Crystal structure and FT-IR study of cesium4-methylbenzenesulfonate

Bo Sun, Ying Zhao, Jin-Guang Wu*, Qing-Chuan Yang, Guang-Xian Xu

State Key Laboratory of Rare Earth Materials Chemistry and Applications Peking University, Beijing 100871, People's Republic of China

Received 14 October 1997; accepted 13 March 1998

Abstract

The crystal structure of the title compound has been determined by X-ray diffraction. The crystal is monoclinic, space group

P21/C with a� 13.483(3)A, b� 7.285(1)A, c � 10.352(2)A, b� 110.43(3)8, and Z� 4, V� 952.8(3)A3, Dc� 2.120 g cm23,

l(MoKa) � 0.71073A, m � 4.033 mm21, F(000) � 576, ®nal weighted R � 0.0391 for 1863 unique re¯ections. The cesium

atom is coordinated to six oxygen atoms from ®ve sulfonate groups to form a distorted octahedron. There is no water molecule

and no H-bond network in the complex. FT-IR spectra was also used to characterize the complex. A preliminary infrared

assignment was performed. q 1998 Elsevier Science B.V. All rights reserved

Keywords: Cesium complexes; Crystal structure; FT-IR; 4-methylbezenesulfonate; X-ray diffraction

1. Introduction

Sulfonate compounds have important functions in

many ®elds such as medicine, chemical separation

and catalysis. Some sulfonate compounds can be

used as medicine to treat many kinds of diseases,

e.g. phentolamine mesylate. Ionic exchange resins

containing sulfonic acid group have been extensively

used for separation of mixtures such as rare earth

elements. Sulfonic acid salts are also used as surfac-

tants in light industry. It was discovered that

complexes with good layered structure have great

potential applications in catalysis and chemical

separation [1, 2]. Arylsulfonatenates always have

some layered structure, in the presence of a catalyst

containing cesium 4-methylbenezenesulfonate,

succinic acid or maleic acid can be hydrogenated to

g-butyrolactone [3]. Because sulfonates are hydro-

philic, the majority of arylsulfonates synthesized

from aqueous solutions usually contain water mole-

cules and have complicated hydrogen bond networks

[4±7]. In this paper, we have synthesized the title

complex from aqueous solution and found it contains

no water and no hydrogen bonding. Therefore, it is

specially suitable as a standard sample to study the

FT-IR spectra of other sulfonates.

2. Experimental

2.1. Synthesis

An aqueous solution of CsOH was added to the

aqueous solution of 4-methyl benzenesulfonic acid

until a pH < 6.0 was reached. After ®ltration, the

®ltrate evaporated at room temperature. Colorless

crystals were obtained after several days.

Journal of Molecular Structure 470 (1998) 63±66

0022-2860/98/$ - see front matter q 1998 Elsevier Science B.V. All rights reserved.

PII S0022-2860(98)00385-8

* Corresponding author. Tel. 0086 1 627 51723; Fax: 0086 1 627

51708; e-mail: Wjg@chemms.chem.pku.edu.cn

2.2. Instruments

All diffraction data were collected on a Ragaku

AFC6S diffractometer, with graphite-monochromated

MoKa radiation (l� 0.71073A) at room temperature.

Corrections to the absorption data were made using

the semi-empirical method. The structure was solved

with the direct method using the SHELXTL

PLUS(VMS) program, and re®ned by the full-matrix

least-squares method to determine the coordinates of

non-hydrogen atoms. The coordinates of the hydrogen

atoms were placed at their calculated positions. FT-IR

spectra were recorded of Nujol mulls using a Nicolet

Magna 750-IR spectrometer.

3. Results and discussion

The structure of the title complex is given in Fig. 1.

The coordination structure of cesium atom is shown in

Fig. 2(a). Selected bond lengths and bond angles are

listed in Table 1. In the complex, the cesium atom is

surrounded by six oxygen atoms from ®ve sulfonate

groups. Four sulfonate groups coordinate to the

cesium atom in unidentate fashion, while the other

in bidentate fashion. From Fig. 2(a) and Table 1, it

may be seen that the coordination geometry around

the cesium atom is a distorted octahedron. O(2),

O(2b), O(3a), O(3b) atoms are essentially co-planar

[O(2b), O(3b) are from the same sulfonate group],

with a mean deviation of 0.068A from planarity.

The cesium atom does not lie in the center of the

plane, but is at a distance of 0.8279A from the center.

The three oxygen atoms of each sulfonate group

exhibit different coordination structure: one is

unidentately coordinated to one cesium atom, another

is coordinated to three cesium. atoms, and the third

one to two cesium atoms [see Fig. 2(b)]. From the

B. Sun et al. / Journal of Molecular Structure 470 (1998) 63±6664

Fig. 1. The structure of Cesium 4-methylbenzenesulfonate.

Fig. 2. The coordination of Cs and sulfonate groups in Cesium 4-

methylbenzenesulfonate: (a) each Cs is surrounded by six oxygen

atoms from ®ve sulfonate groups forming a distorted octahedron;

(b) each sulfonate group is coordinated to 5 Cs atoms, so that the

®nal molar ratio of Cs to sulfonate is 1:1.

S±O bond lengths and bond angles, we can see that

the sulfonate group is nearly a regular tetrahedron.

The infrared spectra of cesium 4-methyl-

benezenesulfonate and 4- methylbenzenesulfonic

acid monohydrate were recorded of Nujol mulls to

prevent the sample from absorbing moisture and to

avoid reaction which may take place in KBr pellets

resulting in the change of the structure of sulfonate

groups. The spectra are shown in Fig. 3 and Fig. 4.

The assignments of the bands related to the sulfonate

group are listed in Table 2. In the IR spectra of the

complex, the absence of broad bands in the 2700±

1700 cm21 region, which is usually attributed to the

H-bonding of the ligand, indicates that the H-bonding

is eliminated in the complex, consistent with the

results from the crystal structure determination. The

coordination of Cs to the sulfonate group results in the

elimination of the H-bonding bands in the spectra of

the sulfonate group. Signi®cant band shifts and

narrowing of bands are observed. These two

compounds show nas(SO3) and ns(SO3) in the

1330±1100 cm21 and 1060±1000 cm21 regions,

respectively. From the splitting of peaks in the

1250±1150 cm21 region, the coordination structure

of the sulfonate group in the complex may be

inferred. The band at 1120.3 cm 2 1 was assigned

to naS±O(1)±CsD, 7 [see Fig. 2(b)]. The two bands

B. Sun et al. / Journal of Molecular Structure 470 (1998) 63±66 65

Table 1

Selected bond lengths (A) and angles(8)

Cs±O(1) 3.707(4) Cs±O(2) 3.050(4)

Cs±O(1a) 3.017(4) Cs±O(2a) 3.194(4)

Cs±O(2b) 3.119(5) Cs±O(3a) 3.056(5)

Cs±O(3b) 3.344(5) S±O(1) 1.441(5)

S±O(2) 1.452(4) S±O(3) 1.442(5)

O(1)±CsD 3.017(4) O(2)±CsC 3.194(4)

O(2)±CsE 3.119(5) O(3)±CsB 3.056(5)

O(3)±CsE 3.344(5)

O(1)±Cs±O(2) 40.0(1) O(1)±CS±O(1a) 130.2(1)

O(2)±Cs±O(1a) 98.3(1) O(1)±Cs±O(2a) 83.0(1)

O(2)±Cs±O(2a) 120.8(1) O(1a)±Cs±O(2a) 139.6(1)

O(1)±Cs±O(2b) 92.0(1) O(2)±Cs±O(2b) 114.5(1)

O(1a)±Cs±O(2b) 83.3(1) O(2a)±Cs±O(2b) 71.8(1)

O(2)±Cs±O(3a) 74.1(1) O(1a)±Cs±O(3a) 131.0(1)

O(2a)±Cs±O(3a) 74.6(1) O(2b)±Cs±O(3a) 144.6(1)

O(1)±Cs±O(3b) 65.0(1) O(2)±Cs±O(3b) 72.5(1)

O(1a)±Cs±O(3b) 79.0(1) O(2a)±Cs±O(3b) 101.7(1)

O(2b)±Cs±O(3b) 43.3(1) O(3a)±Cs±O(3b) 137.9(1)

O(1)±S±O(2) 111.6(3) O(1)±S±O(3) 115.5(3)

O(2)±S±O(3) 111.7(3)

Fig. 3. The IR spectrum of cesium 4-methylbenzenesulfonate (a) and 4-methylbenzenesulfonic acid monohydrate (b) in the 4000±400 cm21

region.

at 1190.3 and 1182.4 cm-1 were assigned to the anti-

symmetric stretching vibrations nasS±O(3)±CsB and

nasS±O(3)±CsE, the three bands at 1212.6, 1223.5 and

1245.3 cm21 were attributed to the antisymmetric

stretching vibration nasS±O(2)±CsC, nasS±O(2)±

CsE and nasS±O(2)±Cs. das(SO3) and ds(SO3) were

observed in the 580±550 cm21 and 490 cm21 regions,

respectively. The bands shift in this region is not as large

as those in the 1250±1150 cm21 region. In the complex,

das(SO3) and ds(SO3) occur at 559.7 and 495.2 cm21,

while in the ligand they are at 566.4 and 493.1 cm21,

respectively. The band in the 600±550 cm21 region is a

combination of several absorptions.

Acknowledgements

This study was supported by National Natural

Sciences Foundation of China (no. 29671002).

References

[1] T.J. Pinnavania, Science 220 (1983) 365.

[2] G. Cao, T.E. Mallouk, Inorganic Chemistry 30 (1991) 1434.

[3] Jpn. Kokai Tokky Koho JP 05, 222, 022[93, 222, 0221]/

(Cl.C07D307/33).

[4] Y. Ohki, Y. Suzuki, T. Takeuchi, A. Ouchi, Bulletin of the

Chemical Society of Japan 61 (1988) 393.

[5] Y. Ohki, Y. Suzuki, M. Nakamura, Bulletin of the Chemical

Society of Japan 58 (1985) 2968.

[6] P. Starynowicz, Acta Cryst. C48 (1992) 1414.

[7] J.W. Bats, P. Coppens, Acta Cryst. B31 (1975) 1467.

B. Sun et al. / Journal of Molecular Structure 470 (1998) 63±6666

Fig. 4. The IR spectrum of cesium 4-methylbenzenesulfonate (a) and 4- methylbenzenesulfonic acid monohydrate (b) in the 1300±400 cm21

region.

Table 2

The assignment of bands of ligand and complex in the FT-IR spectra

Ligand Complex Assignments

2668.9(vb)

2234.5(vb) nO-H

1924.0(w)

1846.1 (b)

1255.2(sh) 1245.3(sh)

1192.3 (sh) 1223.5(vs)

1179.4(sb) 1212.6(vs,sh)

1126.1 (vs) 1190.3(vs) nas SO3

1117.4(vs,sh) 1182.4(vs,sh)

1120.3(m)

1036.2(s) 1035.8(s) nsSO3

1007.4(s) 1012.6(s)

579.6(m, sh) 559.7(vs) das SO3

566.4(m)

493.1 (w) 495.2(w) ds SO3