1991) 893.

[35] P. Popelier, Atoms in Molecules, Pearson Education Ltd., Essex, UK, 2000.
[36] GenNBO 5.G, E.D. Glendening, J.K. Baderhoop, A.E. Read, J.E. Carpenter, J.A.
Bohmann, F. Weinhold, Theoretical Chemistry Institue, University of
Wisconsin Madison, WI, 1996–2001.
[37] U. Koch, P.L.A. Popelier, J. Phys. Chem. 99 (1995) 9747.