Synthesis, spectroscopic study and crystal structure determination by x-ray powder diffractometry of CdCl2(TzTn)J [TzTn=2-(3,4-dichlorophenyl) imino-N(2-thiazolin-2-yl)tetrahydro-l,3-thiazine]

Article abstract of DOI:10.1002/zaac.200700159

The cadmium(II) complex, dichloro[2-(3,4-dichlorophenyl)imino-κN-N- (2-thiazolin-κN-2-yl)tetrahydro-1,3-thiazin]cadmium(II), was synthesized in the form of fine powder with small crystals unsuitable for structure determination by X-ray single-crystal diffractometry, and was therefore characterized by X-ray powder diffractometry. To that end, the molecular structure was first analyzed using various instrumental techniques including elemental analysis, FAB-mass spectroscopy, and infrared spectroscopy, and then optimized via molecular modeling with a semi-empirical quantumchemistry model. From the optimized molecule, the crystal structure wasresolved within the methodological framework of the direct-space methods using a 'Monte-Carlo/parallel tempering' search algorithm, and then refined using the Rietveld method. It was found that the title compound crystallizes in the triclinic system, with the space group Pl, two C₁₃H ₁₃Cl₄CdN₃S₂ molecules in the asymmetric unit, and the following unit cell dimensions: a = 13.558(4) A, b = 13.579(7) A, c = 10.117(4) A, a = 91.07(3)°, β= 95.44(3)°, and γ = 93.03(3)°. It was also found that the environment around the cadmium(II) ion may be described as distorted tetrahedral, with the metallic atom coordinated to two chlorine atoms [Cd(A)-Cl(IA) = 2.44(3) A Cd(A)-Cl(2A) = 2.44(3) A; Cd(B)-Cl(IB) = 2.45(3) A; Cd(B)-Cl(2B) = 2.45(3) A], one imino nitrogen atom [Cd(A)-N(3A) = 2.37(1O)A; Cd(B)-N(3B) = 2.37(9) A], and one thiazoline nitrogen atom [Cd(A)-N(IA) = 2.33(8) A; Cd(B)-N(IB) = 2.33(1O)A].

Full text of DOI:10.1002/zaac.200700159

DOI: 10.1002/zaac.200700159
Synthesis, Spectroscopic Study and Crystal Structure Determination by X-ray
Powder Diffractometry of [CdCl2(TzTn)] [TzTn؍2-(3,4-dichlorophenyl)imino-N-
(2-thiazolin-2-yl)tetrahydro-1,3-thiazine]
a
b
a,
c
a
´
A. M. Lozano-Vila , F. L. Cumbrera , F. Luna-Giles *, A. L. Ortiz , and A. Bernalte-Garcıa
a
Badajoz/Spain, Universidad de Extremadura, Departamento de Quımica Organica e Inorganica, Facultad de Ciencias, b Departamento
´
´
´
c
´
´
´
´
´
de Fısica, Facultad de Ciencias and Departamento de Ingenierıa Mecanica, Energetica y de los Materiales, Escuela de Ingenierıas
Industriales
Received April 2nd, 2007.
th
˜
Dedicated to Professor Alfonso Castineiras Campos on the Occasion of his 65 Birthday
¯
Abstract. The cadmium(II) complex, dichloro[2-(3,4-dichlorophenyl)-
imino-κN-N-(2-thiazolin-κN-2-yl)tetrahydro-1,3-thiazin]cadmium(II),
was synthesized in the form of fine powder with small crystals un-
suitable for structure determination by X-ray single-crystal dif-
fractometry, and was therefore characterized by X-ray powder dif-
fractometry. To that end, the molecular structure was first analyzed
using various instrumental techniques including elemental analysis,
FAB-mass spectroscopy, and infrared spectroscopy, and then opti-
mized via molecular modeling with a semi-empirical quantum-
chemistry model. From the optimized molecule, the crystal struc-
ture wasresolved within the methodological framework of the di-
rect-space methods using a ‘Monte-Carlo/parallel tempering’ se-
arch algorithm, and then refined using the Rietveld method. It was
found that the title compound crystallizes in the triclinic system,
with the space group P1, two C13H13Cl4CdN3S2 molecules in the
asymmetric unit, and the following unit cell dimensions: a ϭ
˚
˚
˚
13.558(4) A, b ϭ 13.579(7) A, c ϭ 10.117(4) A, α ϭ 91.07(3)°, β ϭ
95.44(3)°, and γ ϭ 93.03(3)°. It was also found that the environ-
ment around the cadmium(II) ion may be described as distorted
tetrahedral, with the metallic atom coordinated to two chlorine
atoms [Cd(A)-Cl(1A) ϭ 2.44(3) A; Cd(A)-Cl(2A) ϭ 2.44(3) A;
Cd(B)-Cl(1B) ϭ 2.45(3) A; Cd(B)-Cl(2B) ϭ 2.45(3) A], one imino
nitrogen atom [Cd(A)-N(3A)
2.37(9) A], and one thiazoline nitrogen atom [Cd(A)-N(1A) ϭ
2.33(8) A; Cd(B)-N(1B) ϭ 2.33(10) A].
˚
˚
˚
˚
˚
ϭ
2.37(10) A; Cd(B)-N(3B)
ϭ
˚
˚
˚
Keywords:: Crystal structures; X-ray powder diffractometry; Cad-
mium; Thiazine; Thiazoline
1 Introduction
ation, it is potentially lethal [3]. This explains why most of
the work on Cd has centred so far on investigating health
problems deriving from its toxicity, including Itai Itai dis-
ease, renal tubular dysfunction, hypertensive disorders, and
respiratory problems. It has been demonstrated recently
that Cd causes extreme hyper-mutability via the suppression
of post-replication mismatch repair [4, 5], and that it can
be a potent non-steroidal endocrine disrupter by mimicking
the effects of oestradiol [6].
Because Cd is a noxious non-essential metal, detox-
ification has to be tightly controlled. The general agreement
that the most effective clinical treatment for heavy-metal
poisoning is chelation therapy [7] has motivated the search
for and development of chelating agents to treat Cd intoxi-
cation. It is not surprising therefore that a large number of
therapeutic ligands have been synthesized and investigated
for the elimination of Cd accumulation [8, 9].
Cadmium is a naturally occurring heavy metal typically
bound to oxygen (CdO), chlorine (CdCl2) or sulfur (CdS)
in the solids of the earth’s crust. Since the industrial revol-
ution it has become extensively used in various industrial
sectors, such as the battery, pigment, metal coating, and
plastic industries, to name a few [1]. One direct consequence
of this industrial exploitation is the anthropic release of an
important amount of Cd into the environment. Thus, food
is in general the principal source of exposure to Cd in non-
smokers, although in smokers the cigarette smoke surpasses
food in importance as the principal source of contami-
nation by Cd [2].
Cadmium is teratogenic, mutagenic, and carcinogenic [1].
Owing to its bio-availability, persistence, and bioaccumul-
One group of substances that may hold promise for clini-
cal use as Cd scavengers is that of compounds with thiazine
and/or thiazoline rings. This type of compound has been
the subject of considerable attention in medicine and phar-
macology in recent years due to their attractive biological
and pharmaceutical activities [10Ϫ15]. In particular, it has
been recognized that some of these substances may inhibit
* Prof. F. Luna-Giles
´
´
´
Departamento de Quımica Organica e Inorganica
Universidad de Extremadura
E-06071 Badajoz/Spain
Fax: ϩ34 924289397
E-mail address: pacoluna@unex.es
Z. Anorg. Allg. Chem. 2007, 633, 1801Ϫ1808
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1801

´
A. M. Lozano-Vila, F. L. Cumbrera, F. Luna-Giles, A. L. Ortiz, A. Bernalte-Garcıa
cell division [16], which endows them with anti-HIV [17]
optimization technique with the objective of reaching the
best possible agreement between the theoretical XRD pat-
tern calculated for the simulated crystal structure and the
experimentally measured XRD pattern. Finally, the best
model of the crystal structure is refined using the Rietveld
method.
This is the methodological framework of the present
study, in which we determined the crystal structure of the
title CdII coordination compound by X-ray powder dif-
fractometry aided by various spectroscopic techniques and
molecular modeling.
and anti-cancer activities [18, 19]. Apart from these two ac-
tivities, many of these compounds also exhibit antibiotic,
analgesic, antihistaminic, antiviral, anti-inflammatory,
sedative, and anti-tumoral activities [20Ϫ23]. With respect
to Cd scavenging, the interest in these compounds lies in
the fact that they can potentially act as organic ligands to
form coordination complexes with this element, and in
consequence they have great value as detoxification agents.
Motivated by the great interest in the development of Cd
scavengers for clinical use, we have recently synthesized and
characterized structurally new coordination compounds
with CdII [24Ϫ27]. However, only the crystal structure of
those compounds that crystallized as single crystals of ap-
propriate size and quality for conventional X-ray single-
crystal diffractometry studies were reported because of the
difficulty in resolving organic structures of a certain com-
plexity by X-ray powder diffractometry. Given that the
knowledge of the crystal structure is of vital importance to
understand in detail how Cd links to the organic ligands,
studies in this area are still necessary in the CdII complexes
that crystallize in the form of fine powders.
In comparison with X-ray single-crystal diffractometry,
X-ray powder diffractometry is markedly more difficult and
very far from being routine. This is because the reflections
from different crystal planes are projected onto a single
variable, the diffraction angle, and therefore they overlap.
When the peak overlap is only moderate, the direct methods
borrowed from X-ray single-crystal diffractometry can still
be applied to X-ray powder diffraction patterns to resolve
crystal structures. However, when peak overlap is very sig-
nificant, a simple application of these direct methods is in-
effective. This situation usually occurs for crystal structures
with a low-symmetry space group and large molecules in
the unit cell, as is typically the case of coordination com-
pounds such as that investigated in the present study. The
methodological strategy that has proven most useful in re-
solving the crystal structure of such coordination com-
pounds consists of combining spectroscopic techniques and
molecular modeling procedures with the direct-space meth-
ods and Rietveld method of X-ray diffractometry [28, 29].
Thus, at a first step, a molecular model is elaborated from
the information deduced from the different spectroscopic
techniques, and the molecular geometry is then optimized
by molecular modeling without reference to the XRD data
by searching for the absolute minimum in the potential en-
ergy surface. At a second step, the optimized molecules con-
stituting the asymmetric unit are placed arbitrarily (but
compatible with the chemical constraints) within the unit
cell. The remaining molecules in the unit cell are generated
by the symmetry operations of the space group. Both the
unit cell dimensions and the appropriate space groups are
determined by analyzing the experimentally-collected XRD
data, whereas the number of molecules in the unit cell is
deduced by simple considerations of the volumes of the
molecules and the unit cell. The positions of the asymmet-
ric-unit molecules are then modified repeatedly by a global
2 Experimental Section
2.1 Preparation and characterization of 2-(3,4-
dichlorophenyl)imino-N-(2-thiazolin-2-
yl)tetrahydrothiazine (TzTn)
A volume of 3 mL (21.0 mmoles) of 3,4-dichlorophenyl isothiocy-
anate was treated with 1.5 mL (19.6 mmoles) of 3-amine-1-propa-
nol in 15 mL of dichloromethane. The resulting thiourea was heat-
treated to reflux in 100 mL of 3N hydrochloric acid for 3 hours,
then cooled and the solution made basic with a solution of 12.5 g
of sodium hydroxide in 50 mL of water. Extraction with dichloro-
methane, then drying over anhydrous magnesium sulfate and con-
centration resulted in 5.3 g of 2-(3,4-dichlorobenzylamino)-4H-5,6-
dihydro-1,3-thiazine. Subsequently, a solution was prepared with
2.12 g (8.1 mmoles) of this compound, 1 mL (10.2 mmoles) of
2-chloroethylisothiocyanate [30], and 30 mL of chloroform, which
was stirred and heated to reflux. After 4 hours, a white powder had
precipitated, and the reaction mixture was allowed to cool to room
temperature. A solution of 1.62 g (15.3 mmoles) of sodium carbon-
ate in 20 mL of water was added, and the mixture was stirred again
to completely dissolve the solid phase. The phases were separated,
and the aqueous layer was extracted with dichloromethane. The
combined organic layers were dried over anhydrous magnesium sul-
fate and concentrated under reduced pressure to result in a solid
that was recrystallized from ethanol 96 % (1.9 g; 68 %).
The TzTn ligand was subjected to various characterizations as de-
scribed next. Chemical analyses of carbon, hydrogen, nitrogen, and
sulfur were performed by microanalytical methods using a Leco
CHNS-932 microanalyzer. Measured (in wt%): C, 45.17; H, 3.79;
N, 12.13; S, 18.77; calculated (in wt%) for C13H13Cl2N3S2: C, 45.09;
H, 3.78; N, 12.13; S, 18.52.
1H- and 13C-NMR spectra were both measured with a Bruker AM
400 instrument at 400 and 100 MHz, respectively, in CDCl3 using
Me4Si as internal standard.
Measured by 1H-NMR (deuterochloroform): δ 7.36 (d, J ϭ 8.47 Hz, 1H),
7.04 (d, J ϭ 2.37 Hz, 1H), 6.77 (dd, J ϭ 2.39, 8.70 Hz, 1H), 4.14 (t, J ϭ
6.09 Hz, 2H), 4.02 (t, J ϭ 7.98 Hz, 2H), 3.15 (t, J ϭ 7.98 Hz, 2H), 2.99
(t, J ϭ 6.40 Hz, 2H), 2.24 (m, J ϭ 6.42 Hz, 2H); measured by 13C-NMR
(deuterochloroform):
δ 160.41, 146.49, 146.49, 132.42, 130.44, 127.02,
123.20, 121.07, 57.62, 46.91, 34.29, 27.26, 23.89.
Finally, a UV-Vis spectrum in the 350-200 nm range was collected
on a Shimadzu UV-3101TC spectrophotometer from a sample in
EtOH solution.Measured by UV-Vis (λmax, nm; ε, L molϪ1 cmϪ1):
202 (35855), 237 (17000), 298 (7855).
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[CdCl2(TzTn)]
molecular mass calculated from the elemental chemical
analysis. The peak at m/z 346 is due to the (TzTnϩ) ligand,
which is also the base peak of the spectrum. Similarly, the
peak at m/z 494 is assigned to the [CdCl(TzTn)]ϩ fragment.
One may hence deduce from these observations the integ-
rity of the ligand in the complex.
Scheme 1 Two-dimensional chemical drawing of the TzTn molecule.
3.2 IR spectra
The IR spectrum of the TzTn ligand in the 4000-370 cmϪ1
region shows the presence of bands due to the tetrahydro-
1,3-thiazine ring vibrations at 1024 (νθ1), 919 (νθ2), 819
(νθ3), 700 (νθ4), 667 (νθ5), 588 (δθ1), 488 (δθ2), and 393 (ε1)
cmϪ1 [31, 32]. Likewise, characteristic bands of the thiaz-
oline ring vibrations are detected at 1576 (W1), 998 (W2),
945 (W3), 768 (W4), 711 (W5), 633 (W6), 611 (W8), 560
(W7), and 438 (Γ1) cmϪ1 [33]. In addition, bands of
3,4-dichlorophenyl ring vibrations are registered at 1576
(8b), 1545 (8a), 1463 (19b), 1398 (19a), 1240 (14), 1123 (1),
690 (6a), 633 (12), and 541 (16a) cmϪ1 [34]. Other relevant
bands are observed at 1598 [ν(CϭN)imine], 1353 [ν(C-N)],
and 1051 [ν(C-Cl)orto] cmϪ1 [35, 36].
The IR spectrum of the [CdCl2(TzTn)] complex in the
4000-370 cmϪ1 region shows the presence of bands due to
organic moiety ring vibrations. Comparison of relevant
stretching vibration modes between the free TzTn ligand
and the [CdCl2(TzTn)] complex would thus shed light on
the ligand coordination. Indeed, this comparison showed
that the strong ν(CϭN)imine absorption band at 1598 cmϪ1
in the TzTn ligand is shifted towards the higher wave-
number of 1618 cmϪ1 in the [CdCl2(TzTn)] complex. In ad-
dition, the in-plane stretching vibrations due to ν(CϭN)
skeletal vibration of the heterocyclic ring (W1) in the
[CdCl2(TzTn)] complex appears at 1542 cmϪ1, in contrast
to the higher wavenumber of 1576 cmϪ1 for the uncoordi-
nated thiazolinic nitrogen band in the TzTn ligand. Based
on these two observations, it can be concluded that the co-
ordination of the [CdCl2(TzTn)] complexes has taken place
via the imino nitrogen atoms of the TzTn ligands [37Ϫ40].
In the low-frequency region, the C1 symmetry of the
[CdCl2(TzTn)] complex predicts the appearance of four
bands assignable to the metalϪligand stretching vibrations.
The IR spectrum of the complex shows the appearance of
four such bands at 312, 265, 243, and 199 cmϪ1. The band
at 312 cmϪ1 is attributed to the ν(Cd-Nimino) vibration
mode, which has been detected before in CdII complexes in
the range 365-302 cmϪ1 [24, 40]. The bands at 265 cmϪ1
and 243 cmϪ1 are assigned to the ν(Cd-Clterminal) vibration,
which have been observed previously in several CdII com-
plexes in the 324-200 cmϪ1 range [41Ϫ45]. Finally, the band
at 199 cmϪ1 is due to the ν(Cd-Nthiazoline) vibration, which
has appeared before in several CdII complexes in the 222-
202 cmϪ1 range [24, 46]. Taken together, IR, FAB-mass,
and elemental chemical analyses show that the
[CdCl2(TzTn)] complex has a tetra-coordinated geometry.
2.2 Preparation and characterization of
[CdCl2(TzTn)]
The [CdCl2(TzTn)] complex was isolated from a freshly prepared
96 % ethanol solution (2 ml) of CdCl2 ·21/2H2O (65.9 mg,
0.3 mmol) that was added to a 96 % ethanol solution (15 ml) of
TzTn (100 mg, 0.3 mmol). The resulting solution was allowed to
evaporate slowly at room temperature. After a few hours, a fine
powder was isolated from the solution (109 mg, 71 %). The powder
particles were first separated by filtration, then washed with cold
ether, and finally air-dried.
The [CdCl2(TzTn)] complex was characterized using the microana-
lytical method described above for the TzTn ligand. Measured (in
wt%): C, 29.75; H, 2.53; N, 7.98; S, 12.47; calculated (in wt%) for
C13H13Cl4CdN3S2: C, 29.48; H, 2.47; N, 7.93; S, 12.11 %. Addition-
ally, the [CdCl2(TzTn)] complex was also characterized using FAB-
mass and IR spectroscopies, as described next. The FAB-mass spec-
trum was collected on a Micromass AUTOSPEC spectrophoto-
meter using nitrobenzyl alcohol as matrix (mnba). IR spectra were
recorded on a Perkin-Elmer FT-IR 1720 spectrophotometer from
KBr pellets in the 4000-370 cmϪ1 range, and on a Perkin-Elmer
FT-IR 1700X spectrophotometer from polyethylene pellets in the
500-150 cmϪ1 range.
2.3 Crystal structure determination of
[CdCl2(TzTn)]
The [CdCl2(TzTn)] complex was analyzed using X-ray powder dif-
fractometry to determine its crystal structure. Before being installed
in the XRD holder, the particles resulting from the synthesis of the
[CdCl2(TzTn)] complex were ground to an ultra-fine powder to
avoid texture and granulation effects in the XRD pattern. The re-
sulting powder was then loaded into the XRD holder (3 mm thick)
and pressed slightly with a glass slide to ensure a flat surface and
thus the absence of instrumental shift in the position of the XRD
peaks. The operating conditions for the XRD data collection were
˚
CuKα radiation (λ ϭ 1.54183 A), 5-100° scanning interval, 0.02°
step size, and 20 seconds count time per step, using a D5000 Sie-
mens diffractometer equipped with a graphite secondary mono-
chromator.
3 Results and Discussion
3.1 FAB-mass spectrum
The FAB-mass spectrum of the [CdCl2(TzTn)] complex
shows a fragmentation pattern characteristic of a mono-
meric nature, with no peaks at m/z values greater than the
Z. Anorg. Allg. Chem. 2007, 1801Ϫ1808
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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3.3 Molecular modeling
3.4.2 Monte Carlo methods
A first approximation to the molecular structure in the crys-
talline state was made by determining the most stable con-
formation of the isolated molecule through molecular
modeling with a semi-empirical quantum-chemical model.
The principle behind this approximation is that the molecu-
lar structure of this kind of coordination compound hardly
changes at all with the crystallization process. The molecu-
lar modeling was done using the HyperChem software
package.HyperChem’s front-end launches back-end calcu-
lations including HyperNDO (*), which performs the semi-
empirical calculations. In this approach the main scheme is
based on the neglect of certain differential overlap terms
in the Schrödinger equation, which incorporates adjustable
parameters fitted to experimental results. The input to in-
itialize the molecular optimization process was the raw two-
dimensional model of the C13H13Cl4CdN3S2 molecule elab-
orated from the connectivity information deduced from the
various spectroscopic techniques. Different, independent
optimization sessions were performed using the semi-em-
pirical AM1, PM3, MNDO and MNDO/d quantum-
chemical models. The geometry of the molecule was optim-
ized by searching for the absolute minimum of the potential
energy surface. The algorithms used are designed to deter-
mine the next point to sample by using the previous trajec-
tory points. The best optimization was obtained with the
MNDO/d model (binding energy Eb ϭ Ϫ3508 kcal molϪ1),
with the considerable difference in Eb of 320.7 kcal molϪ1
with respect to the second-best optimized model.
The crystal structure of the [CdCl2(TzTn)] complex was re-
solved within the methodological framework of the direct-
space methods by Monte Carlo algorithms, using the “par-
allel tempering” formulation implemented in the FOX
software package [50]. The structure was described using
the Z-matrix formalism, which is extremely useful for or-
ganic molecules of relative complexity. In this formalism the
geometry of the molecules is described by the bond dis-
tances, the bond angles, and the dihedral angles between
the different atoms. From the optimized molecule structure,
the corresponding Fenske-Hall Z-matrix was constructed
using the BABEL program [51], with the heavy Cd atom as
pivot. The Monte Carlo/parallel tempering search algor-
¯
ithm was applied by first choosing the P1 space group and
taking the molecules to be rigid bodies during the first
500 000 movements, and then relaxing the rigid-body con-
straints imposed on the Z-matrix parameters during the
next 2 000 000 movements. Thus, the aim with the first step
was to refine only the six translational and rotational degree
of freedom, whereas with the second step it was to allow a
certain variation in the bond distances, and bond and di-
hedral angles. The molecular geometry is therefore mainly
(but not exclusively) a result of the molecular modeling,
and the Monte Carlo/parallel tempering search algorithm
is used basically to determine the optimal packing of the
molecules within the unit cell. The final weighted residual
was Rwp ϭ 0.24. To check for uniqueness, the entire pro-
cedure was repeated several times using different random
starting positions for the Cd pivot and molecule orien-
tations. All these attempts converged to the same final crys-
tallographic configuration and Rwp value. Finally, the Z-ma-
trix coordinates were converted to crystallographic coordi-
nates for the Rietveld refinement.
3.4 Crystal structure determination
The sequence followed to resolve the crystal structure of
the novel[CdCl2(TzTn)] complex synthesized in the present
study consisted of the following three stages.
¯
To check for correctness of the P1 space group, the entire
procedure described above was repeated taking the P1 space
group as input. The final Rwp value was markedly greater
than 0.24, and thus the P1 space group was ruled out.
3.4.1 Data reduction and indexing
Firstly, the Bragg angles of the peaks in the XRD pattern were
determined using a derivative-based algorithm included in the
CELREF program [47]. The first 30 Bragg reflections of the total
of 4067 identified as such were then indexed using the CRYSFIRE
software package [48], which launches the commonest indexing
programs: ITO, TREOR90, DICVOL91, KOHL, TAUP, FJZN and
LZON. The best indexing had a de Wolff figure-of-merit of
M(20) ϭ 19.5 and was obtained with TREOR90, which indexed
the XRD pattern in the triclinic system. Subsequent detailed analy-
sis of the indexed peaks with the CHECKCELL program [49]
yielded a triclinic unit cell of approximate dimensions a ϭ 13.294
3.4.3 Rietveld refinement
Finally, the crystal structure determined by the Monte
Carlo/parallel tempering search algorithm was finally re-
fined by the Rietveld method, using the FULLPROF Riet-
veld code [52] included in the WinPLOTR software
packαge [53].In the Rietveld analysis, the peak shape was
assumed to be a pseudo-Voigt function and the refinement
included the following aspects: (i) the background, which
was interpolated by cubic splines, (ii) the scale factor, (iii)
the global instrumental shifts (zero-point shift, and system-
atic shifts depending on transparency and off-centring of
the sample), (iv) the cell parameters, (v) the profile param-
eters (Caglioti half-width parameters, the mixing param-
eters of the pseudo-Voigt function, and the asymmetry par-
ameter for diffraction angles less than 15° 2θ), (vi) the
atomic positions excluding the H atoms that were rigidly
˚
˚
˚
(4) A, b ϭ 13.304 (4) A, c ϭ 9.930 (4) A, α ϭ 91.023 (13)°, β ϭ
3
˚
95.393 (11)°, γ ϭ 93.017 (8)°, V ϭ 1746 (1) A . There was ambi-
guity between the two possible crystallographic space groups: P1
¯
and P1. However, the reasonableness of the P1 space group is very
low since the number of molecules within the unit cell, as deter-
3
˚
mined from the ratio of the unit cell volume (V ϭ 1746 A ) to the
3
˚
expected C13H13Cl4CdN3S2 molecule volume (V ϭ 427 A ), is four
and the possibility of four independent molecules in the triclic unit
cell is extremely low.
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[CdCl2(TzTn)]
Table
1
Main crystallographic data for the [CdCl2(TzTn)]
complex obtained by X-ray powder diffractometry.
Chemical formula
Space group
C13H13Cl4CdN3S2
P1
¯
Cell parameters
˚
a (A)
13.558(4)
13.579(7)
10.117(4)
91.07(3)
95.44(3)
93.03(3)
˚
b (A)
˚
c (A)
α (°)
β (°)
γ (°)
Coordinates
Atoms
x
y
z
CdA
N1A
N2A
N3A
C1A
C2A
C3A
C4A
C5A
C6A
C7A
C8A
C9A
C10A
C11A
C12A
C13A
S1A
0.287(1)
0.235(8)
0.088(7)
0.116(7)
0.155(4)
0.290(8)
0.240(4)
0.055(4)
0.083(4)
Ϫ0.027(4)
Ϫ0.111(7)
0.079(7)
0.019(6)
Ϫ0.021(4)
Ϫ0.000(4)
0.060(7)
0.099(6)
0.130(2)
Ϫ0.073(2)
0.324(2)
0.370(2)
Ϫ0.094(1)
Ϫ0.047(1)
0.264(1)
0.391(7)
0.494(7)
0.396(8)
0.472(3)
0.388(3)
0.484(3)
0.476(5)
0.499(2)
0.588(3)
0.648(3)
0.382(5)
0.403(8)
0.384(4)
0.345(8)
0.324(7)
0.342(7)
0.562(3)
0.571(2)
0.227(2)
0.162(2)
0.411(2)
0.322(1)
Ϫ0.678(1)
Ϫ0.824(6)
Ϫ0.865(6)
Ϫ0.685(6)
Ϫ0.882(4)
Ϫ0.857(5)
Ϫ0.956(4)
Ϫ0.766(4)
Ϫ0.939(4)
Ϫ0.963(4)
Ϫ0.900(7)
Ϫ0.587(7)
Ϫ0.540(4)
Ϫ0.446(4)
Ϫ0.399(4)
Ϫ0.447(6)
Ϫ0.540(5)
Ϫ0.987(1)
Ϫ0.769(2)
Ϫ0.552(2)
Ϫ0.728(2)
Ϫ0.390(1)
Ϫ0.284(1)
Ϫ0.338(1)
Ϫ0.368(8)
Ϫ0.215(7)
Ϫ0.242(7)
Ϫ0.309(5)
Ϫ0.463(3)
Ϫ0.469(3)
Ϫ0.200(5)
Ϫ0.122(2)
Ϫ0.047(3)
Ϫ0.070(5)
Ϫ0.228(2)
Ϫ0.132(5)
Ϫ0.118(5)
Ϫ0.199(2)
Ϫ0.294(2)
Ϫ0.309(4)
Ϫ0.356(3)
Ϫ0.121(2)
Ϫ0.489(2)
Ϫ0.218(2)
0.000(2)
0.718(1)
0.602(9)
0.722(8)
0.751(8)
0.622(4)
0.488(4)
0.420(3)
0.752(3)
0.833(4)
0.868(3)
0.801(7)
0.776(6)
0.673(3)
0.700(3)
0.830(4)
0.933(6)
0.906(3)
0.508(3)
0.787(2)
0.558(3)
0.929(3)
0.573(2)
0.866(2)
0.033(1)
Ϫ0.100(9)
Ϫ0.039(8)
0.150(8)
Ϫ0.109(6)
Ϫ0.178(3)
Ϫ0.258(3)
0.100(5)
Ϫ0.121(5)
Ϫ0.068(3)
0.066(3)
0.291(2)
0.354(2)
0.491(2)
0.564(5)
0.501(3)
0.365(7)
Ϫ0.212(1)
0.191(2)
0.152(3)
Ϫ0.086(3)
0.566(3)
0.732(2)
Figure 1 Plot output from the Rietveld analysis of the X-ray dif-
fraction pattern corresponding to the [CdCl2(TzTn)] complex.
Points are the experimental X-ray diffraction data; the solid line is
the calculated pattern; the residuals are plotted at the bottom.
S2A
Cl1A
Cl2A
Cl3A
Cl4A
CdB
N1B
N2B
N3B
C1B
C2B
C3B
C4B
C5B
C6B
C7B
C8B
C9B
C10B
C11B
C12B
C13B
S1B
S2B
Figure
2
Representation of the crystal structure of the
Cl1B
Cl2B
Cl3B
Cl4B
[CdCl2(TzTn)] complex after refinement using the Rietveld
method.
Ϫ0.183(1)
linked to their bonding atoms, and (vii) the overall Debye-
Waller temperature factor.This makes a total of 180 refined
parameters.The Rietveld refinement was made by first tak-
ing the molecules to be rigid bodies and then replacing the
rigid-body constraints by soft restraints on the atom-atom
angles and distances. The residuals at the completion of the
Rietveld refinement were Rwp ϭ 0.189, Rp ϭ 0.147, and
RF ϭ 0.065, and the refined cell parameters were a ϭ
13.558(4) A, b ϭ 13.579(7) A, c ϭ 10.117(4) A, α ϭ
91.07(3)°, β ϭ 95.44(3)°, and γ ϭ 93.03(3)°. Figure 1 shows
the plotted output from the Rietveld refinement, Figure 2
shows a representation of the refined crystal structure, and
Table 1 lists the most representative crystallographic param-
eters of such a crystal structure.
3.5 Description of the structure
The crystal structure of the [CdCl2(TzTn)] complex is dis-
cussed next, although our interpretation needs to be treated
with some caution since the crystallographic data were de-
termined from powder diffractometry.
˚
˚
˚
The X-ray diffraction study of the CdII complex showed
the crystals to be made up of triclinic unit cells (space group
¯
P1), each containing four C13H13Cl4CdN3S2 molecules.
Only two of these four molecules are independent and
therefore form the asymmetric unit. Table 2 lists selected
Z. Anorg. Allg. Chem. 2007, 1801Ϫ1808
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1805

´
A. M. Lozano-Vila, F. L. Cumbrera, F. Luna-Giles, A. L. Ortiz, A. Bernalte-Garcıa
˚
Table 2 Selected bond lengths /A and bond angles /° for the
[CdCl2(TzTn)] complex.
Cd(A)-Cl(1A)
Cd(A)-N(3A)
S(2A)-C(4A)
N(2A)-C(1A)
C(8A)-N(3A)
C(1A)-N(1A)
Cd(B)-Cl(2B)
Cd(B)-N(1B)
S(1B)-C(1B)
N(2B)-C(4B)
C(4B)-N(3B)
2.44(3)
2.37(10)
1.80(6)
1.45(10)
1.47(13)
1.34(11)
2.45(3)
2.33(10)
1.81(7)
Cd(A)-Cl(2A)
Cd(A)-N(1A)
S(1A)-C(1A)
N(2A)-C(4A)
C(4A)-N(3A)
Cd(B)-Cl(1B)
Cd(B)-N(3B)
S(2B)-C(4B)
N(2B)-C(1B)
C(8B)-N(3B)
C(1B)-N(1B)
2.44(3)
2.33(8)
1.81(5)
1.47(10)
1.34(10)
2.45(3)
2.37(9)
1.80(7)
1.45(11)
1.34(11)
1.310(1)
1.46(10)
1.34(12)
Cl(1A)-Cd(A)-Cl(2A) 134.14(2)
Cl(1A)-Cd(A)-N(3A) 110.62(3)
Cl(1A)-Cd(A)-N(1A) 108.51(4)
Cl(2A)-Cd(A)-N(3A)
Cl(2A)-Cd(A)-N(1A)
C(4A)-N(2A)-C(1A)
S(2A)-C(4A)-N(2A)
N(2A)-C(4A)-N(3A)
Cd(A)-N(3A)-C(8A)
Cd(A)-N(1A)-C(1A)
C(1A)-N(1A)-C(2A)
S(1A)-C(1A)-N(2A)
Cl(1B)-Cd(B)-Cl(2B)
Cl(2B)-Cd(B)-N(3B)
Cl(2B)-Cd(B)-N(1B)
C(4B)-N(2B)-C(1B)
S(2B)-C(4B)-N(2B)
N(2B)-C(4B)-N(3B)
Cd(B)-N(3B)-C(8B)
Cd(B)-N(1B)-C(1B)
C(1B)-N(1B)-C(2B)
S(1B)-C(1B)-N(2B)
104.69(3)
105.60(2)
122.22(5)
112.29(6)
121.81(7)
112.66(5)
125.92(6)
114.37(5)
119.40(4)
134.16(3)
104.80(3)
105.75(4)
122.39(4)
112.69(4)
121.72(4)
112.57(3)
125.58(5)
114.79(6)
119.15(4)
N(3A)-Cd(A)-N(1A)
C(4A)-N(2A)-C(5A)
S(2A)-C(4A)-N(3A)
Cd(A)-N(3A)-C(4A)
C(4A)-N(3A)-C(8A)
Cd(A)-N(1A)-C(2A)
S(1A)-C(1A)-N(1A)
N(2A)-C(1A)-N(1A)
Cl(1B)-Cd(B)-N(3B)
Cl(1B)-Cd(B)-N(1B)
N(3B)-Cd(B)-N(1B)
C(4B)-N(2B)-C(5B)
S(2B)-C(4B)-N(3B)
Cd(B)-N(3B)-C(4B)
C(4B)-N(3B)-C(8B)
Cd(B)-N(1B)-C(2B)
S(1B)-C(1B)-N(1B)
N(2B)-C(1B)-N(1B)
79.98(3)
115.61(6)
125.90(7)
127.17(6)
120.14(7)
119.62(4)
115.27(6)
125.30(6)
110.70(4)
108.11(3)
80.03(3)
115.73(4)
125.59(7)
127.16(6)
120.25(4)
119.53(4)
115.52(5)
125.27(7)
Figure 3 Molecular structure of [CdCl2(TzTn)] complex, showing
the atom-numbering scheme. The thermal ellipsoids are drawn at a
50 % level.
bond lengths and angles, and Figure 3 shows a represen-
tation of the molecules forming the asymmetric unit.
According to the X-ray diffraction analysis, the bond
lengths and angles as well as the rotation rate of the thiaz-
oline ring with respect to the tetrahydro-1,3-thiazine ring
are almost the same for the two independent molecules.
However, the rotation between the 3,4-dichlorophenyl ring
and the tetrahydro-1,3-thiazine fragment is clearly different
in the two molecules [torsion angles of Ϫ77.1° for C(4A)-
N(3A)-C(8A)-C(9A) and of 41.8° for C(4B)-N(3B)-C(8B)-
C(9B)].
˚
oline- hydrazone] [24], [CdCl2(HzTz)]·H2O [2.241(2) A]
[HzTz is (2-thiazolin-2-yl)hydrazine] [25], [CdCl{(µ-
˚
Cl)2CdCl(µ-Cl)-(µ-PITT)Cd}2]n[2.271(2) A]
[PyTT
is
2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine]
[26],
˚
[Cd(NO3)2(PyTT)-(H2O)] [2.351(2) A] [26], [Cd(NO3)2(T-
˚
˚
nInA)2] [2.325(2) A and 2.394(3) A] [TnInA is 2-(indazol-1-
˚
yl)-2-thiazoline] [27], and [Cd(NO3)2(TnInL)2] [2.318(2) A]
The CdII atom is bound to two chlorine atoms [Cd(A)-
[TnInL is 2-(indazol-2-yl)-2-thiazoline] [27].
˚
˚
Cl(1A) ϭ 2.44(3) A and Cd(B)-Cl(1B) ϭ 2.45(3) A; Cd(A)-
The ligand-metal-ligand bite angles differ from the ideal
value of 109.5°, varying between 79.98(3)° [N(3A)-Cd(A)-
N(1A)] and 134.14(2)° [Cl(1A)-Cd(A)-Cl(2A)] in unit A and
80.03(3)° [N(3B)-Cd(B)-N(1B)] and 134.16(3)° [Cl(1B)-
Cd(B)-Cl(2B)] in unit B. The dihedral angle formed by the
Cl(1)-Cd-Cl(2) and N(1)-Cd-N(3) planes is 88.85° (in units
A and B).
Table 3 gives the conformations and puckering param-
eters of the chelate and heterocycle rings calculated for the
[CdCl2(TzTn)] complex according to the Cremer-Pople cri-
terion [56]. It can be observed that the chelate rings and the
six-membered heterocycle rings adopt a near-to-boat con-
formation, whereas the five-membered heterocycle rings are
essentially planar.
˚
˚
Cl(2A) ϭ 2.44(3) A and Cd(B)-Cl(2B) ϭ 2.45(3) A], one
thiazoline nitrogen atom[Cd(A)-N(1A) ϭ 2.33(8) A and
Cd(B)-N(1B) ϭ 2.33(10) A], and one imino nitrogen atom
˚
˚
˚
[Cd(A)-N(3A)
ϭ
2.37(10) A and Cd(B)-N(3B)
ϭ
˚
2.37(9) A], in a distorted tetrahedral geometry.
The Cd-Cl bond lengths in the [CdCl2(TnTz)] complex
˚
are slightly shorter than the average value [2.516(80) A] for
45 tetrahedral CdII complexes with a Cd-Cl bond as calcu-
lated with the CONQUEST program [54] on the basis of
the data from the Cambridge Structural Database (CSD)
[55]. The Cd-Nimine bond distance is similar to the mean
˚
value [2.261(92) A] calculated in the same way for 11 tetra-
hedral CdII complexes with a Cd-Nimine bond [55]. Finally,
the Cd-Nthiazoline bond distance is comparable to the values
found for the following compounds: [Cd(NO3)2(ATH)2]
Supplementary material. Crystallographic data for the structure of
[CdCl2(TzTn)] have been deposited with the Cambridge Crystallo-
˚
˚
[2.230(12) A and 2.384(12) A] [ATH is 2-acetyl-2-thiaz-
1806
www.zaac.wiley-vch.de
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2007, 1801Ϫ1808

[CdCl2(TzTn)]
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[CdCl2(TzTn)] complex.
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Apex deviation Maximum
Puckering
Unit Ring conformation
from the mean mean-plane
parameters
˚
˚
plane (A)
deviation (A)
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q ϭ 0.023 A
Ϫ
C(3A) ϭ 0.014
C(5A) ϭ 0.015
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Q ϭ 0.690 A
´
0.655 [N(2A)]
0.527 [C(7A)]
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A
θ ϭ 94.9°
φ ϭ 302.0°
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˚
Q ϭ 0.556 A
θ ϭ 81.4°
φ ϭ 357.5°
0.632 [Cd(A)]
0.377 [N(2A)]
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C(1A) ϭ 0.013
C(3B) ϭ 0.019
C(5B) ϭ 0.018
˚
q ϭ 0.032 A
Ϫ
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Q ϭ 0.684 A
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0.528 [C(7B)]
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Quımica Farmaceutica, Reverte, Barcelona 1978.
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B
θ ϭ 94.5°
φ ϭ 302.5°
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˚
Q ϭ 0.559 A
θ ϭ 81.3°
φ ϭ 357.9°
0.636 [Cd(B)]
0.379 [N(2B)]
C(1B) ϭ 0.010
´
´
[24] F. J. Barros-Garcıa, A. Bernalte-Garcıa, F. Luna-Giles, M. A.
´
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´
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[25] A. Bernalte-Garcıa, M. A. Dıaz-Dıez, F. J. Garcıa-Barros, F.
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ϩ(1223)336-033; e-mail for inquiry: fileserv@ccdc.cam.ac.uk;
e-mail for deposition: deposit@ccdc.cam.ac.uk).
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and the FEDER [Project 2PR04A011] for financial support. A. M.
Lozano-Vila thanks the Spanish Ministerio de Ciencia y Tecnolo-
´
E. Vin˜uelas-Zahınos, Polyhedron 2006, 25, 43.
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´
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