Coordination behaviour of sulfanilamide derivatives. Crystal structures of [Hg(sulfamethoxypyridazinato)2], [Cd(sulfadimidinato)2(H2O)]·2H2O and [Zn(sulfamethoxazolato)2-(pyridine)2(H2O)2]

Article abstract of DOI:10.1016/S0277-5387(00)00355-7

Hg(II), Cd(II) and Zn(II) complexes with the ligands sulfadimethoxine, sulfamethoxypyridazine, sulfadiazine, sulfamerazine, sulfadimidine and sulfamethoxazole have been prepared and characterised by spectral data. ¹H and ¹³C NMR have been used to interpret the structural characteristics of the complexes in solution. The X-ray crystal structures of [Hg(sulfamethoxypyridazinato)₂] (2a), [Cd(sulfadimidinato)₂(H₂O)]·2H₂O (4b) and [Zn(sulfamethoxazolato)₂(py)₂(H₂O)₂] (6d) have been determined. In complex 2a the Hg(II) ion lies on an inversion centre and exhibits linear coordination by two sulfonamidic nitrogen atoms [Hg-N(1) = 2.071(4) A?] of the two deprotonated sulfamethoxypyridazinato ligands. The polymeric Cd(II) complex (4b) exhibits a high distorted-octahedral geometry, involving the sulfonamidic nitrogen [Cd-N(1) = 2.328(6); Cd-N(1') =2.326(6) A?] and the heterocyclic N(3)/N(2') [Cd-N(3) = 2.307(6) A?; Cd-N(2') = 2.426(6) A?] of two bidentate sulfadimidine ligands, the terminal amino N(4'b) [Cd-N(4'b) = 2.379(7) A?] of a third sulfadimidine which is bonded to an adjacent Cd(II), and the O(3) atom of a coordinated water molecule [Cd-O(3) = 2.334(6) A?]. In complex 6d the geometry around the Zn(II) ion can be described as a slightly distorted compressed octahedron. Two pyridine [Zn-N(16) = 2.1841(17) A?] and two isoxazole N atoms [Zn-N(2) = 2.1736(15) A?] are located in the equatorial plane and two oxygen atoms of two water molecules [Zn-O(4) = 2.0984(14) A?] are placed in the apical positions. IR and NMR spectral studies suggest a similar behaviour of the Cd(II) and Zn(II) complexes, both in solid state and solution, and different to the corresponding Hg(II) complexes. Thus ¹H and ¹³C NMR spectra, in DMSO-d₆, of Cd(II) and Zn(II) compounds show coordination mainly through the heterocyclic nitrogen while the corresponding Hg(II) derivatives seem to be coordinated through the sulfonamidic nitrogen. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(00)00355-7

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 991–1004
Coordination behaviour of sulfanilamide derivatives.
Crystal structures of [Hg(sulfamethoxypyridazinato)2],
[Cd(sulfadimidinato)2(H2O)]P2H2O and [Zn(sulfamethoxazolato)2-
(pyridine)2(H2O)2]
a
a
a
b
Angel Garc´ıa-Raso a, , Juan J. Fiol , Santiago Rigo , Antonio Lopez-Lopez , Elies Molins ,
´
´
*
b
c
c
c
d
´
´
´
˜
Enrique Espinosa , Elisa Borras , Gloria Alzuet , Joaquın Borras , Alfonso Castineiras
a
´
Departament de Quımica, Universitat de les Illes Balears, 07071 Palma de Mallorca, Spain
b
`
Institut de Ciencia de Materials de Barcelona-CSIC, Campus Universitari de Bellaterra, 08193 Cerdanyola, Spain
Departamento de Quımica Inorganica, Universidad de Valencia, 46100 Burjassot (Valencia), Spain
Departamento de Quımica Inorganica, Universidad de Santiago de Compostela, 15703 Santiago de Compostela, Spain
c
´
´
d
´
´
Received 4 January 2000; accepted 3 March 2000
Abstract
Hg(II), Cd(II) and Zn(II) complexes with the ligands sulfadimethoxine, sulfamethoxypyridazine, sulfadiazine, sulfamerazine, sulfadi-
midine and sulfamethoxazole have been prepared and characterised by spectral data. 1H and 13C NMR have been used to interpret the structural
characteristics of the complexes in solution. The X-ray crystal structures of [Hg(sulfamethoxypyridazinato)2] (2a), [Cd(sulfadi-
midinato)2(H2O)]P2H2O (4b) and [Zn(sulfamethoxazolato)2(py)2(H2O)2] (6d) have been determined. In complex 2a the Hg(II) ion
˚
lies on an inversion centre and exhibits linear coordination by two sulfonamidic nitrogen atoms [Hg–N(1)s2.071(4) A] of the two
deprotonated sulfamethoxypyridazinato ligands. The polymeric Cd(II) complex (4b) exhibits a high distorted-octahedralgeometry,involving
˚
˚
the sulfonamidic nitrogen [Cd–N(1)s2.328(6); Cd–N(19)s2.326(6) A] and the heterocyclic N(3)/N(29) [Cd–N(3)s2.307(6) A;
˚
˚
Cd–N(29)s2.426(6) A] of two bidentate sulfadimidine ligands, the terminal amino N(49b) [Cd–N(49b)s2.379(7) A] of a third sulfad-
˚
imidine which is bonded to an adjacent Cd(II), and the O(3) atom of a coordinated water molecule [Cd–O(3)s2.334(6) A]. In complex
6d the geometry around the Zn(II) ion can be described as a slightly distorted compressedoctahedron. Twopyridine[Zn–N(16)s2.1841(17)
˚
˚
A] and two isoxazole N atoms [Zn–N(2)s2.1736(15) A] are located in the equatorial plane and two oxygen atoms of two water molecules
˚
[Zn–O(4)s2.0984(14) A] are placed in the apical positions. IR and NMR spectral studies suggest a similar behaviour of the Cd(II) and
Zn(II) complexes, both in solid state and solution, and different to the corresponding Hg(II) complexes. Thus 1H and 13C NMR spectra, in
DMSO-d6, of Cd(II) and Zn(II) compounds show coordination mainly through the heterocyclic nitrogen while the corresponding Hg(II)
derivatives seem to be coordinated through the sulfonamidic nitrogen.
q2000 Elsevier Science Ltd All rights reserved.
Keywords: Cadmium complexes; Mercury complexes; Sulfamides; X-ray structure; Zinc complexes
1. Introduction
bacterial enzyme DHPS (dihydropteroate synthetase) which
catalyses the incorporation of p-aminobenzoic acid into the
precursorof folicacid,2-amino-4-hydroxy-6-hydroxymethyl
dihydropteridine pyrophosphate (see Scheme 2) [4–7], the
pharmacological activity of these types of molecules is often
enhanced by complexation with metal ions [8,9]. Thus, rapid
healing of skin disorders has been promoted by silver–sul-
fadiazine complex [10,11] in human topical burn therapy,
and zinc–sulfadiazine complex [12,13] in the prevention of
bacterial infection in burned animals, where the effectiveness
of burn treatment seems to depend not only on the presence
The synthesis of metal sulfanilamide compounds has
received much attention due to the fact that sulfanilamides
were the first effective chemotherapeutic agents to be
employed for the prevention and cure of bacterial infections
in humans (see Scheme 1). Although sulfamides present
bacteriostatic activity [1–3] related to the inhibition of the
* Corresponding author. Tel.: q34-971-173263; fax: q34-971-173426;
e-mail: dquagr0@clust.uib.es
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00355-7
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Scheme 1.
of a metal ion [slow release of the Ag(I) or Zn(II)], but
also crucially on the nature of the material to which the metal
ion is bound [12].
Solid state CP/MAS 13C spectrum was recorded on a Varian
Unity 300 spectrometer. Unequivocal C–H assignment was
performed by 2D NMR experiments [HMQC [23] and
HMBC [24]] or by comparison with spectra of related prod-
ucts. The 2D spectra were processed using commercial Bru-
ker software and experimental characteristics are presented
below.
Morevoer, although interesting structural resultshavebeen
described in the literature (sulfadiazine: Ag(I) [10,11,14],
Zn(II) [12,13], Cu(II) [15] and Hg(II) [16]; sulfathia-
zole: Zn(II) [9], Cu(II) [17–20]; sulfadimetoxine: Co(II)
[21]; sulfacetamide: Cu(II) [22]), no general studies
related to the manner with which metal–sulfonamide inter-
actions occur have been described. For this reason, in the
present paper, we report on the synthesis and spectroscopic
characterisation of the Zn(II), Cd(II) and Hg(II) complexes
with six sulfonamides [sulfadimethoxine (1), sulfamethoxy-
pyridazine (2), sulfadiazine (3), sulfadimidine (sulfameth-
azine) (4), sulfamerazine (5) and sulfamethoxazole (6)]
and the X-ray structure determination of [Hg(sulfameth-
oxypyridazinato)2] (2a), [Cd(sulfadimidinato)2(H2O)]P
2H2O (4b) and [Zn(sulfamethoxazolato)2(py)2(H2O)2]
(6d) in order to show the general manner with which inter-
actions between d10 metal ions and these ligands take place.
2.1.1. 1H-detected heteronuclear multiple quantum
coherence spectroscopy (HMQC)
1
The one-bond H–13C shift correlation spectra resulted
from a 502=2048 data matrix size with 48 scans (preceded
by 16 dummy scans) per t1 value. Predelay was 1.0 s, and a
10.3-ms 908 13C pulse width was used. A sine bell squared
filter was used prior to Fourier transformation in the t2 and t1
dimensions.
2.1.2. 1H-detected multiple-bond heteronuclear multiple
quantum coherence spectroscopy (HMBC)
The multiple-bond 1H–13C shift correlation spectra
resulted from a 246=2048 matrix data size with 128 scans
(preceded by 8 or 16 dummy scans) per t1 value. Predelay
was 1.0 s, and a 10.3-ms 908 13C pulse width were used. The
delay between the first and the second 908 13C pulses was 75
ms. A sine bell squared filter was used prior to Fourier trans-
formation in the t2 and t1 dimensions.
2. Experimental
2.1. Analysis and physical measurements
Satisfactory C, H, N and S analyses were obtained for all
compounds and carried out using a Carlo-Erba Model 1106
microanalyser. The IR spectra in the solid state (KBr pellets)
were recorded on a PE 683 spectrometer with a PE 1600 IR
data station and on a Perkin-Elmer 843; electronic spectra
were recorded on PE 552 and Shimadzu UV 2101PC spec-
Sulfamides were used as received from Roig Farma.
Zn(II), Cd(II) and Hg(II) acetates were suppliedbyAldrich
and used without purification.
2.2. Crystallographic studies
1
trophotometers. 1D and 2D H and 13C NMR spectra were
X-ray data from compounds 2a and 4b were collected on
an Enraf-Nonius CAD4 diffractometer with Mo Karadiation
carried out on a Bruker AMX 300. Proton and carbon chem-
ical shifts in DMSO-d6 were referenced to DMSO-d6 (1H
NMR, d(DMSO)s2.60 ppm; 13C NMR, d(DMSO)s43.5 ppm).
˚
(0.71069 A). The cell parameters and space group were
determined from a least-square refinement of 25 reflections
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993
Scheme 2.
randomly searched. Data collection employed an v–2u scan
technique. Three reflections were measured every hour as
intensity controls; an intensity decay of 1.5% (2a) and 7.7%
(4b) was observed and corrected. The MOLEN [25] pack-
age was used for applying Lorentz polarization correction
and c-scan empirical absorption corrections. The structures
were solved by direct methods using the SHELXS 86 pro-
gram [26] and refined by least-squares using the SHELXL
93 program [27]. Hydrogen atoms were placed in calculated
positions, except for those corresponding to water molecules
(for 4b), which were located in Fourier-differencemaps,and
refined with an isotropic thermal factor constrained to 1.2
times Ueq of their bonded atom [1.5 (2a) or 1.3 (4b) times
in the case of methyl groups].
2.3.2. Hg(sulfadimethoxynato)2 (1a)
White solid (87% yield). Found: C, 35.00; H, 3.09; N,
13.52; S, 7.89. Calc. for C24H26N8S2O8Hg: C, 35.18; H, 3.17;
N, 13.68; S, 7.82%. Selected IR data (cmy1): 911m, 946w,
962vw, 984w, 1009m, 1090s, 1113s, 1141vs, 1211vs, 1294s,
1362vs, 1419s, 1575vs, 1635s, 3244m, 3367s, 3454m. UV
(DMSO): l 274 nm (´ 4.5=104 dm3 moly1 cmy1). LM/
Vy1 cm2 moly1 (10y3 mol dmy3 in DMSO, 258C)s0.7.
1H NMR (DMSO-d6): d 7.59d [2H, H(2b)/H(6b), Js8.2
Hz], 6.57d [2H, H(3b)/H(5b), Js8.2 Hz], 5.83s [1H,
H(5a)], 5.80bs (2H, NH2), 3.84s [3H, OCH3(1)], 3.79s
[3H, OCH3(2)]. 13C NMR (DMSO-d6): d 176.2 [C(6a)],
168.0 [C(2a)], 165.8 [C(4a)], 157.2 [C(4b)], 133.7
[C(2b)/C(6b)], 128.3 [C(1b)], 116.8 [C(3b)/C(5b)],
88.6 [C(5a)], 58.8 [OCH3(1)], 58.0 [OCH3(2)].
X-ray data from compound 6d were collected on an Enraf-
Nonius CAD4 automatic diffractometer [28] with Cu Ka
2.3.3. Hg(sulfamethoxypyridazinato)2 (2a)
˚
radiation (ls1.54184 A). Cell constants and an orientation
White solid (94% yield). White crystals in NH4OH–H2O
(1:1). Found: C, 34.71; H, 2.88; N, 14.70; S, 8.33. Calc. for
C22H22N8S2O6Hg: C, 34.80; H, 2.90; N, 14.76; S, 8.44%.
Selected IR data (cmy1): 952s, 1016s, 1041m, 1091s,
1125m, 1153s, 1272vs, 1318m, 1351w, 1402vs, 1460s,
1503m, 1548w, 1602s, 3209m, 3363m. UV (DMSO): l 273
nm (´ 3.5=104 dm3 moly1 cmy1). LM/Vy1 cm2 moly1
(10y3 mol dmy3 in DMSO, 258C)s3.3. 1H NMR (DMSO-
d6): d 7.82d [2H, H(2b)/H(6b), Js8.6 Hz], 7.62d [1H,
H(4a), Js9.6 Hz], 7.31d [1H, H(5a), Js9.6 Hz], 6.68d
[2H, H(3b)/H(5b), Js8.6 Hz], 6.06bs (2H, NH2), 4.01s
(3H, OCH3). 13C NMR (DMSO-d6): d 165.8 [C(6a)],
158.0 [C(3a)], 156.7 [C(4b)], 133.1 [C(2b)/C(6b)],
129.9 [C(1b)], 125.5 [C(4a)], 124.4 [C(5a)], 116.7
[C(3b)/C(5b)], 58.3 (OCH3).
matrix for data collection were obtained by least-squares
refinement of the diffraction data from 25 reflections. Data
collection employed an v-scan technique and were corrected
for Lorentz and polarisation effects [29]. A semi-empirical
absorption correction (C scan) was made [30]. The struc-
ture was solved by direct methods [26] which revealed the
position of all non-hydrogen atoms and refined on F2 by a
full-matrix least-squares procedure using anisotropic dis-
placement parameters [31]. The hydrogen atoms were
located from difference maps and refined isotropically.
Atomic scattering factors were from International Tables for
X-Ray Crystallography [32]. Molecular graphics were from
ZORTEP [33].
Details of the data collection and processing are summar-
ised in Table 1.
2.3.4. Hg(sulfadiazinato)2P2DMSO (3a)
Previously described [16].
2.3. Preparation of Hg(II)–sulfamidato complexes
2.3.5. Hg(sulfadimidinato)2 (4a)
2.3.1. General procedure
White solid (83% yield). Found: C, 37.91; H, 3.43; N,
14.78; S, 8.48. Calc. for C24H26N8S2O4Hg: C, 38.16; H, 3.45;
N, 14.84; S, 8.48%. Selected IR data (cmy1): 892m, 956vw,
992m, 1086m, 1150vs, 1302s, 1343m, 1371s, 1395sh,
1434m(br), 1503m, 1555m(br), 1597s, 1629m, 3348m. UV
(DMSO): l 275 nm (´ 5.2=104 dm3 moly1 cmy1). LM/
Vy1 cm2 moly1 (10y3 mol dmy3 in DMSO, 258C)s0.3.
1H NMR (DMSO-d6): d 7.88bd [2H, H(2b)/H(6b)], 6.66d
Hg(II) acetate (1 mmol) in methanol (20 ml) was added
dropwise to a stirred solution of the corresponding sulfamide
(2 mmol) in methanol (20 ml). A white precipitate begins
to form and the reaction is stirred during 18 h at room tem-
perature. The precipitate is filtered off and air dried. Crystal-
lisation in different mixtures of NH4OH–H2O or DMSO–
MeOH yields white crystals.
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Table 1
Crystal data and structure refinements for complexes 2a, 4b and 6d
Hg(sulfamet)2 (2a)
Cd(sulfadimid)2P3H2O (4b)
Zn(sulfamoxaz)2(py)2(H2O)2 (6d)
Empirical formula
Crystal size (mm)
Crystal system
C22H22HgN8O6S2
0.18=0.20=0.55
monoclinic
C24H32CdN8O7S2
0.14=0.17=0.28
monoclinic
C30H38N8O10S2Zn
0.30=0.15=0.10
triclinic
¯
Space group
C2/c
P21/a
P1
Unit cell dimensions
˚
a (A)
22.424(4)
10.642(1)
11.222(2)
13.357(2)
15.046(1)
15.369(2)
9.0174(4)
9.8677(4)
10.4481(4)
83.996(4)
78.004(4)
86.455(3)
903.55(6)
1
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
Volume (A )
Z
113.11(2)
97.60(1)
3
˚
2463.1(7)
4
3061.6(6)
4
Formula weight
Density (calc.) (Mg my3
759.19
2.047
6.477
721.10
1.564
0.905
800.17
1.471
2.587
416
)
Absorption coefficient (mmy1
F(000)
)
1480
1472
u Range (8)
2.65–26.23
2.33–30.41
4.35–74.31
Index ranges
y27FhF23, y13FkF0, 0FlF13 0FhF19, 0FkF21, y21FlF21 0FhF11, y12FkF12, y12FlF13
Reflections collected
Independent reflections
Data/restraints/parameters
2763
9623
3925
2368 [Rints0.0255]
2368/0/179
9258 [Rints0.1088]
9258/0/401
3680 [Rints0.0111]
3680/0/309
Maximum, minimum transmission
Final R indices [I)2s(I)]
R indices (all data)
0.999, 0.421
0.998, 0.823
0.981, 0.823
R1s0.0301, wR2s0.0877
R1s0.0398, wR2s0.0921
1.101
R1s0.1125, wR2s0.3007
R1s0.2020, wR2s0.3354
1.175
R1s0.0309, wR2s0.0839
R1s0.0365, wR2s0.0875
1.042
Goodness-of-fit on F2
y3
˚
Largest difference peak, hole (e A
)
1.244, y1.114
2.081, y1.372
0.301, y0.351
[2H, H(3b)/H(5b), Js8.5 Hz], 6.85s[1H, H(5a)], 5.97bs
(2H, NH2), 2.37s (6H, CH3). 13C NMR (DMSO-d6): d
171.6 [C(4a)/C(6a)], 163.3 [C(2a)], 156.5 [C(4b)],
134.7 [C(2b)/C(6b)], 130.0 [C(1b)], 116.8 [C(5a)],
115.8 [C(3b)/C(5b)], 27.2 (CH3).
N, 11.92; S, 9.05%. White crystals in DMSO–MeOH. Found:
C, 33.80; H, 3.54; N, 9.99; S, 13.67. Calc. for
C20H20S2O6HgP1.5DMSO: C, 33.59; H, 3.53; N, 10.22; S,
13.63%. Selected IR data (cmy1): 903m, 952s, 1012m,
1061m, 1091s, 1136vs, 1288m(br), 1266s, 1296s, 1378w,
1416s, 1432s, 1472vs, 1504s, 1598s, 1613s, 1630s, 3378s,
3474m. UV (DMSO): l 274 nm (´ 4.5=104 dm3 moly1
cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3 in DMSO,
2.3.6. Hg(sulfamerazinato)2P1.5H2O (5a)
White solid (75% yield). Found: C, 35.05; H, 3.19; N,
14.62; S, 8.35. Calc. for C22H22N8S2O4HgP1.5(H2O): C,
35.03; H, 3.31; N, 14.86; S, 8.49%. Selected IR data (cmy1):
917m, 944w, 975w, 1093s, 1143s, 1289s, 1312m, 1373s,
1391s, 1431m, 1457m, 1505m, 1557s, 1579vs, 1600s,
1638m, 3354s, 3450m. UV (DMSO): l 272 nm (´ 4.9=104
dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3
in DMSO, 258C)s0.7. 1H NMR (DMSO-d6): d 8.41d [1H,
H(6a), Js4.8 Hz], 7.87d [2H, H(2b)/H(6b), Js8.6 Hz],
6.96d [1H, H(5a), Js4.7 Hz], 6.66d [2H, H(3b)/H(5b),
Js8.6 Hz], 5.98bs (2H, NH2), 2.42s (3H, CH3). 13C NMR
(DMSO-d6): d 172.1 [C(4a)], 163.6 [C(2a)], 160.9
[C(6a)], 156.6 [C(4b)], 134.5 [C(2b)/C(6b)], 130.1
[C(1b)], 116.0 [C(3b)/C5b)], 117.7 [C(5a)], 27.4
(CH3).
1
258C)s0.6. H NMR (DMSO-d6): d 7.76d [2H, H(2b)/
H(6b), Js8.5 Hz], 6.69d [2H, H(3b)/H(5b), Js8.5 Hz],
6.13 s[1H, H(4a)], 6.11bs (2H, NH2), 2.38s (3H, CH3).
13C NMR (DMSO-d6): d 174.7 [C(3a)], 165.9 [C(5a)],
157.0 [C(4b)], 133.4 [C(2b)/C(6b)], 129.2 [C(1b)],
116.7 [C(3b)/C(5b)], 99.4 [C(4a)], 16.4 (CH3).
2.4. Preparation of Cd(II) and Zn(II)–sulfamidato
complexes
2.4.1. General procedure
Cd(II) or Zn(II) acetate (1 mmol) in distilled water (20
ml) was added dropwise to a stirred solution of sodium sul-
famidato (2 mmol) in distilled water (20 ml). A white pre-
cipitate begins to form and the reaction is stirred during 18 h
at room temperature. The precipitate is filtered off and air
dried. Crystallisation in different mixtures of NH4OH–H2O
or DMSO–MeOH yields white crystals.
2.3.7. Hg(sulfamethoxazolato)2 and
Hg(sulfamethoxazolato)2P1.5DMSO (6a)
White solid (89% yield). Found: C, 33.93; H, 2.84; N,
11.75; S, 9.08. Calc. for C20H20S2O6Hg: C, 34.06; H, 2.84;
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995
2.4.2. Cd(sulfadimethoxynato)2P1/2(NH3)PH2O and
2.4.5. Zn(sulfamethoxypyridazinato)2P2.5(H2O) (2c)
Cd(sulfadimethoxynato)2PDMSO (1b)
White solid (55% yield). Found: C, 39.41; H, 3.90; N,
16.61; S, 9.84. Calc. for C22H22N8S2O6ZnP2.5(H2O): C,
39.49; H, 4.04; N, 16.76; S, 9.57%. Selected IR data (cmy1):
750m, 840m, 945m, 1015s, 1091s, 1133s, 1185m, 1293s,
1417vs, 1469vs, 1503m, 1599s, 1629m, 3240m(br), 3368m,
3446m(br). UV(DMSO):l 271 nm (´ 3.5=104 dm3 moly1
cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3 in DMSO,
White solid (83% yield). White crystals in NH4OH–H2O
(1:1). Found: C, 37.92; H, 3.84; N, 15.57; S, 8.37. Calc. for
C24H26N8S2O8CdP1/2(NH3)PH2O: C, 38.05; H, 3.89; N,
15.72; S, 8.46%. White crystals in DMSO–MeOH. Found:
C, 38.41; H, 3.95; N, 13.72; S, 11.87. Calc. for
C24H26N8S2O8CdPDMSO: C, 38.59; H, 3.96; N, 13.85; S,
11.87%. Selected IR data (cmy1): 881s, 932w, 961w, 989w,
1086s, 1145s, 1180m, 1215s, 1263s, 1363s, 1369s, 1396m,
1425s, 1461m, 1489m, 1558s, 1585vs, 1602vs, 2953m,
3337m(br), 3491m(br). UV (DMSO): l 274 nm (´
8.6=104 dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3
mol dmy3 in DMSO, 258C)s10.2. 1H NMR (DMSO-d6):
d 7.59d [2H, H(2b)/H(6b), Js8.2 Hz], 6.57d [2H,
H(3b)/H(5b), Js8.2 Hz], 5.83s[1H, H(5a)], 5.80bs(2H,
1
258C)s5.5. H NMR (DMSO-d6): d 7.51d [2H, H(2b)/
H(6b), Js8.4 Hz], 7.49d [1H, H(4a), Js9.7 Hz], 7.11d
[1H, H(5a), Js9.7 Hz], 6.51d [2H, H(3b)/H(5b), Js8.4
Hz], 5.67bs (2H, NH2), 3.90s (3H, OCH3). 13C NMR
(DMSO-d6): d 163.0 [C(6a)], 162.1 [C(3a)], 155.2
[C(4b)], 134.3 [C(1b)], 132.2 [C(2b)/C(6b)], 127.6
[C(4a)], 124.6 [C(5a)], 116.5 [C(3b)/C(5b)], 58.0
(OCH3).
NH2), 3.84s [3H, OCH3(1)], 3.79s [3H, OCH3(2)])]. 13
C
NMR (DMSO-d6): d 175.7 [C(6a)], 169.6 [C(2a)], 167.6
[C(4a)], 155.6 [C(4b)], 132.6 [C(2b)/C(6b)], 132.3
[C(1b)], 116.4 [C(3b)/C(5b)], 87.7 [C(5a)], 58.3
[OCH3(1)], 57.6 [OCH3(2)].
2.4.6. Cd(sulfadiazinato)2P2(NH3) (3b)
White solid (80% yield). White crystals in NH4OH–H2O
(1:1). Found: C, 37.29; H, 3.66; N, 21.56; S, 9.79. Calc. for
C20H18N8S2O4CdP2(NH3): C, 37.24; H, 3.72; N, 21.72; S,
9.93%. Selected IR data (cmy1): 725m, 785m, 806s, 846s,
964s, 980s, 1008s, 1090s, 1108m, 1262s, 1277s, 1352m,
1413vs, 1442s, 1501m, 1554s, 1584s, 1598s, 3154m, 3244m,
3315s, 3460m(br). UV (DMSO): l 271 nm (´ 4.5=104
dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3
in DMSO, 258C)s5.1. 1H NMR (DMSO-d6): d 8.37d [2H,
H(6a), Js4.9 Hz], 7.64d [2H, H(2b)/H(6b), Js8.6 Hz],
6.77t [1H, H(5a)], 6.53d [2H, H(3b)/H(5b), Js8.6 Hz],
5.64s (2H, NH2). 13C NMR (DMSO-d6): d 166.3 [C(2a)],
162.2 [C(4a)/C(6a)], 155.0 [C(4b)], 134.1 [C(1b)],
132.9 [C(2b)/C(6b)], 116.0 [C(3b)/C5b)], 115.1
[C(5a)].
2.4.3. Zn(sulfadimethoxinato)2P3/4(NH3)P3/4(H2O) (1c)
White solid (90% yield). White crystals in NH4OH–H2O
(1:9). Found: C, 40.45; H, 3.98; N, 17.35; S, 8.91. Calc. for
C24H26N8S2O8ZnP3/4(NH3)P3/4(H2O): C, 40.58; H, 4.19;
N, 17.26; S, 9.02%. IR (cmy1): 883s, 996m, 1008sh, 1058s,s
1069w, 1144s, 1181m, 1213s, 1275s, 1362s, 1369s, 1394m,
1431m, 1461w, 1488m, 1599vs, 2953m, 3168m, 3259m,
3373m(br), 3472m(br). UV (DMSO): l 275 nm (´
4.6=104 dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3
mol dmy3 in DMSO, 258C)s11.0. 1H NMR (DMSO-d6):
d 7.58d [2H, H(2b)/H(6b), Js8.4 Hz], 6.59d [2H,
H(3b)/H(5b), Js8.6 Hz], 5.86s [H, H(5a)], 5.77bs (2H,
NH2), 3.81s [3H, OCH3(1)], 3.73s [3H, OCH3(2)]. 13C
NMR (DMSO-d6): d 175.4 [C(6a)], 170.1 [C(2a)], 167.6
[C(4a)], 155.7 [C(4b)], 132.8 [C(2b)/C(6b)], 132.8
[C(1b)], 116.5 [C(3b)/C(5b)], 88.4 [C(5a)], 58.2
[OCH3(1)], 57.6 [OCH3(2)].
2.4.7. Zn(sulfadiazinato)2P2(NH3) (3c)
Only small quantities of the complex have been obtained
using the experimental procedure previously described [12]
or the general procedure describedinthepresentpaper.Under
these conditions, a mixture of neutral sulfadiazine and
Zn(OH)2 is present [14].
2.4.4. Cd(sulfamethoxypyridazinato)2P2(H2O) (2b)
Improved results have been obtained by means of the fol-
lowing procedure. Zn(II) nitrate (1 mmol) in NH4OH–H2O
(1:9) (20 ml) is added dropwise to a stirred solution of
sulfadiazine (2 mmol) in NH4OH–H2O (1:9) (20 ml). The
resulting solution is heated (608C) until a white precipitate
begins to form; the solution is then filtered and crystals are
obtained after cooling (24–48 h). The crystalline complex is
filtered off and air dried (65% yield). Selected IR data
(cmy1): 836m, 978m, 994m, 1014m, 1024m, 1082s, 1102s,
1124s, 1141s, 1182m, 1230s, 1269s, 1282m, 1296m, 1363m,
1418vs, 1426vs, 1453vs, 1502m, 1554s, 1597s, 1635m,
3226m, 3340s, 3459m. 1H NMR (DMSO-d6): d 8.30d [2H,
H(6a), Js4.5 Hz], 7.65d [2H, H(2b)/H(6b), Js8.2 Hz],
6.73t [1H, H(5a)], 6.56d [2H, H(3b)/H(5b), Js8.4 Hz],
5.68s (2H, NH2). 13C NMR (DMSO-d6): d 166.1 [C(2a)],
161.9 [C(4a)/C(6a)], 155.0 [C(4b)], 134.1 [C(1b)],
White solid (90% yield). Found: C, 37.34; H, 3.50; N,
15.71; S, 8.55. Calc. for C22H22N8S2O6CdP2(H2O): C,
37.37; H, 3.68; N, 15.85; S, 9.06%. Selected IR data (cmy1):
836s, 971s, 1016s, 1047m, 1087s, 1138s, 1182m, 1254s,
1299s, 1367m, 1422vs, 1469s, 1503m, 1540m, 1601s,
1637m, 3264m, 3364s. UV (DMSO): l 270 nm (´ 3.5=104
dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3
in DMSO, 258C)s5.1. 1H NMR (DMSO-d6): d 7.65 d[2H,
H(2b)/H(6b), Js8.4 Hz], 7.42 d [1H, H(4a), Js9.6 Hz],
7.16 d [1H, H(5a), Js9.6 Hz], 6.55 d [2H, H(3b)/H(5b),
Js8.4 Hz], 5.72 bs (2H, NH2), 3.95 s (3H, OCH3). 13C
NMR (DMSO-d6): d 164.1 [C(6a)], 162.3 [C(3a)], 155.4
[C(4b)], 133.9 [C(1b)], 132.6 [C(2b)/C(6b)], 125.8
[C(4a)], 124.9 [C(5a)], 116.7 [C(3b)/C(5b)], 58.1
(OCH3).
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133.1 [C(2b)/C(6b)], 116.0 [C(3b)/C5b)], 115.0
[C(5a)].
865m, 980m, 981m, 1014m, 1087s, 1104m, 1113m, 1138s,
1252s, 1327m, 1398s, 1419vs, 1433s, 1462s, 1499m, 1566s,
1582s, 1598vs, 1624m, 3156m, 3247m, 3286m, 3366m,
3491m, 3554m. UV (DMSO): l 272 nm (´ 5.0=104 dm3
moly1 cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3 in
2.4.8. [Cd(sulfadimidinato)2(H2O)]P2H2O (4b)
White solid (80% yield). White crystals in NH4OH–H2O
(3:9). Found: C, 40.09; H, 4.49; N, 15.48; S, 8.67. Calc. for
C24H26N8S2O4CdP3H2O: C, 39.98; H, 4.44; N, 15.55; S,
8.88%. Selected IR data (cmy1): 885s, 982m, 1082s,
1128vs, 1144s, 1184m, 1248s, 1347m, 1380vs, 1398m,
1434s, 1499m, 1564m, 1586s, 1601s, 1641m, 3160m,
3288m, 3371m, 3465m, 3545m. UV (DMSO): l 273 nm (´
6.7=104 dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3
mol dmy3 in DMSO, 258C)s3.5. 1H NMR (DMSO-d6): d
7.67bd [2H, H(2b)/H(6b)], 6.51bd [2H, H(3b)/H(5b)],
6.49s [1H, H(5a)], 5.62bs (2H, NH2), 2.18s (6H, CH3).
13C NMR (DMSO-d6): d 171.2 [C(4a)/C(6a)], 166.1
[C(2a)], 154.9 [C(4b)], 134.2 [C(1b)], 133.5 [C(2b)/
C(6b)], 115.6 [C(3b)/C5b)], 114.0[C(5a)], 27.0(CH3).
1
DMSO, 258C)s3.2. H NMR (DMSO-d6): d 8.13s [1H,
H(6a)], 7.67d [2H, H(2b)/H(6b), Js8.2 Hz], 6.60s [1H,
H(5a)], 6.54d [2H, H(3b)/H(5b), Js8.2 Hz], 5.62bs
(2H, NH2), 2.19s (3H, CH3). 13C NMR (DMSO-d6): d
172.3 [C(4a)], 165.8 [C(2a)], 160.9 [C(6a)], 155.2
[C(4b)], 134.2 [C(1b)], 133.5 [C(2b)/C(6b)], 116.0
[C(3b)/C5b)], 114.8 [C(5a)], 27.3 (CH3).
2.4.12. Cd(sulfamethoxazolato)2P2(H2O) (6b)
White solid (89% yield). Found: C, 37.11; H, 3.69; N,
12.80; S, 9.78. Calc. for C20H20S2O6CdP2(H2O): C, 36.78;
H, 3.67; N, 12.87; S, 9.80%. Selected IR data (cmy1): 792m,
835s, 930s, 942s, 1090s, 1111vs, 1174s, 1216s, 1222s,
1264m, 1302m, 1320m, 1377w, 1418s, 1445m, 1477vs,
1506m, 1604m, 1628s, 3379m, 3431m, 3476m. UV
(DMSO): l 267 nm (´ 3.4=104 dm3 moly1 cmy1). LM/
2.4.9. Zn(sulfadimidinato)2P1.75(NH3)P0.25(H2O) (4c)
White solid (71% yield). White crystals in NH4OH–H2O
(1:9). Found: C, 43.87; H, 4.84; N, 20.90; S, 9.40. Calc. for
C24H26N8S2O4ZnP1.75(NH3)P0.25(H2O): C, 44.06, H,
4.86; N, 20.88; S, 9.79%. Selected IR data (cmy1): 886s,
984m, 1014m, 1058m, 1082s, 1128vs, 1144s, 1186m, 1274s,
1304w, 1349m, 1380s, 1400m, 1436s, 1501m, 1650m,
1588s, 1602s, 1644m, 3158m, 3281m(br), 3368m, 3456m,
3550m UV (DMSO): l 273 nm (´ 2.1=104 dm3 moly1
cmy1). LM/Vy1 cm2 moly1 (10y3 mol dmy3 in DMSO,
V
y1 cm2 moly1 (10y3 mol dmy3 in DMSO, 258C)s12.4.
1H NMR (DMSO-d6): d 7.58d [2H, H(2b)/H(6b), Js8.6
Hz], 6.58d [2H, H(3b)/H(5b), Js8.6 Hz], 5.89s [1H,
H(4a)], 5.71bs (2H, NH2), 2.26s (3H, CH3). 13C NMR
(DMSO-d6): d 172.7 [C(3a)], 168.4 [C(5a)], 155.8
[C(4b)], 133.2 [C(1b)], 133.2 [C(2b)/C(6b)], 117.0
[C(3b)/C(5b)], 100.7 [C(4a)], 16.5 (CH3).
1
258C)s2.7. H NMR (DMSO-d6): d 7.68d [2H, H(2b)/
2.4.13. Zn(sulfamethoxazolato)2P2(H2O) (6c)
H(6b), Js7.9 Hz], 6.53d [2H, H(3b)/H(5b), Js7.6 Hz],
6.46s [1H, H(5a)], 5.62bs (2H, NH2), 2.18s (6H, CH3).
13C NMR (DMSO-d6): d 170.9 [C(4a)/C(6a)], 165.9
[C(2a)], 155.0 [C(4b)], 133.6 [C(1b)], 133.6 [C(2b)/
C(6b)], 115.7 [C(3b)/C5b)], 114.3[C(5a)], 26.8(CH3).
White solid (79% yield). Found: C, 39.52; H, 3.96; N,
13.72; S, 10.52. Calc. for C20H20S2O6ZnP2(H2O): C, 39.64;
H, 3.96; N, 13.87; S, 10.57%. Selected IR data (cmy1):818s,
838s, 884sh, 920s, 951s, 1010m, 1055m, 1086s, 1131vs,
1261s, 1274s, 1305m, 1323m, 1426s, 1476s, 1504m, 1577m,
1601s, 1636s, 1661m, 3071m, 3225s, 3365s, 3496s. UV
(DMSO): l 267 nm (´ 3.3=104 dm3 moly1 cmy1). LM/
2.4.10. Cd(sulfamerazinato)2P2H2O (5b)
White solid (83% yield). Found: C, 39.05; H, 3.67; N,
16.40; S, 9.26. Calc. for C22H22N8S2O4CdP2H2O: C, 39.14;
H, 3.85; N, 16.60; S, 9.48%. Selected IR data (cmy1): 867m,
906m, 978m, 1086m, 1104m, 1113m, 1138s, 1253s, 1328m,
1391s, 1414s, 1436s, 1460m, 1498m, 1558m, 1566m, 1581s,
1597s, 3161m, 3257m, 3292m, 3360m, 3496m, 3553m. UV
(DMSO): l 271 nm (´ 4.8=104 dm3 moly1 cmy1). LM/
Vy1 cm2 moly1 (10y3 mol dmy3 in DMSO, 258C)s3.3.
1H NMR (DMSO-d6): d 8.21bd [1H, H(6a)], 7.64d [2H,
H(2b)/H(6b)], 6.63d [1H, H(5a)], 6.51bd [2H, H(3b)/
H(5b)], 5.62bs (2H, NH2), 2.18s (3H, CH3). 13C NMR
(DMSO-d6): d 171.6 [C(4a)], 166.2 [C(2a)], 161.9
[C(6a)], 154.9 [C(4b)], 134.1 [C(1b)], 133.1 [C(2b)/
C(6b)], 115.8 [C(3b)/C5b)], 114.7[C(5a)], 26.9(CH3).
V
y1 cm2 moly1 (10y3 mol dmy3 in DMSO, 258C)s10.2.
1H NMR (DMSO-d6): d 7.60d [2H, H(2b)/H(6b), Js8.6
Hz], 6.58d [2H, H(3b)/H(5b), Js8.6 Hz], 5.97s [1H,
H(4a)], 5.78s (2H, NH2), 2.28s (3H, CH3). 13C NMR
(DMSO-d6): d 172.8 [C(3a)], 167.3 [C(5a)], 156.2
[C(4b)], 133.2 [C(1b)], 132.2 [C(2b)/C(6b)], 116.9
[C(3b)/C(5b)], 100.9 [C(4a)], 16.4 (CH3).
2.4.14. Zn(sulfamethoxazolato)2(py)2(H2O)2 (6d)
A solution of ZnCl2 containing 10 mmol in 50 ml H2O–py
(3:1) was added to a solution of sulfamethoxazole (5 mmol
in 50 ml H2O–py, 1:1) with continuousstirring.Immediately,
a white solid was obtained. The precipitate was isolated by
filtration and the filtrate was left to stand at room temperature.
From the filtrate colourless prismatic crystals suitable for X-
ray measurement appeared after a month. Selected IR data
(cmy1): 670s, 700s, 750m, 800–820m, 840m, 900m, 930s,
1000m, 1040s, 1060m, 1080s, 1130vs, 1220s, 1250s, 1270s,
1315m, 1410s, 1440s, 1460s, 1500s, 1590s, 1600s, 1630s,
2.4.11. Zn(sulfamerazinato)2P2H2O (5c)
White solid (84% yield). Found: C, 41.76; H, 4.11; N,
17.46; S, 10.29. Calc. for C22H22N8S2O4ZnP2H2O: C, 42.07;
H, 4.14; N, 17.85; S, 10.20%. Selected IR data (cmy1):
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3350s, 3480s. UV (solid): 258 nm. UV (DMSO): l 273 nm
(´ 4.5=104 dm3 moly1 cmy1). LM/Vy1 cm2 moly1 (10y3
mol dmy3 in DMSO at 258C)s10.0. 1H NMR (DMSO-d6):
d 8.69dt [2H, H(o-) py, Js4.2 and 1.7 Hz], 7.96tt [1H,
H(p-) py, Js7.7 and 1.7 Hz], 7.57m [4H, H(2b)/
H(6b)qH(m-) py], 6.61d [2H, H(3b)/H(5b), Js8.6
Hz], 6.05s [1H, H(4a)], 5.87s (2H, NH2), 2.30s (3H,
CH3). 13C NMR (DMSO-d6): d 172.4 [C(3a)], 167.5
[C(5a)], 155.9 [C(4b)], 153.2 [C(o-) py], 142.1 [C(p-)
py], 132.7 [C(2b)/C(6b)], 132.1 [C(1b)], 128.7
[C(m-) py], 116.5 [C(3b)/C(5b)], 100.6 [C(4a)], 16.2
(CH3). Solid 13C NMR (ppm) tentative assignment: 168.2
[(C(3a)], 163.0 [C(5a)], 150.3 [C(4b) and C(o-) py],
140.1 [C(p-) py], 131.1 [C(1b)], 127.0 and 123.1 [C(2b)
or C(6b)qC(m-) py and C(6b) or C(2b)], 115.3 and111.0
[C(5b) and C(3b)], 99.3 [C(4a)], 12.0 (CH3).
Fig. 1. ORTEP plot of [Hg(sulfamethoxypyridazinato)2] (2a).
of two bidentate sulfadimidine ligands generating two four-
3. Results and discussion
membered rings. The terminal amino N(49b) [Cd–
˚
N(49b)s2.379(7) A] of a third sulfadimidine, which is
3.1. Crystal structures
bonded to an adjacent Cd(II), and the O(3) [Cd–
˚
O(3)s2.334(6) A] atom of a water molecule complete the
3.1.1. [Hg(sulfamethoxypyridazinato)2] (2a)
coordination sphere. Although both ligands are bound in a
bidentate form to the metal, only one sulfadimidine presents
two equivalent Cd–N distances. The N(4)–C(4b) and
The molecular structure of complex 2a and the atom num-
bering scheme are shown in Fig. 1. The two sulfamethoxy-
pyridazinato ligands are bound to the mercury atom via the
sulfonamidic nitrogen N(1) in a linear arrangement. The Hg
atom is at the centre of symmetry of the unit complex. The
Hg–N bond distance [Hg–N(1)s2.071(4) A] (Table 2) is
similar to previously reported distances in other Hg–N sys-
tems [16]. The bond lengths and angles of the benzene ring,
˚
N(49)–C(4b9) distances are 1.393(11) and 1.413(9) A,
respectively, greater than the corresponding distances in the
˚
free ligand [N(4)–C(4b)s1.384(6) A], which is consis-
˚
tent with the coordination of the terminal amino group to the
adjacent Cd(II). The bond lengths and angles of the benzene
ring conform well to those found in the free sulfadimidine
˚
the distances C(4b)–N(4b)s1.392(7) A, S(1)–N(1)s
˚
[34], whereas distances S(1)–N(1)s1.609(7) A, S(19)–
˚
˚
1.625(4) A, N(1)–C(3a)s1.403(7) A and the angleS(1)–
N(1)–C(3a) conform well to those found in the free ligand.
Sensitive changes in bonds and angles of the heterocyclic
ring are observed by comparison with those of the free sul-
famethoxypyridazine, as a consequence of a new restructur-
ing of the ring charge. The trigonal arrangement around the
sulfonamidic nitrogen is similar to those observed in the free
ligand and the Hg–sulfadiazine complex [16]. The gauche
conformation between the two rings regarding the S(1)–
N(sulfonamidic) bond, the torsion angle [C(1b)–S(1)–
N(sulfonamidic)–C(3a)s74.598] and the dihedral [O(1)–
S(1)–N(sulfonamidic)–metals20.138] are quite different
to those observed in the Hg–sulfadiazine complex (dihedral
5.808). The monomeric units are held through weak inter-
molecular hydrogen bonds between the SO2 group and the
NH2 of an adjacent unit [N(4b)–H∆OSOs3.048].
˚
˚
N(19)s1.578(7) A, N(2)–C(3a)s1.338(10) A and
˚
N(29)–C(3a9)s1.348(9) A are shorter in the Cd(II) com-
plex. In this case the trigonal arrangement around the sulfon-
amidic nitrogen is similar to those observed in the Zn(II) and
Cu(II)–sulfadiazine complexes [16]. The gauche confor-
mation between the two rings regarding the S(1)–
N(sulfonamidic) bond, with a torsion angle of [C(1b)–
S(1)–N(sulfonamidic)–C(3a)s65.518] is similar tothatof
the Ag–sulfadiazine complex [10,11,14]. The packing of the
complex units is governed by long chains formed by the
bridging sulfadimidine ligands which are bound to Cd(1) via
N(1)/N(3) and Cd(2) via NH2 [N(49b)–Cds2.379(7)
˚
A]. Stacking interactions are present in the crystal structure
˚
involving benzene and heterocyclic rings (3.6 A). In the
complex units there are intramolecular hydrogen bonds
between the NH2 group and SO2 of different ligands, and
between SO2 and coordinated H2O molecules.
3.1.2. [Cd(sulfadimidinato)2(H2O)]P2H2O (4b)
The molecular structure of compound 4b and the atom
numbering scheme are shown in Fig. 2. The Cd(II) ion in
complex exhibits a high distorted-octahedralgeometry,being
coordinated to thesulfonamidicN(1)[Cd–N(1)s2.328(6)
3.1.3. [Zn(sulfamethoxazolato)2(py)2(H2O)2] (6d)
The structure consists of centrosymmetric units of
Zn(sulfamethoxazolato)2P(py)2(H2O)2 (Fig. 3). The
geometry around the Zn(II) ion, placed at a crystallographic
symmetry centre, can be described as a slightly distorted
˚
˚
A; Cd–N(19)s2.326(6) A] and the heterocyclic N(3)/
˚
˚
N(29) [Cd–N(3)s2.307(6) A; Cd–N(29)s2.426(6) A]
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Table 2
˚
Selected bond lengths (A) and angles (8) for complexes 2a, 4b and 6d
Hg(sulfamethoxypyridazinato)2 (2a)
Hg(1)–N(1)
2.071(4)
Hg(1)–N(1) a
2.071(4)
120.8(2)
N(1) a–Hg(1)–N(1)
C(3A)–N(1)–Hg(1)
180.0(3)
114.4(3)
S(1)–N(1)–Hg(1)
Cd(sulfadimidinato)2 (4b)
Cd(1)–N(3)
Cd(1)–N(19)
2.307(6)
2.326(6)
2.328(6)
2.379(7)
Cd(1)–N(49) b
Cd(1)–N(29)
Cd(1)–O(3)
2.379(7)
2.426(6)
2.334(6)
Cd(1)–N(1)
N(49)–Cd(1) c
N(3)–Cd(1)–N(19)
N(3)–Cd(1)–O(3)
N(19)–Cd(1)–O(3)
N(3)–Cd(1)–N(1)
O(3)–Cd(1)–N(29)
N(3)–Cd(1)–N(49) b
N(19)–Cd(1)–N(49) b
O(3)–Cd(1)–N(49) b
C(3A)–N(1)–Cd(1)
S(1)–N(1)–Cd(1)
C(3A)–N(3)–Cd(1)
C(6A)–N(3)–Cd(1)
C(4B9)–N(49)–Cd(1) c
115.1(2)
97.6(2)
86.5(2)
56.7(2)
142.8(2)
144.1(2)
98.5(2)
96.7(3)
96.1(5)
140.9(4)
98.5(5)
144.5(6)
114.3(4)
N(1)–Cd(1)–N(29)
N(1)–Cd(1)–O(3)
N(3)–Cd(1)–N(29)
N(29)–Cd(1)–N(19)
N(19)–Cd(1)–N(1)
N(49) b–Cd(1)–N(29)
N(1)–Cd(1)–N(49) b
120.7(2)
95.7(2)
96.6(2)
56.4(2)
171.7(2)
91.5(2)
89.3(2)
C(3A9)–N(19)–Cd(1)
S(19)–N(19)–Cd(1)
C(3A9)–N(29)–Cd(1)
C(4A9)–N(29)–Cd(1)
97.2(4)
136.1(4)
93.7(4)
147.6(5)
Zn(sulfamethoxazolato)2(pyridine)2(H2O)2 (6d)
Zn–O(4)
Zn–N(2)
Zn–N(16)
2.0984(14)
2.1736(15)
2.1841(17)
Zn–O(4) d
Zn–N(2) d
Zn–N(16) d
2.0984(14)
2.1736(15)
2.1841(17)
N(16) d–Zn–N(16)
N(2) d–Zn–N(16) d
N(2) d–Zn–N(16)
O(4) d–Zn–N(2)
O(4) d–Zn–N(2) d
O(4) d–Zn–N(16) d
O(4) d–Zn–N(16)
O(4) d–Zn–O(4)
C(5A)–N(2)–Zn
O(3)–N(2)–Zn
180.0
N(2)–Zn–N(2) d
N(2)–Zn–N(16)
N(2)–Zn–N(16) d
O(4)–Zn–N(2) d
O(4)–Zn–N(2)
O(4)–Zn–N(16)
O(4)–Zn–N(16) d
180.0
92.50(6)
87.50(6)
90.98(6)
89.02(6)
92.35(7)
87.65(7)
180.0
92.50(6)
87.50(6)
90.98(6)
89.02(6)
92.35(7)
87.65(7)
133.61(12)
119.24(10)
C(11)–N(16)–Zn
C(15)–N(16)–Zn
121.84(15)
120.74(16)
a Symmetry transformations used to generate equivalent atoms: yxq1/2, yyq1/2, yz.
b Symmetry transformations used to generate equivalent atoms: yxq1/2, yq1/2, yz.
c Symmetry transformations used to generate equivalent atoms: yxq1/2, yy1/2, yz.
d Symmetry transformations used to generate equivalent atoms: yxq1, yy, yzq1.
Fig. 2. ORTEP plot of [Cd(sulfadimidinato)2(H2O)P2H2O (4b). All
hydrogen atoms have been omitted for clarity.
Fig. 3. ORTEP plot of [Zn(sulfamethoxazolato)2(pyridine)2(H2O)2]
(6d).
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A. Garc´ıa-Raso et al. / Polyhedron 19 (2000) 991–1004
999
compressed octahedron. The equatorial plane is formed by
two pyridine N atoms [N(16) and N(16A)] and two isox-
azole N atoms [N(2) and N(2A)] from two sulfamethoxa-
zolate anions. Two oxygen atoms of two water molecules are
placed in the apical positions. The equatorial M–N distances
Similar modifications are observed in Zn(II)/Cd(II) com-
plexes which are different to those in Hg(II) complexes. The
bands that appear near 3500 and 3400 cmy1 due to
nasym(NH2)and nsym(NH2)vibrationsoftheNH2 group[16]
are modified with respect to those of the free respective
ligands. In general, these vibration modes appear at higher
and lower wavenumbers, compared with those of the free
ligand. When the amino N atom does not interact with the
metal ion (this excludes the 4b complex) thesemodifications
are consequently due to the hydrogen bonds involving the
amino group. The frequency n(N–H) of the sulfonamido
˚
[2.1841(17) and 2.1736(15) A] are almost equal and mark-
˚
edly longer than the axial M–OW ones [2.0984(14) A]. The
coordination angles around the metal, which range from
87.50(6) to 92.50(6)8, do not deviate significantly from a
regular octahedron.
It should be noted that the coordination behaviour of the
sulfamethoxazolate anion contrasts with that exhibited by the
related sulfathiazolate in the Zn(sulfathiazolato)2PH2Ocom-
pound [18] in spite of the structural similarity between both
sulfonamides. The sulfamethoxazolate acts as monodentate
through the Nisoxazole, whereas the sulfathiazolate anion
behavesas a bridge linking twometal ionsthroughtheNthiazole
group, which in the free ligands is found at about 3125 cmy1
,
is not present in the spectra of the complexes, confirming the
deprotonation of the –SO2NH– moiety. Moreover, for the 6d
complex, in agreement with the coordination of the ligand
through the isoxazole N atom, deduced from the crystalstruc-
ture, the characteristic ring vibration is shifted from 1460
cmy1 in the free ligand to 1410 cmy1 in the complex. The
strong band at (1370–1330 cmy1) related to nasym(SO2–N)
[9,16,18] in each free ligand is also changed in frequency or
split in the same way in Zn(II) and Cd(II) compounds and
differently in Hg(II) derivatives. The 920–975 cmy1 band
in the ligand is assigned to n(S–N) [9,16] and changed to
higher frequencies in all cases as a consequence of coordi-
nation to the metal. This shift to higher frequencies is in
accordance with the shortening of the S–N bond lengths,
which have been observed in the crystal structures of com-
pounds 2a, 4b and 6d. In complex 6d, the bands at 1600,
1460, 1440, 1220, 760 and 700 cmy1 are assigned to vibra-
tions of the pyridine rings [37,38].
and Namino
.
When comparing the bond lengths of the sulfamethoxa-
zolate anion with those of the free sulfamethoxazole [35] a
remarkable similarity of all bond distances is found. The most
significant changes are: a small shortening of the N(1)–
˚
C(5A) distance [from 1.393(4) to 1.370(2) A], a slight
lengthening of the C(1B)–S(1) bond distance [from
˚
1.734(3) to 1.7650(18) A] and a marked shortening of the
˚
S(1)–N(1) length [from 1.645(3) to 1.5675(15) A]. It
must be noted that the S(1)–N(1) bond distance is veryclose
˚
to those of the S_N double bond (1.494–1.580 A) [36].
Since these distances are comparable to the corresponding
ones in the sulfamethoxazole sodium salt [36] and the sul-
fonamido group does not interact with the metal ion, these
changes are ascribed to the deprotonation of this moiety.
Moreover, the C(4B)–N(4) bond distance is longer than the
corresponding one in the free sulfamethoxazole [1.394(3)
3.3. NMR spectra
1H and 13C NMR of the complexes 1–6 are presented in
Tables 3–14.
˚
˚
A in the complex, 1.358(5) A in the ligand]. The lack of
interaction of the amino N atom of the sulfamethoxazolewith
Zn(II) leads us to propose that this lengthening is determined
by the intermolecular hydrogen bonds involving the amino
group [N(4)–H∆OW and N(4)∆H–OWs2.09 and 2.20
˚
˚
A, respectively, N(4)–H∆OSOs2.20 A]. The crystal
structure is stabilised by an extensive network of intra- and
intermolecular hydrogen bonds involving the water mole-
cules, the sulfonamido N and O atoms and the terminalamino
group. To be noticed the strong intramolecular interaction
between a coordinated water molecule and the sulfonamido
˚
N(1) atom [N(1)∆H–O(4)s1.92 A]. As found in metal
complexes with other sulfonamides [18], the coordination
through the heteroaromatic N atom does not significantly
modify the bond lengths and bond angles of the ring. The
isoxazole ring is planar and perpendicular to the benzene ring
(angle between planes, 78.288).
3.2. Infrared spectra
The infrared spectra of the complexes in the far-IR region
to 200 cmy1 were compared with those of the free ligands.
Scheme 3.
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Table 3
a
1H NMR shift assignments of sulfadimethoxine (sulfadime-H, 1) and its Hg (1a), Cd (1b) and Zn (1c) complexes in DMSO-d6
Assignment
1H (1)
1H (1a)
Dd (H) b
1H (1b)
Dd (H) b
1H (1c)
Dd (H) b
N(4a)–H
C(5a)–H
C(2b)–H
C(3b)–H
OCH3(1)
OCH3(2)
NH2
11.23
6.03
7.65
6.69
3.89
3.88
6.21
5.94
7.85
6.72
3.95
3.89
6.18
I0.09
H0.20
q0.03
q0.06
q0.01
y0.03
5.83
7.59
6.57
3.84
3.79
5.80
I0.20
y0.06
I0.12
y0.05
I0.09
I0.41
5.86
7.58
6.59
3.81
3.73
5.77
I0.17
y0.07
I0.10
y0.07
I0.15
I0.44
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
Table 4
a
13C NMR shift assignments of sulfadimethoxine (sulfadime-H, 1) and its Hg (1a), Cd (1b) and Zn (1c) complexes in DMSO-d6
Assignment
13C (1)
13C (1a)
Dd (C) b
13C (1b)
Dd (C) b
13C (1c)
Dd (C) b
C(2a)
C(4a)
C(5a)
C(6a)
168.4
164.2
88.3
175.6
128.2
133.4
116.5
157.4
58.4
168.0
165.8
88.6
176.2
128.3
133.7
116.8
157.2
58.8
y0.4
H1.6
q0.3
y0.4
q0.1
q0.3
q0.3
y0.2
q0.4
q0.3
169.6
167.6
87.7
175.7
132.3
132.6
116.4
155.6
58.3
H1.2
H3.4
y0.6
q0.1
H4.1
y0.8
y0.1
I1.8
y0.1
y0.1
170.1
167.6
88.4
175.4
132.8
132.8
116.5
155.7
58.2
H1.7
H3.4
q0.1
y0.2
H4.6
y0.6
q0.0
I1.7
y0.2
y0.1
C(1b)
C(2b)/C(6b)
C(3b)/C(5b)
C(4b)
OCH3(1)
OCH3(2)
57.7
58.0
57.6
57.6
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
Table 5
1H NMR shift assignments of sulfamethoxypyridazine (sulfamet-H, 2) and its Hg (2a), Cd (2b) and Zn (2c) complexes in DMSO-d6
a
Assignment
1H (2)
1H (2a)
Dd (H) b
1H (2b)
Dd (H) b
1H (2c)
Dd (H) b
N(3a)–H
C(4a)–H
C(5a)–H
C(2b)–H
C(3b)–H
NH2
11.8 (br)
7.66
7.35
7.56
6.65
7.62
7.31
7.82
6.68
6.06
4.01
y0.04
y0.04
H0.26
q0.03
q0.03
q0.05
7.42
7.16
7.65
6.55
5.72
3.95
I0.24
I0.19
q0.09
I0.10
I0.31
y0.01
7.49
7.11
7.51
6.51
5.67
3.90
I0.17
I0.24
y0.05
I0.14
I0.36
y0.06
6.03
3.96
OCH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
All Hg(sulfamidato)2 complexes (1a–6a) present a sim-
ilar NMR pattern with two equivalent sulfamide groups.
Thus, upon complexation, a downfield shift (q1.0 to q4.0
ppm) is observed for the carbon directly bonded to the sul-
fonamidic nitrogen [C(4a) for complex 1a, C(3a) for com-
plex 2a, C(2a) for complexes 3a–5a and C(5a) for complex
6a]. Moreover, the downfield shift for H(2b)/H(6b) reso-
nance (q0.14 to q0.26 ppm) could be related to the prox-
imity of the Hg(II) which can be explained by a direct
interaction, as in solid state, between the metallic ion and the
sulfonamidic nitrogen (Scheme 3).
groups. In these cases, important downfieldshifts,higherthan
in the corresponding Hg(II) compounds, of the carbons
directly bonded to the sulfonamidic moiety [C(4a) for com-
plex 1a, C(3a) for complex 2a, C(2a) for complexes 3a–5a
and C(5a) for complex 6a (q3.4 to q6.4 ppm) and C(1b)
(q3.1 to 5.1 ppm)] together with different Dd (H or C) of
the resonances presented in the heterocyclic ring suggest a
main metal–heterocyclic nitrogen interaction. However, sec-
ondary interaction with the sulfonamidic nitrogen cannot be
completely discarded. On the other hand, the upfield shifts of
the NH2 (y0.31 to y0.47 ppm), H(3b)/H(5b) (y0.10 to
y0.15 ppm) and C(4b) (y1.3 to y2.2 ppm) indicate that
NH2–metal(II) binding is also present, yielding equivalent
Cd(II) (1b–6b) and Zn(II) (1c–6c) complexes also
show similar NMR patterns with two equivalent sulfamide
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1001
Table 6
13C NMR shift assignments of sulfamethoxypyridazine (sulfamet-H, 2) and its Hg (2a), Cd (2b) and Zn (2c) complexes in DMSO-d6
a
Assignment
13C (2)
13C (2a)
Dd (C) b
13C (2b)
Dd (C) b
13C (2c)
Dd (C) b
C(3a)
C(4a)
C(5a)
C(6a)
156.3
128.8
126.8
163.9
130.8
132.7
116.8
156.7
58.5
158.0
125.5
124.4
165.8
129.9
133.1
116.7
156.7
58.3
H1.3
I3.3
I2.4
H1.9
I0.9
q0.4
y0.1
q0.0
y0.2
162.3
125.8
124.9
164.1
133.9
132.6
116.7
155.4
58.1
H6.0
I3.0
I1.9
q0.2
H3.1
y0.1
y0.1
I1.3
y0.4
162.1
127.6
124.6
163.0
134.3
132.2
116.5
155.2
58.0
H5.8
I1.2
I1.9
y0.9
H3.5
y0.5
y0.3
I1.5
0.5
C(1b)
C(2b)/C(6b)
C(3b)/C(5b)
C(4b)
OCH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
Table 7
1H NMR shift assignments of sulfadiazine (sulfadia-H, 3) and its Hg (3a), Cd (3b) and Zn (3c) complexes in DMSO-d6
a
Assignment
1H (3)
1H (3a)
Dd (H) b
1H (3b) c
Dd (H) b
1H (3c) c
Dd (H) b
N(2a)–H
C(4a)–H
C(5a)–H
C(2b)–H
C(3b)–H
NH2
11.35
8.57
7.11
7.70
6.65
6.11
8.59
7.08
7.87
6.67
6.01
q0.02
y0.03
H0.17
q0.02
I0.10
8.37
6.77
7.64
6.53
5.64
I0.19
I0.34
y0.06
I0.12
I0.47
8.30
6.73c
7.64
6.55
5.68
I0.27
I0.38
y0.06
I0.10
I0.43
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
c Spectrum presents broad peaks.
Table 8
13C NMR shift assignments of sulfadiazine (sulfadia-H, 3) and its Hg (3a), Cd (3b) and Zn (3c) complexes in DMSO-d6
a
Assignment
13C (3)
13C (3a)
Dd (C) b
13C (3b)
Dd (C) b
13C (3c)
Dd (C)
C(2a)
C(4a)/C(6a)
C(5a)
161.2
162.2
119.5
128.8
133.8
116.1
157.0
163.7
162.4
118.4
129.8
134.3
116.0
156.6
H2.5
q0.2
I1.1
H1.0
q0.5
q0.1
y0.4
166.3
162.2
115.1
134.1
132.9
116.0
155.0
H5.1
q0.0
I4.4
H5.3
y0.9
y0.1
I2.0
166.1
161.9
115.0
134.1
133.1
116.0
155.0
H4.9
y0.3
I4.5
H5.3
y0.7
y0.1
I2.0
C(1b)
C(2b)/C(6b)
C(3b)/C(5b)
C(4b)
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
Table 9
1H NMR shift assignments of sulfadimidine (sulfadim-H, 4) and its Hg (4a), Cd (4b) and Zn (4c) complexes in DMSO-d6
a
Assignment
1H (4)
1H (4a)
Dd(H) b
1H (4b) c
Dd (H) b
1H (4c) c
Dd (H) b
N(2a)–H
C(5a)–H
C(2b)–H
C(3b)–H
NH2
11.15 (br)
6.84
7.74
6.65
6.06
6.85
7.88
6.66
5.97
2.37
q0.01
H0.14
q0.01
I0.09
q0.03
6.49 d
7.67
6.51
5.61
2.18
I0.35
y0.07
I0.14
I0.45
I0.16
6.46
7.68
6.53
5. 62
2.18
I0.38
y0.06
I0.12
I0.44
I0.16
CH3
2.34
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
c Spectrum presents broad peaks.
d Estimated.
.
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Table 10
a
13C NMR shift assignments of sulfadimidine (sulfadim-H, 4) and its Hg (4a), Cd (4b) and Zn (4c) complexes in DMSO-d6
Assignment
13C (4)
13C (4a)
Dd (C) b
13C (4b)
Dd (C) b
13C (4c)
Dd (C) b
C(2a)
C(4a)/C(6a)
C(5a)
160.7
171.3
117.7
129.0
134.3
115.9
156.9
27.1
163.3
171.6
116.8
130.0
134.7
115.8
156.5
27.2
H2.6
q0.3
I0.9
H1.0
q0.3
y0.1
y0.4
q0.1
166.1
171.2
114.0
134.2
133.5
115.6
154.9
27.0
H5.4
y0.1
I3.7
H5.2
y0.7
y0.3
I2.0
y0.1
165.9
170.9
114.3
133.6
133.6
115.7
155.0
26.8
H5.2
y0.4
I3.4
H4.6
y0.7
y0.2
I1.9
y0.3
C(1b)
C(2b)/C(6b)
C(3b)/C(5b)
C(4b)
CH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
Table 11
a
1H NMR shift assignments of sulfamerazine (sulfamer-H, 5) and its Hg (5a), Cd (5b) and Zn (5c) complexes in DMSO-d6
Assignment
1H (5)
1H (5a)
Dd (H) b
1H (5b) c
Dd (H) b
1H (5c) c
Dd (H) b
N(2a)–H
C(5a)–H
C(6a)–H
C(2b)–H
C(3b)–H
NH2
11.22 (br)
6.98
8.40
7.72
6.66
6.96
8.41
7.87
6.66
5.98
2.42
y0.02
q0.01
H0.15
q0.00
I0.11
q0.01
6.63
8.21
7.64
6.51
5.62
2.18
I0.35
I0.19
y0.08
I0.15
I0.47
I0.23
6.60
8.13
7.67
6.54
5.62
2.19
I0.38
I0.27
y0.05
I0.12
I0.47
I0.22
6.09
2.41
CH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
c Spectrum presents broad peaks.
Table 12
13C NMR shift assignments of sulfamerazine (sulfamer-H, 5) and its Hg (5a), Cd (5b) and Zn (5c) complexes in DMSO-d6
a
Assignment
13C (5)
13C (5a)
Dd (C) b
13C (5b)
Dd (C) b
13C (5c)
Dd (C) b
C(2a)
C(4a)
C(5a)
C(6a)
161.0
172.1
118.9
161.7
129.0
134.2
116.1
157.1
27.4
163.6
172.1
117.7
162.0
130.1
134.5
116.0
156.6
27.4
H2.6
q0.0
I1.2
q0.3
H1.1
q0.3
y0.1
y0.5
q0.0
166.2
171.6
114.7
161.9
134.1
133.1
115.8
154.9
26.9
H5.2
y0.5
I4.2
q0.2
H5.1
I1.1
y0.3
I2.2
y0.5
165.8
172.3
114.8
160.9
134.2
133.5
116.0
155.2
27.3
H4.8
q0.2
I4.1
y0.8
H5.2
y0.7
y0.1
I1.9
y0.1
C(1b)
C(2b)/C(6b)
C(3b)/C(5b)
C(4b)
CH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
Table 13
1H NMR shift assignments of sulfamethoxazole (sulfamoxaz-H, 6) and its Hg (6a), Cd (6b) and Zn (6c) complexes, and [Zn(sulfa-
a
methoxazolato)2(py)2(H2O)2] (6d) in DMSO-d6
Assignment
1H (6)
1H (6a)
Dd (H) b
1H (6b)
Dd (H) b
1H (6c)
Dd (H) b
1H (6d)
Dd (H) b
N(2a)–H
C(4a)–H
C(2b)–H
C(3b)–H
NH2
11.04
6.18
7.58
6.67
6.18
2.38
6.13
7.76
6.69
6.11
2.38
y0.05
H0.18
q0.02
y0.07
q0.00
5.89
7.58
6.58
5.71
2.26
I0.29
q0.00
I0.09
I0.47
I0.12
5.97
7.60
6.58
5.78
2.28
I0.21
q0.02
I0.09
I0.40
I0.10
6.05
7.57(m)
6.60
5.87
2.30
I0.13
y0.01
y0.07
I0.31
y0.08
CH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
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A. Garc´ıa-Raso et al. / Polyhedron 19 (2000) 991–1004
1003
Table 14
13C NMR shift assignments of sulfamethoxazole (sulfamoxaz-H, 6) and its Hg (6a), Cd (6b) and Zn (6c) complexes and [Zn(sulfa-
a
methoxazolato)2(py)2(H2O) (6d) in DMSO-d6
Assignment
13C (6)
13C (6a)
Dd (C) b
13C (6b)
Dd (C) b
113C (6c)
Dd (C) b
13C (6d)
Dd (C) b
C(3a)
C(4a)
C(5a)
C(1b)
C(2b)/C(6b)
C(3b)/C(5b)
C(4b)
174.0
99.4
174.7
99.4
q0.3
q0.0
H3.9
H1.0
q0.5
q0.0
y0.4
q0.3
172.7
100.7
168.4
133.2
133.2
117.0
155.8
16.5
I1.3
H1.3
H6.4
H5.0
q0.3
q0.3
I1.6
q0.4
172.8
100.9
167.3
133.2
132.2
116.9
156.2
16.4
I1.2
H1.5
H5.3
H5.0
y0.7
q0.2
I1.2
q0.3
172.4
100.6
167.5
132.1
132.9
116.5
155.9
16.2
I1.6
H1.2
H5.5
H3.9
q0.0
y0.2
I1.5
q0.1
162.0
128.2
132.9
116.7
157.4
16.1
165.9
129.2
133.4
116.7
157.0
16.4
CH3
a Relative to TMS with DMSO-d6 peak as reference (1H, 2.60 ppm; 13C, 43.5 ppm).
b Ddsd(sulfamide complex)yd(sulfamide)
.
structures to the previously described polymeric Zn(sulfo-
thiazolato)2 [9] (Scheme 3). Similar results are obtained for
compound 6d. Moreover, the solid 13C NMR spectrumshows
the non-equivalence of the aromatic carbons of the bencenic
moiety as can be observed in the crystal structure (Fig. 3).
The LM (10y3 mol dmy3) values in DMSO at 258C imply
the presence of non-electrolyte type species for all the com-
plexes described in this work [39].
for the 2D NMR experiments and F. Estevan (University of
Valencia, Spain) for recording the solid 13C NMR spectrum.
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ccdc.cam.ac.uk) on request, quoting the deposition numbers:
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