Synthesis and structural characterization of zinc complexes with sulfonamides containing 8-aminoquinoleine

Article abstract of DOI:10.1002/zaac.200390041

Sulfonamides obtained by reaction of 8-aminoquinoline with benzenesulfonyl, toluene-4-sulfonyl and naphthalene-2-sulfonyl chlorides have been used to synthetize coordination compounds with Zn^II with a ZnL₂ composition. Determination of the crystal structures for the resulting complexes by X-ray diffraction shows a distorted tetrahedral environment for the Zn²⁺ ions, sulfonamides acting as bidentate ligands through the nitrogen atoms from the sulfonamidate and quinoline groups. FT-IR, ¹H and ¹³C NMR and mass spectra of these compounds are also discussed.

Full text of DOI:10.1002/zaac.200390041

Synthesis and Structural Characterization of Zinc Complexes with Sulfonamides
containing 8-Aminoquinoleine
a
a
a
b
c
´
´
´
´
´
˜
Benigno Macıas *, Isabel Garcıa , Marıa V. Villa , Joaquın Borras , Alfonso Castineiras , and
Francisca Sanzd
a
a,d Salamanca/Spain, Universidad, Departamento de Quımica Inorganica, Facultad de Farmacia and d Servicio de Rayos X
´
´
b
´
´
Valencia/Spain, Universidad, Departamento de Quımica Inorganica, Facultad de Farmacia
Santiago de Compostela/Spain, Universidad, Departamento de Quımica Inorganica, Facultad de Farmacia
c
´
´
Received October 2nd, 2002.
th
˜
Dedicated to Professor Alfonso Castineiras on the Occasion of his 60 Birthday
Abstract. Sulfonamides obtained by reaction of 8-aminoquinoline
with benzenesulfonyl, toluene-4-sulfonyl and naphthalene-2-sul-
fonyl chlorides have been used to synthetize coordination com-
pounds with ZnII with a ZnL2 composition. Determination of the
crystal structures for the resulting complexes by X-ray diffraction
shows a distorted tetrahedral environment for the Zn2ϩ ions, sul-
fonamides acting as bidentate ligands through the nitrogen atoms
1
from the sulfonamidate and quinoline groups. FT-IR, H and 13C
NMR and mass spectra of these compounds are also discussed.
Keywords: Zinc; Sulfonamide complexes; 8-Aminoquinoline; Crys-
tal structures
Synthese und Strukturen von Zink-Komplexen mit Sulfonamid-8-aminochinoleinen
Inhaltsübersicht. 8-Aminochinolin-Sulfonamide mit Phenylsulfo-
nyl-, 4-Tolylsulfonyl- und 2-Naphthylsulfonyl-Resten wurden zur
Synthese von ZnII-Komplexen der Zusammensetzung ZnL2 einge-
setzt. Die Bestimmung ihrer Kristallstrukturen zeigt verzerrt tetrae-
drische Umgebung der Zn2ϩ-Ionen, wobei die Ligandengruppen
als zweizählige Chelatliganden über die N-Atome von Sulfamidi-
nat- und Chinolin-Gruppe fungieren. FT-IR-, 1H-, 13C-NMR- und
Massenspektren werden mitgeteilt.
Introduction
(Hqtsa)
and
N-quinolin-8-yl-naphthalenesulfonamide
(Hqnsa), which have been used to prepare the correspond-
ing coordination compounds with nickel [19] and copper
[20, 21], which nuclease activity has been also tested.
Because of the interesting properties displayed by these
complexes with ZnII, we here report the synthesis and
characterization of the coordination compounds formed by
ZnII with the above mentioned sulfonamides. In addition to
structural determination 1H and 13C NMR spectral proper-
ties are also reported.
Coordination chemistry of sulfonamides has undergone a
noticeable development in recent years because of their
interesting properties, both academic (groups involved in
coordination to the metal ion and the effect of the sulfonyl
group on the donor ability of the adjacent nitrogen atom
[1Ϫ8]), as well as practical, due to the huge number of ap-
plications [9Ϫ12]. Although many of the coordination com-
pounds prepared so far contain copper as the metal ion,
many compounds have been prepared with zinc; the struc-
tures of some of these complexes have been solved [13], and
their applications as carbonic anhydrase inhibitors [10,
14Ϫ16], antifungal activity [17] or as potentially powerful
probes of intracellular zinc chemistry [18] have been investi-
gated.
Experimental
Materials and Methods
We have previously reported on the synthesis and charac-
terization of three sulfonamides: N-quinolin-8-yl-benzene-
sulfonamide (Hqbsa), N-quinolin-8-yl-toluenesulfonamide
8-aminoquinoline and sulfonyl chlorides were provided by Aldrich
and Fluka, respectively, and all reagents were of analytical grade.
Chemical analyses for carbon, hydrogen and nitrogen were per-
formed on a 2400 elemental analyser from Perkin-Elmer. Zinc was
determined on an ICP spectrometer (Perkin-Elmer model 2380
Plasma 2). FT-IR spectra were recorded using KBr mulls and a
Perkin-Elmer FT-IR 1730 instrument. Molecular masses were
´
* Dr. B. Macıas
´
´
Dpto. Quımica Inorganica, Facultad de Farmacia
Campus Unamuno
´
measured by Servicio de Masas (Universidad Autonoma de Mad-
rid, Spain) by the FAB method with samples held on a nitrobenzyl
alcohol (NBA) matrix. 1H and 13C NMR spectra were obtained in
CDCl3 on a Bruker DX400 instrument.
E-37007-Salamanca/Spain
Fax: 34-23-294515
e-mail: bmacias@usal.es
Z. Anorg. Allg. Chem. 2003, 629, 255Ϫ260  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 0044Ϫ2313/03/629/255Ϫ260 $ 20.00ϩ.50/0
255

´
´
´
B. Macıas, I. Garcıa, M. V. Villa, J. Borras, A. Castin˜eiras, F. Sanz
2
ameters for non-H atoms was carried out by minimizing ω(Fo -
Preparation of the compounds
Fc ) . Refinement on F2 for all reflections, weighted R factors and
2 2
all goodness of fit S are based on F2, while conventional R factors
are based on F; R factors based on F2 are statistically about twice
as large as those based on F, and R factors based on all data will
be even larger. All calculations were performed using CRYSOM
[30] software for data collection, XRAY8O [31] for data reduction,
SHELXTL [32] to resolve and refine the structure and to prepare
material for publication.
The sulfonamide ligands were prepared by direct synthesis between
8-aminoquinoline with the corresponding sulfonyl chloride, follow-
ing the method described elsewhere [19Ϫ21].
The complexes were prepared by direct reaction between the sul-
fonamide ligands and ZnII salts. Although the copper complexes
were prepared in a neutral medium [20, 21], addition of a base for
deprotonating the amine nitrogen atom was necessary to prepare
the zinc complexes. The process can be summarized as follows:
1.5 mmol of the sulfonamide are dissolved in 75 ml methanol and
2 ml 2M NH3 are added. While this solution is magnetically stirred,
0.75 mmol ZnCl2 dissolved in 50 ml methanol are dropwise added.
When addition is completed a yellow precipitate is formed which
is separated by filtration. Yield is 80Ϫ85 %.
For the complex [Zn(qnsa)2], a yellow prismatic crystal was
mounted on a glass fiber and used for data collection. Crystal data
were collected using a Bruker SMART CCD 1000 diffractometer.
Graphite monochromated MoKα radiation was used throughout.
The data were processed with SAINT [33] and corrected for ab-
sorption using SADABS (transmissions factors: 1.000-0.694) [34].
The structure was solved using the program SHELXS-97 [25] and
refined by full-matrix least-squares techniques against F2 using
SHELXS-97 [26]. Positional and anisotropic atomic displacement
parameters were refined using a riding model. Isotropic atomic dis-
placement parameters for hydrogen atoms were constrained to be
1.2 times those of the respective C atoms. Criteria of a satisfactory
complete analysis were the ratios of rms shift to standard deviation
less than 0.01 and no significant features in final difference maps.
Atomic scattering factors from “International Tables for Crystal-
lography” [27]. Molecular graphics from PLATON [28] and
SCHAKAL [29].
Analytical data: [Zn(qbsa)2]: Found: C, 56.70; H, 3.32; N, 9.05; Zn,
10.69. Calculated for ZnC30H22N4O4S2: C, 57.02; H, 3.51; N, 8.87;
Zn, 10.34 %.
[Zn(qtsa)2]: Found: C, 58.11; H, 3.91; N, 8.33; Zn, 9.75. Calculated
for ZnC32H26N4O4S2: C, 58.23; H, 3.94; N, 8.49; Zn, 9.91 %.
[Zn(qnsa)2]: Found: C, 61.81; H, 3.54; N, 7.91; Zn, 9.14. Calculated
for ZnC38H26N4O4S2: C, 62.34; H, 3.55; N, 7.66; Zn, 8.94 %.
To prepare the solids in crystalline form, the precipitates are dis-
solved in DMF (dimethylformamide) and, upon standing at room
temperature yellow crystals, suitable for single crystal X-ray diffrac-
tion studies, are formed. As shown below, compound [Zn(qbsa)2]
crystallizes with a molecule of solvent (DMF), while complex
[Zn(qtsa)2] with half a molecule of water.
A summary of the crystal data, experimental details and refinement
results are listed in Table 1 for the three complexes. Table 2 shows
some selected structural information. Complete lists with atomic
coordinates, anisotropic displacement parameters, bond lengths
and angles have been deposited at the Cambridge Crystallographic
Data Center, 912 Union Road, Cambridge CB2 1EZ, UK (fax:
ϩ44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk) [CCDC: 193501, 194345 and 194346].
Crystal Structures Determination
A light yellow plate crystal of [Zn(qbsa)2]·DMF was mounted on
a glass fiber and used for data collection. Cell constants and an
orientation matrix for data collection were obtained by least-
squares refinement of the diffraction data from 25 reflections in the
range of 14.09 <θ < 23.92° on an Enraf Nonius CAD4 automatic
diffractometer [22]. Data were collected using CuKα radiation and
the ω-scan technique, and corrected for Lorentz and polarization
effects [23]. A semi-empirical absorption correction ψscan was
made [24]. The structure was solved by direct methods [25] and
subsequent difference Fourier maps, and refined on F2 by a full-
matrix least-squares procedure using anisotropic displacement par-
ameters [26]. All hydrogen atoms were located in their calculated
Results and Discussion
Crystal Structure of the complexes
Molecular structures for the three zinc complexes are shown
in Figures 1, 2 and 3, which show that, as expected, the
local environment around the Zn2ϩ cations is similar in all
three cases, bearing in mind the similarities among the three
ligands. The structures correspond to highly distorted tetra-
hedron, where the sulfonamide acts as a bidentate ligand.
Zn-ligand bonding takes place through the nitrogen atoms
of the sulfonamide and quinoline groups. Bond distances,
also similar in all three compounds, are slightly larger to
the quinoline nitrogen than to the sulfonamide nitrogen
atoms, as previously reported for the corresponding Ni and
Cu compounds [19Ϫ21], and all them are in the range re-
ported in the literature [15, 16, 18] for complexes of Zn with
other sulfonamides. The distances between the zinc cation
and the oxygen atoms of the sulfonyl groups are larger than
˚
positions (C-H 0.93-0.97 A) and were refined using a riding model.
Atomic scattering factors from “International Tables for X-ray
Crystallography” [27]. Molecular graphics from PLATON [28] and
SCHAKAL [29].
For the yellow complex [Zn(qtsa)2] data were collected on a four
circle Seifert XRD 3003 SC diffractometer using CuKα radiation,
graphite monochromator and the ω-2θ scan technique. The unit
cell parameters were determined by least squares refinement on the
2θ values of 25 strong well centered reflections in the range 16
< 2θ < 40°. Scattering factors for neutral atoms and anomalous
dispersion correction for Zn, C, N, O and S were taken from “Inter-
national Tables for X-ray Crystallography” [27]. The structure was
resolved by direct methods and refined in the monoclinic space
group C2/c. Structure determination of the title compound af-
forded one water molecule at a fully occupied special position (4e)
with point symmetry 2, but its hydrogen atoms were not found.
Full matrix least-squares refinement with anisotropic thermal par-
˚
3.0 A, thus indicating the lack of chemical bonding between
these two atoms, so providing space for coordination of the
amine nitrogen atom. The sulfonamide molecule forms a
stable five-membered ring with the metal cation.
The bond angles N(11)-Zn-(N12) and N(21)-Zn-N(22),
are in the 80Ϫ85° range and depend on the precise param-
256
Z. Anorg. Allg. Chem. 2003, 629, 255Ϫ260

Zinc Complexes with Sulfonamides containing 8-Aminoquinoleine
Table 1 Summary of crystal parameters, data collection and refinement for the three crystal structures
[Zn (qbsa)2]·DMF
[Zn (qtsa)2]·1/2 H2O
[Zn (qnsa)2]
Empirical formula
Formula weight
Temperature
ZnC33H29N5O5S2
705.10
ZnC32H26N4O4.5S2
668.06
ZnC38H26N4O4S2
732.12
213(2) K
293(2) K
293(2) K
˚
˚
˚
Wavelength
1.54184 A
1.54180 A
0.71073 A
Crystal system
Space group
triclinic
P1 (No.2)
monoclinic
C2 /c
monoclinic
P21/n (No.14)
¯
Unit cell dimensions:
˚
a/ A
10.241(3)
10.899(3)
16.434(3)
79.890(16)
75.108(18)
68.98(2)
23.849(5)
16.806(3)
17.035(3)
90
120.85(3)
90
9.9215(9)
22.763(2)
14.7754(13)
90
˚
b/ A
˚
c/ A
α/ °
β/ °
96.507(4)
90
3315.5(5) A
4
γ/ °
3
3
3
˚
˚
˚
Volume
1647.6(7) A
2
5861.9(20) A
8
Z
Calculated density
Absorption coefficient
F (000)
1.421 g/cm3
1.514 g/cm3
1.028 mmϪ1
2752
1.467 g/cm3
0.915 mmϪ1
1504
2.622 mmϪ1
728
Crystal size
θ range for data collection
0.35x0.15x0.05 mm
5.27-64.95°
0.04x0.05x0.06 mm
2.63-59.64°
0.49x0.13x0.07 mm
1.65-26.41°
Index ranges
Ϫ1<h<12
Ϫ12<k<12
Ϫ19<h<26
Ϫ17<k<0
Ϫ12<h<12
0<k<28
Ϫ16<l<19
Ϫ18<l<0
0<l<18
Reflections collected, unique, Rint
Refined method
Data, restraints, parameters
Goodness-of-fit on F2
Final R indices [I>2σ(I)]
R indices (all data)
6526, 5560, 0.0988
Full-matrix least-squares on F2
5560, 0, 390
4043, 4043, 0.0000
Full-matrix least-squares on F2
4041, 0, 444
6752, 6752, 0.0000
Full-matrix least-squares on F2
6752, 0, 442
1.018
1.147
1.032
R1ϭ0.0751, wR2ϭ0.1797
R1ϭ0.1416, wR2ϭ0.2138
1.052 and Ϫ0.662 e A
R1ϭ0.0929, wR2ϭ0.2084
R1ϭ0.2085, wR2ϭ0.2788
0.665 and Ϫ1.426 e A
R1ϭ0.0474, wR2ϭ0.0996
R1ϭ0.0999, wR2ϭ0.1234
0.663 and Ϫ0.357 e A
Ϫ3
Ϫ3
Ϫ3
˚
˚
˚
Largest diff. peak and hole
˚
Table 2 Selected bond lengths/A and angles/° for zinc complexes
[Zn(qbsa)2]
[Zn(qtsa)2]
[Zn(qnsa)2]
Zn-N(11)
Zn-N(12)
Zn-N(21)
Zn-N(22)
N(11)-Zn-N(12)
N(21)-Zn-N(22)
N(11)-Zn-N(21)
N(12)-Zn-N(22)
N(11)-Zn-N(22)
N(12)-Zn-N(21)
2.054(6)
1.940(5)
2.041(6)
1.954(6)
82.4(2)
2.047(1)
1.972(9)
1.981(1)
1.931(1)
85.0(5)
2.054(3)
1.958(3)
2.051(3)
1.966(3)
82.09(1)
82.69(1)
116.33(1)
135.87(1)
121.90(1)
121.94(1)
82.5(2)
82.8(5)
115.2(2)
142.1(2)
116.7(2)
120.4(2)
108.2(5)
135.0(5)
117.9(5)
128.8(5)
eters of the sulfonamide molecule. These values are reason-
able for octahedral complexes, but are quite acute relative
to the optimal 109° value for a tetrahedral center. This can
be explained assuming that the sulfonamide oxygen atoms
hinder the formation of both square planar and octahedral
complexes, thus providing a steric selection for tetrahedral
coordination [18]. Nevertheless, angle N(12)-Zn-N(22) is
rather large (135Ϫ142°) for all three complexes.
It should be noted that the DMF and water molecules
are not coordinated to the metal atoms in complexes
[Zn(qbsa)2] and [Zn(qtsa)2], respectively, and are not shown
in the figures.
Figure 1 Molecular structure of [Zn(qbsa)2] showing the atom num-
bering scheme.
Mass spectrometry
Mass spectra of the complexes show a signal due to the
complex molecular ion. The signal is recorded at m/zϭ631,
659, and 731, respectively, for compounds [Zn(qbsa)2],
[Zn(qtsa)2], and [Zn(qnsa)2]. The values for the first two
Z. Anorg. Allg. Chem. 2003, 629, 255Ϫ260
257

´
´
´
B. Macıas, I. Garcıa, M. V. Villa, J. Borras, A. Castin˜eiras, F. Sanz
Table 3 Selected IR bands/cmϪ1
[Zn(qbsa)2]·DMF
[Zn(qtsa)2]
[Zn(qnsa)2]
νas(SO2)
νs(SO2)
δ(SO2)
νS-N
1323,1276
1143,1120
594,582
961
1326,1284
1143,1119
577,549
959
1324,1279
1142,1117
569,551
962
νC-S
692
661
656
the S-N bonds in two consecutive steps. So, for complex
[Zn(qnsa)2], with a molecular formula ZnC38H26N4O4S2
and
a
m/zϭ 731 two signals, corresponding to
ZnC28H19N4O2S and ZnC18H12N4, both formed by con-
secutive removal of the naphthalene-2-sulfonyl (C10H7O2S)
are recorded at m/zϭ 540 and 349, respectively.
FT-IR spectroscopy
The positions of the most representative bands, together
with their assignments [35], are given in Table 3. The band
close to 3260 cmϪ1, recorded in the spectra of the ligands
and corresponding to the N-H stretching mode [19], is miss-
ing in the spectra of the complexes, confirming depro-
tonation of the nitrogen atom of the sulfonamide and its
coordination to the metal ion. The bands due to the SO2
group split in the spectra of the complexes, probably be-
cause of the different (non equivalent) spatial orientation of
these two groups in the crystal. The bands due to the sym-
metric and antisymmetric modes of this group shift ca.
30 cmϪ1 to lower wavenumbers than in the free ligands,
probably because a larger double bond character of the S-
O bonds in the free ligands. A similar shift is also observed
for the S-N stretching mode, in this case because the N
atom is involved in the bonding to the metal atom. These
shifts are a consecuence of the protonation and/or coordi-
nation of the sulfonamide group. The remaining bands are
recorded in positions very similar to those of the free li-
gands [19], and in the same ranges as previously reported
for other sulfonamide complexes [16, 20, 25].
Figure 2 Molecular structure of [Zn(qtsa)2] showing the atom num-
bering scheme.
NMR spectra
The data and their assignments [36] for the ligand molecules
are summarized in Table 4. The signal at 9.23 (Hqbsa) or
9.37 ppm (Hqnsa) in the H NMR spectra of the ligand is
Figure 3 Molecular structure of [Zn(qtsa)2] showing the atom num-
bering scheme.
1
due to the proton of the amine group. The signal corre-
sponding to the methyl group in the Hqtsa ligand is re-
corded at 2.26 ppm. The remaining signals are recorded in
the 7.30-8.80 ppm range, and are due to the aromatic pro-
tons. Similar features are recorded in the 13C NMR spectra,
where the signal due to the methyl group of ligand Hqtsa
is recorded at 21.25 ppm and the signals due to ring carbon
atoms are recorded in the 120-150 ppm range.
compounds correspond to the “bare” molecules, without
the DMF nor water molecule, respectively, concluded from
elemental chemical analysis and X-ray diffraction analysis,
thus confirming the weak interaction between these mol-
ecules (not directly bonded to the metal ions) and the me-
tal sites.
The signals recorded in the mass spectra give some clue
about the decomposition pattern of these compounds in the
ionisation chamber, suggesting it goes through the break of
The spectra of the Zn complexes are rather similar to
those of the free ligands; the signal due to the amine proton
is not longer recorded; the signals due to hydrogen atoms
258
Z. Anorg. Allg. Chem. 2003, 629, 255Ϫ260

Zinc Complexes with Sulfonamides containing 8-Aminoquinoleine
1
Table 4 Chemical shifts/ppm from H and 13C NMR spectra of the sulfonamide ligands
1H
13C
1H
13C
1H
13C
H(N)
9.23
8.74
7.90
7.92
Ϫ
8.08
7.33
7.82
Ϫ
Ϫ
Ϫ
Ϫ
9.37
8.72
7.73
7.85
Ϫ
8.01
7.40
7.52
Ϫ
Ϫ
Ϫ
8.52
Ϫ
Ϫ
7.89
7.75
Ϫ
7.90
7.36
7.32
7.50
Ϫ
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
148.66
122.13
127.12
132.80
121.90
126.76
115.05
138.49
136.17
139.38
128.13
128.13
128.81
133.70
128.81
Ϫ
8.78
7.73
7.80
Ϫ
8.20
7.20
7.53
Ϫ
150.24
123.14
123.91
127.59
117.49
123.55
106.34
137.50
129.76
137.81
130.40
128.31
145.27
128.31
130.41
21.25
Ϫ
148.65
122.36
127.71
129.15
121.90
126.74
114.91
138.45
131.87
136.16
128.73
122.19
136.28
128.79
128.12
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
7.37
7.37
7.44
7.40
7.44
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
7.47
7.17
Ϫ
7.17
7.47
2.26
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
129.25
133.68
127.36
134.82
Ϫ
Ϫ
Ϫ
s
t
[6] C. Evans, W. Henderson, B.K. Nicholson, Inorg. Chim. Acta
2001, 314, 42.
away from the Zn atom are recorded in almost the same
positions as in the free ligands, and the remaining signals
slightly shift towards lower field values, as a consequence
of electron density transfer from the ligand to the metal.
Although similar features are recorded in the 13C NMR
´
´
´
[7] L. Gutierrez, G. Alzuet, J. Borras, M. Liu-Gonzalez, F. Sanz,
A. Castin˜eiras, Polyhedron 2001, 20, 703.
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[8] J. Castro, S. Cabaleiro, P. Perez-Lourido, J. Romero, J.A. Gar-
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cıa-Vazquez, A. Sousa, Polyhedron 2001, 20, 2329.
1
spectra, correlations are not as evident as for the H spec-
tra.
´
´
[9] J.C. Pedregosa, J. Casanova, G. Alzuet, J. Borras, S. Garcıa-
´
´
Granda, M.R. Dıaz, A. Gutierrez-Rodriguez, Inorg. Chim.
Acknowledgements. The authors thank CICYT (grant PM97-0105-
C02-02) for financial support and critical reading of the manuscript
by Prof. V. Rives is also acknowledged.
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[10] C.T. Supuran, F. Mincione, A. Scozzafava, F. Briganti, G.
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