Palladium(II) complexes of tridentate chalcogenated Schiff bases and related ligands of (S, N, S/Se/Te) type: Synthesis and structural chemistry

Article abstract of DOI:10.1016/j.ica.2012.01.007

The reactions in CH₃CN between PdCl₂ and Schiff base ligands, 2-MeSC₆H₄-CHNCH₂CH₂E-C ₆H₄-4-R (L1-L3) (E = S or Se, R = H; E = Te, R = OCH ₃) and their reduc

Full text of DOI:10.1016/j.ica.2012.01.007

Inorganica Chimica Acta 387 (2012) 441–445
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Note
Palladium(II) complexes of tridentate chalcogenated Schiff bases and related
ligands of (S, N, S/Se/Te) type: Synthesis and structural chemistry
⇑
Pradhumn Singh, Ajai K. Singh
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The reactions in CH3CN between PdCl2 and Schiff base ligands, 2-MeSC6H4–CH@NCH2CH2E–C6H4–4-R
(L1–L3) (E = S or Se, R = H; E = Te, R = OCH3) and their reduced derivatives 2-MeSC6H4CH2–
NHCH2CH2E–C6H4–4-R (L4–L6) followed by treatment with AgPF6 or AgClO4 have resulted in complexes
[PdCl(L)][X] (1–6; L = L1–L6; X = PF6 or ClO4) which have been characterized by IR, 1H, 13C{1H}, 77Se{1H}
and 125Te{1H} NMR spectroscopy. Single crystal structures of complexes 1–6 reveal nearly square planar
geometry around palladium in all of them (Pd–Se = 2.4045(16)–2.4065(6) Å; Pd–Te = 2.5052(9)–
2.5307(13) Å). The various non-covalent interactions in the crystals result in the formation of chains,
rings and caging of anions between cations.
Received 4 September 2011
Received in revised form 5 December 2011
Accepted 4 January 2012
Available online 10 January 2012
Keywords:
Organochalcogen ligand
Schiff base
Secondary amine
Palladium(II)
Ó 2012 Elsevier B.V. All rights reserved.
Synthesis
Crystal structure
1. Introduction
them have chalcogen donor atoms, particularly selenium or tellu-
rium [4,12,13]. Copper complexes of reduced Schiff bases prepared
Chalcogenated Schiff bases containing both ‘soft’ and ‘hard’ do-
nor sites are hybrid ligands which may show hemilabile behavior.
Thus they are not only academic curiosities but also attractive for
catalyst designing as facile reversible generation of a coordinatively
unsaturated metal center [1] is possible in their metal complexes. In
the recent past catalytic applications of Pd(II)-complexes of sulfated
[2–5], selenated [5,6] and tellurated Schiff bases [7,8] have been
reported. Among chalcogenated Schiff bases those containing
thioether donor site have been explored more than selenated and
tellurated ones. In fact selenated and tellurated ones are still
scarcely known.
The secondary amines synthesized from Schiff bases by reduc-
tion of their >C@N bond are stable and more adaptable to form con-
formationally flexible five- or six-membered rings on complexation
with metal ions than their precursors, which are constrained to be
planar. The hydrogen of their >NH formed due to reduction of azo-
methine group of Schiff base becomes significantly better acidic on
coordination of N to a metal ion. Consequently coordinated N–H
may better participate in intermolecular hydrogen-bonding, result-
ing in the supramolecular self-assembly of their metal complexes
[9]. There are many examples of their metal complexes in literature
[9–11]. Some of them have N, O and P donor sites but only few of
from salicylaldehyde and amino acids were explored as models for
intermediate species in biological racemization and transamination
reactions [10]. Recently Rao et al. [14] have reported an air and
moisture insensitive palladacycle [PdCl(L–H)], where L = (N, Se,
CÀ) ligand (C6H5)(2-HOC6H4)CHNH(CH2)3SePh). This palladacycle
shows high catalytic activity for Suzuki–Miyaura coupling reaction
of phenylboronic acid with aryl/heteroaryl chlorides/bromides
(TON for ArCl up to 9200) and is converted to ꢀ8 nm size nano-
particles of composition Pd17Se15, which have been proposed to
be the real catalysts. It was therefore thought worthwhile to study
ligation of L (L1–L6; Scheme 1) with palladium(II). Thus complexes,
[PdCl(L)][PF6/ClO4] of tridentate Schiff bases 2-MeSC6H4CH@NCH2
CH2E–C6H4–4-R (L1–L3) and their reduced derivatives 2-MeSC6
H4CH2–NHCH2CH2E–C6H4–4-R (L4–L6) (where E = S or Se, R = H;
E = Te, R = OCH3) were synthesized and explored for their structural
chemistry. The crystal structures of these complexes have a variety
of non-covalent interactions, which result in interesting structural
patterns. These results are given in the present paper.
2. Experimental
2.1. Physical measurement
Perkin-Elmer 2400 Series II C, H, N analyzer was used for ele-
mental analyses. The 1H, 13C{1H}, 77Se{1H} and 125Te{1H} NMR
spectra were recorded on a Bruker Spectrospin DPXÀ300 NMR
⇑
Corresponding author. Tel.: +91 11 26591379; fax: +91 11 26581102.
E-mail addresses:
aksingh@chemistry.iitd.ac.in,
ajai57@hotmail.com
(A.K. Singh).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2012.01.007

442
P. Singh, A.K. Singh / Inorganica Chimica Acta 387 (2012) 441–445
6
5
3
2
+
6
5
3
2
1
13
10
8
9
N
E
R [ X ]
PdCl2 / AgPF6 or AgClO4
CH3CN / reflux / 8 h
13
10
1
12
11
4
7
8
9
N
E
R
Pd
12
11
4
7
S
Cl
S
Me
Me
1: E = S, X = PF6; 2: E = Se, X = PF6
3: E = Te, X = ClO 4
L1: E = S, R = H; L2: E = Se, R = H; L3: E = Te, R = OMe
EtOH / NaBH4 5 h / r.t. / N2 atm.
6
5
3
2
+
6
5
3
2
1
13
10
PdCl2 / AgPF6 or AgClO4
CH3CN / reflux / 8 h
1
13
8
9
N
E
R [ X ]
8
9
N
E
R
12
11
H
4
7
12
11
H
7
4
Pd
S
S
Cl
10
Me
Me
L4: E = S, R = H; L5: E = Se, R = H; L6: E = Te, R = OMe
4: E = S, X = PF6; 5: E = Se, X = PF6
6: E = Te, X = ClO 4
Scheme 1. Syntheses of Pd(II)–complexes 1–6.
spectrometer at 300.13, 75.47, 57.24 and 94.69 MHz, respectively.
IR spectra in the range 4000–400 cmÀ1 were recorded on a Nicolet
Protége 460 FT-IR spectrometer. The diffraction data on single-
crystals of 1–6 were collected on a Bruker AXS SMART Apex CCD
Caution: Perchlorate is potentially explosive and therefore
should be handled carefully.
Complex 1: Yellow solid. Yield: 0.49 g, 85%; m.p. 152 °C.
KM = 148.4 S cm2 molÀ1
.
Anal. Calc. for C16H17ClNPdS2ÁPF6: C,
diffractometer using Mo K
a
(0.71073 Å) radiations at 298(2) K.
33.47; H, 2.98; N, 2.44. Found: C, 33.41; H, 2.91; N, 2.49%. 1H
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 2.99 (s, 3H, SCH3),
3.23–3.27 (m, 2H, H5), 4.26–4.30 (m, 2H, H6), 7.53–8.09 (m, 9H,
The software SADABS [15] was used for absorption correction (if
needed) and SHELXTL for space group, structure determination and
refinements [16]. All non-hydrogen atoms were refined anisotrop-
ically. Hydrogen atoms were included in idealized positions with
isotropic thermal parameters set at 1.2 times that of the carbon
atom to which they are attached. The least-square refinement
cycles on F2 were performed until the model converged. The con-
ductivity measurements were made in CH3CN (Concentration ca.
1 mM) using ORION conductivity meter model 162. Melting points
determined in open capillary are reported as such.
H
1–3, H10–13), 8.52 (s, 1H, H7). 13C{1H} NMR (CD3CN, 25 °C, versus
Me4Si): (d, ppm): 27.9 (SCH3), 39.5 (C5), 70.3 (C6), 125.2–134.3
(C1–4, C10–13), 137.3 (C8), 139.8 (C9), 166.9 (C7). IR (KBr, mmax
cmÀ1): 3055 (m;
C–H(aromatic)), 2920 (s; C–H(aliphatic)), 1634, 1580
(s; C@N), 1225 (m; C–N), 838 (s; P–F), 748 (m; C–H(aromatic)).
Complex 2: Orange solid. Yield: 0.53 g, 85%; m.p. 148.0 °C.
/
m
m
m
m
m
m
KM = 145.8 S cm2 molÀ1. Anal. Calc. for C16H17ClNPdSSeÁPF6: C,
30.94; H, 2.76; N, 2.26. Found: C, 30.89; H, 2.70; N, 2.20%. 1H
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 3.00 (s, 3H, SCH3),
3.05–3.25 (m, 2H, H5), 4.35–4.81 (m, 2H, H6), 7.54–8.12 (m, 9H,
H1–3, H10–13), 8.50 (s, 1H, H7). 13C{1H} NMR (CD3CN, 25 °C, versus
Me4Si): (d, ppm): 26.0 (SCH3), 32.5 (C5), 72.1 (C6), 126.2–134.6
(C1–4, C10–13), 137.0 (C8), 139.4 (C9), 167.5 (C7). 77Se{1H} NMR
2.2. Chemicals and reagents
2-(Phenylsulfanyl)ethylamine, 2-(phenylseleno)ethylamine and
2-(4-methoxyphenyltelluro)ethylamine were synthesized by re-
ported methods [17–20]. 2-(Methylthio)benzaldehyde, PdCl2,
AgPF6 and AgClO4 were procured from Sigma–Aldrich (USA) and
used as received. All the solvents were dried and distilled before
use by standard procedures [21]. The L1–L6 have been synthesized
according to procedure reported earlier by us [22,23].
(CD3CN, 25 °C, versus Me2Se): (d, ppm): 456.2. IR (KBr, mmax
cmÀ1): 3055 (m;
C–H(aromatic)), 2919 (s; C–H(aliphatic)), 1632, 1579
(s; C@N), 1191 (m; C–N), 839 (m; P–F), 745 (m; C–H(aromatic)).
/
m
m
m
m
m
m
Complex 3: Orange solid. Yield: 0.56 g, 85%; m.p. 147.0 °C.
KM = 142.3 S cm2 molÀ1. Anal. Calc. for C17H19ClNOPdSTeÁClO4: C,
31.11; H, 3.22; N, 2.13. Found: C, 31.02; H, 3.17; N, 2.19%. 1H
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 2.50–2.90 (m, 2H,
H5), 2.97 (s, 3H, SCH3), 3.85 (s, 3H, OCH3), 4.83–5.74 (m, 2H, H6),
2.3. Synthesis of palladium(II) complexes (1–6)
3
7.05 (d, JH–H = 8.7 Hz, 2H, H2), 7.36–7.93 (m, 4H, H10–13), 7.99 (d,
The CH3CN (20 cm3) and solid PdCl2 (0.18 g, 1 mmol) were
mixed and the mixture was refluxed with stirring until a clear light
yellow coloured solution was obtained. The solution of a ligand
from L1 to L6 (0.28–0.42 g, 1 mmol) made in CH3OH (5 cm3) was
added to it and the mixture refluxed for 5 h. Thereafter AgPF6
(0.25 g, 1 mmol)/AgClO4 (0.21 g, 1 mmol) was mixed and the mix-
ture further refluxed for 3 h. It was cooled to room temperature
and turbidity of AgCl was filtered off. The filtrate was concentrated
to ꢀ5 cm3 on a rotary evaporator and mixed with diethyl ether
(10 cm3) to obtain 1–6 as yellow-orange solid, which was filtered
and dried in vacuo. The single crystals of 1–6 were grown by slow
evaporation of their solutions in CH3CN–CH3OH mixture (3:2).
3JH–H = 8.7 Hz, 2H, H3), 8.46 (s, 1H, H7). 13C{1H} NMR (CD3CN,
25 °C, versus Me4Si): (d, ppm): 17.0 (C5), 21.9 (SCH3), 56.3
(OCH3), 74.5 (C6), 105.6 (C4), 117.2 (C2), 128.5–134.0 (C10–13),
136.4(C8), 138.5 (C9), 139.6 (C3), 163.0 (C1), 168.8 (C7). 125Te{1H}
NMR (CD3CN, 25 °C, versus Me2Te): (d, ppm): 792.2. IR (KBr,
m
max/cmÀ1): 3048 (m;
1583 (s; C@N), 1201 (m;
Complex 4: Yellow solid. Yield: 0.49 g, 85%; m.p. 157.0 °C.
m
C–H(aromatic)), 2926 (s;
mC–H(aliphatic)), 1632,
m
m
C–N), 747 (m; C–H(aromatic)).
m
KM = 137.8 S cm2 molÀ1
.
Anal. Calc. for C16H19ClNPdS2ÁPF6: C,
33.35; H, 3.32; N, 2.43. Found: C, 33.30; H, 3.38; N, 2.49%. 1H
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 2.09 (s, 1H, NH),
2.91 (s, 3H, SCH3), 3.38–3.94 (m, 2H, H5), 4.44–4.95 (m, 2H, H6),

P. Singh, A.K. Singh / Inorganica Chimica Acta 387 (2012) 441–445
443
5.13 (s, 2H, H7), 7.53–7.77 (m, 8H, H1–2, H10–13), 8.02–8.09 (m, 2H,
H3). 13C{1H} NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 23.3
(SCH3), 40.5 (C5), 56.8 (C6), 62.6 (C7), 126.9–137.2 (C1–4, C10–13).
spectra of 3 and 6 the signals appear at frequencies higher by
353.9 and 339.5 ppm relative to those of free L3 and L6, respec-
tively [22], which are coordinated to palladium through Te. In 1H
and 13C{1H} NMR spectra of 1–6 signals generally appear at higher
frequency relative to those of corresponding free ligand from L1 to
L6 [22], which coordinate with palladium in a tridentate mode.
However, magnitude of shift to higher frequency is high for C5–
C7 (up to 11.7 ppm in 13C{1H} NMR) and protons attached to them
(up to 1.36 ppm in 1H NMR) [22]. The signals of SCH3 in 13C{1H}
and 1H NMR spectra of 1–6 also appear at higher frequency (up
to 11.1 and 0.54 ppm, respectively) relative to those of appropriate
ligands [22]. The signals of NH in 1H NMR spectra of 4–6 appear at
higher frequencies (up to 0.29 ppm) with respect to those of corre-
sponding free ligand (from L4 to L6) [22].
IR (KBr,
m
max/cmÀ1): 3049 (m;
), 742 (m; C–H(aromatic)).
mC–H(aromatic)), 2922 (s; mC–H(aliphatic)),
1181 (m;
m
m
C–N
Complex 5: Orange solid. Yield: 0.53 g, 85%; m.p. 152.0 °C.
KM = 135.6 S cm2 molÀ1. Anal. Calc. for C16H19ClNPdSSeÁPF6: C,
30.84; H, 3.07; N, 2.25. Found: C, 30.80; H, 3.01; N, 2.20%. 1H
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 2.19 (s, 1H, NH),
2.94 (s, 3H, SCH3), 3.32–3.92 (m, 2H, H5), 4.32–4.63 (m, 2H, H6),
5.00 (s, 2H, H7), 7.53–7.88 (m, 8H, H1–2, H10–13), 8.02–8.10 (m, 2H,
H3). 13C{1H} NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 21.5
(SCH3), 33.0 (C5), 56.1 (C6), 60.0 (C7), 126.6–136.6 (C1–4, C10–13).
77Se{1H} NMR (CD3CN, 25 °C, versus Me2Se): (d, ppm): 429.5. IR
(KBr,
1179 (m;
m
max/cmÀ1): 3049 (m;
C–N), 741 (m; C–H(aromatic)).
m
C–H(aromatic)), 2924 (s;
m
C–H(aliphatic)),
The bands between 1585 and 1637 cmÀ1 in IR spectra of L1–L3
are due to >C@N stretching. The C–N stretching in case of L4–L6
appears from 1184 to 1191 cmÀ1 [22]. On complex formation both
these IR bands show red shift (8–10 cmÀ1) as N is coordinated with
palladium.
m
m
Complex 6: Orange solid. Yield: 0.60 g, 85%; m.p. 154.2 °C.
KM = 134.2 S cm2 molÀ1. Anal. Calc. for C17H21ClNOPdSTeÁClO4: C,
31.11; H, 3.22; N, 2.13. Found: C, 31.18; H, 3.20; N, 2.18%. 1H
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 2.19 (1H, s, NH),
2.90 (s, 3H, SCH3), 3.02–3.70 (m, 2H, H5), 3.85 (s, 3H, OCH3), 4.03–
3.2. Crystal structures
3
4.21 (m, 2H, H6), 4.91 (s, 2H, H7), 7.02 (d, 2H, JH–H = 7.5 Hz, H2),
3
7.49–7.63 (m, 4H, H10–13), 7.89 (d, 2H, JH–H = 7.5 Hz, H3). 13C{1H}
The crystal structures of 1–6 have been solved and their crystal
data and refinements are given in Table S1. The ORTEP diagrams of
representative cations i.e. of 2 and 5 are given in Figs. 1 and 2 with
selected bond lengths and angles (more values are given in Supple-
mentary material; Table S2). For ORTEP diagrams of cations of 1, 3,
4 and 6 see Supplementary material (Figs. S5–S8). The crystal
structures of complexes having cations similar to those of 3 and
6 were solved earlier in orthorhombic and triclinic crystal system,
respectively [14]. However crystal structures of 3 and 6 have been
reported here in monoclinic crystal system. The unit cell parame-
ters (Table S1 in Supplementary material) reveal that complexes
1 and 4 are iso-structural and same is true for 3 and 6. However,
complex 5 is not iso-structural with 2 but with 4. The geometry
around Pd in the cations of 1–6 is nearly square planar and the li-
gands are coordinated with Pd in a tri-dentate (S, N, E) (where E = S
or Se or Te) mode forming six- and five-membered rings. The Pd–S
bond lengths of 1–6, 2.2707(10)–2.345(2) Å and Pd–Se bond
lengths of 2 and 5 (2.4065(6) and 2.4045(16) Å, respectively) are
in expected normal ranges [6,7,14,24]. The Pd–Te bond lengths of
NMR (CD3CN, 25 °C, versus Me4Si): (d, ppm): 16.7 (C5), 18.6
(SCH3), 56.2 (C6), 56.5 (OCH3), 61.2 (C7), 105.7 (C4), 116.9 (C2),
126.2–133.4 (C10–13), 135.5 (C8), 137.2 (C9), 139.3 (C3), 162.8 (C1).
125Te{1H} NMR (CD3CN, 25 °C, versus Me2Te): (d, ppm): 753.8. IR
(KBr,
m
max/cmÀ1): 3052 (m;
C–N), 742 (m; C–H(aromatic)).
mC–H(aromatic)), 2922 (s; mC–H(aliphatic)),
1178 (m;
m
m
3. Results and discussion
Scheme 1 summarizes the syntheses of palladium(II) complexes
1–6. The counter anion in complex 3 is ClO4À. A complex species
À
having cation identical to that of 3 and anion PF6 has been re-
ported earlier [14]. Earlier single crystals of 6 synthesized [14] in
CH3OH by reacting Na2PdCl4 with L6 were grown from chloro-
form–hexane mixture (2:1). However, it has been prepared now
by reacting PdCl2 with L6 in CH3CN and its single crystals have been
grown from CH3CN–CH3OH mixture (3:2). The 1H and 13C{1H} NMR
spectra of presently synthesized 3 or 6 are only marginally different
from those reported earlier [14] for species having cations similar to
theirs. However, crystal data of these species differ from those re-
ported earlier for complexes having similar cations. The difference
in anion and/or absence of solvent molecule may be responsible
for it. The earlier reported complexes containing cations corre-
sponding to 3 or 6 crystallize with at least one CHCl3 molecule
and the complex corresponding to 3 has 0.5 H2O additionally.
The molar conductance values in acetonitrile indicate 1:1 elec-
trolyte nature of all complexes 1–6. The complexes show good sol-
ubility in CH3OH, CH3CN, CH2Cl2 and CHCl3. In diethyl and
petroleum ether the complexes 1–6 were found to be nearly insol-
uble. The solutions of all complexes in DMSO showed signs of
decomposition within few hours.
3
(2.5307(13) Å) and 6 (2.5052(9) Å) are in normal range
[7,14,25,26]. The greater flexibility of skeleton of L6 than that of
L3 (due to reduction of >C@N) gives more room to sterically
demanding Te, resulting in a somewhat stronger bond with Pd
and shorter Pd–Te distance. Small differences in bond distances
3.1. NMR and IR spectra
The 1H and 13C{1H} NMR spectra of complexes 1–6 have been
found characteristic of their molecular structures and support the
presence of ligands L1–L6 in them. The 77Se{1H} and 125Te{1H}
NMR spectra of 2, 3, 5, and 6 are given in supplementary material
(Figs. S1–S4). The signals in 77Se{1H} NMR spectra of 2 and 5 ap-
pear shifted to higher frequencies by 177.9 and 164.5 ppm with re-
spect to those of free L2 and L5, respectively [22], as Se is
coordinated to palladium centre. Similarly in 125Te{1H} NMR
Fig. 1. ORTEP diagram of the cation of 2 with ellipsoids at the 30% probability level.
The PF6À anion has been omitted for clarity. Selected bond lengths (Å): Pd(1)–Se(1)
2.4065(6), Pd(1)–S(1) 2.2864(12), Pd(1)–N(1) 2.012(3), Pd(1)–Cl(1) 2.2680(12);
bond angles (°): Se(1)–Pd(1)–S(1) 178.52(3), Se(1)–Pd(1)–Cl(1) 91.96(4), Se(1)–
Pd(1)–N(1) 87.01(10), S(1)–Pd(1)–Cl(1) 89.10(4), S(1)–Pd(1)–N(1) 91.96(11), N(1)–
Pd(1)–Cl(1) 177.98(10). Symmetry transformation used to generate equivalent
atoms: (i) x, y, z; (ii) Àx, 0.5 + y, 0.5 À z; (iii) Àx, Ày, Àz; (iv) x, 0.5 À y, 0.5 + z.

444
P. Singh, A.K. Singh / Inorganica Chimica Acta 387 (2012) 441–445
CH2–NHCH2CH2E–C6H4–4-R (L4–L6) (where E = S or Se, R = H;
E = Te, R = OCH3); X = PF6 or ClO4] have been synthesized by the
reactions of PdCl2 in CH3CN with L1–L6 and characterized by IR
and multi-nuclei NMR spectroscopy and single crystal X-ray
crystallography. The interesting non-covalent interactions have
been observed in the crystals of 1–6. The PF6À is caged by cationic
Pd(II) species. The C–HÁ Á Á and P–FÁ Á ÁH interactions together result
p
into two-dimensional (2D) sheet structure in the crystals of 1, 4
and 5.
Acknowledgements
Authors thank Council of Scientific and Industrial Research
(CSIR) New Delhi (India) for the Project No. 01(2421)10/EMR-II
and Department of Science and Technology (India) for partial
financial assistance given to establish single crystal X-ray diffrac-
tion facility at IIT Delhi, New Delhi (India) under its FIST program.
P.S. thanks University Grants Commission (India) for the award of
Junior and Senior Research Fellowship.
Fig. 2. ORTEP diagram of the cation of 5 with ellipsoids at the 30% probability level.
The PF6À anion has been omitted for clarity. Selected bond lengths (Å): Pd(1)–Se(1)
2.4045(16), Pd(1)–S(1) 2.292(4), Pd(1)–N(1) 2.056(9), Pd(1)–Cl(1) 2.292(3); bond
angles (°): Se(1)–Pd(1)–S(1) 177.22(10), Se(1)–Pd(1)–Cl(1) 90.09(10), Se(1)–Pd(1)–
N(1) 87.04(3), S(1)–Pd(1)–Cl(1) 87.26(13), S(1)–Pd(1)–N(1) 95.2(3), N(1)–Pd(1)–
Cl(1) 177.5(3). Symmetry transformation used to generate equivalent atoms: (i) x, y,
z; (ii) Àx, 0.5 + y, 0.5Àz; (iii) Àx, Ày, Àz; (iv) x, 0.5 À y, 0.5 + z.
arise due to variation in dentate character of ligands and their ste-
ric compulsions. The PdÀN and PdÀCl bond lengths of complexes
1–6, 2.012(3)–2.096(7) and 2.2680(12)–2.3056(11) Å, respectively
are also normal. The bond angles at the coordinating S/Se/Te and
N atoms are as expected for nearly trigonal-pyramidal and tetrahe-
dral geometries, respectively.
Appendix A. Supplementary material
CCDC 798691, 798692, 798693, 798694, 798695 and 798696
contain the supplementary crystallographic data for complexes
1–6, respectively. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/j.ica.
2012.01.007.
3.3. Secondary interactions
In the crystals of 1–6, due to non-covalent interactions several
structural patterns have been observed. Some inter atomic dis-
tances for these interactions are given in Table S3 and they are
shown in Figs. S9–S43 of Supplementary material. The P–FÁ Á ÁH
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À
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4. Conclusions
The six cationic Pd(II) complexes of composition [PdCl(L)][X]
[L = 2-MeSC6H4CH@NCH2CH2E–C6H4–4-R (L1–L3) and 2-MeSC6H4

P. Singh, A.K. Singh / Inorganica Chimica Acta 387 (2012) 441–445
445
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