Synthesis, characterization and thermal behaviour of ortho-metallated Pd(II) complexes containing N-benzoylthiourea derivatives

Article abstract of DOI:10.1016/j.poly.2008.08.023

The synthesis and characterization (elemental analysis, ¹H and ¹³C NMR spectroscopy and single crystal X-ray diffraction) of the first ortho-metallated Pd(II) complexes containing N-benzoyl thiourea ligands are described. Four of the

Full text of DOI:10.1016/j.poly.2008.08.023

Polyhedron 27 (2008) 3537–3544
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Synthesis, characterization and thermal behaviour of ortho-metallated Pd(II)
complexes containing N-benzoylthiourea derivatives
Alia C. Tenchiu a, Monica Ilißs a, Florea Dumitraßscu b, Adrian C. Whitwood c, Viorel Cîrcu a,
*
a Inorganic Chemistry Department, University of Bucharest, 23 Dumbrava Rosie Street, 020464 Bucharest, Sector 2, Romania
b Centre of Organic Chemistry ‘‘C.D. Nenitzescu”, Romanian Academy, Spl. Independentei 202B, Bucharest 060023, Romania
c Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
a r t i c l e i n f o
a b s t r a c t
The synthesis and characterization (elemental analysis, 1H and 13C NMR spectroscopy and single crystal
X-ray diffraction) of the first ortho-metallated Pd(II) complexes containing N-benzoyl thiourea ligands are
described. Four of these compounds showed liquid crystal properties which were investigated by mean of
DSC and polarised light microscopy and their mesogenic properties are compared to those of ortho-met-
allated imine Pd(II) complexes with other types of co-ligands.
Article history:
Received 23 July 2008
Accepted 14 August 2008
Available online 22 October 2008
Keywords:
Liquid crystals
Palladium
Ó 2008 Elsevier Ltd. All rights reserved.
Orthometallation
Imine
N-Benzoylthiourea
1. Introduction
derivatives as co-ligands in order to investigate their influence on
the mesogenic behaviour of the ortho-metallated imine fragment.
Liquid crystals containing metal ions (metallomesogens) are
intensively studied due to their interesting properties conferred
by the presence of the metal ion, such as colour, polarizability,
electrical and magnetic properties [1]. ortho-Metallated palla-
dium(II) complexes with nitrogen-containing heteroaromatic li-
gands represent one of the most interesting and broadly studied
families of metallomesogens, which form thermally stable com-
plexes that consist of both dinuclear and mononuclear organome-
tallic systems. Imine ligands have been extensively used in the
preparation of such ortho-metallated species with liquid crystal
properties, in particular due to the different possibilities for tuning
the mesogenic properties of these compounds, as well as other
physico-chemical properties [2]. A good strategy for reducing the
transition temperatures and keeping a broad mesomorphic range
in such systems containing the ortho-metallated imine fragment
is to introduce various co-ligands, which lead, in most cases but
not always, to mononuclear compounds with more accessible
and stable mesophases compared with the dinuclear parent com-
plexes. Amongst the various co-ligands used to prepare mononu-
clear species with improved mesogenic properties are b-
We were interested in using N-benzoyl thiourea derivatives as co-li-
gands since they possess very strong donor groups (carbonyl and
thioamide) which make them very attractive for use as ligands in
coordination chemistry and they are readily available by a two-step
synthesis starting from benzoyl chloride and the corresponding
amine, providing access to a whole range of these derivatives [8].
These ligands react with transition metals, mostly in the monoan-
ionic and bidentate forms by deprotonation, forming neutral com-
plexes with S,O-coordination [9]. These derivatives have been
used previously in the design of liquid crystalline materials [10–
12], but none of the examples reported so far showed their use in
the preparation of metal complexes with liquid crystal properties.
2. Results and discussion
2.1. Synthesis
The synthesis of the new compounds described here is summa-
rised in Scheme 1.
The preparation of mononuclear ortho-palladated complexes
was carried out by a ligand exchange reaction of the acetato-
bridged dinuclear Pd(II) complexes using the sodium salts of the
N-benzoyl thiourea derivatives. The cleavage reaction of acetato-
bridged Pd(II) complexes could also be carried out in the presence
of simple N-benzoyl thiourea derivatives, but with lower yields
when compared to the use of their sodium salts.
diketones, [3] b-aminoenonates [3a,4], a-aminoacids [5], cyclopen-
tadienyl [6] or dialkyldithiocarbamate ligands [7]. In this paper we
present the synthesis and characterization of a series of ortho-met-
allated palladium complexes with different N-benzoyl thiourea
* Corresponding author.
E-mail address: viorel_carcu@yahoo.com (V. Cîrcu).
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.08.023

3538
A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
OCnH2n+1
3'
4'
6'
OCnH2n+1
OCnH2n+1
1
2'
1'
5'
2
3
6
5
OAc
OAc
N
O
NaBTU
CH2Cl2
4
N
Pd
Pd
Pd
N
2 – 13 (a, b)
1(a, b)
S
N
O
7
NR1R2
12
11
8
OCnH2n+1
9
10
CnH2n+1
OCnH2n+1
n = 1, a
n = 6, b
R1 = R2 = n-Et
n-Pr
2
R1 = H, R2 = Ph
p-Me-Ph
7
3
4
8
n-Bu
m-Me-Ph
p-F-Ph
9
n-Hex 5
n-Oct 6
10
11
12
p-Cl-Ph
p-Br-Ph
p-MeO-Ph 13
Scheme 1. Synthesis of the new complexes and the N-benzoyl thiourea derivatives used in this study.
The new mononuclear complexes were obtained in moderate to
It is interesting to note that for the complexes 2–6a the signals
corresponding to the alkyl groups from the N(Alk)2 moiety are not
magnetically equivalent, both in the 1H and 13C NMR spectra. This
is due to a hindered rotation about the C–N(Alk)2 bond, which in
turn can be explained through the conjugation between the amine
and the Pd containing ring.
good yields as yellow microcrystalline solid products, which are
stable under atmospheric conditions. Their structures were con-
firmed by elemental analysis, IR spectroscopy as well as 1H and
13C NMR spectroscopy and X-ray diffraction.
The coordination of the N-benzoyl thiourea derivatives in the
deprotonated form was confirmed by the disappearance of the
mNH frequency in the IR spectra of the Pd(II) complexes, which sug-
2.2. Structures
gests the absence of the NH hydrogen located between the car-
bonyl and the thiocarbonyl groups of the benzoyl thioureic
moiety, information that is further supported by 1H NMR spectros-
copy. The formation of the ortho-metallated mononuclear com-
plexes can be confirmed readily by 1H NMR spectroscopy where
a pattern specific to 1,3,4-substitution of an aromatic ring can be
Single crystals of 2a, 10a and 13a suitable for analysis by X-ray
diffraction were obtained from a mixture of dichloromethane and
ethanol (ca. 1/1 v/v) at ꢁ25 °C. Complex 13a crystallised with
two independent molecules in the structural unit. The crystallo-
graphic data are collected in Table 1, while selected bond lengths
and angles for all three complexes are presented in Table 2.
The molecular structure of 2a is shown in Fig. 1. The palladium
atom is surrounded by one sulfur atom and one oxygen atom of the
N-benzoyl thiourea ligand, one aromatic carbon atom (metallated
phenyl ring) and one nitrogen atom (imine group) in an approxi-
matively square-planar arrangement, with the sulfur atom located
cis to the nitrogen atom of the imine group. The corresponding che-
late ring around the Pd centre is essentially planar with a maxi-
mum deviation from the mean plane of 0.040 Å. However, while
the metallated phenyl ring is almost coplanar with respect to the
mean plane, the unmetallated ring of the imine ligand is twisted
by 37.7° with respect to the core plane. The phenyl ring of the ben-
zoyl group from the N,N-diethyl-N0-benzoyl thiourea ligand is also
twisted by 32.9° with respect to the mean plane.
The Pd–Pd distance between two neighbouring molecules is
8.2 Å, precluding any Pd–Pd interactions. The Pd–C and Pd–N bond
lengths are comparable with the values reported for similar ortho-
palladated complexes with Schiff bases, while the Pd–O and Pd–S
bond lengths are very well situated between the two values found
for the simple cis complex of Pd(II) with N,N-diethyl-N0-benzoyl
thiourea, which are 2.10 and 1.99 Å for the Pd–O bonds and
2.215 and 2.31 Å for the Pd–S bonds [14].
3
seen as two doublets (H-2, H-3, JH2,H3 = 8.4 Hz) and a doublet of
4
doublets (H-6, JH2,H6 = 2.4 Hz).
Also, the 1H NMR spectra indicate the presence of only one
isomer in solution (one set of signals) for all the prepared com-
plexes, though it is possible for the complexes to exist as a mix-
ture of two isomers with the sulfur atom of the N-benzoyl
thiourea ligand in a trans or cis position to the nitrogen atom
of the imine group of the Schiff base ligand. This information is
supported by X-ray diffraction studies that showed only one iso-
mer in the solid state for the complexes isolated as single
crystals.
The 13C NMR spectra show all the expected signals. The shift
of the signals (
atoms are consistent with the existence of a Pd–N and a Pd–C-
5 bond. This deshielding effect caused by Pd bonding ( d = 4–
D
d ꢀ 13 ppm) due to the imine and C-5 carbon
D
9 ppm) is also visible for the ortho positions with respect with
the metallated position (C-4, C-6). In the case of the benzoyl
moiety of the N-benzoyl thiourea derivative, coordination to the
metal center leads to a deshielding of C-10 (
C-40 (
corresponding to C@O and C@S undergo relatively large down-
field and upfield chemical shifts of d = 7 and 6 ppm, respec-
D
d = 5 ppm) and para
D
d = 2 ppm), as compared with the free ligand. The signals
D
tively. This behaviour is similar to that observed for simple
Pd(II) complexes with other N,N-dialkyl-N0-aroyl or acyl thiourea
derivatives [13].
Complex 10a (Fig. 2) crystallised with the same square-planar
arrangement around the palladium atom; indeed the bond lengths
and angles for the central core are all very similar to those found in

A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
3539
Table 1
Crystallographic data for 2a, 10a and 13a
Compound
2a
10a
13a
Empirical formula
Formula weight
C27H29N3O3PdS
581.99
C29H24FN3O3PdS
619.97
C30H27N3O4PdS
632.01
(g molꢁ1
)
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
110(2)
110(2)
110(2)
0.71073
triclinic
0.71073
monoclinic
P2(1)/n
0.71073
monoclinic
P2(1)/c
ꢀ
P1
7.6707(8)
11.6553(12)
15.4545(16)
111.219(2)
97.100(2)
97.386(2)
1255.5(2)
2
19.813(17)
6.436(6)
20.501(17)
90
90.18(2)
90
2614(4)
4
1.575
17.8784(13)
9.3708(7)
32.105(2)
90
99.993(2)
90
5297.1(6)
8
1.585
b (Å)
c (Å)
a
(°)
b (°)
(°)
c
Volume (Å3)
Z
Dcalc (Mg mꢁ3
Absorption
coefficient
)
1.539
0.857
0.834
0.822
(mmꢁ1
)
F(000)
Crystal
596
yellow
1256
yellow
2576
yellow
Fig. 1. The molecular structure of 2a.
Crystal size (mm)
h Range for data
collection (°)
0.22 ꢃ 0.14 ꢃ 0.13 0.28 ꢃ 0.09 ꢃ 0.04 0.30 ꢃ 0.24 ꢃ 0.16
1.44–28.30
1.43–28.34
1.16–30.02
Index ranges
ꢁ10 6 h 6 10,
ꢁ15 6 k 6 15,
ꢁ20 6 l 6 20
12837
ꢁ26 6 h 6 15,
ꢁ8 6 k 6 8,
ꢁ27 6 l 6 26
16695
ꢁ24 6 h 6 24,
ꢁ13 6 k 6 13,
ꢁ44 6 l 6 45
58726
Reflections
collected
Independent
reflections (Rint
Completeness to
h = 27.48° (%)
Absorption
correction
Maximum and
minimum
6170 (0.0204)
99.8
6420 (0.0599)
98.3
15249 (0.0429)
98.5
)
semi-empirical
from equivalents
0.890 and 0.814
semi-empirical
from equivalents
0.970 and 0.724
semi-empirical
from equivalents
0.877 and 0.762
transmission
Refinement
method
Data/restraints/
parameters
full-matrix least-
squares on F2
6170/0/320
full-matrix least-
squares on F2
6420/0/386
full-matrix least-
squares on F2
15249/0/717
Goodness-of-fit on 1.045
0.930
1.111
F2
Final R indices
R1 = 0.0253,
wR2 = 0.0619
R1 = 0.0387,
wR2 = 0.0750
R1 = 0.0648,
R1 = 0.0374,
wR2 = 0.0870
R1 = 0.0487,
[F2 > 2 (F2)]
r
R indices (all data) R1 = 0.0283,
wR2 = 0.0632
0.592 and ꢁ0.681
wR2 = 0.0828
0.700 and ꢁ0.530
wR2 = 0.0962
1.605 and ꢁ0.774
Largest difference
in peak and
hole (e Åꢁ3
)
Fig. 2. The molecular structure of 10a.
Table 2
Selected bond lengths (Å) and angles (°)
2a. The same orientation with respect to the core plane was found
for the unmetallated ring of the imine ligand, which is twisted by
54.2°, a larger value when compared to 2a. The phenyl ring of the
benzoyl group from the N-benzoyl thiourea ligand is also twisted
in respect to the core plane by 14.2°, a smaller value compare to
that found for 2a. An interesting feature of this complex is the
two possible configurations adopted by the p-F-phenyl ring of
the N-benzoyl thiourea ligand, with a twist of 73.6°, each with
50% probability as revealed by the site occupancy factors. In both
cases there is a twist of this ring by 49.4° and 57.2° with respect
to the core plane. Another factor that contributes to the crystal
packing of 10a are intermolecular –C–Hꢂ ꢂ ꢂF–C– interactions, found
between the fluorine atom of the N-benzoyl thiourea ligand and
the methoxy group of the metallated ring of the imine ligand.
The measured Hꢂ ꢂ ꢂF distance is 2.50 Å, which is smaller than the
sum of the van der Waals’ radii of fluorine and hydrogen of
2.67 Å (the van der Waals’ radius of fluorine is 1.47 Å)[15].
2a
10a
13a
Molecule A
Molecule B
Pd–C
Pd–N
Pd–S
Pd–O
N–C(Ph)
N–C(S)
N–C(O)
C–O
C–S
C(O)–C(Ph)
C–N (imine)
1.9856(17)
2.1003(14)
2.2382(5)
2.0847(12)
1.325(2)
1.342(2)
1.339(2)
1.265(2)
1.7345(18)
1.503(2)
1.984(3)
2.055(3)
2.2394(16)
2.063(2)
1.342(4)
1.321(4)
1.344(4)
1.260(3)
1.745(3)
1.487(4)
1.306(3)
1.988(2)
2.1113(18)
2.2457(6)
2.0877(15)
1.330(3)
1.342(3)
1.341(3)
1.260(3)
1.723(2)
1.504(3)
1.300(3)
1.977(2)
2.1015(19)
2.2382(6)
2.0759(16)
1.335(3)
1.343(3)
1.347(3)
1.257(3)
1.723(2)
1.499(3)
1.301(3)
1.295(2)
C–Pd–N
N–Pd–O
O–Pd–S
S–Pd–C
81.35(7)
95.63(1)
92.38(4)
90.67(5)
81.17(11)
92.61(8)
92.28(6)
93.84(9)
81.17(3)
96.74(7)
92.78(4)
89.58(6)
81.41(9)
96.24(7)
91.87(5)
90.32(7)

3540
A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
Fig. 3. The molecular structure of 13a.
Table 3
Complex 13a crystallises in the monoclinic crystal system,
Thermal data for the palladium(II) complexes
group P2(1)/c, as a dimer (Fig. 3). The crystal structure of this
compound shows Pd(II) in a square-planar environment bound
to the imine ligand in an ortho-metallated fashion and chelated
to the N-benzoyl thiourea derivative with the same coordinated
atoms (one aromatic C atom (metallated ring), one N atom (imine
group), one O atom (carbonyl group) and one S atom (thiocarbon-
yl group)) as found for 2a and 10a. The two five- and six-mem-
bered chelate rings are almost co-planar with the metallated
ring of the imine ligand while the unmetallated ring is twisted
in respect to the core plane by 34.9° for one molecule, and by
36.3° for the second.
For this compound the maximum deviation from the mean
plane is 0.063 and 0.047 Å for Pd1 and Pd2, respectively. In this
case, the complexes are arranged so that one sits over another with
a short Pd–Pd distance of 3.92 Å. This distance is greater than twice
the van der Waals’ radius of Pd. Additionally, within the dimer the
Pdꢂ ꢂ ꢂPd vector deviates from orthogonality to the coordination
plane (25° angle with the plane normal) and so the relative dispo-
sition of the complexes is not felt to be due to any intermolecular
metal–metal interaction. The C–O and C–S bond lengths of the N-
benzoyl thiourea ligand in 13a are longer than those found in the
free ligand (1.231 and 1.659 Å, respectively) while the N–C(S)
and N–C(O) bond lengths are shorter in 13a than in the free ligand
(1.392 and 1.376 Å, respectively) as a consequence of the coordina-
tion of the ligand to the palladium centre in the deprotonated form
which leads to the partial double-bond character of the C–N bonds
[16]. An important factor that contributes to the crystal packing of
13a is intermolecular N–Hꢂ ꢂ ꢂS hydrogen bonds, found between the
S atom of the thiocarbonyl group and the hydrogen atom of the
amino –NHR group from the N-benzoyl thiourea ligand.1 This type
of interaction is usually found in the uncomplexed N-benzoyl thio-
urea ligands and is typically shorter than the interactions found for
13a [17,18].
Compound
Transition
T (°C)
D )
H (kJ molꢁ1
2b
Cr–I
110
(61)
23.8
(N–I)b
(0.3d)
3b
5b
Cr–I
(I–N)
(N–Cr)
104
30.8
(64a)
(20.4c)
Cr–Cr0
Cr0–I
102
18.2
108
21.5
(I–N)
(N–Cr)
(78a)
(29.8c)
6b
Cr–Cr0
Cr0–I
53
3.4
95
29.9
(I–N)
(N–Cr)
(58a)
(22.2c)
a
These values represent the temperatures taken from microscopy.
In this case T(N–I) is quoted as the sample was cooled from isotropic to nematic
b
and then re-heated back to the isotropic phase.
c
The two transitions could not be separated and the values represent the com-
bined enthalpies.
d
Compound 2b was the only compound for which it was possible to extract the
enthalpy parameter associated with the isotropic to nematic phase transition. The
nematic phase of 2b is stable up to room temperature for several hours after which
a slow crystallization process occurs.
This family of complexes offers a broad and systematic picture
of the possibility to use N-benzoyl thiourea derivatives in design-
ing liquid crystalline materials as well as the effects of changing
the substituents on this type of ligand on the mesogenic behaviour.
The nature of the N-benzoyl thiourea derivative, more specific the
R1 and R2 substituents, has a major influence on the mesogenic
properties of these complexes (Table 3), though it is very clear that
their mesogenic behaviour is driven by the ortho-metallated imine
fragment. Thus, complexes 7–13b show no mesomorphic proper-
ties and this behaviour could be assigned to the more flexible
structures adopted by the N-benzoyl thiourea derivatives bearing
aromatic fragments, in particular due to the aromatic groups
linked to the nitrogen atom, which imposes a less favourable
molecular shape in connection with the intermolecular hydrogen
bonds N–Hꢂ ꢂ ꢂS that can be formed between the S atom of the thio-
carbonyl group and the hydrogen atom of the amino –NHR group.
This type of intermolecular interaction (hydrogen bonding be-
tween the NH2 and the carboxyl groups within the amino acids
groups) within the crystal lattice was supposed to be responsible
for increasing the melting points of the liquid crystals based on
ortho-metallated Pd imine complexes with amino acids [5b]. On
the other hand, the Pd(II) complexes with N,N-dialkyl-N0-benzoyl
thiourea derivatives (2–6b) show a monotropic nematic phase on
cooling, except for 4b (R1 = R2 = Bu) for which no mesophase was
seen either on heating or cooling. This behaviour could be dis-
2.3. Thermal behaviour
The palladium complexes, bearing alkoxy groups with six car-
bon atoms chains (2–13b), were investigated for their potential li-
quid crystal properties by hot stage polarising optical microscopy
and differential scanning calorimetry (DSC). DSC data were re-
corded only for those compounds showing mesomorphic behav-
iour. The thermal data are summarised in Table 3. Mesophases
were assigned by their optical texture and two examples are
shown in Fig. 4.
1
Hydrogen bonds for 13a: N(5)–H(5A)ꢂ ꢂ ꢂS(2)#1, 3.772(2) Å and N(2)–
H(2A)ꢂ ꢂ ꢂS(1)#2, 3.6967(19) Å. Symmetry transformations used to generate equivalent
atoms: (1) ꢁx + 1, yꢁ1/2, ꢁz + 1/2; (2) ꢁx, y + 1/2, ꢁz + 1/2.

A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
3541
Fig. 4. Polarised optical micrograph of the nematic phase of 2b at 60 °C (a) and of 6b at 58 °C (b). In the later case the transition to the nematic phase occurs just before the
crystallisation process.
decrease the melting points and the mesophase range together
with a change of transition type.
3. Conclusions
A series of organometallic palladium(II) complexes bearing
imine ligands and different types of N-benzoyl thiourea derivatives
as co-ligands were prepared and investigated for their liquid
crystal properties. The structures of three of the complexes have
been solved by X-ray diffraction.
The first liquid crystals based on metal complexes containing
the N-benzoyl thiourea moiety are reported here and their meso-
genic properties are compared to those of palladium complexes
with other types of co-ligands. The use of N-benzoyl thiourea
derivatives as co-ligands in company of the ortho-palladated imine
fragment destabilise the mesogenic behaviour of these complexes.
Thus, in the case of complexes bearing N,N-dialkyl-N0-benzoyl thio-
urea derivatives only monotropic behaviour is seen, with the tran-
sitions to nematic mesophase occurring approximately 30–50 °C
below the clearing point, while in the case where N-aryl-N0-ben-
zoyl thiourea derivatives were employed, the mesomorphic behav-
iour was totally suppressed.
These results suggest the possibility of using these simple N-
benzoyl thiourea derivatives in designing liquid crystals together
with the ortho-metallated imine fragment but, probably, the mes-
ogenic behaviour of such compounds can be considerably im-
proved by changing the type of imine ligand employed.
Fig. 5. Thermotropic behaviour of Pd(II) complexes 2–6b.
cussed in terms of molecular anisotropy of these complexes, e.g.
the length-to-breadth ratio [19]. As the terminal alkoxy chains of
the imine are not changed, increasing the length of the alkyl chain
of the N-benzoyl thiourea derivative leads to an increase of the
breadth of the molecule with immediate consequences on the mes-
ogenic behaviour. One can assume that the maximum breadth of
the molecule is reached for R1 = R2 = butyl, when the mesogenic
behaviour is being totally suppressed.
Fig. 5 shows the influence of the chain length on the mesogenic
properties of Pd(II) complexes with N,N-dialkyl-N0-benzoyl thio-
urea derivatives. Though the melting points and the temperature
of the transition from isotropic to nematic phase do not follow
the same trend, there is a clear tendency of increase of TI–N with
the increasing chain length up to hexyl groups, followed by a sig-
nificant drop, 20 °C, on going from hexyl to octyl groups. The same
effect of decreasing the transition temperatures with increasing
the alkyl chain length from ethyl to octyl has been seen for
ortho-metallated imine Pd(II) complexes with dialkyldithiocarba-
mates as chelating ligands [7].
It is very clear that compared with the other types of co-ligands,
such as b-diketones or b-aminoenonates, the use of N-benzoyl
thiourea derivatives as co-ligands destabilise the mesogenic
behaviour to such an extent that only monotropic behaviour is
seen, with the transitions to the nematic mesophase occurring at
approximately 30–50 °C below the clearing point. While changing
b-diketones to b-aminoenonate co-ligands leads to more accessible
nematic phase but over slightly narrower temperature [3a], the ef-
fect of introducing the N-benzoyl thiourea derivatives is to further
4. Experimental
Dichloromethane was distilled from phosphorus pentaoxide,
while acetone was distilled from calcium chloride; other chemicals
were used as supplied. Proton and carbon NMR spectra were re-
corded on a Varian Gemini 300 BB spectrometer operating at
300 MHz, using CDCl3 as solvent. 1H chemical shifts were refer-
enced to the solvent peak position, d 7.26 ppm. Analysis by DSC
was carried out using a Perkin–Elmer DSC7 instrument using a
10 °C/min heating rate. Mesomorphism was studied by hot stage
polarising microscopy using a Nikon 50i Pol microscope equipped
with a Linkam THMS600 hot stage and a TMS94 temperature con-
troller. Mesophases were assigned by their optical texture [20].
Diffraction data were collected at 110 K on a Bruker Smart Apex
diffractometer with Mo Ka radiation (k = 0.71073 Å) using a SMART
CCD camera. Diffractometer control, data collection and initial unit
cell determination was performed using ‘‘SMART” (v5.625 Bruker-
AXS). Frame integration and unit-cell refinement was carried out
with the ‘‘SAINT+” (v6.22, Bruker AXS) sofware. Absorption correc-

3542
A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
tions were applied by SADABS (v2.03, Sheldrick). Structures were
solved by ‘‘direct methods” using SHELXS-97 [21] and refined by
full-matrix least squares using SHELXL-97 [21]. All non-hydrogen
atoms were refined anisotropically. Hydrogen atoms (except for
NH hydrogens) were placed using a ‘‘riding model” and were in-
cluded in the refinement at calculated positions. NH hydrogens
were found by a difference map after all other atoms were found.
170.2 (C–O), 160.3, 158.2, 141.5, 140.2, 138.4 (C-1, C-4, C-5, C-7,
C-10, C-10), 130.7 (C-40), 130.3 (C-3), 129.4 (C-30, C-50), 127.4 (C-
20, C-60), 124.3 (C-8, C-12), 119.1 (C-6), 114.5 (C-9, C-11), 109.9
(C-2). IR (cmꢁ1): 1585(
mC@N); 1525(dNH); 1418(mCN+CS).
4.3.2. Compound 3a
Yield: 55%, m.p. 161 °C. Anal. Calc. for C29H33N3O3PdS: C, 57.1;
H, 5.4; N, 6.9. Found: C, 56.9; H, 5.9; N, 6.5%.
The synthesis of the
l-acetato bridged Pd(II) complexes (1a,b)
was carried out as described elsewhere [22]. The N-benzoyl thio-
urea derivatives used in this work were prepared according to
the methods published in literature [8].
1H NMR (300 MHz, CDCl3): 8.14 (s, 1H), 7.74–7.70 (m, 2H),
4
7.42–7.18 (m, 6H), 7.02 (d, J = 2.3 Hz, 1H), 6.97 (AA0BB0 system,
3J = 8.9 Hz, 2H), 6.59 (dd, 3J = 8.3 Hz, 4J = 2.4 Hz, 1H), 3.90–3.71
(m, 10H), 1.95–1.67 (m, 4H), 1.03 (t, 3J = 7.3 Hz, 3H), 0.92 (t,
3J = 7.4 Hz, 3H). 13C NMR (75 MHz, CDCl3): 173.0 (C–S), 170.9
(CH@N), 170.2 (C–O), 160.3, 158.6, 158.4, 141.1, 140.3, 138.3 (C-
1, C-4, C-5, C-7, C-10, C-10), 130.6 (C-40), 130.1 (C-3), 129.4 (C-30,
C-50), 127.3 (C-20, C-60), 124.3 (C-8, C-12), 117.8 (C-6), 113.9 (C-9,
4.1. Preparation of the sodium salts of N-benzoyl thiourea derivatives
The sodium salts of N-benzoyl thiourea derivatives were pre-
pared by reacting the corresponding N-benzoyl thiourea with so-
dium ethoxide (1:1 molar ratio) in petroleum ether for 2 h under
reflux. A white or off-white precipitate developed for all N-benzoyl
thiourea derivatives, which was filtered off and washed with
petroleum ether several times. The sodium salts were used in the
next step without further purification. Their formation was
checked by IR spectroscopy. Their IR spectra confirmed the loss
of the proton by the disappearance of mNH (ꢀ3300 cmꢁ1) and mC@O
(ꢀ1670 cmꢁ1) frequencies (compare to the IR spectra of the free li-
gands) together with a shift of mC–N frequency towards lower
wavenumbers.
C-11), 110.0 (C-2). IR (cmꢁ1): 1582(
CN+CS).
mC@N); 1507(dNH); 1418
(m
4.3.3. Compound 3b
Yield: 51%, m.p. 106 °C. Anal. Calc. for C39H55N3O3PdS: C, 62.3;
H, 7.3; N, 5.6. Found: C, 62.0; H, 7.7; N, 5.3%.
1H NMR (300 MHz, CDCl3): 8.11 (s, 1H), 7.73 (m, 2H), 7.40–7.19
4
(m, 6H), 7.01 (d, J = 2.4 Hz, 1H), 6.96 (AA0BB0 system, 3J = 8.9 Hz,
2H), 6.59 (dd, 3J = 8.4 Hz, 4J = 2.5 Hz, 1H), 4.03 (m, 4H), 3.90–3.74
(m, 4H), 1.95–1.31 (m, 20H), 1.04 (t, 3J = 7.4 Hz, 3H), 0.93 (m,
9H). 13C NMR (75 MHz, CDCl3): 172.9 (C-S), 170.9 (CH@N), 170.2
(C–O), 160.1, 158.6, 158.3, 141.7, 140.3, 138.5 (C-1, C-4, C-5, C-7,
C-10, C-10), 130.7 (C-40), 130.2 (C-3), 129.4 (C-30, C-50), 127.4
(C-20, C-60), 124.5 (C-8, C-12), 118.6 (C-6), 114.6 (C-9, C-11),
4.2. Synthesis of 2a
110.7 (C-2). IR (cmꢁ1): 1582(
mC@N); 1540(dNH); 1420(mCN+CS).
The solid sodium salt of N,N-diethyl-N’-benzoyl thiourea
(0.0715 g, 0.27 mmol) was added to a solution of the binuclear pal-
ladium complex (0.075 g, 0.09 mmol) in CH2Cl2 (15 cm3) and the
mixture was stirred at room temperature for 24 h. Evaporation of
the solvent gave a yellow solid, which was purified by chromatog-
raphy on silica using CH2Cl2 as the eluant to give a yellow solid.
This was recrystallised from a mixture of CH2Cl2/C2H5OH (1/1) at
ꢁ25 °C.
4.3.4. Compound 4a
Yield: 60%, m.p. 140 °C. Anal. Calc. for C31H37N3O3PdS: C, 58.4;
H, 5.8; N, 6.6. Found: C, 57.9; H, 5.9; N, 6.2%.
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.72 (m, 2H), 7.41–7.17
4
(m, 6H), 7.02 (d, J = 2.4 Hz, 1H), 6.97 (AA0BB0 system, 3J = 8.9 Hz,
2H), 6.59 (dd, 3J = 8.4 Hz, 4J = 2.5 Hz, 1H), 3.99 (q, 3J = 7.1 Hz, 2H),
3.94–3.77 (m, 10H), 1.88–1.28 (m, 8H), 1.02 (t, 3J = 7.3 Hz, 3H),
0.91 (t, 3J = 7.3 Hz, 3H). 13C NMR (75 MHz, CDCl3): 173.0 (C–S),
168.7 (CH@N), 171.0 (C–O), 160.4, 158.7, 158.5, 141.7, 140.3,
138.3 (C-1, C-4, C-5, C-7, C-10, C-10), 130.7 (C-3), 130.2 (C-40),
129.5 (C-30, C-50), 127.4 (C-20, C-60), 124.4 (C-8, C-12), 118.9 (C-
4.2.1. Compound 2a
Yield: 52%, m.p. 144 °C. Anal. Calc. for C27H29N3O3PdS: C, 55.7;
H, 4.6; N, 7.2. Found: C, 55.3; H, 4.1; N, 7.5%.
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.73 (m, 2H), 7.41–7.18
4
(m, 6H), 7.03 (d, J = 2.4 Hz, 1H), 6.97 (AA0BB0 system, 3J = 8.8 Hz,
6), 113.9 (C-9, C-11), 110 (C-2). IR (cmꢁ1): 1581(
1511(dNH); 1418( CN+CS).
mC@N);
2H), 6.60 (dd, 3J = 8.4 Hz, 4J = 2.4 Hz, 1H), 3.99 (q, 3J = 7.1 Hz, 2H),
3.88–3.82 (m, 8H), 1.40 (t, 3J = 7.1 Hz, 3H), 1.25 (t, 3J = 7.1 Hz,
3H). 13C NMR (75 MHz, CDCl3): 172.7 (C–S), 170.9 (CH@N), 170.2
(C-O), 160.3, 158.6, 158.2, 141.6, 140.4, 138.2 (C-1, C-4, C-5, C-7,
C-10, C-10), 130.7 (C-40), 130.2 (C-3), 129.4 (C-30, C-50), 127.3 (C-
20, C-60), 124.4 (C-8, C-12), 118.9 (C-6), 113.9 (C-9, C-11), 109.2
m
4.3.5. Compound 4b
Yield: 43%, m.p. 112 °C. Anal. Calc. for C41H57N3O3PdS: C, 63.3;
H, 7.3; N, 5.4. Found: C, 62.9; H, 7.0; N, 5.0%.
1H NMR (300 MHz, CDCl3): 8.11 (s, 1H), 7.75 (m, 2H), 7.40–7.19
(C-2). IR (cm-1): 1582(
mC@N); 1496(dNH); 1418(mCN+CS).
4
(m, 6H), 7.02 (d, J = 2.4 Hz, 1H), 6.97 (AA0BB0 system, 3J = 8.8 Hz,
2H), 6.59 (dd, 3J = 8.4 Hz, 4J = 2.4 Hz, 1H), 4.06–3.75 (m, 8H),
1.92–1.29 (m, 24H), 1.04 (t, 3J = 7.3 Hz, 3H), 0.91 (m, 9H). 13C
NMR (75 MHz, CDCl3): 173.0 (C–S), 170.9 (CH@N), 170.2 (C–O),
160.3, 158.6, 158.4, 141.1, 140.3, 138.3 (C-1, C-4, C-5, C-7, C-10,
C-10), 130.8 (C-3), 130.3 (C-40), 129.7 (C-30, C-50), 127.5 (C-20, C-
60), 124.5 (C-8, C-12), 118.3 (C-6), 114.6 (C-9, C-11), 110.9 (C-2).
4.3. Synthesis of 2b and 3–13a,b
Compounds 2b and3–13a,b were prepared in the same manner
as 2a by using the binuclear palladium complex/sodium salt of N-
benzoyl thiourea in a molar ratio of 1:3.
IR (cmꢁ1): 1582(
mC@N); 1540, 1516(dNH); 1420(mCN+CS).
4.3.1. Compound 2b
Yield: 50%, m.p. 108 °C. Anal. Calc. for C37H49N3O3PdS: C, 61.5;
H, 6.8; N, 5.8. Found: C, 61.3; H, 6.4; N, 5.3%.
1H NMR (300 MHz, CDCl3): 8.04 (s, 1H), 7.66 (m, 2H), 7.32–7.11
4.3.6. Compound 5a
Yield: 69%, m.p. 138 °C. Anal. Calc. for C35H47N3O3PdS: C, 60.6;
H, 6.5; N, 6.1. Found: C, 60.2; H, 6.1; N, 6.2%.
4
(m, 6H), 6.93 (d, J = 2.4 Hz, 1H), 6.89 (AA0BB0 system, 3J = 8.9 Hz,
2H), 6.51 (dd, 3J = 8.4 Hz, 4J = 2.5 Hz, 1H), 3.94 (m, 6H), 3.78 (q,
3J = 7.0 Hz, 2H), 1.80–1.22 (m, 19H), 1.18 (t, 3J = 7.0 Hz, 3H), 0.84
(m, 6H). 13C NMR (75 MHz, CDCl3): 172.9 (C–S), 170.9 (CH@N),
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.73 (m, 2H), 7.42–7.18
4
(m, 6H), 7.03 (d, J = 2.5 Hz, 1H), 6.98 (AA0BB0 system, 3J = 8.9 Hz,
2H), 6.60 (dd, 3J = 8.3 Hz, 4J = 2.4 Hz, 1H), 3.92–3.75 (m, 10H),

A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
3543
1.87–1.23 (m, 16H), 0.94–0.82 (m, 6H). IR (cmꢁ1): 1583(
1522(dNH); 1421( CN+CS).
m
C@N);
1H NMR (300 MHz, CDCl3): 8.12 (s, 1H), 7.74 (m, 2H), 7.41–7.20
(m, 10H), 6.99 (AA0BB0 system, 3J = 8.9 Hz, 2H), 6.90 (d, 4J = 2.4 Hz,
1H), 6.61 (dd, 3J = 8.4 Hz, 4J = 2.4 Hz, 1H), 3.88 (s, 3H), 3.86 (s,
m
3H), 2.36 (s, 3H). IR (cmꢁ1): 3298(
1399( CN+CS).
mNH); 1584(mC@N); 1501(dNH);
4.3.7. Compound 5b
m
Yield: 59%, m.p. 109 °C. Anal. Calc. for C45H65N3O3PdS: C, 64.8;
H, 7.8; N, 5.0. Found: C, 64.3; H, 7.4; N, 4.8%.
4.3.14. Compound 9b
1H NMR (300 MHz, CDCl3): 8.10 (s, 1H), 7.76 (m, 2H), 7.40–7.19
Yield: 45%, m.p. 179 °C. Anal. Calc. for C40H47N3O3PdS: C, 63.5;
H, 6.2; N, 5.6. Found: C, 63.9; H, 6.0; N, 5.3%.
4
(m, 6H), 7.02 (d, J = 2.5 Hz, 1H), 6.97 (AA0BB0 system, 3J = 8.9 Hz,
2H), 6.58 (dd, 3J = 8.2 Hz, 4J = 2.3 Hz, 1H), 4.05–3.77 (m, 8H),
1.96–1.27 (m, 32H), 0.95–0.83 (m, 12H). 13C NMR (75 MHz, CDCl3):
173.3 (C–S), 171.0 (CH@N), 170.2 (C–O), 160.1, 158.5, 158.3, 141.7,
140.3, 138.5 (C-1, C-4, C-5, C-7, C-10, C-10), 130.8 (C-3), 130.4 (C-
40), 129.6 (C-30, C-50), 127.5 (C-20, C-60), 124.5 (C-8, C-12), 118.6
1H NMR (300 MHz, CDCl3): 8.14 (s, 1H), 7.85 (broad d, 2H),
7.53–7.02 (m, 12H), 6.98 (d broad, 1H), 6.65 (dd, 3J = 8.4 Hz,
4J = 2.3 Hz, 1H), 4.08 (t, 3J = 6.5 Hz, 4H), 2.43 (s, 3H), 1.95–1.40
(m, 16H), 1.01 (m, 6H). IR (cmꢁ1): 3126(
mNH); 1584(mC@N);
1508(dNH); 1451(mCN+CS).
(C-6), 114.6 (C-9, C-11), 110.6 (C-2). IR (cmꢁ1): 1582(
1518(dNH); 1419( CN+CS).
mC@N);
m
4.3.15. Compound 10a
Yield: 52%, m.p. 171 °C. Anal. Calc. for C29H24FN3O3PdS: C, 56.2;
H, 3.9; N, 6.8. Found: C, 55.9; H, 3.5; N, 6.4%.
4.3.8. Compound 6b
Yield: 51%, m.p. 106 °C. Anal. Calc. for C49H73N3O3PdS: C, 66.0;
H, 8.4; N, 4.7. Found: C, 65.6; H, 8.7; N, 4.4%.
1H NMR (300 MHz, CDCl3): 8.12 (s, 1H), 7.79 (broad d, 2H),
7.53–7.19 (m, 8H), 7.06 (AA0MXX system, 3J = 8.3 Hz, 2H), 6.98
(AA0BB0 system, 3J = 8.9 Hz, 2H), 6.87 (broad s, 1H), 6.61 (dd,
3J = 8.3 Hz, 4J = 2.4 Hz, 1H), 3.88 (s, 3H), 3.84 (s, 3H), 2.36 (s, 3H).
1H NMR (300 MHz, CDCl3): 8.06 (s, 1H), 7.70 (m, 2H), 7.35–7.13
4
(m, 6H), 6.96 (d, J = 2.4 Hz, 1H), 6.91 (AA0BB0 system, 3J = 8.9 Hz,
2H), 6.54 (dd, 3J = 8.4 Hz, 4J = 2.3 Hz, 1H), 3.98 (q, 3J = 6.6 Hz, 4H),
IR (cmꢁ1): 3267(
mNH); 1583(mC@N); 1536, 1503(dNH); 1405(mCN+CS).
3.87–3.71 (m, 4H), 1.84–1.16 (m, 38H), 0.91–0.78 (m, 12H).
4.3.16. Compound 10b
4.3.9. Compound 7a
Yield: 41%, m.p. 171 °C. Anal. Calc. for C39H44FN3O3PdS: C, 60.3;
H, 5.7; N, 5.4. Found: C, 59.8; H, 5.4; N, 5.0%.
Yield: 60%, m.p. 145 °C. Anal. Calc. for C29H25N3O3PdS: C, 57.9;
H, 4.2; N, 7.0. Found: C, 57.3; H, 4.6; N, 6.6%.
1H NMR (300 MHz, CDCl3): 8.03 (s, 1H), 7.62 (broad d, 2H), 7.43
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.72 (m, 2H), 7.58 (m,
2H), 7.42–7.20 (m, 9H), 6.99 (AA0BB0 system, 3J = 8.9 Hz, 2H), 6.90
(d, 3J = 2.3 Hz, 1H), 6.61 (dd, 3J = 8.4 Hz, 4J = 2.5 Hz, 1H), 3.88 (s,
(AA0MXX system, 3J = 8.3 Hz, JHF = 4.9 Hz, 2H), 7.35–7.12 (m, 6H),
4
6.99 (AA0MXX system, 3J = 8.4 Hz, 2H), 6.89 (AA0BB0 system,
3J = 9.0 Hz, 2H), 6.78 (broad s, 1H), 6.52 (dd, 3J = 8.3 Hz, 4J = 2.4 Hz,
1H), 3.94 (t, 3J = 6.6 Hz, 4H), 1.91–1.24 (m, 16H), 0.84 (m, 6H). IR
3H), 3.86 (s, 3H). IR (cmꢁ1): 3295(
mNH); 1585(mC@N); 1526,
(cmꢁ1): 3111(
mNH); 1583(mC@N); 1544, 1507(dNH); 1400(mCN+CS).
1501(dNH); 1428(mCN+CS).
4.3.17. Compound 11a
4.3.10. Compound 7b
Yield: 61%, m.p. 199 °C. Anal. Calc. for C29H24ClN3O3PdS: C, 54.7;
H, 3.8; N, 6.6. Found: C, 54.3; H, 3.9; N, 6.2%.
Yield: 47%, m.p. 115 °C. Anal. Calc. for C39H45N3O3PdS: C, 63.1;
H, 6.0; N, 5.7. Found: C, 63.0; H, 6.5; N, 5.3%.
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.69 (d broad, 2H), 7.52
1H NMR (300 MHz, CDCl3): 8.10 (s, 1H), 7.75 (broad d, 2H), 7.58
(m, 2H), 7.43–7.18 (m, 9H), 6.97 (AA0BB0 system, 3J = 8.8 Hz, 2H),
6.89 (broad s, 1H), 6.60 (m, 1H), 4.02 (t, 3J = 6.6 Hz, 4H), 1.94–
3
(AA0BB0 system, J = 8.8 Hz, 2H), 7.45–7.21 (m, 8H), 6.98 (AA0BB0
system, 3J = 8.9 Hz, 2H), 6.87 (d, 4J = 2.3 Hz, 1H), 6.61 (dd,
3J = 8.3 Hz, 4J = 2.4 Hz, 1H), 3.88 (s, 3H), 3.85 (s, 3H). IR (cmꢁ1):
1.25 (m, 16H), 0.94 (m, 6H). IR (cmꢁ1): 3128(
mNH); 1585(mC@N);
3209(mNH); 1582(mC@N); 1527(dNH); 1415(mCN+CS).
1540, 1502(dNH); 1422(
mCN+CS).
4.3.18. Compound 11b
4.3.11. Compound 8a
Yield: 43%, m.p. 199 °C. Anal. Calc. for C39H44ClN3O3PdS: C, 60.3;
H, 5.7; N, 5.4. Found: C, 60.0; H, 5.8; N, 5.0%.
Yield: 47%, m.p. 218 °C. Anal. Calc. for C30H27N3O3PdS: C, 58.5;
H, 4.4; N, 6.8. Found: C, 58.1; H, 4.8; N, 6.4%.
1H NMR (300 MHz, CDCl3): 8.10 (s, 1H), 7.71 (broad d, 2H), 7.52
(AA0BB0 system, 3J = 8.9 Hz, 2H), 7.44–7.21 (m, 8H), 6.97 (AA0BB0 sys-
tem, 3J = 8.9 Hz, 2H), 6.87 (d, 4J = 2.4 Hz, 1H), 6.60 (dd, 3J = 8.3 Hz,
4J = 2.4 Hz, 1H), 4.02 (t, 3J = 6.6 Hz, 4H), 1.89–1.32 (m, 16H), 0.93
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.72 (d broad, 2H),
7.47–7.16 (m, 10H), 6.98 (AA0BB0 system, 3J = 8.9 Hz, 2H), 6.90 (s
broad, 1H), 6.60 (dd, 3J = 8.2 Hz, 4J = 2.4 Hz, 1H), 3.88 (s, 3H), 3.84
(s, 3H), 2.35 (s, 3H). IR (cmꢁ1): 3363(
mNH); 1583(mC@N);
(m, 6H). IR (cmꢁ1): 3209(
mNH); 1584(mC@N); 1525(dNH); 1424(mCN+CS).
1520(dNH); 1419(mCN+CS).
4.3.19. Compound 12a
4.3.12. Compound 8b
Yield: 66%, m.p. 201 °C. Anal. Calc. for C29H24BrN3O3PdS: C, 51.1;
H, 3.5; N, 6.2. Found: C, 50.9; H, 3.9; N, 6.9%.
Yield: 45%, m.p. 156 °C. Anal. Calc. for C40H47N3O3PdS: C, 63.5;
H, 6.2; N, 5.6. Found: C, 63.8; H, 6.0; N, 5.2%.
1H NMR (300 MHz, CDCl3): 8.13 (s, 1H), 7.69 (m, 2H), 7.47–7.21
(m, 10H), 6.99 (AA0BB0 system, 3J = 8.7 Hz, 2H), 6.87 (d, 4J = 2.4 Hz,
1H), 6.61 (dd, 3J = 8.2 Hz, 4J = 2.4 Hz, 1H), 3.88 (s, 3H), 3.85 (s,
1H NMR (300 MHz, CDCl3): 8.11 (s, 1H), 7.75 (broad d, 2H),
7.48–7.17 (m, 10H), 6.98 (AA0BB0 system, 3J = 8.9 Hz, 2H), 6.90 (d
broad, 1H), 6.60 (dd, 3J = 8.3 Hz, 4J = 2.4 Hz, 1H), 4.03 (t,
3J = 6.6 Hz, 4H), 2.36 (s, 3H), 1.90–1.34 (m, 16H), 0.93 (m, 6H). IR
3H). IR (cmꢁ1): 3298(
mNH); 1584(mC@N); 1501(dNH); 1399(mCN+CS).
(cmꢁ1): 3321(
mNH); 1584(mC@N); 1510(dNH); 1425(mCN+CS).
4.3.20. Compound 12b
Yield: 33%, m.p. 191 °C. Anal. Calc. for C39H44BrN3O3PdS: C, 57.0;
H, 5.4; N, 5.1. Found: C, 56.8; H, 5.0; N, 4.9%.
4.3.13. Compound 9a
Yield: 81%, m.p. 153 °C. Anal. Calc. for C30H27N3O3PdS: C, 58.5;
H, 4.4; N, 6.8. Found: C, 58.2; H, 4.8; N, 6.7%.
1H NMR (300 MHz, CDCl3): 8.02 (s, 1H), 7.64 (m, 2H), 7.36–7.14
(m, 10H), 6.90 (AA0BB0 system, 3J = 8.8 Hz, 2H), 6.79 (d, 4J = 2.4 Hz,

3544
A.C. Tenchiu et al. / Polyhedron 27 (2008) 3537–3544
1H), 6.52 (dd, 3J = 8.4 Hz, 4J = 2.4 Hz, 1H), 3.94 (t, 3J = 6.6 Hz, 4H),
1.80–1.24 (m, 16H), 0.86 (m, 6H). IR (cmꢁ1): 3210(
NH);
1584( C@N); 1510(dNH); 1423( CN+CS).
References
m
[1] B. Donnio, D. Guillon, R. Deschenaux, D.W. Bruce, in: J.A. McCleverty, T.J.
Meyer (Eds.), Comprehensive Coordination Chemistry II, vol. 7, Elsevier,
Oxford, 2003, p. 357 (Chapter 7.9).
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m
m
4.3.21. Compound 13a
Yield: 56%, m.p. 162 °C. Anal. Calc. for C30H27N3O4PdS: C, 57.0;
H, 4.3; N, 6.7. Found: C, 56.9; H, 4.6; N, 6.3%.
1H NMR (300 MHz, CDCl3): 8.11 (s, 1H), 7.67 (m, 2H), 7.57–7.19
(m, 10H), 6.99–6.87 (m, 3H), 6.59 (dd, 3J = 8.2 Hz, 4J = 2.4 Hz, 1H),
3.86 (s, 3H), 3.81 (s, 3H). IR (cmꢁ1): 3298(
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1501(dNH); 1399(mCN+CS).
4.3.22. Compound 13b
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Yield: 51%, m.p. 165 °C. Anal. Calc. for C40H47N3O4PdS: C, 62.4;
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1H NMR (300 MHz, CDCl3): 8.10 (s, 1H), 7.72 (br, 2H), 7.49–7.20
(m, 10H), 6.97 (AA0BB0 system, 3J = 8.8 Hz, 2H), 6.92 (d, 4J = 2.4 Hz,
1H), 6.52 (dd, 3J = 8.4 Hz, 4J = 2.4 Hz, 1H), 4.01 (t, 3J = 6.6 Hz, 2H),
3.82 (t, 3J = 6.6 Hz, 2H), 1.90–1.32 (m, 16H), 0.91 (m, 6H). IR
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(cmꢁ1): 3220(
mNH); 1585(mC@N); 1509(dNH); 1420(mCN+CS).
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Acknowledgements
The authors wish to thank MEdC (Romanian Ministry of Educa-
tion and Research, Project CEEX ET-31 and Project PNII ID_954) and
NATO for funding this study and to Prof. Duncan W. Bruce (Univer-
sity of York, UK) for his support.
[16] Y. Cao, B. Zhao, Y.-Q. Zhang, D.-C. Zhang, Acta Crystallogr., Sect. C 52 (1996)
1772.
[17] S. Shanmuga Sundara Raj, K. Puviarasan, D. Velmurugan, G. Jayanthi, H.-K. Fun,
Acta Crystallogr., Sect. C 55 (1999) 1318.
Appendix A. Supplementary data
[18] P. Wagner, S. Niemczyk-Baltro, M. Kubicki, Acta Crystallogr., Sect. C 59 (2003)
o83.
[19] P.J. Collings, M. Hird, Introduction to Liquid Crystals Chemistry and Physics,
Taylor & Francis, London and New York, 2004.
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University of Göttingen, Germany, 1997.
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Bruce, Liq. Cryst. 32 (2005) 1437.
CCDC 684867, 684868 and 684869 contain the supplementary
crystallographic data for 2a, 10a and 13a. These data can be ob-
tained free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.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.2008.08.023.