Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic acid and alkali metal benzenesulfonates

Article abstract of DOI:10.1016/j.saa.2012.02.047

The FT-IR, FT-Raman and NMR (¹H and ¹³C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid.

Full text of DOI:10.1016/j.saa.2012.02.047

Spectrochimica Acta Part A 100 (2013) 41–50
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in
MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic
acid and alkali metal benzenesulfonates
a
a
a
b
a,∗
´
´
G. Swiderski , M. Kalinowska , R. Swisłocka , S. Wojtulewski , W. Lewandowski
a Department of Chemistry, Bialystok University of Technology, Zamenhofa 29, 15-435 Bialystok, Poland
b Department of Chemistry, University at Bialystok, Hurtowa 1, 15-399 Bialystok, Poland
a r t i c l e i n f o
a b s t r a c t
The FT-IR, FT-Raman and NMR (1H and 13C) spectra of benzenesulfonic acid as well as lithium, sodium,
potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The
molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical
calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared
spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal ben-
zenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge
distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and
benzoic acid.
Article history:
Received 30 November 2011
Received in revised form 20 January 2012
Accepted 13 February 2012
Keywords:
Benzenesulfonates
FT-IR
FT-Raman
NMR
© 2012 Elsevier B.V. All rights reserved.
Ab initio calculations
NBO
Aromaticity indices
1. Introduction
instance, in a variant of organometallic compounds, including
Sb5+ [9–18], Bi5+ [19,20], Sn4+ [21,22], Tc+ [23], Ru2+ [24], Rh+
In our previous papers the effect of alkali metals, transition and
heavy toxic metals on the aromatic system and carboxylic anion of
benzoic and pyridine-carboxylic acid derivatives [1–7] was inves-
tigated. The studies showed that alkali and heavy toxic metals
perturb the electronic charge distribution of above mentioned lig-
ands, whereas 3d and 4f metals stabilize it.
In this paper the influence of alkali metals (i.e. Li, Na, K, Rb
and Cs) on the electronic system of the aromatic ring of ben-
zenesulfonic acid and the sulfonic anion was studied. Then the
influence of metals on the aromatic system of ligands through
the carboxylic and sulfonic groups was compared. The following
spectroscopic methods were used: FT-IR, FT-Raman, NMR (1H and
13C) as well as theoretical calculations in MP2/6-311++G(d,p) and
B3LYP/6-311++G(d,p) levels (NBO, ChelpG, AIM study, theoreti-
cal IR spectra and chemical shifts from 1H and 13C NMR spectra).
Moreover the geometrical and magnetical aromaticity indices for
optimized structures were calculated.
[25,26], Pd2+ [27], Ag+ [28], and Re2+ [29] ions, besides the carbon-
coordinated organic ligands, the meta−l ions are also coordinated
by a monodentate (Fig. 1a) C6H5SO3 ligand or its substituted
benzenesulfonate analogues. The weak coordination nature of
−
SO3 makes its coordination mode very flexible and sensi-
tive to the chemical environment. For instance, the coordination
modes of SO3 to Na+ range from ꢀ3ꢁ3 bridging in sodium(I)
−
1,5-naphthalenedisulfonate dihydrate [30] to ꢀ7ꢁ5 in sodium(I)
4,4ꢀ-biphenyletherdisulfonate [8]. In the series of lanthanide
1,5-naphthalenedisulfonate complexes [Ln(OH)(1,5nds)(H2O)]n
(Ln = La, Pr and Nd) [31], the disulfonate ligands are coordinated
by five different Ln ions in an unusual asymmetrical ꢀ2ꢁ2–ꢀ3ꢁ3
mode (Fig. 1). Three solid-state structures of alkali metal 1,5-
naphthalenedisulfonates were investigated [30]. Li−+ is coordinated
by one water molecule and three different SO3 groups. Ever−y
SO3 oxygen atom is coordinated by one Li+ and the SO3
−
group functions as a ꢀ3ꢁ3 bridge, connecting three Li+. While Na+
−
The coordination chemistry of the sulfonate group for many
metal complexes was widely investigated in recent years [8]. For
is 5-coordinated by three different SO3 groups and two water
molecules. Every SO3 oxygen is coordinated by one Na+ ion and
−
the SO3 group functions as a ꢀ3ꢁ3 bridge connecting three Na+
−
ions. The −K+ ion is 8-coordinated by three water molecules and
five SO3 oxygen atoms from four different groups. Two of the
SO3 oxygen atoms are coordinated by two K+ ions, which make
−
∗
Corresponding author. Tel.: +48 857469790; fax: +48 857469782.
E-mail address: w-lewando@wp.pl (W. Lewandowski).
the SO3− group function as a ꢀ5ꢁ4 bridge. Additionally, the K+ ion
1386-1425/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2012.02.047

´
42
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
M
O
M
O
M
M
S
M
M
O
M
O
M
O
O
O
O
O
O
S
S
R
S
R
S
R
O
O
O
O
O
M
R
R
a)
b)
c)
d)
η2,μ2
e)
η3,μ3
η1
η2
η2,μ2
Fig. 1. Coordination types for single sulfonate group.
−
is coordinated by two oxygen atoms from the same SO3 group.
The corresponding characteristic of the OH stretching and SO vibra-
tional frequencies in their IR spectra also clearly indicate the
different coordination behaviour of the sulfonate groups. In the
complex of caesium 4-methylenebenzenesulfonate [32] the cae-
sium ion is surrounded by six oxygen atoms from five sulfonate
groups. Four sulfonate groups coordinate caesium ion in a mon-
odentate fashion (Fig. 1a), whereas the other in bidentate fashion
(Fig. 1b).
Sulfonate compounds have important functions in many fields
such as medicine, chemical separation and catalysis. Salts of sul-
fonic acid are applied as surface-active agents in light industry
[32].
was used to obtain atomic charges Q AIM. This analysis was per-
formed with the help of the AIMAll [35].
2.3. The geometric and magnetic criteria of aromaticity
The idea of the geometric aromaticity indices is based on the
fact that the essential factor in aromatic stabilization is the ꢄ
delocalization manifested in: planar geometry, equalization of the
bonds lengths and angles, and symmetry. These indices were suc-
cessfully applied to determination of aromatic character of many
compounds, e.g. global and local aromaticity in porphyrins [36],
substituent effects [37], structural aromaticity of systems with BN
bonds [38].
1H NMR spectroscopy is very useful for studying aromatic
character of molecules. Exocyclic protons exhibit characteristic
low-field (diatropic) chemical shift due to the induction of a dia-
magnetic ring current in a cyclic ꢄ-system. The 1H NMR data
have been used in discussion of the aromatic character of an
extensive range of compound classes, e.g. tellurophene [39], benzo-
furan series [40], 1,10-phenantroline [41], analogues of pentadienyl
anion [42]. According to Schleyer the most representative aromatic
indices are those based on diamagnetic susceptibility, because
the diamagnetic susceptibility completely depends on ꢄ-electron
structure [9,10]. Moreover according to Krygowski and co-workers
studies on interrelations between energies of rings in benzenoid
hydrocarbons, NICS values, and HOMA and its components, led to
the conclusion that NICS correlates best with the energy and HOMA,
and much less with other aromaticity indices [11].
2. Experimental
2.1. Sample preparation and measurement
The alkali metal benzenesulfonates were obtained by dissolv-
ing benzenesulfonic acid in an aqueous solution of the appropriate
alkali metal bases in a stoichiometric ratio 1:1. The dried lithium,
sodium, potassium, rubidium and caesium benzenesulfonates were
obtained after the solutions were evaporated on the vapour bath
and then dried in 140 ◦C. The IR spectra were recorded with an
Equinox 55 spectrometer within the range of 400–4000 cm−1. Sam-
ples in the solid state were measured in Zn/Se plate (for acid) and in
KBr matrix pellets (for salts) obtained with hydraulic press under
739 MPa pressure. Moreover the FT-IR spectra of acid were also
recorded in H2O solution using ATR accessory. FT-Raman spectra
of solid samples were recorded in capillary tubes in the range of
400–4000 cm−1 with a FT-Raman accessory of a Perkin–Elmer sys-
tem 2000. The resolution of spectrometer was 1 cm−1. The NMR
spectra of D2O saturated solution were recorded with a Bruker
unit 200 MHz at room temperature. TMS was used as an internal
reference.
The geometric and magnetic aromaticity indices, i.e. HOMA [12],
I6 [13], BAC [15] and NICS [16], ꢅ, ꢆꢅ [17,18] were calculated
according to the described below formulas on the basis of obtained
theoretical parameters:
ꢀ
˛
HOMA = 1 −
(Ropt − Ri)2
n
The notations are as follows: n is the number of bonds taken
into account; ˛ is an empirical constant chosen to give HOMA = 0
for hypothetical Kekulé structure of benzene and HOMA = 1 for the
system with all bonds equal to the optimal value Ropt; Ropt is a length
of the CC bond for which the energy of the compression to the length
of a double bond and expansion to the length of a single bond in 1,3-
butadiene is minimal; Ri is an individual bond length. The value of
HOMA index is equal 1 for the entirely aromatic system, HOMA = 0
when structure is non-aromatic and HOMA < 0 for anti-aromatic
ring [12].
2.2. Theoretical calculations
All theoretical calculations (geometries, NBO, ChelpG, IR and
NMR spectra) in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) lev-
els were performed by the use of the GAUSSIAN 03W package of
programs running on a PC computer [33]. The optimized geome-
tries correspond to the ground state stationary points. No imaginary
frequencies were found. Theoretical wavenumbers were scaled
according to the formula: ꢂscaled = 0.9ꢂcalculated [34]. The chem-
ical shifts were calculated using GIAO (gauge including atomic
orbitals) method. Chemical shifts (ıi) were calculated by subtrac-
ting the appropriate isotopic part of the shielding tensor (ꢃi) from
that of TMS (ꢃTMS): ıi = ꢃTMS − ꢃi) [ppm]. The isotropic shielding
constants for TMS calculated in the B3LYP/6-311++G** and MP2/6-
311++G** levels were equal to 31.99762 ppm for the 1H nuclei and
184.1700 ppm for the 13C nuclei (B3LYP) and 31.8974 ppm for the
1H nuclei and 198.6150 ppm for the 13C nuclei (MP2) [34]. QTAIM
ꢁ
ꢀ
2
BAC =
(Rn − Rn+1
)
n
where R and Rn+1 are consecutive bond length in the ring and the
summation runs over a defined cyclic route [12].
ꢂ
ꢃ
V
I6 = 100 · 1 −
Vk

´
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
43
3.2. What changes in the spectrum of ligand are caused by the
replacement of sulfonic group’s hydrogen with a metal ion?
where
ꢆ
1/2
n
ꢀ
ꢄ
ꢅ
2
(N −N
)
100
av
a
2
R
r
av
V =
·
and N =
− b
n
N
3.2.1. Experimental IR and Raman spectra
r=1
The replacement of the sulfonic group’s hydrogen with a metal
ion brings about characteristic changes in the IR and Raman spec-
tra of the complexes in comparison with the spectra of ligand.
There could be observed a disappearance of the symmetric and
asymmetric valence vibration bands: stretching ꢂ(SO3H), as well
as deformation vibration bands of the sulfonyl group; disappear-
ance of group vibration bands ꢂ(O H), ˇ(O H) and ꢇ(O H); as
well as appearance of asymmetric and symmetric vibration bands
of the sulfonate anion ꢂas(SO3−), ꢂs(SO3−) as well as ıas(SO3−) and
ıs(SO3−) and disappearance or changes in positions and intensities
of some aromatic bands.
The notations are as follows: R is the observed bond length, Nr
is the individual bond order, Nav is the mean bond order, n is the
number of bonds, Vk, a and b are constants [13].
Magnetic susceptibility ꢅ is defined:
ꢅaa + ꢅbb + ꢅcc
ꢅ =
3
where ꢅaa, ꢅbb, ꢅcc are diagonal elements of magnetic susceptibility
tensor. The aromatic compounds possess magnetic susceptibility.
Diamagnetic susceptibility anisotropy is defined [16]:
The influence of metals in the series: Li → Na → K → Rb → Cs on
the vibrational structure of sulfonate anion was small but a gen-
eral tendency may be observed. Namely, in the above series the
decrease in the wavenumbers of ꢂs(SO3−) both in the IR and Raman
spectra is observed (from 1062 cm−1 to 1042 cm−1 in IR spectra
and in the range 1061–1041 cm−1 in Raman spectra). Moreover
in Raman spectra of benzenesulfonates the wavenumbers of band
ꢂas(SO3−) decreases as well along the series: Li = Na → K → Rb → Cs
salts (1183–1176 cm−1).
ꢅaa + ꢅbb
ꢆꢅ = ꢅcc
−
2
where c is perpendicular direction to plane of the ring.
The NICS (Nucleus Independent Chemical Shift) is defined as a
negative value of the absolute magnetic shielding computed in the
centers of rings [10]. The more negative are the NICS and ꢆꢅ value,
the more aromatic is the system.
pEDA, applied by Ozimin´ ski and Dobrowolski [43]:
The bands assigned to stretching ꢂCHar vibrations occur in the
range 3175–2927 cm−1 (IR) and 3176–3002 cm−1 (Raman). The
band no. 20b is located at higher wavenumber in the spectra of
acid compared with the spectra of salts. The bands of stretching
ꢂCCar vibrations are located from 1621 cm−1 to 1217 cm−1 (IR) and
1589–1218 cm−1 (Raman). The appropriate bands are of similar
wavenumbers both in the spectra of acid and salts. In the region
of 1143–1020 cm−1 (IR) and 1146–1010 cm−1 (Raman) the bands
of in-plane deformations ˇCHar are present. A visible decrease in
the wavenumber of band no. 9a occurs (the band is located at
1143, 1139, 1134, 1133 and 1132 cm−1 in the IR spectra, and 1143,
1142, 1139, 1136 and 1134 cm−1 in the Raman spectra of Li, Na,
K, Rb and Cs benzenesulfonates, respectively). The peaks assigned
to out-of-plane deforming ꢇCHar vibrations occur at 915–732 cm−1
(IR) and 998–733 cm−1 (Raman). Generally, these bands are located
at higher wavenumbers in the spectra of benzenesulfonates com-
pared to benzenesulfonic acid. In the region of 692–611 cm−1 (IR)
and 632–616 cm−1 (Raman) the bands of in-plane and out-of-plane
deformations CCC of the aromatic ring (ꢈCCC, ˛CCC) are placed.
6
6
ꢀ
ꢀ
pEDA =
ꢄRj −C
−
ꢄCj
H
6
H
6
3
6
j=1
j=1
where ꢄij denotes sum of occupancies of all atomic orbitals of the
jth benzene ring C-atom contributing to the valence ꢄ-molecular
orbitals in the molecule indexed by i.
3. Results and discussion
3.1. Vibrational assignment
In Table 1 the wavenumbers, intensities and assignment of the
selected bands occurring in the FT-IR and FT-Raman spectra of
benzenesulfonic acid and its alkali metal salts are gathered. The
spectral assignment was based on the literature data [44–47] and
the theoretical calculations presented in this paper. The calculated
structures are shown in Fig. 1. One may divide the bands occurred
in the spectra of benzenesulfonic acid and benzenesulfonates into
two groups:
3.2.2. Theoretical IR spectra
Theoretical wavenumbers of infrared vibrations for benzene-
sulfonic acid and its salts were calculated in B3LYP/6-311++G(d,p)
level and gathered in Table 1. Satisfactory results were obtained for
the compared band wavenumbers from experimental and theoret-
ical IR spectra of studied compounds. Mostly all bands from the
theoretical spectra of alkali metal benzenesulfonates are located
at lower wavenumbers than appropriate bands from the spectra
of ligand. Moreover the wavenumber of almost all bands slightly
decrease along the series: Li → Na → K benzenesulfonates. This may
suggest that the specific effect of alkali metal ions on the electronic
structure of ligand depend on certain metal ion parameters
The structures of benzenesulfonic acid and lithium, sodium
and potassium benzenesulfonates were calculated in MP2/6-
311++G(d,p) and B3LYP/6-311++G(d,p) levels. The obtained bond
lengths and angles were gathered in Table 2 and the appropriate
structures are presented in Fig. 2. The replacement of the sulfonic
group’s hydrogen with an alkali metal ions brings about distinct
changes in the bond lengths and angles of sulfonic anion, but
insignificant changes in the bond lengths and angles between car-
bons in the aromatic ring. This may explain small or lack of shifts of
bands derived from aromatic ring vibrations and regular changes
1) those bands connected with sulfonic anion vibrations:
a) wide and intense bands of the stretching vibrations of S
O
group (1200–1195 cm−1 – IR; 1222–1198 cm−1 – Raman);
asymmetric ꢂas(SO3−) (1186 cm−1 IR, 1183–1176 cm−1
–
Raman) and symmetric ꢂs(SO3−) (1062–1041 cm−1 – IR;
1061–1041 cm−1 – Raman) stretching vibrations;
b) bands of medium intensity assigned to symmetric in-plane
deformation of the sulfonate anion ıs(SO3−) (587–568 cm−1
– IR; 571–562 cm−1 – Raman) as well as asymmetric in-plane
deformation of the sulfonate anion ıas(SO3−) (494–484 cm−1
– IR; 492–485 cm−1 – Raman).
2) those bands connected with aromatic ring vibration that
were observed in the whole spectral range, i.e. ꢂ(CH)ar
in the range: 3175–2926 cm−1 – IR, 3176–3060 cm−1
Raman; ꢂ(CC): 1621–1217 cm−1 – IR, 1589–1218 cm−1
Raman; ˇ(CH): 1243–1016 cm−1 – IR, 1244–1019 cm−1
–
–
–
Raman; ꢇ(CH): 998–732 cm−1 – IR, 998–732 cm−1 – Raman;
˛(CCC): 690–611 cm−1 – IR, 616–617 cm−1 – Raman; ꢈ(CCC):
635–623 cm−1 – IR, 632–626 cm−1 – Raman.

Table 1
The selected wavenumbers, intensities and assignments of bands from the IR (experimental and calculated in level B3LYP/6-311++G(d,p)) and Raman spectra of benzenesulfonic acid and its alkali metal salts.
Benzenesulfonic acid
Exp.
Benzenesulfonates
Lithium
Assignments
Calc.
IR
Sodium
Exp.
Potassium
Exp.
Rubidium
Exp.
Caesium
Exp.
a
b
IR
IR
Raman
Intens. Exp.
IR
Calc.
Calc.
IR
Calc.
IR
Raman
–
IR
–
Intens. IR
Raman
–
Intens. IR
Raman
–
3175vw 3200
–
Intens. IR
Raman
–
IR
–
Raman
c
3390m
–
–
–
–
–
–
–
–
–
–
3757
126.4
5.4
1.4
–
–
–
–
–
–
–
–
–
–
ꢂ(OH)
3173vw 3208
3206
3074vw 3194
–
–
3176vw 3202 6.9
3162vw 3200 2.0
3171vw 3202
6.1
3.6
6.8
3.9
17.3
15.3
0.1
0.9
0.0
6.1
11.6
1.1
3172w 3171vw 3175m 3175vw ꢂCH
ar
ar
ar
ar
ar
ar
ar
ar
ar
–
–
3200
3186
3002vw 3175
3199
3184
3172
3162
1627
1623
1509
1473
1344
1326
–
3158vw
3062m 3065w
2961w 3015vw 2960w 3015vw ꢂCH
–
3155vw ꢂCH
3061m 3060m ꢂCH
d
3069vw
6.3 3056s
8.5
0.7 2927m
1.5
3068m
–
–
–
3189 10.7
3178 11.1
3167 0.2
1626 0.1
1625 0.0
1510 5.7
1475 13.6
1346 2.0
1327 0.1
3059s
–
2926m
1621s
–
1485m
1445vs
–
1222vs
1200vs 1209vw 1225
1186vs 1183w
1139vs 1142s
–
3067m
14.9 3061m 3061m
20b
–
–
–
–
–
–
–
3185
3173
1625
–
13.8 2965w
0.1 2926w
–
–
–
–
–
3164
1627
1624
1509
1474
1345
1327
2926w
–
–
1482m
1446s
1243s
1219vs 1218w
1196vs 1201w
–
–
2927w
–
–
–
–
ꢂCH
–
0.6
–
ꢂCC
ꢂCC
ꢂCC
8a
1589vw 1628
0.2 1604s
3.9 1485s
18.6 1446vs
1590m
–
–
1590m
0.0 1608w 1590m
1588m
–
1588w
–
8b
19a
19b
3
1483m
1484w
–
–
–
–
1509
1479
1348
1333
–
–
–
–
6.1 1483m
12.4 1445s
–
–
–
1484m
1448m
1448m
1445vw 1445s
1443vw ꢂCC
–
–
–
–
1.0 1240vs 1244w
3.5
1.4
–
1233vw
–
–
–
–
ˇCH
ar
–
0.1 1217vs
284.8 1195vs 1222vw 1217
0.2
305.7
ꢂCC
ꢂSO
14
ar
–
–
1181vw 1185vw 1316
–
224.2 1198vs 1205vw 1251 262.7
1186vs 1182w
1.1 1143vs 1146s
1195vs 1198w
1176w
1132vs 1134s
–
–
–
1198
–
1101
952
–
–
1178w
1139m
–
–
1197
–
1102
958
–
–
1177w
1136s
–
–
ꢂ SO
as
3
–.
–
–
1201
1167
1102
1200 1.5
3.7 1134s
6.1
1133s
–
1071m
1041s
–
ˇCH
9a
ar
ꢂ SO H
3
1127vs
1072s
–
1128vs
1074w
–
1130m
–
–
276.2
11.7
–
–
–
–
–
–
–
–
–
–
–
s
1102 1.9
946
–
1070m
1050vs 1053w
–
7.3 1070m
–
20.5
240.1
–
1071m
1042vs 1041m
–
ˇCH
18b
ar
1062vs 1061w
216.4
–
235.5 1045s
1049w
–
1044m
–
ꢂ SO
s
3
1036s
1037s
1038vw 1100
28.0
–
–
–
–
–
–
ˇOH
1016vw 1019s
–
1081
1015
–
856
747
712
700
15.8 1022s
3.2 998m
1023w
998vs
932vw
–
1113 57.1
1017 1.5
1005 0.0
1020s
998s
924m
–
752vs
738vs
690vs
630vs
–
1024vs
998w
–
–
–
741m
–
632vw
617w
571vw
–
1115
1017
1001
856
–
764
721
706
630
606
–
57.6 1021s
2.4 998m
0.03 924vw
1023w
998vs
–
–
–
738m
–
629vw
617w
562vs
1115
1017
999
856
–
763
721
708
630
604
–
62.3
3.6
0.02 922w
1020s
998m
1021w
997vs
932vw
854w
–
736m
–
628w
617w
567w
–
1020s
998s
–
864vw
753s
733vs
692s
623vs
–
1020w
997vs
–
855vw
–
735m
–
626vw
617w
564w
–
ˇCH ꢂSC
ar ar
18a
12
17a
10a
995s
–
998m
–
998vs
–
–
–
733w
–
–
ꢇCH
ꢇCH
ꢇCH
ar
ar
ar
–
927w
–
–
0.2 861m
285.2 755s
39.6 738vs
52.2 691vs
630vs
854
–
0.3
–
0.3
–
–
753s
0.2
–
756s
732s
690s
–
611s
–
755w
732w
–
754s
734s
692s
623s
–
568s
–
–
ꢂS–(OH)
ꢇCH
739m
–
628vw
617w
–
768
724
708
629
612
30.4
26.6
43.2
0.02
62.5
31.3 734s
25.8 692s
40.9 635s
29.4
28.8
42.5
0.01
143.2
11
6a
ar
–
–
–
–
–
–
˛(CCC)
ꢈ(CCC)
˛(CCC)
616w
627
–
557
–
0.01
–
122.4
–
587s
–
0.02
–
6b
–
–
–
–
–
573vs
–
485w
0.1 568s
568s
–
485w
ı SO
s
3
562w
–
–
–
–
ꢇOH
ı SO
as
3
–
494w
492vw
537
24.1
485vw
520
11.3 484vw
485vw
520
11.3
490w
489vw
a
Spectrum recorded in Zn/Se plate.
Spectrum recorded in H2O solution.
s – strong; m – medium; w – weak; v – very; sh – shoulder.
b
c
d
Normal vibrations of the aromatic ring were used according to the nomenclature applied by Vársanyi [47].

´
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
45
Table 2
The theoretical geometric parameters calculated in B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels for benzenesulfonic acid and benzenesulfonates.
Benzenesulfonic acid
MP2 B3LYP
Benzenesulfonates
Lithium
Sodium
MP2
Potassium
MP2
MP2
B3LYP
B3LYP
B3LYP
Bond lengths [Å]
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
C6–C1
C1–S
S–O1
1.399
1.393
1.393
1.394
1.395
1.392
1.393
1.792
1.447
1.457
1.651
0.969
1.399
1.393
1.393
1.395
1.395
1.393
1.393
1.799
1.456
1.521
1.521
1.867
1.399
1.393
1.399
1.399
1.401
1.401
1.399
1.399
1.785
1.459
1.500
1.500
2.550
1.393
1.399
1.400
1.401
1.398
1.399
1.773
1.441
1.450
1.637
0.968
1.399
1.401
1.401
1.399
1.399
1.779
1.451
1.513
1.513
1.883
1.399
1.401
1.401
1.399
1.399
1.784
1.458
1.506
1.506
2.268
1.393
1.395
1.395
1.393
1.393
1.804
1.463
1.514
1.514
2.222
1.394
1.395
1.395
1.394
1.393
1.806
1.465
1.509
1.509
2.542
S–O2
S–O3
O3–H/metal
Angles [◦]
C1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–C6
C5–C6–C1
C1–S–O1
118.603
120.277
120.178
120.336
118.558
108.761
108.749
101.836
107.301
107.920
118.687
120.134
120.369
120.180
118.657
108.858
109.054
102.405
106.797
108.423
118.854
120.298
120.068
120.280
118.872
108.131
105.762
115.741
104.847
88.010
118.958
120.197
120.167
120.197
118.958
108.429
106.280
115.480
104.165
87.874
119.076
120.287
119.969
120.287
119.077
107.508
105.261
114.915
108.108
93.103
119.149
120.199
120.071
120.199
119.149
107.875
105.747
114.713
107.315
92.785
119.225
120.272
119.914
120.288
119.210
107.279
105.051
114.858
108.790
96.825
119.264
120.195
120.020
120.196
119.263
107.560
105.570
114.502
108.383
96.695
C1–S–O2
O1–S–O2
O2–S–O3
S–O3–H/metal
Dipole moment [Debye]
Energy [hartree]
4.934
5.054
5.891
5.760
8.112
7.832
9.761
9.374
−854.437
−856.202
−861.401
−863.218
−1015.788
−1017.982
−1453.263
−1455.629
in the wavenumbers of bands of sulfonate group vibrations from
the spectra of benzenesulfonates compared to the spectra of acid.
distribution around the other carbons in the benzene ring. There is
no regularity in the changes of location of the chemical shifts from
the 13C NMR spectra in the series of alkali metal benzenesulfonates.
Considerably good correspondence was found between calculated
and experimentally obtained chemical shifts from NMR spectra.
3.2.3. Experimental and theoretical 1H and 13C NMR spectra
The values of chemical shifts of protons from the experimental
1H NMR spectra of benzenesulfonic acid and its salts are gath-
ered in Table 3. The differences between particular chemical shifts
of appropriate protons do not exceed 0.03 ppm and there is no
regular relationship along the series of Li→. . .→Cs compounds.
In the theoretical 1H NMR spectra of benzenesulfonates a regu-
lar decrease in the chemical shifts of protons H3, H4, H5 along the
series Li → Na → K was observed. A decrease in the chemical shifts
points at an increase in the screening of aromatic protons as a con-
sequence of circular current weakening [7]. Therefore one may say
that disturbance of the aromatic system increases in the series:
Li → Na → K benzenesulfonates.
3.3. In what way alkali metal ions influence the electronic charge
distribution in benzenesulfonic acid?
During salt formation, first the metal ion influences the M
O
bond and this effect is transferred to the S O bonds, then the force
constant of the O S-ring bonds is changed which reflects in the dis-
placement of electronic charge around C C bonds in the aromatic
ring. Therefore the structure of sulfonate anion is very important in
the view of change in the electronic charge distribution in the ring.
In the experimental IR and Raman spectra of benzenesulfonates
two bands derived from stretching vibrations of sulfonate anion
exist: ꢂ(SO3−) and ꢂ(SO). The wavenumbers of ꢂ(SO) do not
change in a significant way along the series of alkali metal ben-
zenesulfonates. The magnitudes of separation ꢆꢂ(SO3−) between
the experimental wavenumbers of asymmetric ꢂas(SO3−) and
In case of experimental and theoretical 13C NMR spectra of stud-
ied compounds a decrease in the value of chemical shifts of all
carbons, (except C1) compared to spectra of ligand was observed
(Table 4). This means a decrease in the electronic charge distri-
bution around atom C1 and an increase in the electronic charge
Table 3
Chemical shifts from experimental and theoretical (in level B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p)) 1H NMR spectra of benzenesulfonic acid and alkali metal
benzenesulfonates.
Proton atom
Benzenesulfonic acid
Benzenesulfonates
Lithium
Exp.
Calc.
MP2
Sodium
Exp.
Potassium
Rubidium
Caesium
Exp.
B3LYP
Exp.
Calc.
MP2
Calc.
MP2
Exp.
Calc.
Exp.
Calc.
Calc.
B3LYP
B3LYP
MP2
B3LYP
H2 (d)
H3 (t)
H4 (t)
H5 (t)
H6 (d)
7.62
7.33
7.37
7.35
7.65
8.09
7.86
7.81
7.92
8.29
8.08
7.62
7.77
7.66
8.22
7.59
7.30
7.35
7.33
7.63
8.22
7.74
7.63
7.42
7.22
8.09
7.50
7.56
7.50
8.09
7.61
7.32
7.34
7.33
7.64
7.54
7.66
8.25
7.66
8.25
8.10
7.45
7.43
7.45
8.10
7.62
7.31
7.36
7.34
7.65
8.25
6.32
7.48
7.32
8.25
8.13
7.41
7.39
7.41
8.11
7.63
7.32
7.37
7.35
7.66
–
–
–
–
–
7.64
7.32
7.37
7.35
7.67
–
–
–
–
–
(d) – doublet, (t) – triplet.

´
46
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
Fig. 2. The theoretical structures of benzenesulfonic and benzenesulfonates (a–d) and benzoic acids and benzoates (e–h).
symmetric ꢂs(SO3−) amount to: 121, 130, 129, 133 and 135 cm−1
(Raman) for Li, Na, K, Rb and Cs benzenesulfonates, respectively.
An increase in the value of ꢆꢂ(SO3−) in the series indicates a
decrease in the symmetrization of the bidentate structure of the
sulfonate ion in the series of Li → Na = K → Rb → Cs compounds.
The same effect in case of alkali metal benzoates and pyridine-
carboxylates was observed [4]. Then the changes in the electronic
charge distribution, which lead to the asymmetrization of the
sulfonate ion structure, are transmitted to the aromatic ring of
molecules.
ions narrowly affect the aromatic ring of ligand but the geome-
try of sulfonate group undergoes modification after substitution of
alkali metal ions in the sulfonic group of acid. As the bond between
metal ion and oxygen atom lengthens the bond length S–O1
increases in the series: acid → Li → Na → K compounds. Whereas
the bond lengths S–O2 and S–O3 become equal and decrease in the
series: Li → Na → K benzenesulfonates. The value of angle C1–S–O1
remains almost unchanged taking into account the structures of
acid and salts whereas angles C1–S–O2 and O1–S–O2 decrease in
the series: Li → Na → K salts. The values of angles O1–S–O2 and
S–O3–metal are smaller in the benzenesulfonate molecules com-
pared to acid and increase in the above series.
On the basis of the calculated geometrical parameters for ben-
zenesulfonic acid and its salts (Table 2, Fig. 2) one can see that metal
Table 4
Chemical shifts from experimental and theoretical (in level B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p)) 13C NMR spectra of benzenesulfonic acid and alkali metal
benzenesulfonates.
Carbon atom Benzenesulfonic acid
Benzenesulfonates
Lithium
Exp.
Calc.
MP2
Sodium
Exp.
Potassium
Rubidium
Exp.
Caesium
Calc. Exp.
B3LYP
Exp.
Calc.
MP2
Calc.
MP2
Exp.
Calc.
Calc.
B3LYP
B3LYP
MP2
B3LYP
C1
C2
C3
C4
C5
C6
147.16
128.56
125.96
129.83
125.96
128.56
146.22
125.54
133.11
132.42
133.64
127.58
151.91
131.96
134.67
139.29
134.12
134.12
148.25
127.65
125.48
128.45
125.48
127.65
150.79
125.51
131.70
130.35
131.70
125.50
156.83
131.32
133.99
136.35
133.99
131.32
147.89
127.77
125.53
128.66
125.53
127.77
152.34
126.14
131.06
129.31
131.06
126.14
158.30
131.86
133.76
135.10
133.76
131.86
148.20
127.66
125.51
128.52
125.51
127.66
159.51
142.20
138.94
144.01
138.94
142.20
159.58
131.85
133.24
134.48
133.31
131.89
147.81
127.86
125.58
128.78
125.58
127.86
–
–
–
–
–
–
148.06
127.74
125.50
128.62
125.50
127.74
–
–
–
–
–
–

´
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
47
Table 5
Results of charge density analysis for benzenesulfonic acid and lithium, sodium and potassium benzenesulfonates calculated in B3LYP/6-311++G(d,p) level.
Atom
Benzenesulfonic acid
Lithium benzenesulfonate
Sodium benzenesulfonate
Potassium benzenesulfonate
Q AIM [a.u.]
NBO
ChelpG
Q AIM [a.u.]
NBO
ChelpG
Q AIM [a.u.]
NBO
ChelpG
Q AIM [a.u.]
NBO
C1
C2
C3
C4
C5
C6
H2
H3
H4
H5
H6
S
0.007
0.001
−0.190
−0.193
−0.175
−0.192
−0.180
−0.280
0.236
0.214
0.212
0.215
0.238
−0.048
−0.087
−0.042
−0.095
−0.042
−0.111
0.102
0.097
0.090
0.099
0.123
0.009
−0.006
−0.011
−0.005
0.009
−0.191
−0.196
−0.189
−0.196
−0.191
−0.264
0.232
0.209
0.208
0.209
0.232
−0.064
−0.080
−0.055
−0.080
−0.064
−0.124
0.132
0.081
0.085
0.081
0.132
0.006
−0.010
−0.014
−0.010
0.006
−0.193
−0.199
−0.195
−0.199
−0.193
−0.262
0.231
0.207
0.205
0.207
0.231
−0.055
−0.091
−0.068
−0.091
−0.055
−0.109
0.122
0.082
0.086
0.082
0.122
0.004
−0.012
−0.016
−0.012
0.005
−0.195
−0.201
−0.198
−0.201
−0.194
−0.262
0.230
0.205
0.204
0.205
0.230
−0.005
0.002
0.016
−0.136
−0.133
−0.129
−0.129
0.071
0.064
0.062
0.060
0.036
0.035
0.038
0.076
0.028
0.026
0.028
0.064
0.023
0.021
0.023
0.062
0.020
0.018
0.020
0.060
2.861
2.251
1.136
2.963
2.264
1.191
2.986
2.269
1.198
3.006
2.282
O1
O2
O3
H1/metal
−1.261
−1.246
−1.089
0.594
−0.905
−0.875
−0.869
0.494
−0.545
−0.501
−0.589
0.413
−1.262
−1.345
−1.345
0.919
−0.895
−1.057
−1.057
0.883
−0.535
−0.763
−0.763
0.826
−1.274
−1.336
−1.336
0.920
−0.917
−1.063
−1.063
0.936
−0.569
−0.765
−0.765
0.875
−1.281
−1.331
−1.331
0.918
−0.927
−1.066
−1.066
0.955
The values of NBO, ChelpG, and AIM atomic charges obtained
for benzenesulfonic acid and benzenesulfonates are collected in
Table 5. For the calculated structures only one type of coordina-
tion was assumed. The formation of alkali metal salts causes an
increase in the electronic charge density around atoms O1, O2 and
O3 (compared to acid molecule). In the series Li → Na → K salts
the negative charge gathered on O1 atom increases. In the case
of O2 and O3 atoms the atomic charges do not change significantly
and their values depend on the applied methods. The electronic
charge density around S atom decreases in the series: benzenesul-
fonic acid → Li → Na → K benzenesulfonates. The negative atomic
charge gathered on carbon atoms of the ring no. C2, C3, C4 and C5
is higher in case of benzenesulfonates than benzenesulfonic acid
molecule, whereas in case of atoms C1 and C6 the opposite situa-
tion is observed. The alteration of the values of atomic charges is
regular in the series Li → Na → K salts.
of acid are bonds: C1–C7, C7–O1, C7–O2 and O–metal as well
as angles: C1–C7–O1, C1–C7–O2, O1–C7–O2. Similarly as it was
shown in case of structures of benzenesulfonates the bond lengths
C
O become equal in the molecules of benzoates and decrease
in the series Li → Na → K salts. On the basis of calculated atomic
charges (Table 8) one may see that benzoic acid and benzoate
molecules possess higher electronic charge density in the ring than
benzenesulfonic acid and benzenesulfonates, respectively. On the
other hand, the atomic charges gathered on oxygen atoms of sul-
fonate group are more negative than in carboxylate group. The
formation of alkali metal compounds causes similar changes in the
values of atomic charges of carbon atoms of the ring in benzoates
and benzenesulfonates compared to appropriate acids, i.e. the elec-
tronic charge density increases around atoms C2, C3, C4 and C5.
But in case of C1 and C6 the opposite result is seen. In benzoate
molecules the electronic charge density around atoms C1 and C6
increases but in benzenesulfonates it decreases.
Table 6.
3.4. The comparison of the influence of SO3H and COOH
substituents on the vibrational structure of ligand
3.5. The application of the indices for quantitative measurement
of aromaticity of the studied compounds
In our previous papers the FT-IR and FT-Raman spectra of ben-
zoic acid and benzoates were reported and studied [2,3]. Comparing
the spectra of benzenesulfonic and benzoic acids in the region of
bands deriving from aromatic system vibrations one may notice
subtle but characteristic changes. Namely, in the spectrum of ben-
zenesulfonic acid most of these bands are shifted towards lower
wavenumbers or they disappear compared with the spectrum of
benzoic acid (Table 7). The shift of the aromatic system bands
towards lower wavenumbers results from weakening of the bonds
in benzene ring of benzenesulfonic acid caused by a decrease in the
force constants of the bonds and polarization of the bonds in the
ring [3].
The wavenumbers of selected bands from FT-IR, FT-Raman spec-
tra of caesium benzoate and benzenesulfonate are gathered in
Table 7. One may see that in the spectrum of benzoate the bands
are shifted towards lower wavenumbers or disappeared compared
with the spectrum of acid. On the other hand, in the spectrum
of benzenesulfonate the bands generally are located at the same
wavenumbers as in the spectrum of benzenesulfonic acid. This sug-
gests that alkali metal ions stronger affect the electronic system of
benzoic acid than benzenesulfonic acid.
The calculated geometric and magnetic indices are gathered
in Table 9. Lower values of HOMA, I6, BAC and higher values of
NICS, ꢆꢅ were obtained for benzoic than for benzenesulfonic acid.
According to the criterion of aromaticity, benzoic acid and ben-
zoates posses lower aromatic properties than benzenesulfonic acid
and benzenesulfonates. Moreover the differences in the values of
appropriate indices are higher for ligands than for their metal
complexes. That means that substitutents in benzene ring affect
the electronic charge distribution to a higher extend than sub-
stitution of metals in the coordinated group, i.e. carboxylic and
sulfonic groups. The values of HOMA, BAC, I6 and NICS indices
undergo small alternations or remain unchanged along the series:
acid → Li → Na → K salts. In case of benzoates the differences are
more visible, especially in case of BAC and I6 indices. It may suggests
that alkali metal ions stronger affect the molecular structure of ben-
zoic acid than benzenesulfonic acid. The indices pEDA and ꢄ-total
suggest a decrease of the aromatic properties of benzenesulfonates
compared to the acid molecule.
Most of the applied indices do not reflect the aromatic prop-
erties of benzoates and benzenesulfonates. In some studies the
magnetic indices are considered to be better in describing the aro-
maticity of molecules. According to Schleyer the magnetic indices
are the most representative criteria among all applied aromatic-
ity indices, because they depend on the magnetic susceptibility
which is completely dependent on ꢄ-electron structure of molecule
In Tables 7 and 8 the geometrical parameters and atomic charges
calculated for benzoic acid and benzoates in B3LYP/6-311++G(d,p)
and MP2/6-311++G(d,p) levels are shown. The main parameters
affected by substitution of alkali metal ions in the carboxylic group

´
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
48
Table 6
The experimental wavenumbers of selected band accruing in the FT-IR and FT-Raman spectra of benzoic and benzenesulfonic acids and their caesium salts.
8a
8b
19a
19b
14
18b
18a
12
10a
11
6b
Benzoic acid
Cs benzoate
IR
R
IR
R
1604
1603
1596
1596
1586
1586
–
1498
1455
1460
–
1324
1326
1309
–
1073
–
1069
–
1027
1027
1024
1019
1000
1001
–
856
855
–
–
796
–
617
616
–
–
–
–
–
–
–
–
–
–
Benzenesulfonic acid
Cs benzenesulfonate
IR
R
IR
R
–
1589
–
–
–
–
1483
–
1484
–
1448
–
1445
1443
–
–
–
–
1072
–
1071
–
1016
–
1020
1020
995
998
998
997
–
–
864
855
732
733
733
735
611
616
–
–
1588
617
Table 7
The theoretical geometric parameters calculated for benzoic acid and benzoates in B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels.
Benzoic acid
MP2
Benzoate
Lithium
MP2
B3LYP
Sodium
MP2
Potassium
MP2
B3LYP
B3LYP
B3LYP
Bond lengths [Å]
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
C6–C1
C1–C7
C7–O1
1.404
1.398
1.400
1.401
1.397
1.403
1.490
1.213
1.358
0.968
1.400
1.403
1.398
1.401
1.401
1.398
1.403
1.500
1.275
1.275
1.880
1.399
1.403
1.398
1.403
1.399
1.401
1.401
1.399
1.403
1.514
1.269
1.269
2.530
1.398
1.393
1.395
1.395
1.393
1.398
1.513
1.267
1.267
2.517
1.392
1.395
1.396
1.390
1.400
1.486
1.209
1.358
0.968
1.392
1.395
1.395
1.392
1.399
1.497
1.274
1.274
1.856
1.399
1.401
1.401
1.399
1.403
1.511
1.272
1.272
2.250
1.393
1.395
1.395
1.393
1.398
1.507
1.269
1.269
2.208
C7–O2
O2–H/metal
Angles [◦]
C1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–C6
C5–C6–C1
C1–C7–O1
C1–C7–O2
O1–C7–O2
C7–O2–H/metal
119.559
120.268
119.909
120.133
119.754
124.850
112.521
122.629
105.557
119.858
120.106
120.129
119.986
120.039
125.100
113.026
121.873
106.661
119.847
120.152
119.849
120.153
119.847
119.146
119.145
121.709
82.809
120.094
120.018
120.043
120.017
120.095
119.608
119.611
120.780
82.960
120.097
120.175
119.691
120.180
120.093
117.913
117.908
124.178
87.912
120.284
120.048
119.898
120.048
120.284
118.329
118.328
123.343
87.926
120.198
120.177
119.620
120.177
120.201
117.555
117.529
124.917
91.162
120.375
120.051
119.840
120.051
120.376
117.980
117.977
124.044
91.573
Dipole moment [Debye]
Energy [hartree]
1.817
2.128
3.721
3.273
6.709
6.095
8.317
7.775
−419.953
−420.949
−426.727
−427.947
−581.112
−582.709
−1018.863
−1020.354
Table 8
Atomic charges calculated for benzoic acid and benzoates in B3LYP/6-311++G(d,p) level.
Atom
Benzoic acid
Q AIM [a.u.]
Lithium benzoate
Q AIM [a.u.]
Sodium benzoate
Q AIM [a.u.]
Potassium benzoate
NBO
ChelpG
NBO
ChelpG
NBO
ChelpG
Q AIM [a.u.]
NBO
C1
C2
C3
C4
C5
C6
H2
H3
H4
H5
H6
C7
−0.010
−0.004
−0.009
−0.012
−0.008
−0.001
0.058
0.026
0.027
0.028
0.065
−0.169
−0.159
−0.206
−0.175
−0.205
−0.150
0.225
0.209
0.207
0.209
0.229
0.000
−0.070
−0.105
−0.058
−0.081
−0.097
0.103
0.095
0.088
0.090
0.108
−0.017
−0.010
−0.017
−0.019
−0.017
−0.010
0.059
0.017
0.017
0.017
0.059
−0.154
−0.160
−0.211
−0.187
−0.211
−0.160
0.227
0.204
0.203
0.204
0.227
0.109
−0.166
−0.078
−0.072
−0.078
−0.166
0.136
0.081
0.080
0.081
0.136
−0.018
−0.013
−0.021
−0.022
−0.021
−0.013
0.056
0.011
0.012
0.011
0.056
−0.147
−0.167
−0.213
−0.195
−0.213
−0.167
0.226
0.201
0.200
0.201
0.226
0.091
−0.154
−0.070
−0.102
−0.070
−0.154
0.119
0.076
0.084
0.076
0.119
−0.021
−0.016
−0.024
−0.025
−0.024
−0.016
0.054
0.008
0.009
0.008
0.054
−0.145
−0.171
−0.214
−0.199
−0.214
−0.171
0.225
0.199
0.199
0.199
0.225
1.492
0.790
0.659
1.518
0.764
0.675
1.543
0.764
0.687
1.560
0.772
O1
O2
H1/metal
−1.144
−1.091
0.585
−0.600
−0.691
0.486
−0.551
−0.612
0.432
−1.258
−1.257
0.918
−0.818
−0.818
0.889
−0.785
−0.785
0.833
−1.241
−1.241
0.902
−0.818
−0.818
0.919
−0.779
−0.779
0.856
−1.234
−1.234
0.900
−0.823
−0.823
0.940
[9,10]. Moreover high linear correlation between the magnetic
indices and energy of studied systems was found. The geometri-
cal indices do not correlate in a linear fashion with the magnetic
ones. This suggests that aromaticity indices, which are based on
different physico-chemical properties of molecules, do not reflect
the same aspects of aromaticity. The multidimensional character of
aromaticity has been proved for many groups of compounds [12].
Small differences between geometric indices calculated for par-
ticular compounds may be explained as follows: chemical factors
which reveal the character of substituents in benzene ring weakly
influence the aromaticity of system in contradiction to topological
factors [48].

´
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
49
Table 9
The aromaticity indices calculated for benzoic and benzenesulfonic acids and their alkali metal salts (on the basis of data calculated in B3LYP/6-311++G(d,p) level).
Benzoic acid
Benzoates
Lithium
Benzenesulfonic acid
Benzenesulfonates
Sodium
Potassium
Lithium
Sodium
Potassium
HOMA
GEO
EN
I6
BAC
NICS
ꢄ-total
pEDA
0.983
0.003
0.014
96.88
0.951
−8.01
5.035
–
0.984
0.002
0.014
97.74
0.964
−7.94
5.938
0.9032
0.984
0.001
0.015
98.03
0.969
−8.02
5.955
0.917
0.984
0.001
0.015
98.21
0.972
−8.01
5.957
0.922
0.993
0.003
0.007
99.11
0.987
−9.27
5.982
–
0.991
0.000
0.008
99.21
0.990
−9.25
6.004
0.022
0.991
0.00
0.991
0.000
0.009
99.42
0.990
−9.24
6.802
0.819
0.009
99.42
0.990
−9.24
6.029
0.047
3.6. Conclusions
[7] M. Kalinowska, J. Piekut, W. Lewandowski, Spectrochim. Acta A 82 (2011)
432–436.
[8] J. Cai, Coord. Chem. Rev. 248 (2004) 1061–1083.
The molecular structure of benzenesulfonic acid and alkali metal
benzenesufonates was discussed in this paper on the basis of exper-
imental and theoretical FT-IR, FT-Raman, 1H and 13C NMR spectra
and calculated geometrical parameters and atomic charges (AIM,
NBO, ChelpG). Alkali metal ions mostly affect the electronic charge
density of sulfonate group whereas the structure aromatic ring
is slightly affected. Some bands from FT-IR, FT-Raman, NMR as
well as values of atomic charges gathered on some atoms undergo
regular placement in the series: Li → Na → K → Rb → Cs benzene-
sulfonates. This suggests that certain metal ion parameters (such
as ionic potential, ionic radius, atomic mass) play an important
role in the influence of metal ions on the molecular structure of
ligand. Alkali metal ions mostly affect the electronic charge density
in sulfonate group than in the rest of molecule. The substitution of
alkali metal ions in the sulfonic group of acid causes an increase in
the electronic charge density around atoms O1, O2 and O3 and a
decrease around S atom in salt molecules compared to acid. Then
the negative atomic charge gathered on carbon atoms of the ring
no. C2, C3, C4 and C5 increases whereas in case of atoms C1 and
C6 decreases. Alkali metal ions in a different way affect the struc-
ture of benzenesulfonic acid and benzoic acid. Benzoic acid and
benzoate molecules possess higher electronic charge density in
the ring than benzenesulfonic acid and benzenesulfonates, respec-
tively. Whereas the atomic charges gathered on oxygen atoms
of sulfonate group are more negative than in carboxylate group.
The electronic charge density around atoms C2, C3, C4 and C5 is
higher in benzenesulfonate and benzoate molecules compared to
appropriate acids. Whereas the negative atomic charge collected
on atoms C1 and C6 increases in benzoates compared to benzoic
acid and decreases in benzenesulfonates compared to benzenesul-
fonic acid. Among studied aromaticity indices pEDA and ꢄ-total
in the best way describe the influence of alkali metal ions on the
aromatic system of ligands.
[9] P.v.R. Schleyer, H. Jiao, Pure Appl. Chem. 68 (1996) 209–218.
[10] P.v.R. Schleyer, P.K. Freeman, H. Jiao, B. Goldfuss, Angew. Chem. Int. Ed. 34
(1995) 337–340.
[11] M.K. Cyran´ ski, T.M. Krygowski, Tetrahedron 55 (1999) 6205–6210.
[12] T.M. Krygowski, M.K. Cyran´ ski, Chem. Rev. 101 (2001) 1385–1419.
[13] C.W. Bird, Tetrahedron 49 (1993) 8441–8448.
[14] T.M. Krygowski, A. Ciesielski, M. Cyran´ ski, Chem. Pap. 49 (1995) 128–132.
[15] P.v.R. Schleyer, C. Maerker, A. Dransfeld, H. Jiao, N.J.R. van Eikema Hommes, J.
Am. Chem. Soc. 118 (1996) 6317–6318.
[16] W.H. Flygare, Chem. Rev. 74 (1974) 653–687.
[17] R.C. Benson, C.L. Norris, W.H. Flygare, P. Beak, J. Am. Chem. Soc. 93 (1971)
5591–5593.
[18] T.G. Schmalz, T.D. Gierke, P. Beak, W.H. Flygare, Tetrahedron Lett. (1974)
2885–2888.
[19] R. Ruther, F. Huber, H. Preut, Z. Anorg, Allg. Chem. 539 (1986) 110–115.
[20] V.V. Sharutin, O.K. Sharutina, I.V. Egorova, V.S. Senchurin, A.N. Zakharova, V.K.
Bel’sky, Russ. J. Gen. Chem. 69 (9) (1999) 1470.
[21] S.W. Ng, W.G.K. Das, J. Crystallogr. Spectrosc. Res. 22 (1992) 615–618.
[22] A. Ruzicka, A. Lycka, R. Jambor, P. Novak, I. Cisarova, M. Holcapek, M. Erben, J.
Holecek, Appl. Organomet. Chem. 17 (2003) 168–174.
[23] R. Schibli, R. Alberto, U. Abram, S. Abram, A. Egli, P.A. Schubiger, T.A. Kaden,
Inorg. Chem. 37 (1998) 3509–3516.
[24] G. Fachinetti, T. Funaioli, F. Marchetti, J. Organomet. Chem. 498 (1995) C20.
[25] U. Kolle, R. Gorissen, T. Wagner, Chem. Ber. 128 (1995) 911–917.
[26] A. Vigalok, D. Milstein, Organometallics 19 (2000) 2341–2345.
[27] A.A.D. Tulloch, S. Winston, A.A. Danopoulos, G. Eastham, M.B. Hursthouse, J.
Chem. Soc. Dalton Trans. 4 (2003) 699–708.
[28] D. Rais, D.M.P. Mingos, R. Vilar, A.J.P. White, D.J. Williams, J. Organomet. Chem.
652 (2002) 87–93.
[29] I.L. Eremenko, V.I. Bakhmutov, F. Ott, H. Berke, Russ. J. Inorg. Chem. 38 (1993)
1541.
[30] J. Cai, C.H. Chen, C.Z. Liao, X.L. Feng, C.M. Chen, Acta Crystallogr. B 57 (2001)
520–530.
[31] N. Snejko, C. Cascales, B. Gomez-Lor, E. Gutierrez-Puebla, M. Iglesias, C. Ruiz-
Valero, M.A. Monge, Chem. Commun. (2002) 1366–1367.
[32] B. Sun, Y. Zhao, J.G. Wu, Q.H. Yang, G.X. Xu, J. Mol. Struct. 470 (1998) 63–66.
[33] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada,
M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery Jr., J.E. Peralta, F. Ogliaro, M.
Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, R. Kobayashi, J.
Normand, K. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M.
Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo,
J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C.
Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth,
P. Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, Ö. Farkas, J.B. Foresman,
J.V. Ortiz, J. Cioslowski, D.J. Fox, Gaussian 03W, Gaussian Inc., Wallingford, CT,
2009.
Acknowledgement
This work was supported by Bialystok University of Technology
´
(project no. S/WBiIS/1/12).
[34] J.E. Rode, J.Cz. Dobrowolski, M.H. Jamróz, M.A. Borowiak, Vib. Spectrosc. 25
(2001) 133–149.
[35] T.A. Keith, AIMAll, Version 10.05.04, 2010. aim.tkgristmill.com.
[36] M.K. Cyran´ ski, T.M. Krygowski, M. Wisiorowski, N.J.R. van Eikema Hommes,
P.vR. Schleyer, Angew. Chem. Int. Ed. 37 (1998) 177–180.
[37] T.M. Krygowski, M.K. Cyran´ ski, M. Wisiorowski, Pol. J. Chem. 70 (1996)
1351–1356.
References
[1] P. Koczon´ , P. Mos´cibroda, K. Dobrosz-Teperek, W. Lewandowski, J. Mol. Struct.
565–566 (2001) 7–11.
[2] W. Lewandowski, J. Mol. Struct. 101 (1983) 93–103.
[38] I.D. Madura, T.M. Krygowski, M.K. Cyran´ ski, Tetrahedron 54 (1998)
14913–14918.
[3] W. Lewandowski, H. Baran´ ska, J. Raman Spectrosc. 17 (1986) 17–22.
[4] W. Lewandowski, B. Dasiewicz, P. Koczon´ , J. Skierski, K. Dobrosz-Teperek, R.
[39] P. Diehl, M. Kellerhals, J. Lounila, R. Wasser, Y. Hiltunen, J. Jokisaari, T. Väänänen,
Magn. Reson. Chem. 25 (2005) 244–247.
[40] M. Baiwir, G. Llabrès, L. Christiaens, J.-L. Piette, Org. Magn. Res. 18 (2005)
33–37.
[41] M. Goto, S. Msu, T. Matsumoto, M. Iwasaki, Y. Tanaka, H. Kurosaki, K. Yuto, Y.
Yoshikawa, Bull. Chem. Soc. Jpn. 73 (2000) 1589–1598.
´
Swisłocka, L. Fuks, W. Priebe, A.P. Mazurek, J. Mol. Struct. 604 (2002), 189-183.
[5] W. Lewandowski, M. Kalinowska, H. Lewandowska, J. Inorg. Biochem. 99 (2005)
1407–1423.
[6] P. Koczon´ , J.Cz. Dobrowolski, W. Lewandowski, A.P. Mazurek, J. Mol. Struct. 655
(2003) 89–95.

´
G. Swiderski et al. / Spectrochimica Acta Part A 100 (2013) 41–50
50
[42] M. Rabinovitz, A. Ayalon, Pure Appl. 65 (1993) 111–118.
[43] P. Ozimin´ ski, J.Cz. Dobrowolski, J. Phys.Org. Chem. 22 (2009) 69.
[44] L. Pejov, M. Ristova, B. Soptrajanov, J. Mol. Struct. 555 (2000) 341–349.
[45] H.G.M. Edwards, D.R. Brown, J.R. Dale, S. Plant, J. Mol. Struct. 595 (2001)
11–125.
[46] L. Pejov, M. Ristova, Z. Zdravkovski, B. Soptrajanov, J. Mol. Struct. 524 (2000)
179–188.
[47] G. Versányi, Assignments for Vibrational Spectra of 700 Benzene Derivatives,
Akadémiai Kiadó, Budapest, 1973.
[48] M.K. Cyran´ ski, Doctoral dissertation, Warszawa, 1998.