Binding of arylsulphonates by cationic cobalt(III) complex: Syntheses, characterization and single crystal structure determination of [Co(phen) 2CO3](arylsulphonate)snH2O

Article abstract of DOI:10.1016/j.molstruc.2012.08.039

In an effort to study the binding of substituted arylsulphonates by cationic cobalt(III) complex [Co(phen)₂CO₃]⁺, two complex salts [Co(phen)₂CO₃](4- chlorobenzenesulphonate)s3H₂O, 1 and [Co(phen)₂CO ₃] (2,4-dinitrobenzenesulphonate)sH₂O, 2 have been synthesized. These complex salts were characterized by elemental analysis, solubility product, conductivity measurements, thermal and spectroscopic studies. The crystal structures of 1 and 2 have been determined by single-crystal X-ray structure determination. Both complex salts crystallize in triclinic system (space group P1?) with cell dimensions a = 10.215(5) , b = 12.013(5) , c = 12.822(5) , α = 69.497(5), β = 88.855(5), γ = 78.430(5)°, Z = 2, V = 1441.6(11) ³ for 1 and a = 7.730(5) , b = 13.958(5) , c = 14.020(5) , α = 73.763(5), β = 88.352(5), γ = 81.035(5)°, Z = 2, V = 1434.5(11) ³ for 2. The hydrogen bonding (CH?O and OH?O) and π-π stacking interactions result in the formation of bi-layered and zig-zag structures in 1 and 2 respectively. The facile formation of complex salts with small K_sp values and detailed packing analysis suggests that the [Co(phen)₂CO₃] ⁺ complex ion may be effective as a binding agent for substituted arylsulphonates in an aqueous medium.

Full text of DOI:10.1016/j.molstruc.2012.08.039

Journal of Molecular Structure 1033 (2013) 208–214
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Binding of arylsulphonates by cationic cobalt(III) complex: Syntheses,
characterization and single crystal structure determination
of [Co(phen)2CO3](arylsulphonate)ꢀnH2O
a
a
b
b,
Raj Pal Sharma a, , Ajnesh Singh , Paloth Venugopalan , Antonio Rodríguez-Diéguez , Juan M. Salas
⇑
⇑
a Department of Chemistry, Panjab University, Chandigarh 160 014, India
b Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
h i g h l i g h t s
"
"
"
"
Two cobalt(III) complexes containing arylsulphonate anions have been synthesized.
Complexes have been characterized by TGA, spectroscopy and X-ray crystallography.
Non-covalent interactions are playing crucial role in lattice stabilization.
Bi-layered and zig–zag layered packing arrangements have been observed.
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 May 2012
Received in revised form 21 August 2012
Accepted 21 August 2012
Available online 30 August 2012
In an effort to study the binding of substituted arylsulphonates by cationic cobalt(III) complex [Co(phen)2-
CO3]+, two complex salts [Co(phen)2CO3](4-chlorobenzenesulphonate)ꢀ3H2O, 1 and [Co(phen)2CO3] (2,4-
dinitrobenzenesulphonate)ꢀH2O, 2 have been synthesized. These complex salts were characterized by ele-
mental analysis, solubility product, conductivity measurements, thermal and spectroscopic studies. The
crystal structures of 1 and 2 have been determined by single-crystal X-ray structure determination. Both
0
ꢀ
complex salts0 crystallize in triclinic system (space group P1) with cell dimensions a = 10.215(5) ÅA,
0
0
Keywords:
b = 12.013(5) ÅA, c = 12.822(5) ÅA,
a
= 69.497(5), b = 808.855(5),
c
= 78.430(5)°, Z = 2, V = 1441.6(11) ÅA3 for 1
0
0
Hydrogen bonding
Cobalt(III) complexes
Arylsulphonates
Binding agents
and a = 7.730(5) ÅA, b = 13.958(5) ÅA, c = 14.020(5) ÅA,
a
= 73.763(5), b = 88.352(5),
c
= 81.035(5)°, Z = 2,
0
V = 1434.5(11) ÅA3 for 2. The hydrogen bonding (CAHꢀ ꢀ ꢀO and OAHꢀ ꢀ ꢀO) and
p–p stacking interactions
result in the formation of bi-layered and zig–zag structures in 1 and 2 respectively. The facile formation
of complex salts with small Ksp values and detailed packing analysis suggests that the [Co(phen)2CO3]+
complex ion may be effective as a binding agent for substituted arylsulphonates in an aqueous medium.
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
and effective binding agents. The directional nature of OAHꢀ ꢀ ꢀO,
OAHꢀ ꢀ ꢀN and NAHꢀ ꢀ ꢀO hydrogen bonds has been extensively uti-
The recognition and binding of anionic species is an area of cur-
rent interest in supramolecular chemistry [1]. The continuing inter-
est in the development of new binding agents (anion receptors) and
detailed study of their interactions with anionic species originates
from their potential applications in analytical chemistry, biology,
catalysis, etc. [2]. On the other hand, anions play crucial role in bio-
logical processes, medicine, catalysis and molecular assembly.
Additionally, various pollutant anions are believed to have deleteri-
ous effects on the environment [3,4]. A number of methodologies
have been devised to achieve the goal to synthesize new, cheap
lized to generate well-defined host–guest association patterns [5].
One strategy to achieve the effective binding is to use metal com-
plexes as cationic hosts because they can provide Lewis-acidic
binding sites, carry positive charge and also potentially increase
the strength of the non-covalent interactions by optimal orienta-
tion of the hydrogen-bond donor groups. The presence of a metal
centre confers useful optical, electrochemical and catalytic proper-
ties to the receptor molecules, which are helpful in detection of an-
ions and in determining the degree of receptor molecule–anion
association.
Our previous investigations have demonstrated that second-
sphere interactions along with other non-covalent interactions
impart significant binding opportunities to different organic and
inorganic anions [6]. In continuation of our studies on anion recogni-
tion properties, the binding of substituted arylsulphonates by
⇑
Corresponding authors. Tel.: +91 0172 2534433; fax: +91 0172 2545074 (R.P.
Sharma), tel.: +34 958248525; fax: +34 958248526 (J.M. Salas).
E-mail addresses: rpsharmapu@yahoo.co.in (R.P. Sharma), jsalas@ugr.es (J.M.
Salas).
0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.08.039

R.P. Sharma et al. / Journal of Molecular Structure 1033 (2013) 208–214
209
6H2O, 1,10-phenanthroline and sodium bicarbonate according to
the modified literature method [11]. C, H and N were estimated
micro-analytically by automatic PERKIN ELMER 2400CHN elemen-
tal analyzer. Cobalt was determined by standard volumetric meth-
od of estimation [12]. UV/Visible spectra were recorded using
HITACHI 330 spectrometer in water as solvent. Infrared spectra
of the title complex salts were recorded using PERKIN ELMER spec-
trum RX-1 FT-IR system using KBr pallet. 1H NMR and 13C NMR
spectra of title complex salts were recorded in the solvent
DMSO-d6 at 25 °C by using BRUKER AC 400 F (400 MHz) spectro-
photometer. The chemical shift values are expressed as d value
(ppm) down field from tetramethylsilane as an internal standard.
Conductance measurements were performed on Pico Conductivity
Meter (Model CNO4091201, Lab India) in aqueous medium at 25 °C
by using double distilled water.
Scheme 1. The arylsulphonate anions used.
cationic Co(III) complex [Co(phen)2CO3]+ has been investigated. The
interesting characteristic features of [Co(phen)2CO3]+ as a binding
agent include its high water solubility as its chloride salt, its positive
charge for electrostatic interactions with the anions and no fewer
than 16 CAH groups of its two coordinated phenanthroline ligands
that might act as weak hydrogen bond donor groups in CAHꢀ ꢀ ꢀX
interactions. The arylsulphonates were chosen for study because
they have number of industrial applications as surfactants, dyes,
lubricants, detergents and non-linear optical materials [7], besides
these, they are used in pharmaceutical preparations [8]. These inter-
esting applications of arylsulphonates prompted us to investigate
the binding of substituted arylsulphonates such as 4-chloro-
benzenesulphonate and 2,4-dinitrobenzenesulphonate (Scheme 1)
by using cationic cobalt(III) complex [Co(phen)2CO3]+. Although,
these substituted arylsulphonates have been used as catalysts for
nitration, sporadic reports are available in the literature related to
their structural characterization [9,10]. We now describe the
syntheses, spectroscopic studies and single crystal X-ray structure
determinations of [Co(phen)2CO3](4-chlorobenzenesulphonate)ꢀ
3H2O, 1 and [Co(phen)2CO3] (2,4-dinitrobenzenesulphonate)ꢀH2O, 2.
2.2. General synthesis
2.2.1. Synthesis of [Co(phen)2CO3](4-chlorobenzenesulphonate)ꢀ3H2O
(1)
[Co(phen)2CO3]Clꢀ5H2O (0.2 g, 0.33 mmol) was dissolved in
5 mL of water and to this, 5 mL aqueous solution of 0.063 g
(0.33 mmol) 4-chlorobenzenesulphonic acid and 0.013 g
(0.33 mmol) sodium hydroxide was added. When the resultant
solution was allowed to evaporate slowly at room temperature,
reddish-pink coloured crystals started appearing next day, which
were collected and dried in air (yield 75%). The complex salt decom-
posed at 210 °C. Anal. Calcd. for C31H26CoClN4O9S: C, 51.31; H, 3.59;
N, 7.72; Co, 8.14. Found (%): C, 51.03; H, 3.40; N, 7.50; Co, 7.96. IR/
cmꢁ1 (KBr pellet, b = broad, s = strong, m = medium, w = weak):
3440(b), 3057(w), 1657(s), 1633(s), 1517(m), 1427(s), 1341(w),
1223(m), 1190(s), 1120(w), 1004(s), 856(s), 752(s), 719(s), 647(s),
562(w), 482(m). 1H NMR/ppm (DMSO-d6): cation, [Co(phen)2CO3]+,
d = 9.25(d, H9), 9.20(d, H7), 8.91(d, H2), 8.89–8.40(m, H8/6/5),
7.83–7.75(m, H3/4); anion [C6H4SO3Cl]ꢁ d = 7.57(d, H2/6), 7.35(d,
H3/5). 13C NMR/ppm (DMSO-d6): d = 163.14, 154.11, 151.66,
147.31, 147.04, 146.82, 140.83, 139.82, 139.73, 132.88, 130.31,
130.16, 128.12, 127.99, 127.79, 127.66, 127.49, 127.45, 126.85. Sol-
2. Experimental
2.1. Materials and physical measurements
ubility (H2O, 25 °C) = 0.205 g/100 mL, Ksp = 8.0 ꢂ 10ꢁ6
(kmax, H2O): 509, 351, 272 and 224 nm.
. UV/Vis
All reagents and solvents were commercially available and used
directly without any further purification. The starting material,
[Co(phen)2CO3]Clꢀ5H2O was prepared by the reaction of CoCl2ꢀ
Table 1
2.2.2. Synthesis of [Co(phen)2CO3](2,4-dinitrobenzesulphonate)ꢀH2O
(2)
Crystal data, data collection ad refinement details of complex salts 1 and 2.
Complex salt
1
2
[Co(phen)2CO3]Clꢀ5H2O (0.3 g, 0.5 mmol) was dissolved in
10 mL of water in a beaker and to this, 10 mL aqueous solution
of 0.134 g (0.5 mmol) sodium 2,4-dinitrobenzenesulphonate, sepa-
rately dissolved in another beaker, was added. When the resultant
solution was allowed to evaporate slowly at room temperature,
reddish-pink coloured crystals started appearing next day, which
were collected and dried in air (yield 78%). The complex salt
decomposed at 205 °C. Anal. Calcd. (%) for C31H21CoN6O11S: C,
49.96; H, 2.82; N, 11.28; Co, 7.92. Found (%): C, 49.50; H, 2.70; N,
11.35; Co, 7.52. IR/cmꢁ1(KBr): 3479(b), 3068(w), 1671(s),
1636(m), 1603(w), 1522(s), 1430(m), 1347(m), 1246(m), 1115(s),
1026(w), 850(s), 748(m), 718(s), 637(w), 555(w), 481(w). 1H
NMR/ppm (DMSO-d6): cation, [Co(phen)2CO3]+, d = 9.26–9.20(m,
H9/7), 8.90(d, H2), 8.53–8.36(m, H8/5/6), 7.83–7.75(m, H3/4); An-
ion, [C6H3N2O7S]ꢁ, d = 8.53–8.36(m, H3/5), 8.07(d, H6). 13C NMR/
ppm (DMSO-d6): d = 163.14, 154.08, 151.62, 147.39, 147.03,
146.81, 144.69, 140.81, 139.76, 130.75, 130.29, 130.14, 127.98,
127.77, 126.82, 125.65, 118.35, Solubility (H2O, 25 °C) = 0.034 g/
100 mL, Ksp = 2.07 ꢂ 10ꢁ7. UV/Vis (kmax, H2O): 509, 349, 271, 224
and 206 nm.
Chemical formula
CCDC
C31 H26 N4O9SClCo
879592
725.00
100
0.71073
Triclinic
C31H21N6O11SCo
879593
744.53
100
0.71073
Triclinic
M (g molꢁ1)
T (K)
k (Å)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
ꢀ
ꢀ
P1
P1
10.215(5)
12.013(5)
12.822(5)
69.497(5)
88.855(5)
78.430(5)
1441.6(11)
2
1.670
0.827
14302
0.033
7.730(5)
13.958(5)
14.020(5)
73.763(5)
88.352(5)
81.035(5)
1434.5(11)
2
1.724
0.751
14182
0.032
a
(°)
b (°)
c
(°)
V (Å3)
Z
q
l
(g cmꢁ3
(mmꢁ1
)
)
Unique reflections
R(int)
GOF on F2
1.094
0.045
0.118
1.099
0.038
0.099
R1 [I > 2
wR2 [I > 2
r
(I)]
(I)]
r

210
R.P. Sharma et al. / Journal of Molecular Structure 1033 (2013) 208–214
Scheme 2. Schematic representation of synthetic procedure.
Table 2
Selected bond lengths and bond angles around Co(III) metal centre in complex salt 1.
Bond distances (Å)
Co1AO2C
Co1AO1C
Co1AN1A
1.898(2)
1.905(2)
1.924(3)
Co1AN1B
Co1AN8B
Co1AN8A
1.932(3)
1.943(3)
1.962(3)
Bond angles (°)
O1CACo1AN1A
O2CACo1AN1B
O1CACo1AN1B
O2CACo1AN8B
N1AACo1AN8B
O2CACo1AN8A
N1AACo1AN8A
N8BACo1AN8A
91.36(10)
92.65(10)
91.11(9)
165.13(9)
94.52(10)
94.50(9)
O2CACo1AO1C
O2CACo1AN1A
N1AACo1AN1B
O1CACo1AN8B
N1BACo1AN8B
O1CACo1AN8A
N1BACo1AN8A
69.30(9)
89.11(10)
177.35(10)
96.17(9)
84.27(11)
163.33(9)
93.64(10)
Fig. 1. ORTEP diagram of complex salt 1. The displacement ellipsoids are drawn at
40% probability and hydrogen atoms are removed for clarity.
84.25(10)
100.20(10)
ters [16]. All hydrogen atoms were located in difference Fourier
maps and included as fixed contributions riding on attached atoms
with isotropic thermal displacement parameters 1.2 times those of
the respective atoms. In general, the structures have disorder prob-
lems with the solvent molecules. For this reason, in complexes 1
and 2 some hydrogen atoms have been omitted. Crystal data, data
collection and final refinement parameters are reported in Table 1.
Table 3
Selected bond lengths and bond angles around Co(III) metal centre in complex salt 2.
Bond lengths (Å)
Co1AO1C
Co1AO2C
Co1AN1A
1.8879(17)
1.8928(18)
1.921(2)
Co1AN1B
Co1AN8B
Co1AN8A
1.933(2)
1.947(2)
1.955(2)
3. Results and discussion
Bond angles (°)
O1CACo1AO2C
O2CACo1AN1A
O2CACo1AN1B
O1CACo1AN8B
N1AACo1AN8B
O1CACo1AN8A
N1AACo1AN8A
N8BACo1AN8A
69.91(8)
88.93(8)
90.67(8)
99.75(8)
96.11(9)
169.92(7)
84.21(8)
89.92(8)
O1CACo1AN1A
O1CACo1AN1B
N1AACo1AN1B
O2CACo1AN8B
N1BACo1AN8B
O2CACo1AN8A
N1BACo1AN8A
91.89(8)
87.97(8)
179.60(8)
168.71(8)
84.28(9)
100.66(8)
95.86(8)
3.1. Syntheses
The complex salts 1 and 2 were synthesized by the reaction of
[Co(phen)2CO3]Clꢀ5H2O with sodium salts of respective sulphonic
acids in the aqueous medium in 1:1 M ratio (Scheme 2). The newly
formed complex salts are soluble in methanol, dimethylformam-
ide, dimethylsulphoxide and sparingly soluble in water. The com-
plex salts 1 and 2 decomposed in the range 200–210 °C. These
new complexes have been characterized on the basis of elemental
analyses, spectroscopic studies (IR, UV/Visible, 1H and 13C NMR)
and conductance measurements. The crystal structures of both
these complex salts have been unambiguously established by sin-
gle crystal X-ray structure determination.
2.2.3. Single-crystal structure determination
Suitable single crystals of 1–2 were mounted on glass fibre and
used for X-ray data collection. Data were collected with a Bruker
AXS APEX CCD area detector equipped with graphite monochro-
mated Mo K
a radiation (k = 0.71073 Å) by applying the x-scan
method. The data were processed with APEX2 [13] and corrected
for absorption using SADABS [14]. The structures were solved by
direct methods using SIR97 [15], revealing positions of all non-
hydrogen atoms. These atoms were refined on F2 by a full matrix
least-squares procedure using anisotropic displacement parame-
3.2. Thermal studies
The thermal behaviour of complex salts 1 and 2 were examined
by TGA under nitrogen atmosphere. In complex salts 1, the weight
Table 4
A comparison of structural parameters of complex salts 1,2 and related complex salts.
S. no.
Complex salt
Bond lengths
Bond angles
References
SAO
SAC
SACl
OASAO
Complex salt 1
1
2
3
4
2,4-dichloroanilinium 4-chlorobenzenesulphonate
2,5-dichloroanilinium 4-chlorobenzenesulphonate
1-Methyl-4-[(E)-2-(2-thienyl)ethenyl] pyridinium 4-chlorobenzenesulphonate
[Co(phen)2CO3](4-chlorobenzenesulphonate)ꢀ3H2O
1.441(2)
1.436(2)
1.455(1)
1.453(2)
1.753(3)
1.766(2)
1.781(2)
1.785(3)
1.733(4)
1.744(3)
1.711(2)
1.740(3)
112.32(17)
112.75(10)
113.09(7)
113.10(15)
[26a]
[26b]
[26c]
Present work
Complex salt 2
SAO
SAC
NAO
OANAO
OASAO
1
2
3
1H-1,2,4-Triazol-4-ium 4-nitro-benzene-sulphonateꢀH2O
1.446(2)
1.456(1)
1.447(2)
1.779(2)
1.787(1)
1.799(2)
1.223(3)
1.225(2)
1.226(3)
123.5 (2)
123.5(1)
124.5(2)
112.9(1)
113.3(1)
113.6(1)
[27a]
[27b]
Present work
Triethyl-ammonium 4-nitrobenzene-sulphonate
[Co(phen)2CO3](2,4-dinitrobenzenesulphonate)ꢀH2O

R.P. Sharma et al. / Journal of Molecular Structure 1033 (2013) 208–214
211
Table 5
Hydrogen bonding parameters of [Co(phen)2CO3](4-chlorobenzenesulphonate) 3H2O,
1.
DAHꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA (Å)
Hꢀ ꢀ ꢀA (Å)
DAHꢀ ꢀ ꢀA (°)
O1WAH11Wꢀ ꢀ ꢀO43D
O2WAH21Wꢀ ꢀ ꢀO41D
O2WAH22Wꢀ ꢀ ꢀO3Ci
C3BAH3Bꢀ ꢀ ꢀO1Wiii
C4AAH4Aꢀ ꢀ ꢀO41Div
C4BAH4Bꢀ ꢀ ꢀO1Wv
2.854
2.822
2.891
3.363
3.246
3.464
3.160
3.615
3.057
3.169
3.182
3.382
3.468
3.353
2.094
2.076
2.130
2.521
2.368
2.567
2.410
2.782
2.353
2.546
2.381
2.624
2.596
2.458
161.38
166.51
162.03
150.73
157.39
162.55
137.65
149.65
132.26
124.69
144.27
139.13
156.48
161.61
C10AAH10Aꢀ ꢀ ꢀO42Diii
C6DAH6Dꢀ ꢀ ꢀO41Dvi
C9BAH9Bꢀ ꢀ ꢀO2Wvi
C13AAH13Aꢀ ꢀ ꢀO3Wvii
C13AAH13Aꢀ ꢀ ꢀO2Cvii
C13BAH13Bꢀ ꢀ ꢀO1Cviii
C14AAH14Aꢀ ꢀ ꢀO43Div
C14BAH14Bꢀ ꢀ ꢀO3C ix
Equivalent positions: (i) x ꢁ 1, +y + 1, +z, (ii) ꢁx + 2, ꢁy + 1, ꢁz, (iii) ꢁx + 1, ꢁy + 1,
ꢁz + 1, (iv) x + 1, +y, +z, (v) x, +y ꢁ 1, +z, (vi) ꢁx + 1, ꢁy + 2, ꢁz, (vii) ꢁx + 2, ꢁy + 1,
ꢁz + 1, (viii) ꢁx + 1, ꢁy + 1, ꢁz, (ix) x ꢁ 1, +y, +z.
loss of 7.21% in the temperature range of 30–100 °C, corresponds to
the loss of three water molecules of crystallization (calc 7.44%).
Further heating to 1000 °C led to continuous weight loss and no
clear steps were observed.
In case of complex salt 2, the first weight loss of 2.9% (calc
2.42%) corresponds to the loss of one water molecule of crystalliza-
tion. After the loss of water molecule, the complex has shown sim-
ilar thermal behaviour as to that of complex 1.
Fig. 3. ORTEP diagram of complex salt 2. The displacement ellipsoids are drawn at
40% probability and hydrogen atoms are removed for clarity.
of solubility product (Ksp) determined at 25 °C for complex salts 1
and 2 were 8.0 ꢂ 10ꢁ6 and 2.07 ꢂ 10ꢁ7 respectively. These values
showed that complex cation [Co(phen)2CO3]+ has more affinity
for 2,4-dinitrobenzenesulphonate than 4-chlorobenzenesulpho-
nate. This affinity may be due to the increased interactions be-
tween cations and anions.
3.3. Solubility products measurement
3.4. Molar conductivity measurements
Solubility of ionic salts in the water differ to greater extend. The
measurement of the solubility product provides an idea about the
magnitude of interactions between cations and anions. The values
Molar conductivities of complex salts 1 and 2 were measured at
25 °C in aqueous medium. The limiting molar conductivity at
Fig. 2. Packing diagram of complex salt 1 showing bi-layered structure. The benzene sulphonate anions are shown in space-filling model while on right side bottom only
complex cations are shown in space filling model for clarity.

212
R.P. Sharma et al. / Journal of Molecular Structure 1033 (2013) 208–214
to
m(OAH) of H2O, m(@CAH), m(C@O) and m(C@C/N) d(HAC@) and
Table 6
m
(CoAN) vibrations, respectively. These spectral assignments have
Hydrogen bonding parameters of [Co(phen)2CO3](2,4-dinitrobenzene sulphonate)
H2O, 2.
been made in consultation with literature values [20].
In case of complex salt 1, the bands at 1233, 1189, 562 and
DAHꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA (Å)
Hꢀ ꢀ ꢀA (Å)
DAHꢀ ꢀ ꢀA (°)
671 cmꢁ1 were assigned to
m
as(SO3),
respectively, while in case of complex salt 2, the bands at 1246,
1226, 554, 509 and 637 cmꢁ1 were assigned to
as(SO3), s(SO3),
das(SO3), ds(SO3) and (CAS) respectively. These bands are charac-
ms(SO3), das(SO3) and m(CAS)
O1WAH12Wꢀ ꢀ ꢀO1Ci
O1WAH12Wꢀ ꢀ ꢀO3Ci
O1WAH11Wꢀ ꢀ ꢀO21D
C2AAH2Aꢀ ꢀ ꢀO12Di
C4AAH4Aꢀ ꢀ ꢀO3Ci
3.122
3.073
2.898
3.310
3.127
3.352
3.465
3.349
3.310
3.240
3.303
3.288
3.302
3.196
3.177
3.474
2.496
2.331
2.158
2.547
2.358
2.492
2.672
2.555
2.596
2.609
2.705
2.541
2.562
2.399
2.509
2.669
131.5
146.4
152.3
139.6
139.8
153.9
143.6
143.6
134.0
125.5
122.8
137.6
136.9
143.7
129.0
145.4
m
m
m
teristic for the presence of anion, i.e. sulphonates. The presence
of similar bands were also reported in complex salts [Co(en)2(N3)2]
[(CH3)3ꢀC6H2ꢀSO3]ꢀ0.5H2O [21a] and [Co(NH3)6](CH3SO3)3 [21b].
C4BAH4Bꢀ ꢀ ꢀO21Dii
C6DAH6Dꢀ ꢀ ꢀO2C
C9AAH9Aꢀ ꢀ ꢀO51Diii
C9BAH9Bꢀ ꢀ ꢀO3Civ
The IR bands due to mas(NO2) and ms(NO2) vibrations were observed
C10BAH10Bꢀ ꢀ ꢀO1Wv
C11AAH11Aꢀ ꢀ ꢀO52Div
C11AAH11Aꢀ ꢀ ꢀO23Dvi
C11BAH11Bꢀ ꢀ ꢀO1Cvii
C13AAH13Aꢀ ꢀ ꢀO23Dvi
C14AAH14Aꢀ ꢀ ꢀO11Div
C11BAH11Bꢀ ꢀ ꢀO1Wviii
at 1522 and 1347 cmꢁ1, respectively in case of complex salt 2. IR
bands at 1573, 1322 cmꢁ1 and 1586, 1337 cmꢁ1 due to
s(NO2)
and as(NO2) vibrations have been reported in the complex salts
m
m
containing nitrophenolate anions; [Co(NH)6](4-np)3ꢀ4H2O [22]
and [PPh3)3Cu(4-np)]2 [23], respectively.
In complex salts 1 and 2, 1H and 13C NMR chemical shift values
are in good agreement with literature values reported for complex
cation [Co(phen)2CO3]+ and different arylsulphonates [19b,24]. The
detailed NMR peak assignments for complexes 1 and 2 are given in
experimental section.
Equivalent positions: (i) ꢁx, ꢁy + 1, ꢁz + 1, (ii) x + 1, +y ꢁ 1, +z, (iii) ꢁx, ꢁy, ꢁz + 2,
(iv) x ꢁ 1, +y, +z, (v) ꢁx ꢁ 1, ꢁy + 1, ꢁz + 1, (vi) ꢁx ꢁ 1, ꢁy + 1, ꢁz + 2, (vii) ꢁx, ꢁy,
ꢁz + 1, (viii) x, +y ꢁ 1, +z.
infinite dilution (Ko) was calculated by plotting molar conductivity
versus square root of concentration. The Ko values obtained for
salts 1 and 2 (116 and 61 S cm2 molꢁ1) were closer to the range
of 1:1 electrolytes [17]. The lower value observed in the case of
complex salt 2 may be ascribed to ion-pair formation.
3.6. Structure descriptions
3.6.1. Coordination geometry and bonding
The geometry around Co(III) metal centre is distorted octahedral
and the extent of distortion is 20.7 and 20.09° in 1 (Fig. 1) and 2
(Fig. 3) respectively from the ideal value of 90° for cis NACoAN bond
angles (as revealed from the geometrical parameters reported in
Tables 2 and 3). The coordination around Co(III) is completed by
two bidantate 1,10-phenanthroline and one carbonato ligands. In
complex salts 1 and 2, the average CoAN, CoAO bond lengths
and bond angles O(1)ACoAO(2), N(1)ACoAN(2) and N(3)ACoAN(4)
are quite similar to those of reported related complexes
[11,18,19b,c,25]. The density values of the two structures are in the
range 1.501–1.769 g/cm3 reported for similar complexes in the liter-
atures. Therefore, complex salts 1 and 2 can be classified as ionic salts.
The aromatic rings of the phen moieties attached to the cobal-
t(III) centre are almost planar in both complex salts. The angles be-
tween the least square planes of phen rings in complex salts 1 and
2 are 114.38° and 87.36°, respectively. The significant deviation
3.5. Spectroscopic characterization
For low spin Co(III) complexes, two types of transitions i.e.
1A1g ? T1g and 1A1g ? 1T2g are expected. In [Co(phen)2CO3]+ com-
plex salts, these transitions were observed around 500 and
350 nm as reported in the literature [18]. For the complex salts 1
and 2, these values were observed around 510 and 350 nm, respec-
tively. Other transitions due to phen (1,10-phenantholine) groups
coordinated to the cobalt(III) were also observed. Peaks observed
around 272 and 224 nm in complex salts 1 and 2 were assigned
to
p–
p⁄ transition in coordinated phen groups [19]. The detailed
peak assignments are given in experimental section.
Vibrational spectra of newly synthesized complex salts have been
recorded in the range 400–4000 cmꢁ1. In the FT IR spectra of complex
salts 1 and 2, bands in the regions 3479–3440, 3069–3057,
1671–1657, 1630–1620, 856–850 and 482–481 cmꢁ1 were assigned
from orthogonality in
arrangement of anions in the ‘V’ shaped arrangement of phen rings
1 can be explained on the basis of
Fig. 4. Packing diagram of complex salt 2 showing the zig–zag arrangement of complex cations and anions are shown by space filling model. For clarity the arrangement of
only complex cations is shown in ball-stick model.

R.P. Sharma et al. / Journal of Molecular Structure 1033 (2013) 208–214
213
coordinated to Co(III) centre. In the complex salt 2, the nitro group
at the ortho position in 2,4-dinitrobenzesulphonate anion is out of
plane from the aromatic ring (C2DAC1DAN11DAO12D torsion
angle of ꢁ61.73°) while nitro group presents at para position is al-
most planar to the benzene ring (C4DAC5DAN51DAO51D = 4.59°).
Probably, the presence of sulphonate group and nitro groups at
adjacent positions (steric crowding) necessitates this out of plane
twist of NO2 group. As expected, the bond lengths and bond angles
for anions (i.e. arylsulphonates) are similar to those ionic com-
plexes of arylsulphonates reported in the literature [19b,10,26–
28]. A comparison of structural parameters is given in Table 4
shows that there is no significant effect of change of counter cat-
ions on structural parameters of arylsulphonates.
aromatic ring of anion and central phen-ring is 3.756 Å). In the cat-
ionic layers, the carbonato oxygen atom O3C plays a crucial role by
connecting different cationic units. It is involved in two CAHꢀ ꢀ ꢀO
and one OAHꢀ ꢀ ꢀO hydrogen bonding interactions. Additionally,
O3C is also involved in Oꢀ ꢀ ꢀ
p interaction with phen moiety with
oxygen to centroid of aromatic ring distance of 3.081 Å. These
interactions are complemented by stacking interaction
p–p
between phen rings of the complex cations (centeroid to centeroid
distance between phen rings is 3.659 Å).
4. Conclusions
In an effort to investigate the binding of substituted arylsulph-
onates by cationic cobalt(III) complex, two salts [Co(phen)2CO3](4-
chlorobenzenesulphonate)ꢀ3H2O, 1 and [Co(phen)2CO3] (2,4-dini-
trobenzenesulphonate)ꢀH2O, 2 have been synthesized and charac-
terized by elemental analyses, solubility product, conductivity
measurement, thermal, spectroscopy (FT IR, NMR and UV/Vis)
studies and single crystal X-ray crystallography. Single crystal X-
ray structure determination revealed the presence of ionic struc-
tures with [Co(phen)2CO3]+ complex cation, respective arylsulpho-
nate anions and water molecules of crystallization. The crystal
packing of complex salts is stabilized by interplay of non-covalent
3.6.2. Packing
3.6.2.1. Complex salt 1. The complex salt 1 crystallizes in triclinic crys-
ꢀ
tal system with space group P1. The asymmetric unit of 1 contains one
4-chlorobenzenesulphonate anion, one [Co(phen)2CO3]+ cation and
three water molecules of crystallization (Fig. 1). The hydrogen
bonding parameters are given in Table 5. The crystal lattice is stabilized
by the non-covalent interactions like OAHꢀ ꢀꢀO(water/sulphonate),
CAHꢀꢀꢀO(water/sulphonate), anionꢀꢀꢀp and p–p stacking. In the
crystal lattice, the water molecules of crystallization are involved in
the OAHꢀ ꢀꢀO interaction with oxygen O3C of complex cation and
oxygen atoms O41D and O43D of anion i.e. they act as a linker between
the cationic and anionic moieties. These OAHꢀ ꢀꢀO interactions results
R43ð9Þ graph set pattern [29] (Fig. 2). When packing of the complex salt
is viewed down a axis, a bilayered structure can be visualized as shown
in Fig. 2. One layer is constituted by complex cations which are ar-
ranged in such a way that both the phen moieties of the complex cation
interactions like OAHꢀ ꢀ ꢀO, CAHꢀ ꢀ ꢀO,
p
ꢀ ꢀ ꢀ
p
and Oꢀ ꢀ ꢀ
p besides elec-
trostatic forces of attraction. Thus, non-covalent interactions play
crucial role in binding of substituted arylsulphonates. On the basis
of solubility product measurements and packing analyses, it has
been shown that cationic metal complex is a promising binding
agent for substituted arylsulphonates in aqueous medium.
are involved in the
originated from the other two complex cations on the respective sides.
These phen moieties have stacking of 3.637 and 3.585 Å (distance
p–p stacking interactions with the phen moieties
Acknowledgements
p–p
The authors gratefully acknowledges the financial support of
CSIR vide Grant No. 09/135/0594/2010/EMR-1. We thank financial
support by the Junta de Andalucía (FQM-3705 and FQM-4228).
between the centroids of respective rings). The other layer is formed by
anions and water molecules of crystallization. These cationic and anio-
nic layers are anchored in the crystal lattice by hydrogen bond interac-
tion as described in the graph set pattern. Each of the anionic moieties
are placed in the ‘V’ shaped arrangement of two phen moieties that are
coordinated to cobalt(III) centre. The anionic moiety has short contacts
to both the phen moieties as C2DꢀꢀꢀC13A = 3.228 Å and
C5Dꢀꢀ ꢀC9B = 3.387 Å. This may be the reason for the strong deviation
of the phen moieties from the orthogonality. The anionic species are
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