Different coordinative behaviour of methyl-substituted 2-pyridylsulfonamide derivatives as ligands in zinc complexes

Article abstract of DOI:10.1016/S0277-5387(03)00096-2

Neutral zinc complexes [ZnL₂L′] of a series of methyl-substituted N-2-pyridylsulfonamide ligands (HL) and 1,10-phenanthroline or 2,2′-bipyridine (L′) have been synthesised by electrochemical oxidation of anodic zinc metal in an acetonitrite solution of the ligand and the coligand. The compounds obtained have been characterised by microanalysis, IR and ¹H NMR spectroscopy, LSI mass spectrometry studies and some of the mixed complexes by single-crystal X-ray diffraction. The crystal structures show different octahedral environments around the metal (N6 or N4O2) depending on the position of the substituent on the pyridine ring.

Full text of DOI:10.1016/S0277-5387(03)00096-2

Polyhedron 22 (2003) 1099Á1111
/
www.elsevier.com/locate/poly
Different coordinative behaviour of methyl-substituted
2-pyridylsulfonamide derivatives as ligands in zinc complexes
Inmaculada Beloso a, Jesu´s Castro a,*, Jose´ A. Garc´ıa-Va´zquez b, Paulo Pe´rez-Lourido a,
Jaime Romero b, Antonio Sousa b,*
a Departamento de Qu´ımica Inorganica, Universidade de Vigo, 36200 Vigo, Galicia, Spain
b Departamento de Qu´ımica Inorganica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain
Received 21 November 2002; accepted 17 January 2003
Abstract
Neutral zinc complexes [ZnL2L?] of a series of methyl-substituted N-2-pyridylsulfonamide ligands (HL) and 1,10-phenanthroline
or 2,2?-bipyridine (L?) have been synthesised by electrochemical oxidation of anodic zinc metal in an acetonitrile solution of the
ligand and the coligand. The compounds obtained have been characterised by microanalysis, IR and H NMR spectroscopy, LSI
1
mass spectrometry studies and some of the mixed complexes by single-crystal X-ray diffraction. The crystal structures show different
octahedral environments around the metal (N6 or N4O2) depending on the position of the substituent on the pyridine ring.
# 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Zinc complexes; Sulfonamide ligands; Electrochemical synthesis; Crystal structures
1. Introduction
exocyclic nitrogen atom. In addition, the electron-with-
drawing effect of this substituent increases the acid
character of the NH group and makes the process of
ligand deprotonation easier.
Recently, the chemistry of metal complexes contain-
ing amide ligands has been a subject of great interest.
The reason for this interest stems from the fact that such
complexes can be easily made and variation of the
substituents is facile. These characteristics provide the
possibility of tailoring the bite angle and degree of steric
hindrance present in the ligand. The chemistry of metal
complexes containing pyridine-functionalised amido
ligands of the type shown below (Scheme 1) has received
It has been found that these ligands can coordinate to
the metal in a number of different ways (see Scheme 3).
Coordination modes I has been found in zinc
compounds. However, it is worth noting that a weak
interaction between the metal and the exocyclic nitrogen
atom is present [6]. Coordination mode II is the most
common, and this has been found in cobalt(II) [7],
nickel(II) [8] and cadmium(II) [9] complexes. Coordina-
tion mode III has been found in cadmium(II) com-
pounds [11]. To date, coordination mode IV has only
a great deal of attention [1Á5].
It is believed that the presence of bulky substituents
on these ligands stabilises the metal complexes.
/
Consequently, it was decided to study the chemistry
of the metal complexes of sulfonyl-2-pyridine-amines.
These ligands, which are represented in Scheme 2,
contain a bulky sulfonyl group as a substituent on the
Scheme 1.
* Corresponding authors. Tel.: ꢀ
813-798 (J.C.); Tel.: ꢀ34-981-563-100x14245; fax: ꢀ
(A.S.).
E-mail addresses: fojo@uvigo.es (J. Castro), qiansoal@usc.es (A.
Sousa).
/
34-986-812-278; fax: ꢀ
/
34-986-
/
/34-981-597-525
Scheme 2.
0277-5387/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00096-2

1100
I. Beloso et al. / Polyhedron 22 (2003) 1099Á1111
/
2. Experimental
Acetonitrile, dichloromethane, 2-amino-3-picoline, 2-
amino-6-picoline, p-toluenesulfonyl chloride, 2-mesityl-
sulfonyl chloride, 2,2?-bipyridine, 1,10-phenanthroline
monohydrate, sodium carbonate, anhydrous magne-
sium sulfate, and all other reagents were commercial
products and were used as supplied. Zinc (Aldrich) was
used as 2ꢁ2 cm plates.
/
2.1. Preparation of ligands
The ligands were prepared by reaction of the corre-
sponding 2-aminopyridine and the sulfonyl chloride
(1:1) in dichloromethane as described previously [8,10].
Experimental details are given for a representative
example.
Scheme 3.
been found in copper(II) [11,12] and silver(I) [11,13]
complexes. Coordination modes V and VI were found in
a polymer compound of cadmium(II) [9] and coordina-
tion mode VII has thus far only been found in silver(I)
complexes [11].
2.1.1. HTs3mepy
This ligand was synthesised by dissolving 2-amino-3-
picoline (2 g, 18.4 mmol) and 4-methylphenylsulfonyl
chloride (3.51 g, 18.4 mmol) in dichloromethane. To this
solution was added dropwise 20 cm3 of an aqueous
solution containing sodium carbonate (1.95 g, 18.4
mmol). The reaction mixture was stirred overnight and
water (100 cm3) was added. The organic layer was dried
with anhydrous magnesium sulfate, the solvent was
evaporated and the resulting crude oil was treated with
ethanol. The resulting white precipitate was isolated by
filtration and identified as HTs3mepy: Anal. C, 58.7; H,
5.7; N, 10.2; S, 11.8%. Calc. for C13N2H14O2S: C, 59.5;
H, 5.4; N, 10.7; S, 12.2%. 1H NMR (CDCl3, ppm): 2.15
As a continuation of our work on different sulfona-
mide compounds [6Á10], here we report the synthesis of
/
a series of neutral zinc complexes through an electro-
chemical procedure in which the metal is the anode in a
cell containing an acetonitrile solution of different
substituted N-2-pyridyl-benzenesulfonamide ligands.
These ligands are characterised by the presence of an
additional donor nitrogen atom in the a-position
belonging to a picoline group. With the aim of
investigating whether the position of the methyl group
on the pyridine ring has any influence on the coordina-
tive behaviour of these compounds, the 3- and 6-methyl
derivatives were chosen for this study. The benzene ring
is also substituted by one methyl group (p-toluene
group) or, alternatively, by three methyl groups (mesityl
group) (see Scheme 4, HL).
[s, 3H, CH3(py)]; 2.35 [s, 3H, CH3(tolyl)]; 6.50 (t, Jꢂ
Hz, 1H, py); 7.22 (d, Jꢂ8.2 Hz, 2H, tolyl); 7.39 (d, Jꢂ
6.6 Hz, 1H, py); 7.49 (d, Jꢂ6.6 Hz, 1H, py); 7.84 (d,
8.2 Hz, 2H, tolyl); 12.14 (b, 1H, NH). IR (KBr,
/6.6
/
/
/
Jꢂ
/
cmꢃ1): 3248(m), 2951(w), 1.632(m), 1594(s), 1544(s),
1399(m), 1371(m), 1342(m), 1126(s), 1127(m), 1080(s),
964(m), 828(m), 767(m) 682(s), 570(m), 552(m), 424(w).
EI MS: m/z: 262 (8%, Mꢀ); 108 (20%, Mꢀ
*{O2S-
/
tolyl}).
2.1.2. HTs6mepy
Anal. C, 58.8; H, 5.6; N, 10.6; S, 12.3%. Calc. for
1
C13N2H14O2S: C, 59.5; H, 5.4; N, 10.7; S, 12.2%. H
NMR (CDCl3, ppm): 2.36 [s, 3H, CH3(tolyl)]; 2.41 [s,
Scheme 4.
3H, CH3(py)]; 6.60 (d, Jꢂ
8.5 Hz, 1H, py); 7.21 (d, Jꢂ
Jꢂ
/
7.3 Hz, 1H, py); 7.05 (d, Jꢂ
8.2 Hz, 2H, tolyl); 7.46 (dd,
8.2 Hz, 2H,
/
/
/
7.3 and 8.5 Hz, 1H, py); 7.79 (d, Jꢂ
/
tolyl); 9.95 (b, 1H, NH). IR (KBr, cmꢃ1): 3231(w),
3092(m), 2958(w), 1612(vs), 1534(m), 1369(s), 1253(m),
1135(s), 1089(m), 855(m), 787(m), 661(m), 572(m),
554(m), 440(w). EI MS: m/z: 262 (6%, Mꢀ); 108 (3%,
Code
R1
R2
HTs3mepy
HTs6mepy
HMs6mepy
4-Me
4-Me
2,4,6-Me3
3-Me
6-Me
6-Me
Mꢀ
*{O2S-tolyl}).
/

I. Beloso et al. / Polyhedron 22 (2003) 1099Á
/1111
1101
2.1.3. HMs6mepy
in acetonitrile (50 cm3) led to the dissolution of 19.0 mg
of zinc, Efꢂ Anal. Calc. for
0.52 mol Fꢃ1
C38H34N6O4S2Zn: C, 59.4; H, 4.5; N, 10.9; S, 8.3%.
Found: C, 58.5; H, 4.7; N, 10.7; S, 8.1%. IR (KBr,
cmꢃ1): 3062(m), 2920(w), 1601(m), 1540(w), 1519(w),
1418(s), 1333(m), 1243(m), 1114(m), 1085(m), 1002(m),
845(w), 728(w), 664(m), 588(m), 545(w), 420(w). 1H
Anal. C, 61.3; H, 6.4; N, 9.5; S, 10.9% Calc. for
C15N2H18O2S: C, 62.1; H, 6.2; N, 9.6; S, 11.0%. 1H
NMR (CDCl3, ppm): 2.23 [s, 3H, CH3(p-tolyl)]; 2.37 [s,
/
.
3H, CH3(py)]; 2.69 [s, 6H, CH3(o-tolyl)]; 6.54 (d, Jꢂ
Hz, 1H, py); 6.74 (d, Jꢂ8.4 Hz, 1H, py); 6.88 (s, 2H,
tolyl); 7.37 (dd, Jꢂ7.6 and 8.4 Hz, 1H, py); 9.40 (b, 1H,
/7.6
/
/
NH). IR (KBr, cmꢃ1): 3237(w), 3028(w), 2932(m),
1617(vs), 1533(m), 1457(m), 1362(vs), 1289(m),
1137(vs), 1064(m), 834(m), 790(m), 748(m), 656(m),
579(m), 527(m). EI MS: m/z: 291 (4%, Mꢀ); 108
NMR (CDCl3, ppm): d 9.19Á6.60 (m, 22H), 2.14 [s, 6H,
/
p-Me(Tos)], 1.98 [s, 6H, Me(py)]. LSIMS (m/z): 767
[Zn(Ts3mepy)2phen]ꢀ; 505 [Zn(Ts3mepy)phen]ꢀ; 263
(Ts3mepy)ꢀ. Suitable crystals for X-ray studies were
obtained by crystallisation of the initial product from
acetonitrile/methanol.
(13%, Mꢀ
*{O2S-mesityl}).
/
2.2. Preparation of complexes
2.2.3. [Zn(Ts6mepy)2bipy] (3)
The complexes were prepared by an electrochemical
method. The cell consisted of zinc foil suspended from a
platinum wire as the anode and a platinum wire as the
cathode. The sulfonamide ligand (HL) and the corre-
sponding coligand, 2,2?-bipyridine or 1,10-phenanthro-
line (L?), were dissolved in acetonitrile and a small
amount of tetraethylammonium perchlorate was added
to the solution as a supporting electrolyte. Applied
Electrolysis of a solution of the ligand (0.15 g, 0.56
mmol) and 2,2?-bipyridine (0.04 g, 0.28 mmol) in
acetonitrile (50 cm3) at 11 V and 10 mA for 1.5 h
dissolved 20.1 mg of zinc, Efꢂ
0.55 mol Fꢃ1. Anal.
/
Calc. for C36H34N6O4S2Zn: C, 58.2; H, 4.6; N, 11.3; S,
8.6%. Found: C, 59.1; H, 4.7; N, 11.8; S, 8.7%. IR (KBr,
cmꢃ1): 3067(w), 2921(w), 1591(s), 1456 (s), 1324(s),
1276(w), 1140(s), 1099(m), 1019(w), 1012(w), 858(m),
766(m), 736(w), 664(m), 581(m), 552(m), 415(w). 1H
voltages of 8Á15 V allowed sufficient current flow for
/
smooth dissolution of the metal. Nitrogen was bubbled
through the solution during electrolysis to stir the
reaction mixture. The cell can be summarised as
NMR (CDCl3, ppm): d 9.7Á6.4 (m, 22H), 2.2 [s, 6H,
/
Me(py)], 2.1 [s, 6H, p-Me(Tos)]. LSIMS (m/z): 743
[Zn(Ts6mepy)2bipy]ꢀ; 481 [Zn(Ts6mepy)bipy]ꢀ; 263
(Ts6mepy)ꢀ.
Zn(ꢀ)/CH3CNꢀ
/
HLꢀL?/Pt(ꢃ). At the end of the reac-
/
tion colourless crystals were filtered off, washed with
acetonitrile and diethyl ether and dried at room
temperature. In some cases air concentration was
required to obtain a crystalline solid.
2.2.4. [Zn(Ts6mepy)2phen] (4)
A solution of the ligand (0.15 g, 0.56 mmol) and 1,10-
phenanthroline (0.05 g, 0.28 mmol) in acetonitrile (50
cm3) was electrolysed at 15 V and 10 mA during 1.5 h;
17.9 mg of zinc metal was dissolved from the anode,
2.2.1. [Zn(Ts3mepy)2bipy] (1)
Electrolysis of a solution of the ligand (0.15 g, 0.56
mmol) and 2,2?-bipyridine (0.04 g, 0.28 mmol) in
acetonitrile (50 cm3) at 15 V and 10 mA for 1.5 h
Efꢂ
0.49 mol Fꢃ1. Anal. Calc. for C38H34N6O4S2Zn:
/
C, 59.4; H, 4.5; N, 10.9; S, 8.3%. Found: C, 58.7; H, 4.8;
N, 10.9; S, 8.1%. IR (KBr, cmꢃ1): 3063(w), 2922(w),
1590(m), 1576(w), 1517(w), 1456(s), 1322(m), 1275(m),
1138(m), 1099(m), 1004(vw), 858(m), 786(m), 727(m),
667(m), 581(m), 553(w), 419(w). 1H NMR (CDCl3,
dissolved 16.5 mg of zinc, Efꢂ
0.45 mol Fꢃ1. A colour-
/
less solid was obtained and identified as [Zn(Ts3me-
py)2bipy] CH3CN. Anal. Calc. for C38H37N7O4S2Zn: C,
58.1; H, 4.7; N, 12.5; S 8.2%. Found: C, 57.6; H, 4.6; N,
11.8; S, 8.4%. IR (KBr, cmꢃ1): 3037(w), 2916 (w), 1600
(m), 1442(m), 1413 (s), 1324 (m), 1243(m), 1186(w),
1117(m), 1064(m), 1001(w), 984(w), 845(w), 812(m),
771(m), 742(m), 662(m), 590(m), 546(w), 419(w). 1H
ppm): d 9.7Á
6H, p-Me(Tos)].
[Zn(Ts6mepy)2phen]ꢀ; 505 [Zn(Ts6mepy)phen]ꢀ; 263
(Ts6mepy)ꢀ. Suitable crystals for X-ray studies were
obtained by air concentration of the resulting solution.
/
6.4 (m, 22H), 2.2 [s, 6H, Me(py)], 2.1 [s,
LSIMS (m/z): 767
NMR (CDCl3, ppm): d 8.64Á6.57 (m, 22H), 2.15 [s, 6H,
/
p-Me(Tos)], 1.99 [s, 6H, Me(py)]. LSIMS (m/z): 743
[Zn(Ts3mepy)2bipy]ꢀ; 481 [Zn(Ts3mepy)bipy]ꢀ; 263
(Ts3mepy)ꢀ. Air-sensitive crystals were obtained from
the liquor and these were used for X-ray studies at low
temperature.
2.2.5. [Zn(Ms6mepy)2bipy] (5)
Electrolysis of a solution of the ligand (0.165 g, 0.565
mmol) and 2,2?-bipyridine (0.04 g, 0.28 mmol) in
acetonitrile (50 cm3) at 12 V and 10 mA for 1.5 h
dissolved 16.8 mg of zinc, Efꢂ
0.46 mol Fꢃ1. Anal.
/
Calc. for C40H42N6O4S2Zn: C, 59.9; H, 5.3; N, 10.5; S,
8.0%. Found: C, 59.3; H, 5.4; N, 10.4; S, 7.6%. IR (KBr,
cmꢃ1): 2966(w), 2932(w), 1588(s), 1453(s), 1404(w),
1311(s), 1289(w), 1134(s), 1076(m), 1023(w), 967 (w),
867(m), 850(w), 780(m), 734(m), 655(m), 589(w), 535(w),
2.2.2. [Zn(Ts3mepy)2phen] (2)
A similar experiment to that described above (12 V,
10 mA, 1.5 h) with the same sulfonamide ligand (0.15 g,
0.56 mmol) and 1,10-phenanthroline (0.05 g, 0.28 mmol)

1102
I. Beloso et al. / Polyhedron 22 (2003) 1099Á1111
/
1
416(w). H NMR (CDCl3, ppm): d 9.4Á
/
6.4 (m, 18H),
alous dispersion corrections for all atoms were taken
from International Tables for X-ray Crystallography
[16]. For the compounds [Zn(Ts3mepy)2phen],
[Zn(Ts6mepy)2phen] and [Zn(Ms6mepy)2bipy] the
SQUEEZE program [17] was used to correct the reflection
data for the diffuse scattering due to disordered solvent.
The crystal parameters and other experimental details of
data collection and refinement are summarised in Table
1.
2.3 [s, 6H, Me(py)], 2.2 [s, 6H, p-Me(Tos)], 2.1 [s, 12H,
o-Me(Tos)]. LSIMS (m/z): 798 [Zn(Ms6mepy)2bipy]ꢀ;
509 [Zn(Ms6mepy)bipy]ꢀ; 291 (Ms6mepy)ꢀ. Suitable
crystals for X-ray studies were obtained by air concen-
tration of the resulting solution.
2.2.6. [Zn(Ms6mepy)2phen] (6)
A solution of the ligand (0.165 g, 0.56 mmol) and
1,10-phenanthroline (0.05 g, 0.28 mmol) in acetonitrile
(50 cm3) was electrolysed at 8 V and 10 mA during 1.5 h;
17.5 mg of zinc metal was dissolved from the anode,
3. Results and discussion
Efꢂ
0.48 mol Fꢃ1. Anal. Calc. for C42H42N6O4S2Zn:
/
C, 61.1; H, 5.1; N, 10.2; S, 7.7%. Found: C, 59.9; H, 5.3;
N, 10.6; S, 7.2%. IR (KBr, cmꢃ1): 3055(w), 2934(w),
1592(s), 1520(m), 1456(s), 1418(w), 1326(s), 1287(w),
1132(s), 1085(m), 1004(vw), 966(w), 848(s), 781(m),
727(m), 654(m), 589(m), 532(m), 422(w). 1H NMR
The analytical results show that the electrochemical
procedure described above is an effective method for the
synthesis of zinc complexes with these sulfonamide
ligands. The method represents a simple alternative to
other standard chemical procedures. The compounds
are of general formula [ZnL2L?], where L represents the
anion of the corresponding sulfonamide ligand and L?
the co ligand, i.e. 2,2?-bipyridine (bipy) or 1,10-phenan-
throline (phen). The electrochemical efficiency value, Ef,
defined as the amount of metal dissolved per Faraday of
charge, was close to 0.5 mol Fꢃ1 in all cases. This fact,
along with the evolution of hydrogen at the cathode, is
compatible with the following reaction mechanisms:
(CDCl3, ppm): d 9.6Á6.4 (m, 18H), 2.3 [s, 6H,
/
Me(py)], 2.1 [s, 6H, p-Me(Tos)], 2.0 [s, 12H, o-
Me(Tos)]. LSIMS (m/z): 825 [Zn(Ms6mepy)2phen]ꢀ;
533 [Zn(Ms6mepy)phen]ꢀ; 291 [Ms6mepy]ꢀ. Suitable
crystals for X-ray studies were obtained by crystal-
lisation of the initial product from acetonitrile.
2.3. Physical measurements
Cathode: 2HLꢀ2eꢃ 0 2Lꢃ ꢀH2
Anode: Znꢀ2Lꢃ 0 [ZnL2]ꢀ2eꢃ
Elemental analyses were performed using a CarloÁ
/
Erba EA 1108 microanalyser. IR spectra were recorded
in KBr mulls using a Bruker Vector-22 spectrophot-
ometer. LSI mass spectra were recorded using a Micro-
mass VG Autospec M instrument. The 1H NMR spectra
were recorded using a Bruker ARX-400 MHz spectro-
meter with CDCl3 as solvent.
or
Znꢀ2Lꢃ ꢀL? 0 [ZnL2L?]ꢀ2eꢃ
3.1. Crystal structure of HTs3mepy
2.4. Crystal structure determination
The molecular structure of HTs3mepy is shown in
Fig. 1 together with the atomic numbering scheme.
Selected bond lengths, angles and hydrogen bond
parameters are given in Table 2.
A relevant feature of this structure is the presence of a
hydrogen atom on the N-pyridine ring, indicating that
the free ligand exists as the imido tautomer (I) rather
than the amido tautomer (II) (see Scheme 5). This
situation is similar to that found in other N-2-pyridi-
nylbenzenesulfonamide derivatives described previously
[8,10].
Both the phenyl and the pyridine rings are almost
planar. The sulfur atom is out of the best plane of the
˚
benzene ring by 0.043(4) A and the imine nitrogen atom
˚
is out of the pyridine ring plane by 0.0314(5) A. The
interplanar angle, 79.2(1)8, is slightly lower than those
found in other sulfonamides.
The data collections were taken on a SIEMENS
Smart CCD area-detector diffractometer with gra-
phite-monochromated Mo Ka radiation. In the case of
[Zn(Ts3mepy)2bipy] the data collection was made at 173
K since the crystalline product decomposed at room
temperature, probably due the evaporation of the
CH3CN present in the network. Absorption corrections
were carried out using SADABS [14]. All the structures
were solved by direct methods and refined by full-matrix
least-squares based on F2 [15]. All non-hydrogen atoms
were refined with anisotropic displacement parameters.
For all the complexes, hydrogen atoms were also
included in idealised positions and refined with isotropic
displacement. In the case of HTs3mepy, hydrogen atoms
were located on a difference electron density map and
refined with isotropic displacement parameters, except
those of the methyl groups, which were included in
idealised positions and refined with isotropic displace-
ment parameters. Atomic scattering factors and anom-
It is worth noting that the molecules of [(4-methyl-
phenyl)sulfonyl]imino-1H-3-methyl-2-pyridine are asso-
ciated by intermolecular hydrogen bonds. The hydrogen

I. Beloso et al. / Polyhedron 22 (2003) 1099Á
/1111
1103
Table 1
Summary of crystal data and structure refinement
Compound
HTs3mepy
13H14N2O2S
[Zn(Ts3mepy)2bipy]
[Zn(Ts3mepy)2phen]
C38H34N6O4S2Zn
768.20
Empirical formula
Formula weight
Temperature (K)
C
C38H37N7O4S2Zn
785.24
173(2)
262.32
293(2)
0.71073
293(2)
0.71073
triclinic
˚
Wavelength (A)
0.71073
orthorhombic
Pna21
Crystal system
Space group
Unit cell dimensions
triclinic
¯
¯
P1
P/1
/
˚
a (A)
7.200(2)
8.316(2)
11.199(3)
99.131(4)
99.651(5)
95.164(5)
648.0(3)
2
11.3562(8)
18.831(2)
16.973(2)
90
12.448(2)
12.647(2)
14.504(2)
103.860(2)
106.459(2)
97.121(2)
2080.4(3)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
Dcalc (Mg mꢃ3
90
90
3
˚
3629.7(4)
4
)
1.344
0.245
276
1.437
0.843
1632
1.226
0.734
796
Absorption coefficient (mmꢃ1
F(0 0 0)
)
Crystal size (mm)
u Range for data collection (8)
0.14ꢁ
/
0.20ꢁ
/0.25
0.29ꢁ
/
0.18ꢁ
/0.16
0.13ꢁ
/
0.20ꢁ
/
0.37
1.87Á28.11
/
1.62Á28.03
/
1.53Á28.03
/
Index ranges
ꢃ
/
80h 0
90k 0
110l 0
3939
/
/
9
ꢃ
/
140h 0
240k 0
150l 022
21 489
/
/
14
ꢃ
/
140h 0
160k 0
190l 0
12 247
/
/
16
ꢃ
/
/
/
10
ꢃ
/
/
/
20
ꢃ
/
/
/
16
ꢃ/
/
/
14
ꢃ/
/
/
ꢃ/
/
/
8
Reflections collected
Independent reflections
Completeness to theta max.
Max. and min. transmission
Data/restraints/parameters
Goodness-of-fit on F2
2737 [Rint
86.6%
ꢂ
/
0.0366]
6532 [Rint
98.8%
ꢂ
/
0.0772]
8517 [Rint
84.6%
ꢂ0.0299]
/
1.0000 and 0.5162
2737/0/197
0.907
1.0000 and 0.7740
6532/1/474
0.868
1.0000 and 0.8230
8517/0/464
0.736
Final R indices [I ꢀ
R indices (all data)
Absolute structure parameter [18]
/
2s(I)]
R1ꢂ
wR2ꢂ
/
0.0636
R1ꢂ
wR2ꢂ
/
0.0477
0.0583
R1ꢂ
wR2ꢂ
/
0.0402
0.0706
/0.1437
/
/
R1ꢂ0.1013
/
R1ꢂ0.0959
wR2ꢂ0.0662
0.011(11)
0.768 and ꢃ
/
R1ꢂ0.0903
/
wR2ꢂ0.1572
/
/
wR2ꢂ0.0777
/
ꢃ/
ꢃ3
˚
Largest difference peak and hole (e A
)
0.442 and ꢃ
/0.534
/
0.704
0.251 and ꢃ0.270
/
Compound
[Zn(Ts6mepy)2phen]
C38H34N6O4S2Zn
768.20
[Zn(Ms6me)2bipy]
C40H42N6O4S2Zn
800.29
[Zn(Ms6mepy)2phen]
C42H42N6O4S2Zn
824.31
Empirical formula
Formula weight
Temperature (K)
293(2)
0.71073
triclinic
293(2)
0.71073
293(2)
0.71073
˚
Wavelength (A)
Crystal system
Space group
Unit cell dimensions
orthorhombic
Pbca
monoclinic
P21/c
¯
P1
/
˚
a (A)
10.244(2)
11.839(3)
17.154(4)
99.591(4)
95.962(4)
103.358(5)
1973.6(7)
2
18.014(2)
18.296(2)
25.313(3)
90
17.485(2)
11.6697(9)
19.675(2)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
Dcalc (Mg mꢃ3
90
90
103.188(2)
90
3
˚
8342.9(17)
8
3908.7(5)
4
1.401
)
1.293
0.773
796
1.274
0.734
3344
Absorption coefficient (mmꢃ1
F(0 0 0)
)
0.786
1720
Crystal size (mm)
u Range for data collection (8)
0.05ꢁ
/
0.14ꢁ
/0.27
0.19ꢁ
/
0.34ꢁ
/0.38
0.35ꢁ
/
0.22ꢁ
/
0.16
1.80Á28.04
/
1.61Á28.08
/
2.04Á25.00
/
Index ranges
ꢃ
/
130h 0
150k 0
220l 022
10 592
/
/
11
ꢃ
/
200h 0
240k 0
330l 026
39 451
/
/
23
ꢃ
/
200h 0
120k 0
230l 022
17 796
/
/
19
ꢃ
/
/
/
15
ꢃ
/
/
/
24
ꢃ
/
/
/
13
ꢃ/
/
/
ꢃ/
/
/
ꢃ/
/
/
Reflections collected

1104
I. Beloso et al. / Polyhedron 22 (2003) 1099Á1111
/
Table 1 (Continued)
Independent reflections
Completeness to theta max.
Max. and min. transmission
Data/restraints/parameters
Goodness-of-fit on F2
7445 [Rint
77.7%
ꢂ
/
0.0677]
9751 [Rint
88.7%
ꢂ
/
0.1278]
6592 [Rint
90.9%
ꢂ0.0472]
/
1.0000 and 0.6818
7445/0/464
0.751
1.0000 and 0.4802
9751/0/486
0.876
1.0000 and 0.6409
6592/0/504
0.803
Final R indices [I ꢀ
R indices (all data)
Largest difference peak and hole (e A
/
2s(I)]
R1ꢂ
wR2ꢂ
/
0.0664
0.1205
R1ꢂ
wR2ꢂ
/
0.1134
0.2619
R1ꢂ
wR2ꢂ
/
0.0384
0.0640
/
/
/
R1ꢂ0.1795
wR2ꢂ0.1439
0.521 and ꢃ0.359
/
R1ꢂ0.2722
wR2ꢂ0.3086
3.729 and ꢃ0.687
/
R1ꢂ0.0951
wR2ꢂ0.0721
0.296 and ꢃ0.251
/
/
/
/
ꢃ3
˚
)
/
/
/
bonds are established between the pyridine nitrogen
atom and two sulfonamide oxygen atoms, one from the
same molecule, giving an intramolecular contact, and
the other from a neighbouring molecule, which is
involved in an intermolecular contact. The sulfonamide
nitrogen atom is not implicated in these hydrogen
bonds. This arrangement contrasts with the hydrogen
network found in HTspy and HTs6mepy, where the
hydrogen bonds involve the Npy and the Nsulfonamide
atoms. It appears that, for steric reasons, the presence of
the methyl group in position 3 of the pyridine ring
precludes the use of the Nsulfonamide atom in the case of
HTs3mepy. This behaviour will be described again in
the ligational mode of HTs3mepy (vide infra).
acetonitrile, which has been omitted for clarity. Selected
bond lengths and angles, with the estimated deviations,
are summarised in Table 3.
Both compounds consist of discrete molecules, with
the zinc atom coordinated to two (Npy,O) didentate
sulfonamide ligands and an (N,N) didentate 2,2?-bipyr-
idine or 1,10-phenanthroline. The sulfonamide nitrogen
atom of the ligand is not bonded to the metal. This
behaviour contrasts with that found in [Zn(Tspy)2bipy]
[6], where the pyridine ring is unsubstituted. In this case,
one ligand behaves as an Npy monodentate system and
the other as an (Npy,Nsulfonamide) didentate ligand. It is
feasible that in the case of the HTs3mepy ligand, for
steric reasons, the presence of the methyl group pre-
cludes the use of the sulfonamide nitrogen as a donor
atom.
3.2. Molecular structures of [Zn(Ts3mepy)2bipy] (1)
and [Zn(Ts3mepy)2phen] (2)
The environment around the metal can be described
in both cases as a slightly distorted octahedron, but
some differences are found between the two complexes.
In [Zn(Ts3mepy)2bipy] (1) the pyridine nitrogen atoms
of the sulfonamide ligands are in trans positions and the
The molecular structures of 1 and 2 are shown in Figs.
2 and 3, respectively, together with the labelling scheme
used. Compound 1 crystallises with a molecule of
Fig. 1. Molecular structure of HTs3Mepy.

I. Beloso et al. / Polyhedron 22 (2003) 1099Á
/1111
1105
Table 2
with the best plane defined by the two oxygen atoms and
the bipyridine nitrogen atoms. The dihedral angle
between the bipyridine ligand and this plane is 6.5(1)8.
The pyridine ring of each anionic ligand is almost
perpendicular to this plane [dihedral angle of 85.4(1)8
and 89.9(1)8] and the pyridines are slightly twisted with
respect to each other [dihedral angle of 17.5(2)8]. The
dihedral angle between the rings in each ligand are
54.2(2)8 and 74.9(1)8, far from the values usually found
for the free ligand (close to 908).
˚
Selected bond lengths (A) and angles (8) for HTs3mepy
Bond lengths
S(1)ꢀ
S(1)ꢀ
N(1)ꢀ
N(1)ꢀ
/
O(2)
1.442(2)
1.582(3)
1.360(4)
S(1)ꢀ
S(1)ꢀ
N(1)ꢀ
N(2)ꢀ
/
O(1)
1.448(2)
1.761(3)
1.361(4)
1.335(4)
/
N(2)
/C(7)
/
C(1)
/C(5)
/
H(1N) 0.84(3)
/C(5)
Bond angles
O(2)ꢀS(1)ꢀ
O(1)
O(1)ꢀS(1)ꢀ
N(2)
O(1)ꢀS(1)ꢀ
C(7)
C(1)ꢀN(1)ꢀ
C(5)
C(5)ꢀN(1)ꢀ
H(1N)
/
/
114.69(15)
112.63(13)
107.92(14)
124.0(3)
O(2)ꢀ
/
S(1)ꢀ
/
111.30(15)
107.08(14)
102.25(13)
120.4(19)
124.0(2)
N(2)
/
/
O(2)ꢀ
/
S(1)ꢀ
/
In [Zn(Ts3mepy)2phen] (2) the zinc(II) atom lies at a
˚
distance of 0.047(1) A from the best calculated plane
C(7)
/
/
N(2)ꢀ
/
S(1)ꢀ
/
C(7)
formed by the four nitrogen atoms. The dihedral angle
formed by the 1,10-phenanthroline and this plane is
14.91(6)8. The pyridine ring of the anionic ligand
implicated in the p,p-stacking interaction is almost
perpendicular to the aforementioned plane [dihedral
angle of 79.28(7)8]. The other pyridine ring forms a
dihedral angle close to 458 [49.98(9)8], probably due to
the freedom to adopt this disposition, which is only
restricted by chelation and not by a p,p-stacking
interaction.
For the complexes discussed above, bond angles
around the Zn(II) centre are close to the theoretical
values, with the only exception being the bond corre-
sponding to the chelate rings of the coligands [76.16(13)8
/
/
C(1)ꢀ
H(1N)
C(5)ꢀN(2)ꢀ
S(1)
/
N(1)ꢀ
/
/
/
115.5(19)
/
/
˚
Hydrogen bonds for HTs3mepy [A and 8]
Dꢀ
N(1)ꢀ
Á Á ÁO(1)
N(1)ꢀH(1n)
Á Á Á
O(2)i
C(3)ꢀH(3)
O(1)ii
C(12)ꢀH(12)
Á Á ÁO(2)
/
H
/
Á Á Á
/
A
d(Dꢀ/H)
d(H
/
Á Á Á
/
A)
d(D
/
Á Á Á
/
A)
ꢁ(DHA)
/
/
H(1n)
/
0.84(3)
0.84(3)
0.90(3)
0.81(3)
2.15(3)
2.39(3)
2.54(3)
2.51(3)
2.805(4)
3.042(4
3.361(4)
2.892(4)
135(3)
135(3)
151(2)
110(3)
/
/
/
/
/
/
Á Á Á
/
/
/
/
and 76.74(8)8] [6,19,20]. The Znꢀ
/
N and Znꢀ/O bond
i
Symmetry transformations used to generate equivalent atoms: 1ꢃ
/
lengths are similar to those found in other octahedral
Zn(II) complexes with similar ligands [6,21,22] and do
not warrant further comment.
x, 2ꢃy, 1ꢃ 1, z.
/
/
z; iix, yꢃ
/
3.3. Crystal structure of [Zn(Ts6mepy)2phen] (4)
The molecular structure of 4 is shown in Fig. 4
together with the labelling scheme used. Selected bond
lengths and angles, with the estimated deviations, are
summarised in Table 5.
The compound consists of monomeric units with the
six-coordinated zinc atoms associated with two (N,N)
didentate anionic ligands and an (N,N) 1,10-phenan-
throline molecule. This behaviour is similar to that
found in the case of [Zn(Tspy)2bipy] [6].
The coordination polyhedron around the Zn(II) atom
can be described as intermediate between an octahedron
and a trigonal prism in geometry, with the sulfonamide
nitrogen atoms in trans positions and the pyridine
nitrogen atoms in cis positions with respect to each
Scheme 5.
oxygen atoms are in cis positions with respect to each
other. However, in [Zn(Ts3mepy)2phen] (2) the oxygen
atoms are in trans positions and the pyridine nitrogen
atoms of the sulfonamide ligand in cis positions. This
latter disposition is stabilised by a p,p-stacking interac-
tion between the toluene group of one of the ligands and
the central benzene ring of the 1,10-phenanthroline
molecule, with the distances between the centroids being
other. The value of the angles f are ꢃ
/
35.3(2)8,
ꢃ
/
36.7(2)8 and ꢃ34.0(2)8 [23] and these reflect the
/
high degree of distortion towards a trigonal prism (see
Scheme 6).
˚
3.7755(3) A and the dihedral angle between the rings
only 2.24(11)8. Some short distances are given in Table
4.
The disposition of the anionic ligands around the
metal corresponds to a non-crystallographic twofold
point symmetry. The pyridine rings are arranged almost
perpendicular to the plane formed by the pyridine
In [Zn(Ts3mepy)2bipy] (1) the zinc atom is almost
˚
coplanar*
/
with a maximum deviation of 0.057(2) A*
/

1106
I. Beloso et al. / Polyhedron 22 (2003) 1099Á1111
/
Fig. 2. Molecular structure of [Zn(Ts3mepy)2bipy] (1).
nitrogen atoms and the phenanthroline nitrogen atoms
[dihedral angles of 76.8(2)8 and 88.6(2)8].
3.4. Crystal structure of [Zn(Ms6mepy)2bipy] (5)
Unfortunately the crystal data for [Zn(Ms6me-
py)2bipy] (5) are rather poor. However, the refinement
gives the final map shown in Fig. 5 and the final R1
converged to 11.3%. Several attempts to obtain a better
quality monocrystal were unsuccessful. Selected bond
In one of the ligands the Znꢀ
shorter than the ZnꢀNsulfonamide distance but the situa-
Znꢀ
/
Npy bond distance is
/
tion is reversed for the other ligand. The Nꢀ
angles are smaller than the theoretical values expected
/
/
N
for an octahedron.
Fig. 3. Molecular structure of [Zn(Ts3mepy)2phen] (2).

I. Beloso et al. / Polyhedron 22 (2003) 1099Á
/1111
1107
Table 3
Table 5
˚
˚
Selected bond lengths (A) and angles (8) for compounds 1 and 2
[Zn(Ts3mepy)2bipy] (1) [Zn(Ts3mepy)2phen] (2)
Bond lengths
Selected bond lengths (A) and angles (8) for [Zn(Ts6mepy)2phen] (4),
[Zn(Ms6mepy)2bipy] (5) and [Zn(Ms6mepy)2phen] (6)
4
5
6
Znꢀ
Znꢀ
Znꢀ
Znꢀ
Znꢀ
Znꢀ
/
N(11)
N(21)
O(11)
O(21)
N(31)
N(32)
2.154(3)
2.161(3)
2.140(3)
2.102(2)
2.186(3)
2.163(3)
2.138(2)
2.121(2)
2.1328(19)
2.1548(18)
2.211(2)
2.145(2)
Bond lengths
/
Znꢀ
Znꢀ
Znꢀ
Znꢀ
Znꢀ
Znꢀ
/
N(11)
N(12)
N(21)
N(22)
N(31)
N(32)
2.267(5)
2.117(5)
2.132(5)
2.242(5)
2.083(6)
2.170(6)
2.578(7)
2.037(6)
2.673(7)
2.033(6)
2.074(8)
2.093(7)
2.238(3)
2.137(1)
2.145(2)
2.245(3)
2.144(5)
2.137(2)
/
/
/
/
/
/
/
/
/
Bond angles
O(21)ꢀZnꢀO(11)
O(11)ꢀZnꢀ
O(11)ꢀZnꢀ
N(11)ꢀZnꢀ
O(21)ꢀZnꢀ
N(11)ꢀZnꢀ
N(31)ꢀZnꢀ
O(21)ꢀZnꢀ
O(21)ꢀZnꢀ
O(11)ꢀZnꢀ
N(21)ꢀZnꢀ
N(21)ꢀZnꢀ
N(11)ꢀZnꢀ
O(11)ꢀZnꢀ
O(21)ꢀZnꢀ
/
/
93.23(10)
172.37(7)
85.63(8)
91.49(8)
158.71(8)
86.03(7)
89.31(8)
76.74(8)
101.13(8)
84.13(8)
80.49(8)
98.57(9)
168.78(9)
97.85(9)
97.68(8)
93.95(8)
Bond angles
N(31)ꢀZnꢀ
N(31)ꢀZnꢀ
N(31)ꢀZnꢀ
N(21)ꢀZnꢀ
N(12)ꢀZnꢀ
N(32)ꢀZnꢀ
N(11)ꢀZnꢀ
N(32)ꢀZnꢀ
N(12)ꢀZnꢀ
N(12)ꢀZnꢀ
N(31)ꢀZnꢀ
N(21)ꢀZnꢀ
N(31)ꢀZnꢀ
N(21)ꢀZnꢀ
N(22)ꢀZnꢀ
/
/N(11) 86.38(12)
/
/
N(12)
N(21)
N(32)
N(32)
N(22)
N(22)
N(12)
N(11)
N(21)
N(32)
N(22)
N(22)
N(11)
N(11)
N(11)
101.0(2)
101.3(2)
77.5(2)
108.5(2)
159.0(2)
78.0(3)
89.9(2)
129.5(3)
108.6(2)
56.9(2)
157.9(2)
91.5(2)
108.2(3)
112.0(2)
55.6(2)
91.0(2)
105.8(2)
93.2(2)
103.03(9)
95.69(9)
77.25(9)
158.29(9)
156.23(9)
98.76(9)
61.57(9)
98.24(9)
102.54(9)
99.07(9)
96.14(8)
61.19(8)
163.42(9)
93.89(8)
100.33(9)
/
/N(21) 85.99(12)
/
/
/
/
N(32) 97.44(12)
/
/
/
/N(31) 94.61(12)
/
/
151.9(2)
159.4(2)
91.0(2)
/
/
N(31) 92.22(13)
/
/
/
/
N(32) 76.16(13)
/
/
/
/
N(11) 85.66(11)
N(21) 85.72(12)
N(32) 96.11(11)
/
/
61.5(2)
89.9(2)
/
/
/
/
/
/
/
/
108.5(2)
99.2(2)
/
/
N(32) 92.38(13)
N(31) 96.58(13)
N(21) 168.15(13)
N(31) 171.91(12)
N(32) 170.32(12)
/
/
/
/
/
/
98.70(19)
61.3(2)
/
/
/
/
/
/
/
/
156.9(2)
98.84(19)
100.8(2)
/
/
/
/
/
/
Table 4
Some short contacts between rings for [Zn(Ts3mepy)2bipy] (1)
C17ꢀ
C18ꢀ
C18ꢀ
C19ꢀ
C110ꢀ
C110ꢀ
C111ꢀ
C112ꢀ
/
N31
C31
C311
C33
3.429(4)
3.466(4)
3.764(4)
3.486(4)
3.688(5)
3.660(5)
3.636(5)
3.557(4)
C17ꢀ
C18ꢀ
C19ꢀ
C19ꢀ
C110ꢀ
C111ꢀ
C111ꢀ
C112ꢀ
/
C311
C32
C32
C34
3.532(4)
3.688(4)
3.607(5)
3.689(4)
3.511(5)
3.642(5)
3.782(5)
3.543(4)
/
/
/
/
/
/
/
C35
C33
C35
C312
/
C34
C34
C36
C311
/
/
/
/
/
/
Scheme 6.
Fig. 4. Molecular structure of [Zn(Ts6mepy)2phen] (4).

1108
I. Beloso et al. / Polyhedron 22 (2003) 1099Á1111
/
Fig. 5. Molecular structure of [Zn(Ms6mepy)2bipy] (5).
lengths and angles, with the estimated deviations, are
summarised in Table 5.
equatorial plane, which deviates significantly from
planarity. In this system N(11) and N(31) are located
˚
0.281(1) and 0.357(1) A, respectively, below the plane
˚
and N(21) and N(32) are 0.293(1) and 0.345(1) A,
respectively, above the best plane. The Zn(II) atom is
The compound is a monomer with Znꢀ
/
Nsulfonamide
˚
˚
and ZnꢀNpy distances of 2.037(6) and 2.578(7) A in the
/
case of one ligand, and 2.033(6) and 2.673(7) A for the
other. Consequently, the metal atom can be considered
as being coordinated to two Nsulfonamide monodentate
anionic ligands and to a bipyridine molecule in a
tetrahedral environment. It is noteworthy that in the
complexes [Zn(Tspy)2bipy)] and [Zn(Ts6mepy)2phen]
the sulfonamide ligands act as (Nsulfonamide,Npy) diden-
tate ligands. This difference can be attributed to the fact
that such a didentate mode in [Zn(Me6mepy)2bipy]
would cause too many methyl groups to be packed in
a small volume. If the interaction between the pyridine
nitrogen and the metal atom is considered as a bonding
contact, the coordination around the zinc atom can be
described as a trigonal prism, with each triangular face
of the prism formed by one of the nitrogen atoms of the
bipyridine, a sulfonamide nitrogen of one of the anionic
ligands and a pyridine nitrogen of the other. These
planes are almost parallel [dihedral angle of 0.2(2)8] in
spite of the small bite of the anionic ligands. The values
of the angles f are 22.9(3)8, 24.8(3)8 and 24.3(3)8 [23].
˚
also 0.037(1) A below the best plane. The pyridine rings
are arranged in an almost perpendicular manner with
respect to the equatorial plane [dihedral angle of
87.98(7)8 and 89.38(7)8] and the phenanthroline plane
deviates slightly from the equatorial plane [dihedral
angle of 13.86(9)8]. As found in the case of [Zn(Ts6me-
py)2phen], the Znꢀ
/
Npy bond distance is shorter than
Nsulfonamide in one ligand, but the situation is
reversed in the other ligand.
Znꢀ
/
The disposition of the two anionic ligands around the
metal corresponds to a non-crystallographic twofold
point symmetry with a significant p,p-stacking inter-
action*
/
also found in [Zn(Ts3mepy)2phen] (2)*which
/
in this case takes place between the phenanthroline
plane and the two mesityl groups of the sulfonamide
ligands. The dihedral angles between the mesityl and
phenanthroline planes are 3.9(1) and 0.2(1)8, respec-
tively. Short distances between ring atoms are shown in
Table 6.
It should be noted that in [Zn(Ms6mepy)2bipy] (5) the
sulfonamide ligands act in an Nsulfonamide monodentate
mode, but in [Zn(Ms6mepy)2phen] (6) they act in an
(Npy,Nsulfonamide) didentate way. The difference in
behaviour can be attributed to the existence of a p,p-
stacking interaction in the case of [Zn(Ms6mepy)2phen].
The bipyridine coligand does not allow intramolecular
p,p-stacking interactions, but the phenanthroline moiety
does due to the presence of a third aromatic ring.
3.5. Molecular structure of [Zn(Ms6mepy)2phen] (6)
The molecular structure of 6 is shown in Fig. 6
together with the labelling scheme used. Selected bond
lengths and angles, with the estimated deviations, are
summarised in Table 5.
Compound 6 consists of monomeric units with a six-
coordinated zinc atom associated with two anionic
ligands and a molecule of 1,10-phenanthroline.
The coordination polyhedron around the Zn(II) atom
is best described as a very distorted octahedron. The
sulfonamide nitrogen atoms are in a trans arrangement
and the pyridine nitrogen atoms in a cis disposition with
respect to each other. The distortion can be noted in the
3.6. Spectroscopic studies
The IR spectra of these complexes do not show a
H) band, which appears at 3248Á
3220 cmꢃ1 in the
sulfonamide ligand. This is indicative that the ligand is
n(Nꢀ
/
/

I. Beloso et al. / Polyhedron 22 (2003) 1099Á
/1111
1109
Fig. 6. Molecular structure of [Zn(Ms6mepy)2phen] (6).
higher than the value found in the case of coordination
through the nitrogen atom. However, more work is
Table 6
Some short contacts between rings for [Zn(Ms6mepy)2phen] (6)
needed to show that the value of D(nasym
used to distinguish between both ways of coordination.
ꢃnsym) can be
/
C(110)ꢀ
C(112)ꢀ
/
C(36)
3.766(5)
3.695(4)
3.842(4)
3.611(4)
3.678(5)
C(210)ꢀ
C(212)ꢀ
/
C(36)
C(312)
3.583(5)
3.728(4)
3.651(4)
3.501(4)
3.562(5)
/C(312)
/
C(19)ꢀ
C(18)ꢀ
C(111)ꢀ
/
C(34)
C(29)ꢀ
C(28)ꢀ
C(211)ꢀC(37)
/
C(34)
C(311)
The spectra also show bands in the aromatic region
1415 cmꢃ1), which are characteristic of the n(Cꢂ
/
/C(311)
/
(1460Á
C) vibrations, and also a band at 2920Á
CH3). Bands at 1520, 850
/
/
C(37)
/
/
2940 cmꢃ1
,
which is attributable to n(ꢀ
/
and 725 cmꢃ1 for 1,10-phenanthroline and 770 and 730
cmꢃ1 for 2,2?-bipyridine confirm the presence of the
coligands in the metal coordination sphere.
in the anionic form in the complex. Bands in the region
1590Á N), appear in the
1616 cmꢃ1, attributable to n(Cꢂ
/
/
1
The H NMR spectra show that the signal due to the
complexes in similar positions to those of the free
ligands. In the derivatives of ligands Ts6mepyꢃ and
Ms6mepyꢃ, these bands are shifted to lower frequencies
as a result of the coordination through the sulfonamide
nitrogen atom. Table 7 collects the values of the main
vibrations associated with the sulfonic group. As can be
seen, when this group coordinates the metal atom
ꢀ
/
NH hydrogen atom, which in the free ligand appears
around d 12, is not present in the complexes. This
provides good evidence that the ligand has been
deprotonated. The aromatic resonances, including those
of the coligands, appear between d 9.5Á
region of d 2.0Á2.3 ppm appear all the methyl group
signals that are shifted to higher field respect to their
/6.4. In the
/
through an oxygen atom, the value of D(nasym
ꢃnsym) is
/
Table 7
Selected IR bands associated with the sulfonic group in cmꢃ1
Compound
nasym(Sꢂ/O)
nsym(Sꢂ/O)
D(nasym
ꢃ
/
nasym
)
rwSO2
rtSO2
Environment around the metal
[Zn(Ts3mepy)2bipy]
[Zn(Ts3mepy)2phen]
[Zn(Ts6mepy)2phen]
[Zn(Ms6mepy)2bipy]
[Zn(Ms6mepy)2phen]
1324
1333
1322
1311
1326
1117
1114
1138
1134
1132
207
219
184
177
194
590
588
581
589
589
546
545
553
535
532
[ZnN4O2]
[ZnN4O2]
[ZnN6]
[ZnN4]
[ZnN6]

1110
I. Beloso et al. / Polyhedron 22 (2003) 1099Á1111
/
Table 8
Summary of geometrical conclusions
Complex
Sulfonamide ligand behaviour Coordination polyhedra Environment around the metal Other features
[Zn(Ts3mepy)2bipy] (Npy,O) didentate
[Zn(Ts3mepy)2phen] (Npy,O) didentate
octahedral
octahedral
[ZnN4O2]
[ZnN4O2]
[ZnN6]
one p,p-stacking interaction
two long Npy Zn interactions
[Zn(Ts6mepy)2phen] (Npy,Nsulfonamide) didentate
[Zn(Ms6mepy)2bipy] (Nsulfonamide) monodentate
[Zn(Ms6mepy)2phen] (Npy,Nsulfonamide) didentate
trigonal bipyramidal
tetrahedral
very distorted octahedral [ZnN6]
[ZnN4]
Á/
two p,p-stacking interactions
position in the free ligands. In the case of the methyl
group from the picoline ring appears in the range d 2.0Á
2.3 and is also observed a signal at about d 2.1, assigned
to the toluene methyl group of the complexes with
Ts3mepyꢃ and Ts6mepyꢃ ligands. The Ms6mepyꢃ
effect produced by the methyl group in position 3 in the
pyridine ring is more important than the stabilising
effect of the p,p-stacking interaction.
/
complexes show two signals at about d 2.2Á
/2.0 due to
5. Supplementary material
the mesityl methyl groups.
In all cases, the LSIMS mass spectra show the
molecular ion with the appropriate isotope distribution
as well as the peak corresponding to the free ligand. In
most cases, peaks corresponding to the ion formed by
the loss of one ligand from the initial complex are also
observed.
Crystallographic data have been deposited with the
CCDC, (12 Union Road, Cambridge CB2 1EZ, UK
(Fax: ꢀ44-1223-336033; e-mail: deposit@ccdc.cam.ac.
/
uk or www: http://www.ccdc.cam.ac.uk)) and are avail-
able on request quoting the deposition numbers
197 497Á197 502.
/
Acknowledgements
4. Conclusions
This work was supported by the Xunta de Galicia
(Spain) under the grant PGIDT00PXI20305PR. We
thank http://angus.uvigo.es for X-ray solution and
refinement facilities.
The work described here involved the electrochemical
synthesis and the X-ray structure characterisation of
several zinc mixed complexes derived from a series of
pyridine sulfonamides. Table 8 summarises the main
structural features of the compounds under investiga-
tion.
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