Different coordinative (N, N) and (N, O) bidentate behaviour of N-2-pyridyl-sulfonamides. Electrochemical synthesis and characterization of cadmium(II) complexes

Article abstract of DOI:10.1002/zaac.200390044

Electrochemical oxidation of cadmium in an acetonitrile solution of N-2-pyridyl-sulfonamides (HL) afforded cadmium coordination compounds of composition [CdL₂]. Heteroleptic complexes of composition [CdL₂L′] (L′ = 2,2′-bipyridine or

Full text of DOI:10.1002/zaac.200390044

Different Coordinative (N, N) and (N, O) Bidentate Behaviour of
N-2-Pyridyl-Sulfonamides. Electrochemical Synthesis and Characterization of
Cadmium(II) Complexes
a
a, 1
b
a
b
´
´
´
´
´
Inmaculada Beloso , Jesus Castro *, Jose A. Garcıa؊Vazquez , Paulo Perez؊Lourido , Jaime Romero , and
Antonio Sousab, 2
*
a
´
´
Vigo, Galicia / Spain, Universidade, Departamento de Quımica Inorganica
b
´
´
Santiago de Compostela, Galicia / Spain, Universidade, Departamento de Quımica Inorganica
Received October 25th, 2002.
th
˜
Dedicated to Professor Alfonso Castineiras on the Occasion of his 60 Birthday
Abstract. Electrochemical oxidation of cadmium in an acetonitrile
solution of N-2-pyridyl-sulfonamides (HL) afforded cadmium co-
ordination compounds of composition [CdL2]. Heteroleptic com-
plexes of composition [CdL2LЈ] (LЈ ϭ 2,2Ј-bipyridine or 1,10-phen-
anthroline) were obtained when the coligand LЈ was added to the
electrolytic phase. The crystal structures of several compounds have
been determined by X-ray diffraction. In all cases the cadmium
atom is hexacoordinated, but the coordinative behaviour of the
N-2-pyridyl-sulfonamide ligand depends on the location of the sub-
stituents in the pyridyl ring. When the substituent is in position 3,
the ligands act as N,O-donors. In all other cases, the ligands act as
N,NЈ-bidentate systems.
Keywords: Cadmium; Amide ligands; Electrochemical synthesis;
Crystal structure
Unterschiedliches, zweizähniges Koordinationsverhalten (N,N) und (N,O) von
N-2-pyridyl-Sulfonamiden. Elektrochemische Synthesen und Charakterisierung von
Cadmium(II)-Komplexen
Inhaltsübersicht. Die elektrochemische Oxidation von Cadmium in
Acetonitrillösungen von N-pyridyl-Sulfonamiden (HL) führt zur
Bildung von Koordinationsverbindungen des Cadmiums der Zu-
sammensetzung [CdL2]. Heteroleptische Komplexe [CdL2LЈ] (LЈ ϭ
2,2Ј-Dipyridin oder 1,10-Phenanthrolin) werden in Gegenwart des
Koliganden LЈ im Elektrolyten erhalten. Die Kristallstrukturen
mehrerer Verbindungen wurden röntgenographisch ermittelt. In al-
len Fällen ist das Cadmiumatom sechsfach koordiniert, jedoch
hängt das koordinative Verhalten von der Stellung der Substituen-
ten am Pyridylring ab. Substitution in 3-Stellung führt zur N,O-
Koordination, in allen anderen Fällen zu N,NЈ-Chelatbildung.
1 Introduction
their steric hindrance. The chemistry of metal complexes
containing pyridine-functionalized amido ligands of the
type showed below, Scheme 1, has received a lot of atten-
tion [1Ϫ5].
Recently, the chemistry of metal complexes containing
amide ligands has been a subject of great interest. The rea-
son for it stems from the fact that they are easily made,
and variations of the substituents are facile, providing the
possibility of changing almost at will their bite angle and
Scheme 1
1* Prof. Dr. J. Castro
Departamento de Quımica Inorganica
Universidade de Vigo
´
´
E-36200 Vigo, Galicia, Spain
Tel: ϩ34-986-812-278
Fax: ϩ34-986-813-798
It is believed that the presence of bulky substituents on
these ligands stabilizes the metal complexes.
E-mail: fojo@uvigo.es
Consequently, it was decided to study the chemistry of
the metal complexes of sulfonyl-2-pyridine-amines. These li-
gands, Scheme 2, contain a bulky sulfonyl group as a sub-
stituent of the exocyclic nitrogen atom. In addition, its elec-
tron withdrawing effect increases the acid character of the
NH group and makes the process of ligand deprotonation
easier.
2* Prof. Dr. A. Sousa
´
´
Departamento de Quımica Inorganica
Universidade de Santiago de Compostela
E-15782 Santiago de Compostela, Galicia / Spain
Tel: ϩ34-981-563-100 ext 14245
Fax: ϩ34-981-597-525
E-mail: qiansoal@usc.es.
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 0044Ϫ2313/03/629/275Ϫ284 $ 20.00ϩ.50/0
275

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´
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I. Beloso, J. Castro, J. A. GarcıaϪVazquez, P. PerezϪLourido, J. Romero, A. Sousa
2 Results and Discussion
Cadmium complexes with N-2-pyridyl-sulfonamides, as
well as their adducts with 2,2Ј-bipyridine (bipy) or
1,10-phenanthroline (phen), were easily prepared in good
yields by the simple one-step electrochemical method. In all
cases, the product formed was easily isolated as a crystalline
species from the bottom of the cell by filtration. The ana-
Scheme 2
It has been found that these ligands can coordinate to
lytical data are in good agreement with the expected values.
The values of the electrochemical efficiencies, defined as
the amount of metal dissolved per Faraday of charge, were
close to 0.5 mol·FϪ1 independent of the presence or absence
of additional ligands. This fact, along with the evolution of
hydrogen at the cathode, is compatible with the following
mechanism:
the metal atom in several different ways, Scheme 3.
Cathode: 2HL ϩ 2 eϪ Ǟ 2LϪ ϩ H2
Anode: Cd ϩ 2LϪ Ǟ [CdL2] ϩ 2 eϪ
or Cd ϩ 2LϪ ϩ LЈ Ǟ [CdL2LЈ] ϩ 2 eϪ
HL ϭ N-2-pyridyl-sulfonamides, and LϪ its deprotonation product.
LЈ ϭ bipy or phen
2.1 X-ray Structural Studies
Scheme 3
Table 1 lists crystal data, experimental details, refinement
results and details of structure determination.
Coordination modes I and II have been found in zinc
compounds. However, it is worth noting that in the case of
the complex showing coordination mode I, a weak interac-
tion between the metal and the exocyclic nitrogen atom is
present [6]. In the case of the compound showing coordi-
nation mode II, a weak interaction between the zinc and
the pyridine nitrogen atom is found [7]. Coordination mode
III is the most common, and it has been found in cobalt(II)
[8], nickel(II) [9] and cadmium (II) [10] complexes. To this
moment, coordination mode IV was only found in cop-
per(II) [7, 11] and silver(I) [7, 12] complexes. Coordination
modes V and VI were found in a polymer compound of
cadmium(II) [10] and the coordination mode VII was only
found, at the moment, in silver(I) complexes [7].
Molecular Structure of HMs6mepy (1)
Figure 1 shows a view of the compound together with the
atomic numbering scheme. Selected bond lengths and
angles, along with the estimated deviations, are listed in
Table 2.
The work described in this paper deals with the electro-
chemical synthesis and characterization of cadmium(II)
complexes [CdL2]. HL stands for phenylsulfonyl-2-pyridyl
amine derivatives containing methyl substituent groups in
both phenyl and pyridine rings, Scheme 4. In addition, ter-
nary 2,2Ј-bipyridine and 1,10-phenanthroline adducts
[CdL2bipy] or [CdL2phen] are also described.
Figure 1 Molecular structure of HMs6mepy.
The asymmetric unit contains two molecules connected
by hydrogen bonds. The positions of the hydrogen atoms at
˚
distances of only 0.83(2) and 0.91(2) A from the hetero-
cyclic nitrogen, and the short values of C(15)ϪN(12) and
˚
C(25)ϪN(22) [1.347(2) and 1.343(2) A, respectively] are
consistent with an imide (I) tautomer (see Scheme 5) similar
to those found in other N-2-pyridinyl benzenesulfonamide
derivatives [9].
Scheme 4
276
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284

Electrochemical Synthesis and Characterization of Cadmium(II) Complexes
Table 1 Crystal data and structure refinement
Compound
HMs6mepy
C30 H36N4O4S2
580.75
[Cd(Ts3mepy)2bipy]
[Cd(Ms3mepy)2bipy]
C40 H38N6 O4 S2 Cd
843.28
Empirical formula
Formula weight
Temperature
Wavelength
Crystal system
Space group
791.21
293(2) K
0.71073 A
293(2) K
293(2) K
0.71073 A
˚
˚
˚
0.71073 A
orthorhombic
Pna21
monoclinic
triclinic
¯
P21/n
a ϭ 8.8059(5) A
P1
a ϭ 9.589(4) A
˚
˚
˚
Unit cell dimensions
a ϭ 11.5776(14) A
˚
˚
˚
b ϭ 21.9898(13) A
c ϭ 15.3219(9) A
b ϭ 19.285(2) A
b ϭ 13.843(5) A
˚
˚
˚
c ϭ 17.005(2) A
c ϭ 16.456(7) A
α ϭ 79.750(10)°.
β ϭ 79.621(9)°.
γ ϭ 86.453(11)°.
β ϭ 94.3260(10)°
β ϭ 102.795(2)°.
β ϭ 91.5570(10)°.
3
3
3
3
3
˚
˚
˚
˚
˚
Volume
Z
Density (calculated)
Absorption coefficient
F(000)
2958.5(3) A
4
3332.6(6) A
4
7032.1(7) A
4
3796.7(8) A
4
2113.3(15) A
2
1.304 Mg/m3
0.222 mmϪ1
1232
1.485 Mg/m3
0.831 mmϪ1
1536
1.495 Mg/m3
0.788 mmϪ1
3232
1.384 Mg/m3
0.730 mmϪ1
1616
1.325 Mg/m3
0.660 mmϪ1
864
Crystal size
0.27 ϫ 0.49 ϫ 0.63 mm3 0.24 ϫ 0.36 ϫ 0.66 mm3 0.25 ϫ 0.27 ϫ 0.69 mm3 0.18 ϫ 0.18 ϫ 0.30 mm3 0.08 ϫ 0.20 ϫ 0.23 mm3
Theta range for data collection 1.62 to 28.02°
1.43 to 28.04°.
Ϫ21 Յ h Յ 18
Ϫ12 Յ k Յ 11
Ϫ28 Յ l Յ 29
19339
1.58 to 28.02°.
Ϫ24 Յ h Յ 30
Ϫ20 Յ k Յ 19
Ϫ25 Յ l Յ 24
39101
1.60 to 28.06°.
Ϫ8 Յ h Յ 15
Ϫ24 Յ k Յ 25
Ϫ22 Յ l Յ 22
21881
1.28 to 28.13°.
Ϫ12 Յ h Յ 12,
Ϫ18 Յ k Յ 10
Ϫ20 Յ l Յ 21
10864
Index ranges
Ϫ10 Յ h Յ 11,
Ϫ29 Յ k Յ 28,
Ϫ16 Յ l Յ 20
17649
Reflections collected
Independent reflections
Completeness to theta
Absorption correction
Max. and min. Transmission
6868 [R(int) ϭ 0.0330] 7676 [R(int) ϭ 0.0512]
theta ϭ 28.02°: 95.8 % theta ϭ 28.04°: 95.1 %
Empirical
15532 [R(int) ϭ 0.0378] 8578 [R(int) ϭ 0.0758] 7761 [R(int) ϭ 0.2051]
theta ϭ 28.02° : 91.2 % theta ϭ 28.06°: 98.3 % theta ϭ 28.13°: 75.1 %
Empirical
Empirical
Empirical
1.000 and 0.488
1.000 and 0.847
15532 / 0 / 891
0.909
1.000 and 0.582
8578 / 1 / 446
0.870
1.000 and 0.322
7761 / 0 / 486
0.724
Data / restraints / parameters 6868 / 0 / 417
7676 / 4 / 421
1.016
Goodness-of-fit on F2
0.933
Final R indices [I>2sigma(I)] R1ϭ0.0457, wR2 ϭ0.0997 R1ϭ0.0613, wR2 ϭ0.1494 R1ϭ0.0395, wR2 ϭ0.0816 R1ϭ0.0586, wR2 ϭ0.1102 R1ϭ0.0853, wR2 ϭ0.1995
R indices (all data)
Absolute structure parameter [28]
Largest diff. peak and hole 0.250 and Ϫ0.275 e.A
R1ϭ0.0956, wR2 ϭ0.1129 R1ϭ0.1178, wR2 ϭ0.1659 R1ϭ0.0792, wR2 ϭ0.0912 R1ϭ0.1163, wR2 ϭ0.1244 R1ϭ0.2811, wR2 ϭ0.2551
0.00(3)
Ϫ3
Ϫ3
Ϫ3
Ϫ3
Ϫ3
˚
˚
˚
˚
˚
0.938 and Ϫ0.724 e.A
0.791 and Ϫ0.465 e.A
1.704 and Ϫ0.559 e.A
0.861 and Ϫ0.725 e.A
In addition, the molecules of HMs6mepy are associated
by intermolecular hydrogen bonds between the atoms in
two independent molecules of the unit cell, leading to the
formation of a dimer. These hydrogen bonds are between
the pyridine nitrogen atom of one molecule and the amide
nitrogen atom of the other neighbour. In addition, one oxy-
gen atom of the sulfone group [O(22), O(12)] of one mole-
cule is involved in a hydrogen bond with the nitrogen of the
pyridine ring [N(11), N(21)] of the other, so each H(N)
atom is participating in a bifurcated hydrogen bond with
the Namide and one oxygen atoms of the other molecule in
the asymmetric unit. This situation causes a distortion of
the bond angles around the sulfur atom, with values in the
range of 104.39(8)Ϫ116.40(9)°.
˚
Table 2 Selected bond lengths/A and angles/° for HMs6mepy.
S(1)ϪO(11)
S(1)ϪO(12)
S(1)ϪN(12)
S(1)ϪC(17)
N(11)ϪC(11)
N(11)ϪC(15)
N(11)ϪH(1)
N(12)ϪC(15)
C(11)ϪC(12)
C(11)ϪC(16)
C(12)ϪC(13)
1.4371(16)
1.4382(16)
1.6034(16)
1.790(2)
1.362(2)
1.367(2)
0.83(2)
1.347(2)
1.364(3)
1.490(3)
1.388(3)
S(2)ϪO(21)
S(2)ϪO(22)
S(2)ϪN(22)
S(2)ϪC(27)
N(21)ϪC(21)
N(21)ϪC(25)
N(21)ϪH(2)
N(22)ϪC(25)
C(21)ϪC(22)
C(21)ϪC(26)
C(22)ϪC(23)
1.4370(14)
1.4383(15)
1.6091(15)
1.783(2)
1.363(2)
1.366(2)
0.91(2)
1.343(2)
1.356(3)
1.495(3)
1.383(3)
O(11)ϪS(1)ϪO(12)
O(11)ϪS(1)ϪN(12)
O(12)ϪS(1)ϪN(12)
O(11)ϪS(1)ϪC(17)
O(12)ϪS(1)ϪC(17)
N(12)ϪS(1)ϪC(17)
C(11)ϪN(11)ϪC(15)
C(15)ϪN(12)ϪS(1)
N(11)ϪC(11)ϪC(12)
N(11)ϪC(11)ϪC(16)
C(12)ϪC(11)ϪC(16)
116.25(10)
111.78(9)
105.48(9)
108.71(10)
106.26(10)
107.93(9)
125.28(19)
120.56(14)
117.9(2)
O(21)ϪS(2)ϪO(22)
O(21)ϪS(2)ϪN(22)
O(22)ϪS(2)ϪN(22)
O(21)ϪS(2)ϪC(27)
O(22)ϪS(2)ϪC(27)
N(22)ϪS(2)ϪC(27)
C(21)ϪN(21)ϪC(25)
C(25)ϪN(22)ϪS(2)
C(22)ϪC(21)ϪN(21)
C(22)ϪC(21)ϪC(26)
N(21)ϪC(21)ϪC(26)
116.40(9)
104.39(8)
110.53(9)
107.72(9)
109.26(9)
108.18(8)
124.78(18)
121.77(14)
118.1(2)
117.42(19)
124.66(19)
124.97(19)
116.96(19)
˚
Hydrogen bond parameters /A° for HMs6mepy.
DϪH···A
d(DϪH)
d(H···A)
d(D···A)
<(DHA)
N(11)ϪH(1)···N(22)
N(21)ϪH(2)···N(12)
0.83(2)
0.91(2)
0.96
0.95(2)
0.96
0.96
0.96
0.95(2)
0.92(2)
2.15(2)
2.11(2)
2.37
2.52(2)
2.63
2.45
2.40
2.57(2)
2.49(2)
2.975(2)
3.004(2)
2.708(3)
3.069(3)
3.066(3)
3.097(3)
3.187(3)
3.308(3)
3.350(3)
174.4(19)
167.8(19)
100.1
116.8(16)
108.1
124.7
139.5
134.5(16)
154.4(18)
C(113)ϪH(11B)···O(11)
C(14)ϪH(14)···O(11)
C(215)ϪH(21G)···N(22)
C(215)ϪH(21H)···O(21)
C(26)ϪH(26°)···O(12)
C(13)ϪH(13)···O(22) 1
C(23)ϪH(23)···O(21) 11
Scheme 5
Both the phenyl and the pyridine rings are almost planar,
with the largest deviations from planarity being 0.013(3)
and 0.012(8) A, respectively. The interplanar angles of
Symmetry transformations used to generate equivalent atoms:
1
ϭ x Ϫ 1/2, Ϫy ϩ 1/2, z Ϫ 1/2
˚
11
ϭ x ϩ 1, y, z
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284
277

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I. Beloso, J. Castro, J. A. GarcıaϪVazquez, P. PerezϪLourido, J. Romero, A. Sousa
83.83(13)° and 86.73(11)° are similar to those found in
gen bonds. The cadmium atom is coordinated by two
anionic (N,NЈ)-bidentate sulfonamide ligands and by two
water molecules. In this arrangement the metal atom is
hexacoordinated in an environment that is best described
as a distorted trigonal prism. The triangular faces of the
prism are formed by a sulfonamide nitrogen atom, a pyri-
dine nitrogen atom of a different ligand and by a water
molecule, with the sulfonamide ligands situated at the edge
of the parallelogram faces in an alternating fashion. The
angles φ (see scheme 6) [13], have values of Ϫ23.4(2),
Ϫ29.2(2) and Ϫ27.6(3)°.
other sulfonamides [9].
Molecular Structure
of[Cd(Ms6mepy)2(H2O)2]·H2O (2)
The molecular structure of [Cd(Ms6mepy)2(H2O)2]·H2O is
shown in Figure 2, together with the atomic numbering
scheme adopted. Selected bond distances and angles are
listed in Table 3.
˚
Table 3 Selected bond lengths/A and angles/° for
[Cd(Ms6mepy)2(H2O)2] H2O
CdϪO(1W)
CdϪN(22)
CdϪN(21)
S(1)ϪO(12)
S(1)ϪN(12)
S(2)ϪO(21)
S(2)ϪN(22)
N(11)ϪC(15)
N(12)ϪC(15)
N(21)ϪC(21)
2.316(5)
2.320(4)
2.333(4)
1.418(4)
1.583(4)
1.440(4)
1.590(5)
1.337(6)
1.384(6)
1.346(7)
CdϪN(12)
CdϪO(2W)
CdϪN(11)
S(1)ϪO(11)
S(1)ϪC(17)
S(2)ϪO(22)
S(2)ϪC(27)
N(11)ϪC(11)
N(21)ϪC(25)
N(22)ϪC(25)
2.318(4)
2.325(6)
2.351(4)
1.441(4)
1.779(6)
1.459(4)
1.791(5)
1.341(7)
1.335(7)
1.384(6)
Scheme 6
O(1W)ϪCdϪN(12)
N(12)ϪCdϪN(22)
N(12)ϪCdϪO(2W)
O(1W)ϪCdϪN(21)
N(22)ϪCdϪN(21)
O(1W)ϪCdϪN(11)
N(22)ϪCdϪN(11)
N(21)ϪCdϪN(11)
O(12)ϪS(1)ϪN(12)
O(12)ϪS(1)ϪC(17)
N(12)ϪS(1)ϪC(17)
O(21)ϪS(2)ϪN(22)
O(21)ϪS(2)ϪC(27)
N(22)ϪS(2)ϪC(27)
110.44(18)
152.61(15)
93.6(2)
144.45(19)
57.14(16)
93.57(18)
103.94(15)
104.06(14)
112.6(3)
107.7(2)
108.0(2)
112.1(3)
108.7(3)
O(1W)ϪCdϪN(22)
O(1W)ϪCdϪO(2W)
N(22)ϪCdϪO(2W)
N(12)ϪCdϪN(21)
O(2W)ϪCdϪN(21)
N(12)ϪCdϪN(11)
O(2W)ϪCdϪN(11)
O(12)ϪS(1)ϪO(11)
O(11)ϪS(1)ϪN(12)
O(11)ϪS(1)ϪC(17)
O(21)ϪS(2)ϪO(22)
O(22)ϪS(2)ϪN(22)
O(22)ϪS(2)ϪC(27)
C(15)ϪN(11)ϪC(11)
88.96(18)
82.9(3)
108.3(2)
105.05(16)
97.0(2)
57.28(15)
147.4(2)
115.5(3)
105.3(2)
107.5(3)
115.8(3)
104.7(2)
107.7(3)
120.8(5)
The triangular faces form a dihedral angle of 20.0(1)° as
a consequence of the small bite of the bidentate ligands.
This is the main source of distortion, with angles Npy-Cd-
Nsulfonamide of 57.28(15) and 57.14(16)°, respectively. This
angle is not very different from those found in similar com-
plexes that have been reported previously [10, 14]. The
˚
CdϪNamide bond distances, 2.318(4) and 2.320(4) A, are
107.4(2)
similar to those described in the aforementioned references
and are slightly longer than those found in
K[Cd(ClC6H4SO2NCONH-n-Pr)3][15] and in [Cd(bipy)2-
(bsglyNO)2] [16] with mean CdϪNamide distances of 2.21(2)
˚
Hydrogen bonds parameters /A,° for [Cd(Ms6mepy)2(H2O)2]H2O
DϪH···A
d(DϪH)
d(H···A)
d(D···A)
<(DHA)
˚
and 2.215 A, respectively. The two CdϪNpy bond distances
O(1W)ϪH(1A)···O(22)
O(2W)ϪH(2B)···O(11)
O(2W)ϪH(2°)···O(3W)
O(1W)ϪH(1B)···O(3W)
0.83(2)
0.83(2)
0.82(2)
0.80(2)
2.19(5)
2.59(6)
2.48(5)
2.12(5)
2.907(7)
3.161(9)
3.061(11)
2.781(8)
146(7)
128(7)
129(6)
141(7)
˚
are 2.333(4) and 2.351(4) A, which are similar to those
found in other hexacoordinated cadmium complexes
˚
(2.310Ϫ2.346 A) [17, 18].
The CdϪOw bond lengths are 2.316(5) and 2.325(6) A
˚
and are not very different to those found in other diaquo-
complexes of hexacoordinated cadmium(II) [see for ex-
ample catena-{hexakis[µ2-1,3-bis(4-pyridyl)propane]-bis(µ2-
sulfato-O,OЈ,OЈЈ)-hexa-aqua-bis(hydrogensulfato-O)-tetra-
cadmium nonahydrate} [19], catena-[bis(µ2-4,4Ј-bipyridyl)-
diaqua-cadmium(II) dinitrate tetrahydrate] [20] or
[10,16-dioxa-3,13,23,29-tetra-azatetracyclo(23.3.1.04,9.017,22)-
nonacosa-(29),2,4(9)5,7,17,19,21,23,25,27-undecaene]-diaqua-
cadmium(II) diperchlorate [21]. The coordinated water mo-
lecules are implicated in two intramolecular hydrogen
bonds, one involves the SO2 group of one of the ligands
and the other involves the water of crystallization (see
Table 5). This water molecule is undoubtedly implicated in
some hydrogen bonds with the SO2 groups and the supra-
molecular structure should probably be maintained through
hydrogen bonds. Unfortunately, the quality of the data does
not allow location of the hydrogen atoms.
Figure 2 Molecular structure of [Cd(Ts6mepy)2(H2O)2]H2O. The
insert represents the environment around the metal atom.
The compound crystallises with a water molecule, which
establishes a relationship with the molecule through hydro-
The dihedral angles between the benzene and pyridine
rings are 83.6(2) and 74.4(2)° for the two ligands, respec-
278
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284

Electrochemical Synthesis and Characterization of Cadmium(II) Complexes
tively, and these values are slightly different to those found
in the free ligand [9] due to the effect of the coordination.
The two pyridine rings coordinated to the metal atom are
almost perpendicular to one another and form a dihedral
angle of 87.7(2)°. These rings are planar to within
Molecular Structure of [Cd(Ts6mepy)2 bipy] (3)
The asymmetric unit contains two independent molecules
of the compound. For the sake of clarity Figure 3 shows
only one of these molecules, together with the atomic num-
bering scheme adopted. Selected bond distances and angles
are listed in Table 4.
˚
0.015(5)A and the cadmium atoms are 0.204(7) and
˚
0.274(8) A out of the best planes, respectively, as a conse-
quence of the constraint caused by the bidentate character
of the ligands.
˚
Table 4 Bond lengths/A and angles/° for [Cd(Ts6mepy)2bipy]
Cd(1)ϪN(12)
Cd(1)ϪN(32)
Cd(1)ϪN(21)
S(1)ϪO(11)
S(1)ϪN(12)
N(12)ϪC(15)
N(11)ϪC(15)
S(2)ϪO(22)
S(2)ϪC(27)
N(21)ϪC(25)
Cd(2)ϪN(51)
Cd(2)ϪN(42)
Cd(2)ϪN(41)
S(4)ϪO(42)
S(4)ϪN(42)
N(41)ϪC(41)
N(42)ϪC(45)
S(5)ϪO(52)
S(5)ϪC(57)
2.299(2)
2.345(3)
2.387(2)
1.434(3)
1.594(3)
1.378(4)
1.360(4)
1.448(2)
1.772(3)
1.349(4)
2.305(3)
2.339(2)
2.373(2)
1.439(2)
1.593(2)
1.345(4)
1.373(4)
1.445(3)
1.776(4)
1.361(4)
Cd(1)ϪN(31)
Cd(1)ϪN(22)
Cd(1)ϪN(11)
S(1)ϪO(12)
S(1)ϪC(17)
N(11)ϪC(11)
S(2)ϪO(21)
S(2)ϪN(22)
N(21)ϪC(21)
N(22)ϪC(25)
Cd(2)ϪN(61)
Cd(2)ϪN(62)
Cd(2)ϪN(52)
S(4)ϪO(41)
S(4)ϪC(47)
2.344(3)
2.358(2)
2.427(3)
1.436(3)
1.770(3)
1.346(4)
1.434(2)
1.584(3)
1.342(4)
1.388(4)
2.338(2)
2.339(2)
2.486(3)
1.442(2)
1.765(3)
1.353(3)
1.437(3)
1.592(3)
1.350(4)
1.371(4)
N(41)ϪC(45)
S(5)ϪO(51)
S(5)ϪN(52)
N(51)ϪC(51)
N(52)ϪC(55)
N(51)ϪC(55)
Figure 3 Molecular structure of [Cd(Ts6mepy)2bipy]. The insert
represents the environment around the metal atom.
N(12)ϪCd(1)ϪN(31)
N(31)ϪCd(1)ϪN(32)
N(31)ϪCd(1)ϪN(22)
N(12)ϪCd(1)ϪN(21)
N(32)ϪCd(1)ϪN(21)
N(12)ϪCd(1)ϪN(11)
N(32)ϪCd(1)ϪN(11)
N(21)ϪCd(1)ϪN(11)
O(11)ϪS(1)ϪN(12)
O(11)ϪS(1)ϪC(17)
O(21)ϪS(2)ϪO(22)
O(22)ϪS(2)ϪN(22)
O(22)ϪS(2)ϪC(27)
N(51)ϪCd(2)ϪN(61)
N(61)ϪCd(2)ϪN(42)
N(61)ϪCd(2)ϪN(62)
N(51)ϪCd(2)ϪN(41)
N(42)ϪCd(2)ϪN(41)
N(51)ϪCd(2)ϪN(52)
N(42)ϪCd(2)ϪN(52)
N(41)ϪCd(2)ϪN(52)
O(42)ϪS(4)ϪN(42)
O(42)ϪS(4)ϪC(47)
N(42)ϪS(4)ϪC(47)
O(51)ϪS(5)ϪN(52)
O(51)ϪS(5)ϪC(57)
N(52)ϪS(5)ϪC(57)
99.61(9)
70.51(9)
143.77(9)
102.23(9)
101.08(8)
56.64(8)
106.94(8)
142.50(8)
112.38(15)
106.75(16)
117.18(14)
113.36(14)
106.17(14)
115.14(9)
145.06(9)
70.23(9)
137.47(9)
56.73(8)
55.71(10)
109.81(8)
96.51(9)
106.20(13)
106.66(14)
107.52(13)
106.09(15)
107.52(18)
106.75(15)
N(12)ϪCd(1)ϪN(32)
N(12)ϪCd(1)ϪN(22)
N(32)ϪCd(1)ϪN(22)
N(31)ϪCd(1)ϪN(21)
N(22)ϪCd(1)ϪN(21)
N(31)ϪCd(1)ϪN(11)
N(22)ϪCd(1)ϪN(11)
O(11)ϪS(1)ϪO(12)
O(12)ϪS(1)ϪN(12)
O(12)ϪS(1)ϪC(17)
O(21)ϪS(2)ϪN(22)
O(21)ϪS(2)ϪC(27)
N(22)ϪS(2)ϪC(27)
N(51)ϪCd(2)ϪN(42)
N(51)ϪCd(2)ϪN(62)
N(42)ϪCd(2)ϪN(62)
N(61)ϪCd(2)ϪN(41)
N(62)ϪCd(2)ϪN(41)
N(61)ϪCd(2)ϪN(52)
N(62)ϪCd(2)ϪN(52)
O(42)ϪS(4)ϪO(41)
O(41)ϪS(4)ϪN(42)
O(41)ϪS(4)ϪC(47)
O(51)ϪS(5)ϪO(52)
O(52)ϪS(5)ϪN(52)
O(52)ϪS(5)ϪC(57)
155.37(9)
107.41(8)
92.05(9)
94.75(9)
56.61(9)
117.70(8)
97.45(8)
The two independent molecules of the compound are
chemically identical. In both molecules the cadmium atom
is coordinated by the two nitrogen atoms of two
monoanionic (N,NЈ)-bidentate ligands and by two nitrogen
atoms of the 2,2Ј-bipyridine coligand. The torsion angle φ
has an average value of 22.3(1)°. Therefore, the coordi-
nation polyhedron around the cadmium atom is best de-
scribed as a distorted trigonal prism, with the (N,N)-donor
atoms of each ligand defining two of the edges of the paral-
lelogram-shaped faces of the prism. The nitrogen atoms of
the 2,2Ј-bipyridine form the other edge. The triangular
faces of the prism are formed by one of the 2,2Ј-bipyridine
nitrogen atoms and the Namide and Npy atoms of each li-
gand. These triangular faces are not parallel but have a di-
hedral angle of 8.2(1) or 5.3(2)° for each molecule due to
the small bite of the anionic ligand [NϪCdϪN 56.61(9),
56.64(8), 55.71(10) and 56.73(8)°]. The NϪCdϪN angles of
the neutral ligands, 70.23(9) and 70.51(9)°, are similar to
those reported for hexacoordinated cadmium complexes
containing coordinated 2,2Ј-bipyridine.
118.06(17)
105.48(14)
106.25(16)
105.89(14)
106.72(15)
106.93(14)
99.55(8)
112.32(10)
93.59(9)
96.45(8)
104.56(9)
93.90(9)
154.71(9)
116.22(14)
113.15(13)
106.63(13)
116.13(17)
113.22(17)
106.65(17)
˚
Hydrogen bonds parameters /A,° for [Cd(Ts6mepy)2bipy].
DϪH···A
d(DϪH)
d(H···A)
d(D···A)
<(DHA)
C(14)ϪH(14)···O(11)
C(24)ϪH(24)···O(22)
C(38)ϪH(38)···O(52i)
C(44)ϪH(44)···O(41)
C(46)ϪH(46B)···O(12ii)
C(54)ϪH(54)···O(52)
C(56)ϪH(56A)···O(42)
C(112)ϪH(112)···O(11)
C(212)ϪH(212)···O(22)
C(411)ϪH(411)···O(11iii
C(412)ϪH(412)···O(41)
C(512)ϪH(512)···O(52)
0.93
0.93
0.93
0.93
0.96
0.93
0.96
0.93
0.93
0.93
0.93
0.93
2.48
2.46
2.49
2.50
2.58
2.40
2.35
2.53
2.55
2.58
2.54
2.55
3.017(5)
3.021(4)
3.273(4)
3.046(4)
3.432(4)
2.983(5)
3.263(5)
2.909(4)
2.914(4)
3.201(4)
2.910(4)
2.917(5)
117.1
119.2
142.0
117.5
148.3
120.8
159.5
104.7
103.8
124.9
103.9
104.2
The benzene and pyridine rings of the anionic ligands
adopt an almost perpendicular disposition, with dihedral
angles of 81.3(1), 82.5(1), 86.5(1) and 89.7(1)°. These angles
are very similar to those found in the free ligand. The coor-
dinated pyridine rings also adopt a perpendicular dispo-
sition, with dihedral angles of 88.5(1) and 89.7(1)° with re-
spect to each other when coordinated to the same metal
atom. The cadmium atom is 0.485(4), 0.298(4), 0.427(4) and
)
Symmetry transformations used to generate equivalent atoms:
i Ϫxϩ1, yϪ0.5, 0.5Ϫz; ii x, yϩ1, z; iii 2-x, yϩ0.5, 0.5Ϫz.
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284
279

´
´
´
I. Beloso, J. Castro, J. A. GarcıaϪVazquez, P. PerezϪLourido, J. Romero, A. Sousa
˚
0.377(5) A out of the best plane defined by each pyridine
ring.
The two planar pyridine rings of the coordinated bipyri-
dine ligands form dihedral angles of 8.5(2) and 8.8(1)°. The
˚
Cd1 atom is 0.118(5) and 0.509(5) A out of the best plane
˚
of these rings and the Cd2 atom is 0.203(5) and 0.590(5) A
out of the best planes.
It is worth noting that the coordination mode of this li-
gand, i.e. an (N,NЈ)-donor, is similar to that described pre-
viously by our group [10] for a complex without a substitu-
ent on the pyridine ring but is different to those described
in this paper (vide infra).
Molecular Structure of[Cd(Ts3mepy)2bipy] (4)
The molecular structure of [Cd(Ts3mepy)2bipy] is shown in
Figure 4, together with the atomic numbering scheme
adopted. Selected bond distances and angles are listed in
Table 5.
Figure 4 Molecular structure of [Cd(Ts3mepy)2bipy]. The insert
represents the environment around the metal atom.
˚
Table 5 Selected bond lengths/A and angles/° for [Cd(Ts3mepy)2-
bipy]
The cadmium atom is coordinated by two (N,O)-biden-
tate anionic ligands and an (N,NЈ)-bidentate 2,2Ј-bipyridine
molecule. The arrangement of the two ligands is such that
the two oxygen atoms are in cis positions and the two pyri-
dine nitrogen are trans with respect to each other. These
positions can be defined as the axial positions. The cad-
CdϪO(21)
CdϪN(21)
CdϪN(31)
S(1)ϪO(12)
S(1)ϪN(12)
S(2)ϪO(22)
S(2)ϪN(22)
N(11)-C(15)
N(12)-C(15)
N(21)-C(25)
2.272(4)
2.316(5)
2.352(5)
1.440(5)
1.572(6)
1.420(5)
1.555(7)
1.353(8)
1.368(8)
1.352(9)
CdϪO(11)
CdϪN(11)
CdϪN(32)
S(1)ϪO(11)
S(1)ϪC(17)
S(2)ϪO(21)
S(2)ϪC(27)
N(11)-C(11)
N(21)-C(21)
N(22)-C(25)
2.305(5)
2.320(6)
2.369(6)
1.465(5)
1.764(7)
1.486(5)
1.762(8)
1.361(9)
1.318(10)
1.354(10)
˚
mium atom is only 0.002(2) A out of the best equatorial
plane (rms of 0.0906). The two pyridine rings of the bipyri-
˚
O(21)ϪCdϪO(11)
O(11)ϪCdϪN(21)
O(11)ϪCdϪN(11)
O(21)ϪCdϪN(31)
N(21)ϪCdϪN(31)
O(21)ϪCdϪN(32)
N(21)ϪCdϪN(32)
N(31)ϪCdϪN(32)
O(12)ϪS(1)ϪN(12)
O(22)ϪS(2)ϪO(21)
O(21)ϪS(2)ϪN(22)
O(21)ϪS(2)ϪC(27)
97.27(19)
87.86(19)
82.9(2)
164.17(19)
93.8(2)
94.9(2)
97.7(2)
70.1(2)
108.1(3)
113.4(3)
114.6(3)
103.9(3)
O(21)ϪCdϪN(21)
O(21)ϪCdϪN(11)
N(21)ϪCdϪN(11)
O(11)ϪCdϪN(31)
N(11)ϪCdϪN(31)
O(11)ϪCdϪN(32)
N(11)ϪCdϪN(32)
O(12)ϪS(1)ϪO(11)
O(11)ϪS(1)ϪN(12)
O(22)ϪS(2)ϪN(22)
O(22)ϪS(2)ϪC(27)
N(22)ϪS(2)ϪC(27)
82.91(19)
85.28(18)
164.0(2)
98.08(19)
100.43(19)
167.19(18)
94.0(2)
113.5(3)
114.3(3)
108.0(4)
108.6(3)
108.0(4)
dine moiety are planar within 0.006 A, with a dihedral an-
gle between them of 5.5(4)°, and are almost coplanar with
the best equatorial plane [dihedral angles of 7.3(3) and
7.8(3)°]. One of the sources of distortion of the polyhedron
is the small bite of the bipyridine ligand [70.1(2)°], which
forms a 5-membered chelate ring. All the other angles
around the cadmium atom are close to 90°. The CdϪN
bond distances are similar to those found in other com-
plexes containing this ligand [10] and the CdϪO bond dis-
tances are slightly different, probably due to packing effects.
These bond lengths are shorter than those found in other
cadmium(II) complexes with this kind of bond [10, 22]. The
benzene ring and the pyridine ring of each anionic ligand,
which are almost perpendicular in the free ligand, form di-
hedral angles of 77.3(3) and 57.9(3)° as a result of coordi-
nation. The pyridine rings of the anionic ligands form a
dihedral angle of 88.3(2) and 88.0(2)° with the equatorial
plane, but they are not parallel to each other [dihedral angle
of 17.6(3)°].
˚
Hydrogen bonds parameters /A,° for [Cd(Ts3mepy)2bipy].
DϪH···A
d(DϪH)
d(H···A)
d(D···A)
<(DHA)
C(12)ϪH(12)···O(12i)
C(28)ϪH(28)···O(21)
C(34)ϪH(34)···N(12ii)
C(37)ϪH(37)···N(12ii)
C(112)ϪH(112)···O(11)
0.93
0.93
0.93
0.93
0.93
2.55
2.57
2.44
2.48
2.56
3.406(9)
2.905(11)
3.348(9)
3.363(10)
2.927(9)
153.8
101.9
165.5
158.2
103.6
Symmetry transformations used to generate equivalent atoms:
i 2Ϫx, 1Ϫy, zϩ0.5 ii xϪ0.5, 0.5Ϫy, z.
The central cadmium atom is six-coordinated, but there
are two important differences in comparison to the complex
[Cd(Ts6mepy)2bipy]. Firstly, the anionic ligands behave in
an (N,O) bidentate way, using one of the oxygen atoms of
the sulfonyl groups and the nitrogen atom of the pyridine
ring. The second difference concerns the coordination poly-
hedron. In this case, the arrangement is closer to an octa-
hedron as the torsion angles φ now have values of 30.6(2),
49.4(2) and 49.0(2)°, which are not far removed from the
expected values for an ideal octahedron (45°).
Molecular Structure of [Cd(Ms3mepy)2bipy] (5)
Unfortunately, the crystal data for the complex
[Cd(Ms3mepy)2bipy] are of poor quality. Nevertheless, the
refinement gives the final map shown in Figure 5 and the
final R1 converged to 8.5 %. Several attempts to crystallize
280
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284

Electrochemical Synthesis and Characterization of Cadmium(II) Complexes
a better quality monocrystal were unsuccessful. Selected
The average value of φ is 24.3(5)°, so the coordination
bond distances and angles are listed in Table 6.
polyhedron around the cadmium atom can be described as
a distorted trigonal prism. The triangular faces of the prism
are formed by three different donor atoms and these form
a dihedral angle of 7.4(6)°. The three chelating ligands are
in the vertical edges of the prism.
Once again it is worth noting the coordination mode of
the ligand, which employs one of the oxygen atoms of the
sulfone groups for coordination to the cadmium atom. The
other donor atom is the pyridine nitrogen atom and, conse-
quently, the sulfonamide nitrogen atoms are not implicated
in the coordination, a situation similar to that in the pre-
vious complex but different to those described in the litera-
ture [10].
˚
Table 6 Selected bond lengths/A and angles/° for [Cd(Ms3mepy)2-
bipy]
CdϪN(21)
CdϪN(31)
CdϪO(11)
2.293(12)
2.347(13)
2.365(9)
CdϪN(11)
CdϪO(22)
CdϪN(32)
2.310(12)
2.359(8)
2.388(11)
1.480(9)
1.776(14)
1.467(9)
1.755(13)
1.384(16)
1.351(15)
1.344(17)
S(11)ϪO(12)
S(11)ϪN(12)
S(21)ϪO(21)
S(21)ϪN(22)
N(11)ϪC(15)
N(12)ϪC(15)
N(21)ϪC(21)
1.479(9)
1.572(12)
1.464(9)
1.616(13)
1.336(16)
1.387(16)
1.364(17)
S(11)ϪO(11)
S(11)ϪC(17)
S(21)ϪO(22)
S(21)ϪC(27)
N(11)ϪC(11)
N(21)ϪC(25)
N(22)ϪC(25)
N(21)ϪCdϪN(11)
N(11)ϪCdϪN(31)
N(11)ϪCdϪO(22)
N(21)ϪCdϪO(11)
N(31)ϪCdϪO(11)
N(21)ϪCdϪN(32)
N(31)ϪCdϪN(32)
O(11)ϪCdϪN(32)
O(12)ϪS(11)ϪN(12)
O(12)ϪS(11)ϪC(17)
N(12)ϪS(11)ϪC(17)
O(21)ϪS(21)ϪN(22)
O(21)ϪS(21)ϪC(27)
N(22)ϪS(21)ϪC(27)
145.9(4)
89.6(5)
83.8(4)
82.2(4)
150.6(4)
98.3(4)
69.2(4)
89.1(4)
104.7(7)
107.7(6)
109.3(7)
105.8(7)
107.0(7)
110.9(7)
N(21)ϪCdϪN(31)
N(21)ϪCdϪO(22)
N(31)ϪCdϪO(22)
N(11)ϪCdϪO(11)
O(22)ϪCdϪO(11)
N(11)ϪCdϪN(32)
O(22)ϪCdϪN(32)
O(12)ϪS(11)ϪO(11)
O(11)ϪS(11)ϪN(12)
O(11)ϪS(11)ϪC(17)
O(21)ϪS(21)ϪO(22)
O(22)ϪS(21)ϪN(22)
O(22)ϪS(21)ϪC(27)
119.2(4)
78.4(4)
90.8(4)
79.0(4)
114.4(3)
109.5(4)
155.2(3)
113.7(6)
114.3(6)
106.8(7)
112.7(7)
113.1(6)
107.2(7)
2.2 Spectroscopic studies
The IR spectra of the complexes do not show the band
attributable to ν(NϪH), which in the free ligands appears
at 3248Ϫ3222 cmϪ1, thus confirming that the hydrogen
atom of the amide group is lost during the electrolysis. The
bands of the ligands in the range 1590Ϫ1616 cmϪ1, attribu-
table to the ν(CϭN), appear in similar positions except in
the complexes with the ligands Ts6mepyϪ and Ms6mepyϪ,
in which they are shifted to lower frequencies as a result of
the coordination through the sulfonamide atom. The bands
of the ligands in the range 1135Ϫ1125 cmϪ1, attributable to
the νsym(SϭO), appear slightly shifted to lower frequencies
in the spectra of complexes with Ts3mepyϪ and Ms3mepyϪ
as a result of the coordination through the sulfonyl group.
In addition, the IR spectra of the mixed complexes show
IR absorptions typical of coordinated 2,2Ј-bipyridine
(around 765 and 735 cmϪ1) and 1,10-phenanthroline (1520,
850 and 720 cmϪ1).
˚
Hydrogen bonds parameters /A,° for for [Cd(Ms3mepy)2bipy]
DϪH···A
d(DϪH)
d(H···A)
d(D···A)
<(DHA)
C(11)ϪH(11)···O(22)
C(113)ϪH(11D)···O(12)
C(21)ϪH(21)···O(11)
C(213)ϪH(21A)···O(22)
C(215)ϪH(21I)···O(21)
C(310)ϪH(310)···O(12)
C(34)ϪH(34)···N(12i)
C(39)ϪH(39)···O(12ii)
0.93
0.96
0.93
0.96
0.96
0.93
0.93
0.93
2.50
2.43
2.34
2.42
2.22
2.53
2.48
2.51
3.061(18)
2.828(19)
2.96(2)
2.761(18)
2.718(18)
3.038(18)
3.385(19)
3.262(18)
118.8
104.4
124.4
100.5
111.1
114.6
163.7
138.0
Symmetry transformations used to generate equivalent atoms:
i 2Ϫx, 1Ϫy, 1Ϫz, ii 1Ϫx, 1Ϫy, 1Ϫz
The complexes were also studied by 1H NMR spec-
troscopy but, unfortunately, the binary compounds of
general formula CdL2 are insoluble in most organic sol-
vents. The 1H NMR spectra of the mixed complexes do not
show the peak at about 9Ϫ13 ppm, as one would expect for
a deprotonated ligand. All of the other expected signals are
present in the spectra. A peak at about 2.35 ppm due to
the toluene methyl group for the cadmium complexes of
Ts3mepyϪ and Ts6mepyϪ, and for Ms3mepyϪ and
Ms6mepyϪ two peaks are observed at about 2.70 and
2.25 ppm due to the mesytilene methyl groups. For
Ts3mepyϪ and Ms3mepyϪ the pyridine methyl group gives
rise to a signal close to 2.15 ppm and for Ts6mepyϪ and
Ms6mepyϪ the pyridine methyl group appears in the range
2.20 to 2.40 ppm. Aromatic peaks, including those for the
coligands, are between 6 and 8 ppm.
Figure 5 Molecular structure of[Cd(Ms3mepy)2bipy]. The insert
represents the environment around the metal atom.
The mass spectra of some of the complexes could not be
recorded for solubility reasons. For the other complexes the
LSIMS show the molecular ion with appropriate isotope
distributions. In many cases, the ions formed by loss of one
ligand from the initial complex are also observed, as well
as a peak attributed to the free ligand.
The cadmium atom is six-coordinated by two anionic sul-
fonamide ligands that act as (N,O) donors and by a
2,2Ј-bipyridine molecule acting in an (N,NЈ) chelating man-
ner.
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284
281

´
´
´
I. Beloso, J. Castro, J. A. GarcıaϪVazquez, P. PerezϪLourido, J. Romero, A. Sousa
1595(s), 1544(s), 1338(s), 1098(s). EI MS: m/z: 291 (100 %, Mϩ); 108 (10 %,
Mϩ Ϫ {O2S-mesityl}).
3 Conclusions
This paper describes a series of cadmium complexes of sev-
eral sulfonamides ligands. The features of the X-ray diffrac-
tion determined structures are summarized in Table 7.
HTs6mepy: Anal. C. 58.8, H. 5.6, N. 10.6, S. 12.3 % Calcd. for
C13N2H14O2S C. 59.5, H. 5.4, N. 10.7, S. 12.2 %.
1H NMR (CDCl3, ppm) 2.41(s), 3H, CH3(py); 2.36(d), 3H, CH3(tolyl);
6.60(d), 1H, py; 7.46(dd), 1H, py; 7.06(d), 1H, py; 7.22(d), 2H, tolyl; 7.79(d),
2H, tolyl; 9.95(b), 1H, NH. IR (KBr, cmϪ1): 3231(w), 2958(w), 1612(vs),
Table 7 Conclusions.
1534(m), 1369(s), 1134(s). EI MS: m/z: 262 (6 %, Mϩ); 108 (3 %, Mϩ
Ϫ
Complex
Sulfonamide ligand
behaviour
Environment around
the metal atom
{O2S-tolyl}).
HTs3mepy: Anal. C. 58.7, H. 5.7, N. 10.2, S. 11.8 % Calcd. for
C13N2H14O2S C. 59.5, H. 5.4, N. 10.7, S. 12.2 %.
[Cd(Ms6mepy)2(H2O)2]
[Cd(Ts6mepy)2 bipy]
[Cd(Ts3mepy)2bipy]
[Cd(Ms3mepy)2bipy]
(N, N) bidentate
(N, N) bidentate
(N, O) bidentate
(N, O) bidentate)
[CdN4O2]
[CdN6]
[CdN4O2]
[CdN4O2]
1H NMR (CDCl3, ppm) 2.15(s), 3H, CH3(py); 2.35(d), 3H, CH3(tolyl);
6.50(d), 1H, py; 7.40(d), 1H, py; 7.49(d), 1H, py; 7.85(d), 2H, tolyl; 7.21(d),
2H, tolyl; 12.14(b), 1H, NH. IR (KBr, cmϪ1): 3248(m), 2951(w), 1594(s),
1544(s), 1342(s), 1126(s). EI MS: m/z: 262 (8 %, Mϩ); 108 (20 %, Mϩ
Ϫ
{O2S-tolyl}).
As can be seen, the ligands behave in a (N, O) bidentate
way when a substituent is located in position 3. However,
when the substituent is in position 6, the ligands behave in
a (N, N) bidentate way. Probably the difference can be
traced to a steric effect. A substituent in position 3 pushes
the sulfonyl group towards the proximity of the metal atom,
and induces a (N, O) bidentate behaviour. It should be
noted that the ligands behave in a (N, N) way when they
have not substituents neither in position 3 nor in position
6 [10].
Preparation of complexes
The complexes were obtained by following an electrochemical pro-
cedure [23, 24]. The cell consisted of a 100 mL tall-form beaker
fitted with a rubber bung through which the electrochemical leads
entered. An acetonitrile solution of either the ligand (HL) or of a
mixture of the ligand and the coligand [2,2Ј-bipyridine or 1,10-
phenanthroline monohydrate (LЈ)], containing about 20 mg of
tetraethylammonium perchlorate as a current carrier, was electro-
lysed using a platinum wire as the cathode and a cadmium plate
suspended from another platinum wire as the sacrificial anode.
Direct current was supplied by a purpose-built d.c. power supply.
Applied voltages of 5Ϫ15 volts allowed sufficient current flow for
smooth dissolution of the cadmium metal. The current was main-
tained at 10 mA during one hour. In all cases, hydrogen was
evolved from the cathode. These cells can be summarised as:
4 Experimental Section
Acetonitrile, dichloromethane, 2-amino-3-picoline, 2-amino-6-pico-
line, p-toluenesulfonyl chloride, 2-mesitylenesulfonyl chloride, 2,2Ј-
bipyridine, 1,10-phenanthroline monohydrate, sodium carbonate,
anhydrous magnesium sulfate, and all other reagents were commer-
cial products and were used as supplied. Cadmium (Aldrich) was
used as 2 ϫ 2 cm plates.
Cd(ϩ)/CH3CNϩHLϩ LЈ/Pt(Ϫ)
After electrolysis the colourless solutions were filtered to remove
any particles of metal and then left to concentrate, yielding crystal-
line products. The solids were washed with acetonitrile and diethyl
ether and dried at room temperature.
Preparation of ligands
Ligands were prepared by reaction of the corresponding amine and
the sulfonyl chloride in a 1:1 ratio. Experimental details are given
for a representative example.
[Cd(Ts6mepy)2]. Electrochemical oxidation of a cadmium anode
in a solution of the ligand N-(6-methyl-2-pyridyl)-p-toluenesulfon-
amide, (0.19 g, 0.75 mmol) in acetonitrile (50 cm3 ), at 7 V and
10 mA for 2 hour caused 33.9 mg of cadmium to be dissolved, Efϭ
0.41 mol·FϪ1. Anal.: Calc. for CdC26H26N4O4S2: C, 49.2; H, 4.1;
N, 8.8; S, 10.1. Found: C, 50.2; H, 4.5; N, 9.2; S, 9.7 %.
HMs6mepy: This ligand was synthesized by mixing 2-amino-6-
picoline (2 g, 18.4 mmol) and 2-mesitylenesulfonyl chloride (4.05 g,
18.4 mmol) in dichloromethane. An aqueous solution of sodium
carbonate (1.95 g, 18.4 mmol in 20 mL water) was added dropwise
to the above solution. The mixture was stirred overnight and water
(100 mL) was added. The organic layer was dried with anhydrous
magnesium sulfate, the solvent was evaporated and the resulting
oil was treated with ethanol. A white solid was obtained and was
identified as HMs6mePy. Anal. C. 61.3, H. 6.4, N. 9.5, S. 10.9 %
Calcd. for C15N2H18O2S C. 62.1, H. 6.2, N. 9.6, S. 11.0 %.
1H NMR (CDCl3, ppm) 2.37(s), 3H, CH3(py); 2.24(s), 3H, CH3(p-tolyl);
2.69(s), 6H, CH3(o-tolyl); 6.55(d), 1H, py; 6.74(d), 1H, py; 6.88(s), 2H, tolyl;
7.37(d), 1H, py; 12.33(b), 1H, NH. IR (KBr, cmϪ1): 3236(w), 2931(w),
1616(vs), 1533(m), 1362(vs), 1136(vs). EI MS: m/z: 291 (4 %, Mϩ); 108
(13 %, Mϩ Ϫ {O2S-mesityl}).
IR (KBr, cmϪ1): 2931 (w), 1593 (m), 1459 (s), 1322 (m), 1138 (s).
[Cd(Ts6mepy)2bipy]. Electrolysis of a solution of the ligand
(0.19 g, 0.75 mmol) and 2,2Ј-bipyridine (0.06 g, 0.37 mmol) in
acetonitrile, (50 cm3) at 8 V and 10 mA for 2 hour dissolved
30.9 mg of cadmium, Ef
ϭ
0.37 mol·FϪ1.Anal. Calc. for
CdC36H34N6O4S2: C, 54.7; H, 4.3; N, 10.6; S, 8.1.Found: C, 54.4;
H, 4.3; N, 10.7; S, 7.8 %. Suitable crystals for X-ray studies were
obtained by air concentration of the resulting solution.
IR (KBr, cmϪ1): 2922 (w), 1590 (s), 1455 (s), 1321 (s), 1135 (s), 767 (m), 738
(m). 1H NMR (CDCl3, ppm): δ 9.8Ϫ6.4 (m, 22H), 2.2 (s, 6H, Me(py)), 2.1
(s, 6H, p-Me(Tos)). LSIMS (m/z): 790 [Cd(Ts6mepy)2bipy]ϩ; 531
[Cd(Ts6mepy)bipy]ϩ; 263 (Ts6mepy)ϩ.
HMs3mepy: Anal. C. 61.3, H. 6.0, N. 9.3, S. 11.2 %. Calcd. for
C15N2H18O2S C. 62.1, H. 6.2, N. 9.6, S. 11.0 %.
[Cd(Ts6mepy)2phen]. A solution of the ligand (0.15 g, 0.56 mmol)
and 1,10-phenantroline (0.05 g, 0.28 mmol) in acetonitrile (50 cm3)
was electrolyzed at 6 V and 10 mA during 1.5 hour; 37.0 mg of
1H NMR (CDCl3, ppm) 2.15(s), 3H, CH3(py); 2.25(s), 3H, CH3(p-tolyl);
2.71(s), 6H, CH3(o-tolyl); 6.47(d), 1H, py; 6.89(s), 2H, tolyl; 7.36(d), 1H, py;
7.42(d), 1H, py; 12.33(b), 1H, NH. IR (KBr, cmϪ1): 3222(m), 2940(w),
282
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284

Electrochemical Synthesis and Characterization of Cadmium(II) Complexes
cadmium metal was dissolved from the anode, Efϭ 0.59 mol·FϪ1
.
acetonitrile (50 cm3) led to the dissolution of 32.2 mg of cadmium,
Ef ϭ 0.51 mol·FϪ1. Anal. Calc. for CdC38H34N6O4S2: C, 56.0; H,
4.2; N, 9.7; S, 7.8. Found: C, 55.8; H, 4.9; N, 10.3; S, 7.3 %.
Anal. Calc. For CdC38H34N6O4S2 : C, 56.0; H, 4.2; N, 9.7; S, 7.8.
Found: C, 55.2; H, 4.0; N, 9.9; S, 7.8 %.
IR (KBr, cmϪ1): 2930 (w), 1590 (m), 1515 (w), 1455 (s), 1323 (m), 1138 (s),
847 (m), 727 (w). 1H NMR (CDCl3, ppm): δ 10.2Ϫ6.4 (m, 22H),2.2 (s, 6H,
Me(py)), 2.1 (s, 6H, p-Me(Tos)). LSIMS (m/z): 816 [Cd(Ts6mepy)2phen]ϩ;
555 [Cd(Ts6mepy)phen]ϩ.
IR (KBr, cmϪ1): 2922 (w), 1594 (s), 1519 (m), 1399 (m), 1324 (m), 1117
(m),843 (s), 727 (w). LSIMS (m/z): 816 [Cd(Ts3mepy)2 phen]ϩ; 555
[Cd(Ts3mepy) phen]ϩ; 263 (Ts3mepy)ϩ.
[Cd(Ms3mepy)2]. A solution of the ligand N-(6-methyl-2-pyridyl)-
mesitylenesulfonamide, (0.14 g, 0.50 mmol) in acetonitrile (50 cm3)
was electrolyzed at 7 V and 10 mA during 1.5 hour; 34.5 mg of
cadmium were dissolved from the anode, Ef ϭ 0.55 mol·FϪ1. Anal.
Calc. for CdC30H34N4O4S2: C, 52.1; H, 4.9; N, 8.1; S, 9.3. Found:
C, 49.2 H, 4.7 N, 7.6 S, 9.4 %.
[Cd(Ms6mepy)2]. A solution of the ligand N-(6-methyl-2-pyridyl)-
mesitylenesulfonamide, (0.22 g, 0.75 mmol) in acetonitrile (50 cm3)
was electrolyzed at 7 V and 10 mA during 2 hour; 32.2 mg of cad-
mium were dissolved from the anode, Ef ϭ 0.38 mol·FϪ1. Anal.
Calc. for CdC30H34N4O4S2: C, 52.1; H, 4.9; N, 8.1; S, 9.3. Found:
C, 50.5 H, 4.7 N, 7.8 S, 9.5 %. Suitable crystals for X-ray studies
were obtained by air concentration of the resulting solution.
IR (KBr, cmϪ1): 2932 (w), 1602 (m), 1452 (m), 1320 (m), 1123 (m).
IR (KBr, cmϪ1): 2934 (w), 1616 (m), 1458 (s), 1324 (m), 1134 (s). LSIMS
[Cd(M3mepy)2bipy]. Electrolysis of a solution of the ligand
(0.16 g, 0.57 mmol) and 2,2Ј-bipyridine (0.04 g, 0.29 mmol) in
acetonitrile, (50 cm3) at 5 V and 10 mA for 1.5 hour dissolved
(m/z): 693 [Cd(Ms6mepy)2]ϩ; 402 [Cd(Ms6 mepy)]ϩ; 291 (Ms6mepy)ϩ.
[Cd(Ms6mepy)2bipy]. Electrolysis of a solution of the ligand
(0.22 g, 0.75mmol) and 2,2Ј-bipyridine (0.06 g, 0.37 mmol) in
acetonitrile, (50 cm3) at 13 V and 10 mA for 2 hour dissolved
31.2 mg of cadmium, Ef
ϭ . Anal. Calc. for
0.50 mol·FϪ1
CdC40H42N6O4S2:C, 56.6; H, 5.0; N, 9.9; S, 7.5. Found: C, 56.6;
H, 4.9; N, 10.0; S, 7.1 %. Suitable crystals for X-ray studies were
obtained by air concentration of the resulting solution.
IR (KBr, cmϪ1): 2931 (w), 1597 (s), 1440 (s), 1315 (m), 1119 (m), 767 (m),
738 (m). 1H NMR (CDCl3, ppm): δ 8.7Ϫ6.5 (m, 18H), 2.7(s, 12H, o-
Me(Tos)), 2.3(s, 6H, p-Me(Tos)), 2.1(s, 6H, Me(py)).
33.3 mg of cadmium, Ef
ϭ . Anal. Calc. for
0.39 mol·FϪ1
CdC40H42N6O4S2:C, 56.6; H, 5.0; N, 9.9; S, 7.5. Found: C, 56.5;
H, 5.3; N, 9.7; S, 7.5 %.
IR (KBr, cmϪ1): 2932 (w), 1616 (s), 1456 (m), 1323 (w), 1137 (s), 779 (m),
735 (m). 1H NMR (CDCl3, ppm): δ 9.6Ϫ6.4 (m, 18H), 2.32(s, 12H, o-
Me(Tos)), 2.29(s, 6H, Me(py)), 2.22(s, 6H, p-Me(Tos)). LSIMS (m/z): 849
[Cd(Ms6mepy)2bipy]ϩ; 291 (Ms6mepy)ϩ.
[Cd(Ms3mepy)2phen].
A
solution of the ligand (0.16 g,
0.57 mmol) and 1,10-phenantroline (0.05 g, 0.29 mmol) in aceto-
nitrile (50 cm3) was electrolyzed at 5 V and 10 mA during 2 hour;
41.8 mg of cadmium metal was dissolved from the anode, Efϭ
0.50 mol·FϪ1. Anal. Calc. for CdC42H42N6O4S2: C, 57.8; H, 4.8;
N, 9.6; S, 7.3. Found: C, 58.1; H, 4.8; N, 9.7; S, 7.2 %.
IR (KBr, cmϪ1): 2934 (w), 1594 (m), 1518 (w), 1416 (s), 1320 (m), 1118 (m),
843 (m), 728 (m). 1H NMR (CDCl3, ppm): δ 9.3Ϫ6.6 (m, 18H), 2.4(s, 12H,
o-Me(Tos)), 2.2(s, 6H, p-Me(Tos)), 1.8(s, 6H, Me(py)). LSIMS (m/z): 873
[Cd(Ms3mepy)2phen]ϩ; 581 [Cd(Ms3mepy)phen]ϩ; 291 [Ms3mepy]ϩ.
[Cd(Ms6mepy)2phen].
A
solution of the ligand (0.22 g,
0.75 mmol) and 1,10-phenantroline (0.07 g, 0.37 mmol) in aceto-
nitrile (50 cm3) was electrolyzed at 9 V and 10 mA during 2 hour;
38.3 mg of cadmium metal was dissolved from the anode, Efϭ
0.46 mol·FϪ1. Anal. Calc. for CdC42H42N6O4S2: C, 57.8; H, 4.8;
N, 9.6; S, 7.3. Found: C, 57.8; H, 5.2; N, 9.6; S, 7.3 %.
IR (KBr, cmϪ1): 2930 (w), 1591 (m), 1516 (w), 1455 (s), 1322 (m), 1131 (s),
848 (m), 726 (w). 1H NMR (CDCl3, ppm): δ 9.9Ϫ6.5 (m, 18H), 2.31(s, 12H,
o-Me(Tos)), 2.26(s, 6H, Me(py)), 2.20(s, 6H, p-Me(Tos)). LSIMS (m/z): 873
[Cd(Ms6mepy)2phen]ϩ; 291 [Ms6mepy]ϩ.
Physical measurements
[Cd(Ts3mepy)2]. Electrochemical oxidation of a cadmium anode
The C, N, H and S contents of the compounds were determined
on a Carlo-Erba EA 1108 microanalyser. IR spectra were recorded
as KBr mulls on a Bruker Vector-22 spectrophotometer. The
1H NMR spectra of the compounds were recorded on a Bruker
ARX-400 MHz spectrometer using CDCl3 as solvent. EI (70 eV,
250 °C) and LSI mass spectra were recorded on a Micromass VG
Autospec M instrument.
in
a solution of N-(3-methyl-2-pyridyl)-p-toluenesulfonamide,
(0.15 g, 0.56 mmol) in acetonitrile (50 cm3 ), at 6 V and 10 mA for
2 hour, caused 35.2 mg of cadmium to be dissolved, Ef
ϭ
0.42 mol·FϪ1. During the electrolysis hydrogen was evolved at the
cathode. Anal. Calc. for CdC26H26N4O4S2: C, 49.2; H, 4.1; N, 8.8;
S, 10.1. Found: C, 48.5; H, 4.2; N, 8.7; S, 9.8 %.
IR (KBr, cmϪ1): 2921 (w), 1594(s), 1417 (m), 1312 (w), 1123 (s). 1HNMR
(CDCl3, ppm): δ 7.8Ϫ6.5 (m, 14H), 2.4 (s, 6H, p-Me(Tos)), 2.1 (s, 6H,
Me(py)). LSIMS (m/z): 635 [Cd(Ts3mepy)2]ϩ; 263 (Ts3mepy)ϩ.
Crystal structure determination
[Cd(Ts3mepy)2bipy]. Electrolysis of a solution of the ligand
(0.19 g, 0.75 mmol) and 2,2Ј-bipyridine (0.06 g, 0.37 mmol) in
acetonitrile, (50 cm3) at 8 V and 10 mA for 2 hour dissolved
The data collections were taken on a SIEMENS Smart CCD area-
detector diffractometer with graphite-monochromated Mo-Kα
radiation. Absorption corrections were carried out using SADABS
[25]. All the structures were solved by direct methods and refined
by full-matrix least-squares based on F2 [26]. All non-hydrogen
atoms were refined with anisotropic displacement parameters. In
the case of HMs6mepy, hydrogen atoms were located on a differ-
ence electron density map and refined with isotropic displacement
parameters Ϫ except those of the methyl groups, which were in-
cluded in idealised positions and refined with isotropic displace-
ment parameters. For all the complexes, hydrogen atoms were also
included in idealised positions and refined with isotropic displace-
ment parameters Ϫ except those in the coordinated water molecule
of [Cd(Ts6mepy)2(H2O)2]H2O, which were located and refined with
44.6 mg of cadmium, Ef
ϭ . Anal. Calc. for
0.53 mol·FϪ1
CdC36H34N6O4S2: C, 54.7; H, 4.3; N, 10.6; S, 8.1.Found: C, 54.2;
H, 4.5; N, 10.5; S, 8.0 %. Suitable crystals for X-ray studies were
obtained by air concentration of the acetonitrile solution.
IR (KBr, cmϪ1): 2916 (w), 1597 (s), 1414 (s), 1326 (m), 1114 (m), 769 (m),
738(m). 1H NMR (CDCl3, ppm): δ 8.8Ϫ6.7 (m, 22H), 2.3 (s, 6H, p-Me(Tos)),
2.0 (s, 6H, Me(py)). LSIMS (m/z): 790 [Cd(Ts3mepy)2bipy]ϩ; 531
[Cd(Ts3mepy)bipy]ϩ; 263 (Ts3mepy)ϩ.
[Cd(Ts3mepy)2phen]. A similar experiment to that described
above (10 V, 10 mA, 1.5 h.) with the same sulfonamine ligand
(0.15 g, 0.56 mmol) and 1,10-phenantroline (0.05 g, 0.28 mmol) in
Z. Anorg. Allg. Chem. 2003, 629, 275Ϫ284
283

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I. Beloso, J. Castro, J. A. GarcıaϪVazquez, P. PerezϪLourido, J. Romero, A. Sousa
´
´
´
´
isotropic displacement parameters. Atomic scattering factors and
anomalous dispersion corrections for all atoms were taken from
International Tables for X-ray Crystallography [27].
[10] S. Cabaleiro, J. Castro, E. Vazquez-Lopez, J. A. Garcıa-Vaz-
quez, J. Romero, A. Sousa, Inorg. Chim. Acta 1999, 294, 87,
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[13] P. B. Donaldson, P. A. Tasker, N. W. Alcock, J. Chem. Soc,
Supplementary material
The atomic positions, full list of bond lengths and angles and other
crystallographic data are available on request from J.C. Crystallo-
graphic data have been deposited with the CCDC, (12 Union Road,
Cambridge CB2 1EZ, UK) and are available on request quoting
the deposition numbers 192777 and 187517 to 187520.
Dalton Trans. 1977, 1160.
´
´
´
[14] A. Garcıa-Raso, J. J. Fiol, S. Rigo, A. Lopez-Lopez, E.
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´
Molins, E. Espinosa, E. Borras, G. Alzuet, J. Borras, A. Casti-
n˜eiras Polyhedron, 2000, 19, 991.
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Acknowledgements. This work was supported by the Xunta de
Galicia (Spain) under the grant PGIDT00PXI20305PR. We thank
fergus.uvigo.es (http://fergus.uvigo.es/) for X-ray solution and re-
finement facilities.
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