Reactivity of benzil bis(4-methyl-3-thiosemicarbazone) with cadmium nitrate. Crystal structure of [Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 · H2O

Article abstract of DOI:10.1016/j.poly.2008.04.036

The reaction between cadmium nitrate dihydrate and benzil bis(4-methyl-3-thiosemicarbazone), LMe₂H₄, depends on the working conditions. In methanol the reaction gives the novel complex [Cd(LMe₂H₄)(NO₃)₂][Cd(LMe₂H₄)(NO₃)(H₂O)]NO₃ · H₂O (1). Its crystal structure shows the presence of two cadmium atoms with different coordination numbers, seven and eight, and the ligands acting as N₂S₂ neutral molecules. One cadmium has the coordination sphere completed by a bidentate nitrato group and a water molecule, whereas the other one is bonded to two bidentate nitrato groups. Both molecules are joined to one nitrate ion and to an additional water molecule by hydrogen bonds. In the presence of lithium hydroxide, the reaction leads to a binuclear complex with the ligand doubly deprotonated [Cd(LMe₂H₂)]₂ (2). The complexes were characterized by elemental analysis, mass spectrometry, ¹³C and ¹¹³Cd CP/MAS NMR and, in the case of complex 1, by X-ray diffraction.

Full text of DOI:10.1016/j.poly.2008.04.036

Polyhedron 27 (2008) 2277–2284
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Reactivity of benzil bis(4-methyl-3-thiosemicarbazone) with cadmium nitrate.
Crystal structure of [Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 Á H2O
*
David G. Calatayud, Elena López-Torres , M. Antonia Mendiola
Departamento de Química Inorgánica, c/ Francisco Tomás y Valiente, 7, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction between cadmium nitrate dihydrate and benzil bis(4-methyl-3-thiosemicarbazone),
LMe2H4, depends on the working conditions. In methanol the reaction gives the novel complex
[Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 Á H2O (1). Its crystal structure shows the presence of
two cadmium atoms with different coordination numbers, seven and eight, and the ligands acting as
N2S2 neutral molecules. One cadmium has the coordination sphere completed by a bidentate nitrato
group and a water molecule, whereas the other one is bonded to two bidentate nitrato groups. Both mol-
ecules are joined to one nitrate ion and to an additional water molecule by hydrogen bonds. In the pres-
ence of lithium hydroxide, the reaction leads to a binuclear complex with the ligand doubly deprotonated
[Cd(LMe2H2)]2 (2). The complexes were characterized by elemental analysis, mass spectrometry, 13C and
113Cd CP/MAS NMR and, in the case of complex 1, by X-ray diffraction.
Received 11 March 2008
Accepted 9 April 2008
Available online 9 June 2008
Keywords:
Bis(thiosemicarbazone) ligands
Cadmium(II) complexes
X-ray diffraction
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
we know, there are only two complexes containing simultaneously
both seven- and eight-coordinate cadmium(II), a cluster and a
In recent years, the heavy element cadmium has received in-
creased attention due to its impact on plants and toxicity to hu-
mans, as well as for the luminescent properties of its complexes
[1–6]. Cadmium is an extremely toxic element that is naturally
present in the environment and also as a result of human activities.
Its toxicity derives from the fact that it is rapidly localized intracel-
lularly, mainly in the liver, and then is bound to metallothionein
forming a complex that is slowly transferred to the bloodstream
to be deposited in the kidneys. Therefore, it is an interesting area
of research to get compounds which are able to form stable com-
plexes with cadmium, because they could be employed as detoxif-
icating agents. For this purpose thiosemicarbazone ligands could
be very appropriate as both the ligands and their complexes have
shown a wide range of pharmacological properties [7–9]. In partic-
ular, cadmium and mercury complexes of the related ligand benzil
bis(thiosemicarbazone) have antimicrobial and antifungal activity
[10], so it could be expected that these cadmium derivatives also
possess some activity and studies are underway.
complex with the ligand acting as bridge [20,21]. On the other
hand, there are only two seven-coordinate cadmium(II) complexes
of thiosemicarbazones that have been structurally characterized,
one with a tridentate ligand and another containing 2,6-diacetyl-
pyridine bis(2N-methylthiosemicarbazone) [17,21]. Benzil bis(4-
methyl-3-thiosemicarbazone) LMe2H4 (see Scheme 1) has four do-
nor atoms that can lead to a tetradentate coordination mode, so
there are at least two sites available on the Cd(II) ion for the
À
NO3 coordination. This ligand has shown versatile behaviour with
PbPh2Cl2, depending on the pH it acts as a monodeprotonated or
dideprotonated ligand, it also acts as a bridge through a sulfur
atom [22].
Following our systematic study on the coordination chemistry
of thiosemicarbazone ligands with toxic metals [22], here we re-
port the synthesis and structural characterization of two new cad-
mium coordination compounds derived from benzil bis(4-methyl-
3-thiosemicarbazone). Complex 1 is obtained in methanol and it
contains two different types of Cd(II) ions. The Cd(1) atom is se-
ven-coordinate by two nitrogen and two sulfur atoms from the li-
gand and three oxygen from a bidentate nitrato ligand and one
water molecule, but in the Cd(2) coordination sphere the water
molecule is replaced by an additional bidentate nitrato group. Both
units are linked to a nitrate ion and a water molecule by hydrogen
bonds. Complex 2 is synthesised in the presence of lithium hydrox-
ide, so the ligand is doubly deprotonated and the cadmium(II)
atom could be penta-coordinate in a binuclear structure. To the
best of our knowledge, here we report the first thiosemicarbazone
The coordination number of six for Cd(II) ions is well docu-
mented [11–13], but seven-coordinate complexes are scarce [14–
17], and they are rarely found together in one compound [18].
An eight-coordinate structure is usually formed with species hav-
ing larger ion radius, such as lanthanides and third row transition
metals, and it is relatively unusual for the Cd(II) ion [19]. As far as
* Corresponding author.
E-mail address: elena.lopez@uam.es (E. López-Torres).
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.04.036

2278
D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
MeHN
NHMe
N
Ph
N
Ph
N
Ph
N
S
N
S
N
Ph
HN
NH
Cd
Cd
MeOH, LiOH.H2O
S
S
S
+ Cd(NO3)2.4H2O
Ph
N
N
S
NHMe
MeHN
N
N
Ph
MeHN
NHMe
LMe2H4
Complex 2
MeOH
O
N
Ph
Ph
Ph
Ph
O
O
OH2
Cd
N
S
N
S
NH
HN
N
S
N
S
NO3.H2O
NH
HN
Cd
N
MeHN
NHMe
MeHN
O
O
NHMe
O
N
O
O
O
Complex 1
Scheme 1. A drawing showing the working conditions and the complexes obtained.
complex with eight-coordinate Cd(II). Moreover, it also is the first
compound in which two cadmium ions are present with seven and
eight coordination spheres in two independent units.
13C CP/MAS NMR (300 MHz, 25 °C): d/ppm 177.2 (CS), 139.8 (CN),
130.6, 128.1, 124.7 (Ph), 32.1 (CH3). FTIR (KBr, cmÀ1): 3420,
3386, 3342, 3330, 3210, 3151 (s) [m(NH)], 1608 (w) [m(CN)], 1581
(s) [d(NH2)] and 848 (w) [m(CS)].
2. Experimental
2.3. Synthesis of
[Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 Á H2O (1)
2.1. Materials and methods
Cadmium nitrate tetrahydrate (0.12 g, 0.39 mmol) dissolved in
methanol (15 mL) was added to a LMe2H4 (0.15, 0.39 mmol) solu-
tion in methanol (15 mL). The mixture was stirred under reflux for
6 h. The solution was concentrated whereby a solid precipitated,
which was filtered off, washed with methanol and dried in vacuo.
M.p.: 187 °C. The compound was isolated as a yellow solid (0.16 g,
64%). Suitable crystals for X-ray analysis were obtained by slow
evaporation of the mother liquor. M.p.: 187 °C. Anal. Calc. for
4-Methyl-3-thiosemicarbazide, 1,2-diphenylethanedione and
cadmium nitrate tetrahydrate were used as received. Microanaly-
ses were carried out using a Perkin–Elmer 2400 II CHNS/O Elemen-
tal Analyser. IR spectra in the 4000–400 cmÀ1 range were recorded
as KBr pellets on a Jasco FT/IR-410 spectrophotometer. Fast atom
bombardment mass spectra were recorded on a VG Auto Spec
instrument using Cs as the fast atom and m-nitrobenzylalcohol
(mNBA) as the matrix. 13C NMR spectra were recorded on a Bruker
AMX-300 spectrometer using methanol-d4 and DMSO-d6 as sol-
vents and TMS as an internal reference. 113Cd NMR spectra were
recorded in the same spectrometer using methanol-d4 or DMSO-
d6 as solvents and using absolutes as references, the chemical shifts
are reported relative to Cd(ClO4)2 0.1 M. 13C CP/MAS NMR spectra
were recorded at 298 K in a Bruker AV400WB spectrometer
equipped with a 4 mm MAS-NMR probe (magic-angle spinning)
and obtained using a cross-polarization pulse sequence. For the re-
corded spectra a contact time of 4 ms was used and recycle delays
of 4 s were used. Chemical shifts are reported relative to TMS,
using the CH group of adamantano as a secondary reference
(29.5 ppm). 113Cd CP/MAS NMR spectra were also recorded in the
same spectrometer and the chemical shifts are reported relative
to Cd(ClO4)2 0.1 M, using Cd(NO3)2 Á 4H2O as secondary reference
(À100 ppm).
C36H42N16O14S4Cd2 (1275.9): C, 33.88; H, 3.32; N, 17.57; S, 10.03.
Found: C, 33.75; H, 3.44; N, 17.16; S, 10.19%. 13C NMR (300 MHz,
methanol-d4): d/ppm 181.0 (CS), 148.8 (CN), 131.9, 130.9, 130.7,
130.3, 130.1, 129.8, 129.5, 129.2, 128.1, 128.0 (Ph), 32.1 (CH3).
113Cd NMR (300 MHz, methanol-d4): d/ppm 167.3 13C CP/MAS
NMR (300 MHz): d/ppm 180.2 (CS), 148.1, 147.0 (CN), 134.1,
131.9, 130.8, 129.0, 128.1, 127.1 125.8 (Ph), 35.3, 31.4 (CH3).
113Cd CP/MAS NMR (300 MHz): d/ppm 186.3, 144.3. MS (FAB+):
m/z 496.8 ([Cd(LMe2H3)]+, 100%). FTIR (KBr, cmÀ1) 3446, 3344,
3222 (m) [
m
(NH)], 1617 (w) [
(CS)].
m(CN)], 1574 (s) [d(NCS)], 1384 (s)
[m
(NO)], 819 (w) [m
2.4. Synthesis of [Cd(LMe2H4)]2 (2)
The reaction was carried out as described previously, but in the
presence of LiOH Á H2O (0.04 g, 0.79 mmol). Complex 2 was isolated
as an orange solid (0.17 g, 88%), washed with methanol and dried
in vacuo. M.p.: 247 °C. Anal. Calc. for C36H36N12S4Cd2 (988.8): C,
43.68; H, 3.67; N, 16.98; S, 12.96. Found: C, 43.52; H, 3.65; N,
16.84; S, 12.87%. 113Cd NMR (300 MHz, DCM + CDCl3): d/ppm
410.4. 13C CP/MAS NMR (300 MHz): d/ppm 178.7, 162.5, 158.7
2.2. Synthesis of benzil bis(4-methyl-3-thiosemicarbazone), LMe2H4
This molecule was synthesised as reported earlier [23]. Selected
spectroscopic data: 13C NMR (DMSO-d6, 300 MHz, 25 °C): d/ppm
178.6 (CS), 140.4 (CN), 133.2, 130.3, 129.1, 126.8 (Ph), 31.5 (CH3).

D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
2279
Table 1
water molecule. However, the reaction in the presence of lithium
hydroxide yields complex (2), which analytical data are in agree-
ment with a 1:1 ratio and the absence of nitrate groups. The FAB
mass spectrum (Fig. 1b) shows a peak at 494.9 corresponding to
[Cd(LMe2H3)]+ and another one at 990.8, relatively intense, corre-
sponding to [Cd2(LMe2H2)2+1]+, suggesting a binuclear structure
for this complex.
Crystal data and structure refinement for [Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(-
H2O)]NO3 Á H2O (1)
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
C36H42Cd2N16O14S4
1275.90
100(2)
1.54178
triclinic
ꢀ
P1
3.2. Spectroscopic studies
9.396(4)
b (Å)
c (Å)
12.069(5)
23.862(11)
The shifts observed in the m(CN) and m(CS) bands in the IR spec-
tra of both complexes are in accordance with the ligand being
bonded to the cadmium through the imine nitrogen and the sulfur
atoms, acting as a tetradentate chelate in both complexes. More-
a
b (°)
(°)
83.65(3)
86.63(3)
68.10(2)
2495.0(19)
c
(°)
Volume (Å3)
over, the IR spectrum of 1 shows a sharp and strong band at
Z
2
1385 cmÀ1 corresponding to
m
(N–O) of the NO3 group. Several
À
Dcalc (Mg/m3)
1.698
9.072
1284
Absorption coefficient (mmÀ1
F(000)
)
bands in the m(N–H) and d(N–H) regions are observed, which
agrees with the ligand being in the neutral form. By contrast, the
spectrum of 2 only shows two bands in the amine tension region
and the absence of any band assignable to the nitrate group.
Complex 2 is sparingly soluble in all common solvents and its 1H
and 13C NMR spectra are useless, indicating the decomposition.
Therefore 13C and 113Cd CP/MAS of both complexes were measured
for comparison. The 13C CP/MAS NMR spectrum of 1 shows one sig-
nal corresponding to the thioamide carbon atom, two to the imine,
three to the methine carbon and seven corresponding to the aro-
matic carbon atoms. By contrast, the spectrum of complex 2 shows
three signals corresponding to the thioamide group, one to the
imine and the methine carbons and six to the aromatic carbon
atoms. These differences can be explained due to the presence of li-
gands with a different behaviour in each complexes: in complex 1
the two ligands act in the same way, but there are a slight differ-
ences in the bonds lengths and angles; in complex 2 at least one sul-
fur atom is bonded to two cadmiums, acting as a bridge as observed
in the organolead(IV) derivative and in the binuclear cadmium
complex obtained from benzil bis(thiosemicarbazone) [22,26].
It is well known that the 113Cd chemical shift is very sensitive to
changes in the coordination number of cadmium as well as to the
nature of the bonding, so it is a useful tool to determine the envi-
ronment of this metal in a complex. Replacement of sulfur by
nitrogen and oxygen atoms tends to give greater shielding [27–
30] and a decrease in the coordination number tends to give great-
er deshielding [31,32]. 113Cd CP/MAS NMR spectrum of complex 1
shows two signals at 186.3 and 144.3 ppm, whereas complex 2
only shows a signal at 425.4 ppm. These data are consistent with
two cadmium atoms with different environments in complex 1
and only one kind of geometry around the metal ion in complex
2. The values of the chemical shifts agree with the presence of se-
ven and eight-coordinate cadmium atoms, with several oxygen
atoms in the coordination sphere of both Cd(II) centres in complex
1, while a lower coordination number and the absence of oxygen
atoms is suggested for complex 2 [11,13]. The 113Cd NMR spectrum
of 1 in methanol only exhibits one signal at 167.3 ppm, which is al-
most the average between the solid state signals, indicating partial
substitution of the nitrato ligands and/or the water molecule by
solvent molecules, giving the same coordination sphere. The
113Cd NMR spectrum of complex 2 in DCM shows the signal has
been slightly displaced to 410 ppm, which indicates that the coor-
dination sphere remains in this solvent and it is in the range ex-
pected for S3N2 coordination.
Crystal size (mm)
h Range for data collection (°)
Index ranges
0.14 Â 0.12 Â 0.06
1.86–66.67
À11 6 h 6 11, À14 6 k 6 14,
À28 6 l 6 28
Reflections collected
Independent reflections [Rint
Completeness to theta = 66.67° (%)
Absorption correction
Refinement method
19983
]
8342 [0.0427]
94.4
semi-empirical from equivalents
full-matrix least-squares on F2
8342/0/661
Data/restraints/parameters
Goodness-of-fit on F2
1.028
Final R indices I > 2
R indices (all data)
r(I)
R1 = 0.0371, wR2 = 0.0960
R1 = 0.0447, wR2 = 0.1020
0.862 and À0.760
Largest difference in peak and hole
(e ÅÀ3
)
(CS), 146.0 (CN), 137.5, 135.5, 132.8, 130.4, 128.9, 127.0 (Ph), 29.9
(CH3). 113Cd CP/MAS NMR (300 MHz): d/ppm 425.4. MS (FAB+): m/z
990.8 ([M+1]+, 31%), 496.9 ([CdLMe2H3]+, 100%). FTIR (KBr, cmÀ1
)
3415, 3370 (s) [
836 (w) [ (CS)].
m(NH)], 1618, 1600 (w) [m(CN)], 1561 (s) [d(NCS)],
m
2.5. X-ray crystallography
Data for 1 (see Table 1) were collected at 100 K with a Bruker
SMART 6K CCD area-detector three-circle diffractometer with a
MAC Science Co., Ltd. Rotating Anode (Cu
k = 1.54178 Å) generator. The unit cell parameters were obtained
by full-matrix least-squares refinements of 8342 independent
reflections. The structures were solved by direct methods (SHELXS
97), completed with difference Fourier syntheses, and refined with
Ka radiation,
-
full-matrix least squares using SHELXL-97 minimizing
x
(F2o À F2c)2.
Weighted R factors (Rw) and all goodness-of-fit S are based on F2; con-
ventional R factors (R) are based on F, giving R1 = 0.0371, wR2 = 0.0960
using 19983 reflections with I > 2r(I) [24,25]. All non-hydrogen
atoms were refined with anisotropic displacement parameters. All
scattering factors and anomalous dispersions factors are contained
in the SHELXTL 6.10 program library. All the hydrogen atoms were in-
cluded in geometric positions except those of the water molecule,
which were located by difference maps and refined isotropically.
3. Results and discussion
3.1. Synthesis
The reaction between LMe2H4 and cadmium nitrate depends on
the presence of a basic medium (Scheme 1). The reaction carried
out in methanol gives a crystalline solid (1), which analytical data
agree with a 1:1 cadmium:ligand ratio, confirmed by its FAB mass
spectrum (Fig. 1a), and the presence of two nitrate groups and one
3.3. Crystal structure of
[Cd(LMe2H4)(NO3)2][Cd(LMe2H4)(NO3)(H2O)]NO3 Á H2O (1)
The X-ray structural analysis of complex 1 revealed the pres-
ence of two units, each containing one cadmium atom and one li-

2280
D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
Fig. 1. (a) FAB mass spectrum of complex 1 (theoretical and experimental isotope distribution in the inset); (b) FAB mass spectrum of complex 2 (theoretical and
experimental isotope distribution in the inset).
gand, with one nitrate group and a water molecule linking them
(Fig. 2). The two Cd(II) ions have different coordination environ-
ments with the ligand acting, as it could be expected for this com-
pound, as a N2S2 chelate and where the coordination spheres are
completed by oxygen atoms. The N2S2O3 coordination environ-
ment of the seven-coordinate Cd(1) (Fig. 3) is made up of the imine
nitrogen and the sulfur atoms of the two arms of LMe2H4, one oxy-
gen from a water molecule and two oxygens from a bidentate nit-
rato anion. The environment of the eight-coordinate Cd(2) is
similar (Fig. 4), the difference being that the water molecule has
been substituted by another nitrato ligand coordinated in a biden-
tate fashion.
The hepta-coordinate cadmium has a geometry based on a
capped distorted octahedron, with the water molecule and the nit-

D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
2281
Fig. 2. The crystal structure of 1 at 50% probability including the intermolecular hydrogen bonds.
Fig. 3. The molecular structure of the complex cation in 1 with ellipsoids at 50%.

2282
D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
Fig. 4. The molecular structure of the neutral unit in 1 with ellipsoids at 50%.
rato group located above and under the tetradentate ligand, which
is virtually planar (Fig. 3). The angle of 173.35° formed by the N
atom of the bidentate nitrato group, the Cd atom and the water
molecule is very close to that expected for a trans disposition.
The Cd(1)–OH2 bond length [2.320(3) Å] (see Table 2) is in the
range observed in other Cd(II) complexes that contain nitrato ions
and water molecules in their coordination sphere [20]. The Cd–O
distances from the bidentate nitrato group, at 2.484(3) and
2.647(3) Å, fall within the range observed for Cd(II) compounds
containing bidentate nitrato ligands and show a significant asym-
metry d = 0.16 Å, which is of the same order as those observed in
other cadmium complexes [14].
Cd(2) is eight-coordinate, with two nitrogen and two sulfur
atoms from the benzil bis(thiosemicarbazone) ligand and four oxy-
gen atoms from two bidentate nitrato ions (Fig. 4), which is not a
common coordination number for Cd(II). The arrangement of the
eight atoms around the Cd(II) centre corresponds to a distorted
dodecahedron, with the angle between the N2S2Cd and O4Cd
planes very close to 90°. The Cd–O distances show two asymmet-
rically bidentate nitrato ligands with short Cd–O distances of
2.425(3) and 2.393(3) Å, and longer ones of 2.598(3) and
2.698(3) Å [33,34].
The presence of two distances for Cd–N and Cd–S bonds in each
unit agrees with the distorted geometry. The Cd–N distances are
not identical in both units, but they are in the range expected for
a cadmium imine bond. The average bond lengths of Cd–S bonds
in the seven and eight-coordinate structures are 2.583 and
2.609 Å, respectively, the difference of which arises from the in-
crease in coordination number of the cadmium(II) ion in this com-
plex. Similar variations are observed for the Cd–N distances.
The pseudomacrocyclic coordination mode of the ligand affords
three five-member chelate rings. The bis(thiosemicarbazone) cores
can be considered planar with a maximum deviation from the
Table 2
Selected bond and lengths (Å) and angles (°) for complex 1
Cd(1)–O(1)
Cd(1)–N(2)
Cd(1)–N(3)
Cd(1)–O(2)
Cd(1)–S(2)
Cd(1)–S(1)
Cd(1)–O(3)
Cd(2)–O(8)
Cd(2)–O(5)
Cd(2)–N(9)
Cd(2)–N(10)
2.320(3)
2.429(3)
2.438(3)
2.484(3)
2.5753(14)
2.5912(14)
2.647(3)
2.393(3)
2.425(3)
2.439(3)
2.457(3)
Cd(2)–O(7)
Cd(2)–S(4)
Cd(2)–S(3)
Cd(2)–O(10)
S(1)–C(1)
S(2)–C(4)
C(1)–N(1)
C(2)–N(2)
C(3)–N(3)
C(4)–N(4)
2.598(3)
2.6070(15)
2.6110(14)
2.698(3)
1.690(4)
1.699(4)
1.367(5)
1.297(5)
1.295(5)
1.368(5)
O(1)–Cd(1)–N(2)
O(1)–Cd(1)–N(3)
N(2)–Cd(1)–N(3)
O(1)–Cd(1)–O(2)
N(2)–Cd(1)–O(2)
N(3)–Cd(1)–O(2)
O(1)–Cd(1)–S(2)
N(2)–Cd(1)–S(2)
N(3)–Cd(1)–S(2)
O(2)–Cd(1)–S(2)
O(1)–Cd(1)–S(1)
N(2)–Cd(1)–S(1)
N(3)–Cd(1)–S(1)
O(2)–Cd(1)–S(1)
S(2)–Cd(1)–S(1)
O(1)–Cd(1)–O(3)
N(2)–Cd(1)–O(3)
N(3)–Cd(1)–O(3)
O(2)–Cd(1)–O(3)
S(2)–Cd(1)–O(3)
S(1)–Cd(1)–O(3)
O(8)–Cd(2)–O(5)
O(8)–Cd(2)–N(9)
O(5)–Cd(2)–N(9)
S(3)–Cd(2)–(10)
84.65(10)
88.09(10)
65.50(10)
157.43(10)
74.24(10)
76.07(10)
92.81(8)
138.92(8)
73.45(8)
97.83(8)
88.53(8)
73.75(8)
139.25(8)
93.06(8)
147.29(3)
151.97(9)
115.23(10)
117.52(10)
49.62(9)
O(8)–Cd(2)–N(10)
O(5)–Cd(2)–N(10)
N(9)–Cd(2)–N(10)
O(8)–Cd(2)–O(7)
O(5)–Cd(2)–O(7)
N(9)–Cd(2)–O(7)
N(10)–Cd(2)–O(7)
O(8)–Cd(2)–S(4)
O(5)–Cd(2)–S(4)
N(9)–Cd(2)–S(4)
N(10)–Cd(2)–S(4)
O(7)–Cd(2)–S(4)
O(8)–Cd(2)–S(3)
O(5)–Cd(2)–S(3)
N(9)–Cd(2)–S(3)
N(10)–Cd(2)–S(3)
O(7)–Cd(2)–S(3)
S(4)–Cd(2)–S(3)
O(8)–Cd(2)–O(10)
O(5)–Cd(2)–O(10)
N(9)–Cd(2)–O(10)
N(10)–Cd(2)–O(10)
O(7)–Cd(2)–O(10)
S(4)–Cd(2)–O(10)
79.49(9)
93.36(9)
65.13(10)
138.40(8)
50.78(8)
134.52(9)
132.63(9)
96.55(8)
86.78(7)
138.07(7)
72.99(7)
74.94(7)
91.53(7)
90.04(7)
73.39(8)
138.50(7)
78.85(7)
148.50(3)
49.98(8)
139.23(8)
121.93(9)
118.26(9)
88.50(8)
79.53(7)
84.60(8)
79.23(8)
170.79(8)
78.20(10)
93.58(9)
82.66(7)

D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
2283
Table 3
Intermolecular hydrogen bonds (Å, °) in complex 1
D–HÁ Á ÁA
d(D–H)
d(HÁ Á ÁA)
d(DÁ Á ÁA)
<(DHA)
O(14)–H(14B)Á Á ÁO(5)
O(14)–H(14A)Á Á ÁO(12)
N(13)–H(13)Á Á ÁN(16)#1
N(13)–H(13)Á Á ÁO(12)#1
N(12)–H(12A)Á Á ÁO(9)#2
N(11)–H(11A)Á Á ÁO(11)#1
N(8)–H(8A)Á Á ÁO(9)#2
N(6)–H(6)Á Á ÁO(13)
0.73(6)
0.82(6)
0.88
0.88
0.88
0.88
0.88
0.88
0.88
2.35(5)
2.14(6)
2.58
1.97
2.23
2.14
2.24
2.20
2.21
2.929(4)
2.961(5)
3.427(4)
2.833(4)
2.995(4)
2.926(4)
3.028(4)
2.882(4)
2.989(5)
2.877(4)
2.976(4)
136(5)
173(6)
161.2
167.3
145.7
147.9
148.4
133.5
147.5
148.4
144.6
N(5)–H(5)Á Á ÁO(4)#3
N(4)–H(4)Á Á ÁO(14)
0.88
0.88
2.09
2.21
N(1)–H(1)Á Á ÁO(4)#3
Symmetry transformations used to generate equivalent atoms: #1 x + 1, y, z; #2 Àx + 1, Ày + 1, Àz + 1; #3 Àx + 2, Ày + 2, Àz.
main plane of 0.0760 Å for C(3) in the seven-coordinate unit and a
0.0616 Å deviation for the N(9) atom in the eight-coordinate one.
In accordance with the symmetry of the ligand, the bond distances
and angles in both thiosemicarbazone moieties in both units are
very similar. The bond lengths agree well with an imine–thione
form of the ligand, but with considerable electronic delocalisation
through the thiosemicarbazone backbone. Thus, the thione bond
distances of ca. 1.69 Å are intermediate between a theoretical C–
S single and double bond (1.82 and 1.56 Å, respectively) as occurs
with the N–N– bonds (ca. 1.35 vs. 1.44 Å calculated for a single N–
N) and the three C–N bonds of each 4-methyl-3-thiosemicarbazone
branch.
Appendix A. Supplementary data
CCDC 670708 contains the supplementary crystallographic data
for 1. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.poly.2008.04.036.
References
[1] J.E. Fegusson, The Heavy Elements: Chemistry Environmental Impact and
Health Effects, Pergamon Press, Oxford, 1990.
[2] G. Parkin, Chem. Rev. 104 (2004) 699.
[3] Y.Q. Huang, B. Ding, H.B. Song, B. Zhao, P. Ren, P. Cheng, H.G. Wang, D.Z. Liao,
S.P. Yan, Chem. Commun. (2006) 4906.
[4] L. Yi, B. Ding, B. Zhao, P. Cheng, D.Z. Liao, S.P. Yan, Z.H. Jiang, Inorg. Chem. 43
(2004) 33.
The two units are connected through hydrogen bonds involving
the amino groups, the non-coordinated nitrate ion and the crystal-
lization water molecule (Fig. 2). Finally, the molecules are held to-
gether in the crystal packing through an extended network of
intermolecular hydrogen bonds involving the same groups (see Ta-
ble 3).
[5] L. Yi, B. Ding, B. Zhao, P. Cheng, D.Z. Liao, S.P. Yan, Z.H. Jiang, H.B. Song, H.G.
Wang, J. Chem. Soc., Dalton Trans. (2006) 665.
[6] M. Kadarkaraisamy, A.G. Sykes, Polyhedron 26 (2007) 1323.
[7] D. Sriram, P. Yogeeswari, R. Thirumurugan, R.K. Pavana, J. Med. Chem. 49
(2006) 3448.
4. Conclusions
[8] H. Beraldo, D. Cambino, Mini-Rev. Med. Chem. 4 (2004) 31.
[9] N.C. Kasuga, K. Onodera, S. Nakano, K. Hayashi, K. Nomiya, J. Inorg. Biochem.
100 (2006) 1176.
[10] F. Zani, D.G. Calatayud, E. López-Torres, M.A. Mendiola, J.R. Procopio, EUROBIC
8 Conference Book, Aveiro, Portugal, 2006, p. 153, ISBN: 989-20-0305-5.
[11] E. Bermejo, A. Castiñeiras, L.M. Fostiak, I. García Santos, J.K. Swearingen, D.X.
West, Polyhedron 23 (2004) 2303.
[12] E. López-Torres, M.A. Mendiola, J. Rodríguez-Procopio, M.T. Sevilla, E. Colacio,
J.M. Moreno, I. Sobrados, Inorg. Chim. Acta 323 (2001) 130.
[13] M.R. Bermejo, A.M. González-Noya, M. Martínez-Calvo, R. Pedrido, M. Maneiro,
M.I. Fernández, E. Gómez-Fórneas, Z. Anorg, Allg. Chem. 633 (2007) 1911.
[14] A. Tamayo, E. Oliveira, B. Covelo, J. Casabó, L. Escrische, C. Lodeiro, Z. Anorg,
Allg. Chem. 633 (2007) 1809.
[15] J. Granifo, M.T. Garland, R. Baggio, Inorg. Chem. Commun. 7 (2004) 77.
[16] M.A. Ali, A.H. Mirza, W.B. Ejau, P.V. Bernhardt, Polyhedron 25 (2006) 3337.
[17] J. Chakraborty, B. Samanta, G. Pilet, S. Mitra, Inorg. Chem. Commun. 10 (2007)
40.
The importance of the working conditions in the structure of
coordination complexes from a bis(thiosemicarbazone) is reflected
in the complexes obtained by the reaction of cadmium nitrate and
benzil bis(4-methyl-3-thiosemicarbazone). Complex 1 is obtained
in methanol and it contains two different types of Cd(II) ions.
The Cd(1) atom is seven-coordinate by two nitrogen and two sulfur
atoms from the ligand and three oxygens from a bidentate nitrato
ligand and one water molecule, but the Cd(2) coordination sphere
expands to eight by the exchange of the water molecule by an
additional bidentate nitrato group. Both units are linked to a ni-
trate ion and a water molecule by hydrogen bonds. Complex 2 is
synthesised in the presence of lithium hydroxide, so the ligand is
doubly deprotonated and the cadmium(II) atom could be penta-
coordinate in a binuclear structure. To the best of our knowledge,
complex 1 is the first thiosemicarbazone complex containing
eight-coordinate Cd(II). Moreover, it also is the first example in
which two cadmium ions show seven and eight coordination in
two independent units within the same crystal.
[18] H-S. Wang, W. Shi, J. Xia, H.-B. Song, H.-G. Wang, P. Cheng, Inorg. Chem.
Commun. 10 (2007) 856.
[19] D.B. Cordes, L.R. Hanton, Inorg. Chem. Commun. 8 (2005) 967.
[20] G. Anantharaman, M.G. Walawalkar, R. Murugaved, B. Gäbor, R. Herbst-Irmer,
M. Baldus, B. Angerstein, H.W. Roesky, Angew. Chem., Int. Ed. 42 (2003) 4482.
[21] J.S. Casas, A.E. Castellano, M.S. García-Tasende, A. Sánchez, J. Sordo, J.
Zukerman-Schpector, Z. Anorg. Allg. Chem. 523 (1997) 825.
[22] D.G. Calatayud, E. López-Torres, M.A. Mendiola, Inorg. Chem. 46 (2007) 10434.
and refs therein.
[23] D.G. Calatayud, F.J. Escolar, E. López-Torres, M.A. Mendiola, Helv. Chim. Acta 90
(2007) 2201.
Acknowledgements
[24] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[25] G.M. Sheldrick, SHELXL-97, Program for Crystal Structure Refinement,
Universität Göttingen, Göttingen, Germany, 1997.
[26] E. López-Torres, M.A. Mendiola, C.J. Pastor, B. Souto Pérez, Inorg. Chem. 43
(2004) 5222.
We thank César J. Pastor and Manuela E. Medina of ‘‘Servicio
Interdepartamental de Investigación de la Universidad Autónoma
de Madrid”(SIDI) (Spain). We also thank DGICYT for financial sup-
port (Project CT2005-07788/BQU) and Universidad Autónoma de
Madrid for a grant to David G. Calatayud.
[27] P.S. Marchetti, S. Bank, T.W. Bell, M.A. Kennedy, P.D. Ellis, J. Am. Chem. Soc. 111
(1989) 2063.

2284
D.G. Calatayud et al. / Polyhedron 27 (2008) 2277–2284
[28] M.F. Summers, Coord. Chem. Rev. 86 (1988) 43.
[32] M.L. Helm, L.L. Hill, J.P. Lee, D.G. Van Derveer, G.J. Grant, J. Chem. Soc., Dalton
Trans. (2006) 3534.
[33] S.A. Barnett, A.J. Blake, N.R. Champness, C. Wilson, J. Chem. Soc., Dalton Trans.
(2005) 3852.
[29] R. Pedrido, M.R. Bermejo, M.J. Romero, M. Vázquez, A.M. González-Moya, M.
Maneiro, M.J. Rodríguez, M.I. Fernández, J. Chem. Soc., Dalton Trans. (2005)
572.
[30] R. Pedrido, M.J. Romero, M.R. Bermejo, A.M. González-Moya, I. García-Lema, G.
Zaragoza, Chem. Eur. J. 14 (2008) 500.
[34] E.R. Acuña-Cueva, R. Faure, N.A. Illán-Cabeza, S.B. Jiménez-Pulido, M.N.
Moreno-Carretero, M. Quirós-Olozábal, Inorg. Chim. Acta 342 (2003) 209.
[31] D.L. Reger, S.M. Meyers, S.S. Mason, A.L. Rheingold, B.S. Haggerty, P.D. Ellis,
Inorg. Chem. 34 (1995) 4996.