Mixed ligand palladium(II) complex with NS-bidentate S-allyldithiocarbazate Schiff base: Synthesis, spectral characterization, crystal structure and ecoding intermolecular interactions with Hirshfeld surface analysis

Article abstract of DOI:10.1002/cjoc.201090057

A new mixed ligand palladium(II) complex with bidentate NS-donor chelate, [PdCl(PPh₃)L] (L: S-allyl β-N-(benzylidene)dithiocarbazate), has been prepared and characterized using single crystal X-ray diffraction and spectroscopic (electronic, IR, ¹H NMR and ¹³C NMR) techniques. The shorter Pd-P bond distance, 2.255(7) A, than the sum of the single bond radii for palladium and phosphorus (2.41A), showed partial double bond character. Visualizing and exploring the crystal structure using Hirshfeld surface analysis showed the presence of π···π, N···π, C-H···π, Cl···H and weak C-H···S interactions as most important intermolecular interactions in the crystal lattice, which are responsible to extension of the supramolecular network of the compound and stabilization of the crystal structure.

Full text of DOI:10.1002/cjoc.201090057

FULL PAPER
Mixed Ligand Palladium(II) Complex with NS-Bidentate
S-Allyldithiocarbazate Schiff Base: Synthesis, Spectral Char-
acterization, Crystal Structure and Decoding Intermolecular
Interactions with Hirshfeld Surface Analysis
Takjoo, Reza*,a
Takjoo, Rozitab
Yazdanbakhsh, Mohammadc
Chen, Yaguange
Aghaei kaju, Amird
a Department of Chemistry, Faculty of Science, Islamic Azad University-Mashhad Branch, Mashhad, Iran
b Shirvan Azad University-Shirvan Branch, Shirvan, Iran
c Department of Chemistry, School of Sciences, Ferdowsi University of Mashhad, Mashhad 91779-1436, Iran
d Department of Chemistry, Research Institute of Sciences & Food Technology, Khorasan Science & Technology
Park, Mashhad, 91735-139, Iran
e Faculty of Chemistry, Northeast Normal University, 138 Renmin Street, Changchun 130024, China
A new mixed ligand palladium(II) complex with bidentate NS-donor chelate, [PdCl(PPh3)L] (L: S-allyl
β-N-(benzylidene)dithiocarbazate), has been prepared and characterized using single crystal X-ray diffraction and
1
spectroscopic (electronic, IR, H NMR and 13C NMR) techniques. The shorter Pd—P bond distance, 2.255(7) Å,
than the sum of the single bond radii for palladium and phosphorus (2.41 Å), showed partial double bond character.
Visualizing and exploring the crystal structure using Hirshfeld surface analysis showed the presence of π…π, N…π,
C—H…π, Cl…H and weak C—H…S interactions as most important intermolecular interactions in the crystal lat-
tice, which are responsible to extension of the supramolecular network of the compound and stabilization of the
crystal structure.
Keywords palladium(II), S-allyldithiocarbazate, X-ray crystal structure, Hirshfeld surface analysis
Introduction
dithiocarbazate can be found. Herein, as a part of our
longstanding efforts in the synthesis of SN donor Schiff
base complexes,12 we report the synthesis, structure and
spectral characterization of new mixed ligand Pd(II)
complex [PdCl(PPh3)L] (L: S-allyl β-N-(benzylidene)-
dithiocarbazate) using the bidentate ligand "S-allyl-
dithiocarbazate" Schiff base.
Transition metal chelates of hard-soft nitrogen-sulfur
dithiocarbazic acid, its S-alkyl/aryl esters and their
Schiff bases have been studied, mainly due to their po-
tential anticancer,1 antifungal,2 antiamoebic3 and insec-
ticidal4 activities. Various transition and innertransition
metal complexes with SN donor Schiff bases play an
important role in biological systems and represent in-
teresting models for metalloenzymes that efficiently
catalyze the reduction of dinitrogen and dioxygen.5,6
Furthermore, macrocyclic derivatives of these Schiff
bases were found to have many fundamental biological
functions, such as photosynthesis and transport of oxy-
gen in respiratory systems of mammalian.7 Coordination
chemistry of Pd(II) Schiff bases has been appealing for
research in recent years due to its application to several
catalytic and biological systems.3,8 Although, plenty of
studies have been done on the complexes of Pd(II) with
dithiocarbazic acid,9 Schiff bases of S-methyl,3,8
S-benzyl3,10 and S-acetyl3a dithiocarbazate and other
N-substituted derivatives of S-methyl dithiocarbazate11
have been reported, few complexes based on S-allyl-
McKinnon et al.13 have recently presented a detailed
review of the application of the Hirshfeld surface14 to
explain and describe a wide variety of molecular crystal
structures, and it was clear from the work that graphical
tools based on the Hirshfeld surface and the associated
two dimensional (2D) fingerprint plot15 offered consid-
erable promise for exploring packing modes and inter-
molecular interactions in molecular crystals.
In this paper, according to Hirshfeld surface-based
tools, we use CrystalExplorer to decoding of intermo-
lecular interactions in crystal network. The 3D shape
and curvature surfaces and breakdown of fingerprint
plots16 (existing new techniques and tools based on the
Hirshfeld surface and already incorporated in Crys-
talExplorer computer program) were applied to visual-
*
E-mail: rezatakjoo@yahoo.com; Tel.: 098-0511-6082637
Received May 1, 2009; revised August 28, 2009; accepted October 9, 2009.
Chin. J. Chem. 2010, 28, 221— 228
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221

Takjoo et al.
Table 1 Crystallographic data for the title compound
FULL PAPER
izing and exploring intermolecular interactions in crys-
tal lattice.
Formula
Formula weight
T/K
C29H26ClN2PPdS2
639.51
Experimental
296(2)
All chemicals used for the ligand and the complex
preparation have analytical quality, which were used
without further purification. Spectrograde solvents were
used for spectral measurements. Deuterated solvents
CDCl3 and DMSO-d6 were used for NMR measure-
ments.
Crystal system
Crystal size/mm3
Space group
a/Å
Triclinic
0.151×0.121×0.082
P-1
10.2376(7)
b/Å
11.3048(8)
c/Å
12.5828(8)
Physical measurements
α/(°)
90.5660(10)
100.7140(10)
102.5310(10)
1394.87(16)
2
1H NMR and 13C NMR spectral measurements were
performed on a Bruker BRX 100 AVANCE spectrome-
ter and Bruker BRX 500 AVANCE 500 MHz spec-
trometer (CDCl3 or DMSO-d6). All chemical shifts were
reported downfield from standards. Elemental analyses
were carried out by using a Thermo Finnigan Flash
Elemental Analyzer, model 1112EA and a Shimadzu
AA-670 atomic absorption spectrometer. IR spectra
(KBr pellets) were recorded on a Buck-500 Scientific
infrared spectrophotometer (4000—600 cm－ 1). Elec-
tronic spectra of the complexes in methanol solution (ca.
25 ℃) were recorded on an Agilent 8453 single beam
UV-Vis spectrophotometer (250—900 nm). The mass
spectra were recorded on a Varian CH-7 instrument at
70 eV. Melting point was determined using an electro-
thermal digital melting point apparatus.
β/(°)
γ/(°)
V/Å3
Z
calc/(Mg•m－
)
1.475
3
D
µ/mm－
0.987
1
F(000)
620
θ range/(°)
1.85 to 28.31
－13≤h≤13, －14≤k≤13,
－10≤l≤16
8603
Index ranges
Reflections collected
Data/restraints/parameters
Goodness-of-fit on F2
Radiation (λ/Å)
6212/2/325
1.025
Mo Kα (0.71073)
6212 [R(int)＝0.0144]
89.4%
Crystallographic analysis
Independent reflections
Completeness to θ＝28.31°
Experimental parameters pertaining to single crystal
X-ray analysis are given in Table 1. Data were collected
on an orange cubic crystal mounted and centered on a
glass capillary, which was put on a Smart-Apex CCD
(Bruker-AXS) diffractometer equipped with graphite
monochromated Mo Kα radiation (λ＝0.71073 Å). The
final unit cell was determined from 8603 reflections in
the range of 1.85°＜θ＜28.31°. The diffraction data
were collected at 296 K with φ- and ω-scan techniques.
The structure was solved by direct methods and refined
by full-matrix least squares based on F2 with weight
Semi-empirical from
equivalents
Full-matrix least-squares on F2
Absorption correction
Refinement method
Final R indices [for 4865 rfln.
with I＞2σ(I0)]
R1＝0.0394, wR2＝0.0870
R1＝0.0555, wR2＝0.0952
R indices (all data)
0.710 and －0.695 e.Å－
3
Largest diff. peak and hole
w＝1/[σ2(Fo )＋(0.0362P)2＋1.2160P] where P＝(Fo
2
2
(CCDC number＝671381). Copies of the data can be
obtained free of charge via www.ccdc.cam.ac.uk/
conts/retrieving.html (or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: 0044 1223 336033; or deposit@ccdc.
cam.ac.uk).
＋ 2Fc2)/3 using the SHELXTL-97 software.17 All
non-hydrogen atoms were refined with anisotropic
displacement parameters and hydrogen atoms were
placed isotropically on calculated positions. Refinement
of F2 was against all reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for nega-
tive F2. The threshold expression of F2＞2σ (F2) was
used only for calculating R-factors (geometrical treated)
etc., and is not relevant to the choice of reflections for
refinement. R-factors based on F2 are statistically about
twice as large as those based on F, and R-factors based
on all data will be even larger.
Preparation of S-allyl β-N-(benzylidene)dithiocar-
bazate (HL)
This compound was prepared and characterized by
following, a previously published procedure.12b To an
ethanolic solution (30 mL) of 5 mL (0.1 mol) of hydra-
zine hydrate and 5.6 g (0.1 mol) KOH, was added
dropwise a solution of 6.1 mL (0.1 mol) of carbon di-
sulfide in an ice bath. After 30 min 8.6 mL (0.1 mol) of
allyl bromide was added. The solution was stirred con-
Crystallographic information has been deposited
with the Cambridge Crystallographic Data Centre
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© 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2010, 28, 221— 228

Mixed Ligand Palladium(II) Complex with Schiff Base
tinuously at 5 ℃ for 1 h. The ethanolic solution (25
mL) of benzaldehyde (11.1 mL, 0.1 mol) was added to
this mixture and heated with continuous stirring. After
15 min, a yellow product was separated by filtration,
washed with water and dried in vacuum. HL was re-
crystallized from ethanol. Yield 49.5% (based on ben-
zaldehyde), m.p. 137 ℃. UV-Vis (CH2Cl2) λmax/nm
[ε/(dm3•mol－ 1•cm－ 1)]: 240 (36450), 334 (9640) (in-
tra-ligand transition); 1H NMR (DMSO-d6, 500 MHz) δ:
3.90 (d, J＝7 Hz, 2H, SCH2), 5.24 (dd, J＝18, 10 Hz,
2H, CH2), 5.87—5.96 (m, H, CH), 7.45 (dd, J＝2, 4 Hz,
3H, o,p-C6H5), 7.71 (dd, J＝2, 4 Hz, 2H, o-C6H5), 8.24
(s, 1H, CH ＝ N), 13.34 (s, 1H, NH); 13C NMR
(DMSO-d6, 500 MHz) δ: 196.44 (C＝S), 146.56 (CH＝
N), 133.28 [C(6)], 133.16 (p-C6H5), 130.77 (CH),
128.95 (o-C6H5), 127.42 (m-C6H5), 118.45 (CH2), 35.98
(SCH2); IR (KBr) ν: 751 δ(out-of-plane of CH, phenyl
deformation), 1025 (νN N), 1097 (νCSS), 1609 (νC N),
Scheme 1 The thione and thiol tautomeric forms of the Schiff
base (HL)
It has two potential donor atoms available for
coordination with a metal ion. The reaction of HL with
K2PdCl4 and triphenylphosphine at a molar ratio of 1∶
1∶1 gave an orange complex, [PdCl(PPh3)L]. The
complex was characterized by 1H NMR, IR and UV-Vis
spectroscopies, besides elemental analyses, and its mo-
lecular structure was determined by single-crystal X-ray
analyses.
Infrared spectra
—
—
－
1
2962 (νCH aliphatic), 3109 (νN H) cm ; MS m/z: 236, 162,
—
The HL can exhibit thione-thiol tautomerism. In the
solid state the absence of ν(S—H) at ca. 2570 cm－
1
118, 104, 92, 77, 41 and 28. Anal. calcd for HL
(C11H12N2S2): C 55.90, H 5.12, N 11.85, S 27.13; found
C 55.96, H 5.00, N 11.85, S 28.26.
from the IR spectra shows that only the thione form ex-
ists, as shown in Scheme 1.18 The band at 3097 cm－
1
and the strong intensity band at 1025 cm－ were attrib-
1
Preparation of chloro-[allyl-2-(phenylmethylidene)-
1-hydrazinecarbodithioato-N,S]-(triphenylphos-
phine)-palladium(II) ([PdCl(PPh3)L])
uted to ν(N—H) and ν(N—N) vibration modes, respec-
tively. The ν(N—H) and ν(C＝S) are missing from the
IR spectra of complex, suggesting that the ligand exists
in complex in deprotonated thione form, which is
further supported by the red shift of the ν(C＝N) band
for the complex with respect to the free ligand,
indicating shorter C＝N bond lengths in free ligand. The
A solution of HL (0.236 g, 1 mmol) and triphenyl-
phosphine (0.262 g, 1 mmol) in acetonitrile (15 mL)
was added to a solution of K2PdCl4 (0.362 g, 1 mmol) in
water under magnetic stirring for 20 min. An orange
solid product was filtered, washed with water, dried in
vacuum and recrystallized from acetonitrile. Yield 51%
(based on HL), m.p. 198 ℃; UV-Vis (CH2Cl2) λmax/nm
bands at 1487, 1090 and 688 cm－ were attributed to
1
triphenylphosphine.19
－
－
1
1
[ε/(dm3•mol •cm )]: 242 (18240), 262 (26460) (in-
tra-ligand transition); 312 (29000) (LMCT), 444 (500)
(d-d); 1H NMR (CDCl3, 100 MHz) δ: 3.76 (d, J＝7 Hz,
2H, SCH2), 5.18 (dd, J＝17, 10 Hz, 2H, CH2), 5.70—
5.97 (m, 1H, CH), 7.25—8.19 (m, 20H, aromatic rings),
8.87 (d, J＝4 Hz, 1H, CH＝N); IR (KBr) ν: 754
Electronic spectra
The electronic spectra of the ligand and complex
have been recorded in chloroform as solvent and were
listed in experimental section. For free ligand two ab-
sorptions, 240 and 334 nm, in the ultraviolet region is
assignable to intra-ligand orbital transitions. As the
same, two bands appeared around 242 and 262 nm have
been assigned to intra-ligand transition in the complex.
In addition, charge transfer band is appeared at ap-
proximately 312 nm. This intense band may be assigned
to a combination S→Pd(II), N→Pd(II), P→Pd(II) and
Cl→Pd(II) charge transfer bands.
(out-of-plane of CH, phenyl deformation), 1011 (νN N),
—
－
1
1582 (νC N), 1487, 1091 & 688 (for PPh3) cm . Anal.
—
calcd for C29H26ClN2PPdS2: C 54.47, H 4.10, N 4.38, S
10.03, Pd 16.64; found C 52.98, H 3.97, N 4.34, S 9.69,
Pd 16.21.
Results and discussion
In the visible region of the square planar palladium
complexes, three spin-allowed d-d transitions were con-
sidered.20 These transitions were expected to correspond
The Schiff base S-allyl β-N-(benzylidene)dithio-
carbazate [HL], was readily prepared by condensation
of benzaldehyde with S-allyldithiocarbazate in ethanol
solution as a fluffy pale-yellow crystalline solid. Like all
other Schiff bases derived from S-alkyl/aryl dithiocar-
bazates, the HL is also capable of exhibiting thione-thiol
tautomerism since they contain the thioamide, —NH—
C(S)S— functional group (Scheme 1).12b The thione
group is relatively unstable and tends to convert to the
more stable C—S bond by enolization, if there is at least
one proton adjacent to the thione group.
1
1
1
to the transitions A1g→1A2g, A1g→1B1g and A1g→1Eg
but the presence of sulfur covers these bands, because of
its very intense charge transfer band, and the band
1A1g→1Eg in the range of 444 nm was merely observed.
1H NMR, 13C NMR and EI mass spectra
The d8 square planar palladium(II) complexes give
well resolved NMR spectra, which confirm the nature of
the binding. In 1H NMR spectrum of the free ligand, the
extreme downfield is assignable to NH, which disap-
Chin. J. Chem. 2010, 28, 221— 228
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223

Takjoo et al.
FULL PAPER
pears on coordination and deuteration. The aromatic
portion is sharply divided to two parts: the downfield
portion and the upper field part which are referred to
2,3,4-H and 1,5-H, respectively. The singlet at δ 8.24
parable with the values found in most square-planar
palladium(II) complexes of Schiff base ligands derived
from thiosemicarbazid and S-alkyl esters of dithiocarba-
zic acid8,22 and other N-substituted derivatives11 of di-
thiocarbazates.
1
was assigned to the imine proton. The H NMR spec-
trum of the ligand revealed existence of the thione form
as a single form. In the complex, downfield shifts were
also observed for the imine hydrogen, indicating de-
creased electron density on coordination. However, all
of allyl hydrogens were shifted upfield, which may be
considered for increasing conjugation following com-
plexation.
The 1H NMR spectrum of the complex showed a se-
ries of multiple overlapping signals for aromatic protons
in δ 7.25—8.19. The azomethine proton resonance is
splitted into a doublet maybe due to the splitting of CH
resonance by protons of phenyl group occurring in δ
8.85—8.89.19
The 13C NMR spectrum of the ligand showed a sig-
nal at downfield δ 196.44 corresponding to the
thioamide carbon, which was found in DMSO at room
temperature. In addition, the azomethine carbon signal
of the ligand appeared at δ 146.56. The SCH2, CH and
CH2 carbons in the allyl group show signals at δ 35.98,
130.77 and 118.45, respectively. The signals of the car-
bons on the phenyl ring appear in δ 127.42 to 133.28.
Figure 1 An ORTEP drawing of complex [PdCl(PPh3)L] with
the atom labeling scheme (50% probability thermal ellipsoids).
Table 2
Selected bond lengths (Å) and angles (°) for
[PdCl(PPh3)L]
Pd(1)—N(1)
Pd(1)—S(2)
Pd(1)—P(1)
2.098(0) N(1)-Pd(1)-S(2)
2.250(2) N(1)-Pd(1)-P(1)
2.255(7) N(1)-Pd(1)-Cl(1)
83.21(3)
171.46(7)
95.49(4)
92.43(2)
178.06(3)
89.03(3)
112.79(7)
110.67(3)
121.57(7)
105.43(9)
113.39(0)
143.44(3)
Crystal structure
The reaction of K2PdCl4 and PPh3 with [H-(L)] at a
1∶1∶1 molar ratio afforded complex of the type
[PdCl(PPh3)L] (where L＝NS bidentate S-allyl β-N-
(benzylidene)dithiocarbazate ligand). The single crystals
of [PdCl(PPh3)L] suitable for X-ray diffraction studies
were obtained from CH3CN at room temperature. As
predicted by the spectral data, [PdCl(PPh3)L] has a
monomeric square-planar structure in which Schiff base
ligand is coordinated to palladium metal via the azome-
thine nitrogen and thiolate sulfur atoms, forming one
stable five membered metallacycle [containing atoms
Pd(1)/S(2)/C(25)/N(2)/N(1)]. This ring obtained from
chelating of the S-allyl β-N-(benzylidene)dithiocarba-
zate ligand [L]－ , of type Pd-NNCS, is essentially planar.
The NS ligand is coordinated in its deprotonated thiolate
form. The remaining coordination sites are occupied by
triphenylphosphine [trans to N(1)] and chlorine atom
[trans to S(2)]. Then Pd(II) has an NSPCl coordination
environment. The relevant bond lengths and bond an-
gles are given in Table 2. The ORTEP diagram of the
complex is shown in Figure 1. The intermolecular dis-
tance between Pd atoms of consecutive molecules in the
packing is 8.798 Å. The C(25)—S(2) bond length is
1.739 Å, which is shorter than 1.82 Å for a C—S single
bond and longer than 1.56 Å for a C＝S double bond.21
The C—N bond distance, C(25)—N(2) 1.279 Å, con-
forms to the double bond [d(C＝N) 1.28 Å].21 The Pd—
S distance, 2.250 Å, is in the range normally found in
four-coordinate Pd(II) complexes of sulfur-nitrogen
chelating agents.8,22 The Pd—N distances are also com-
Pd(1)—Cl(1) 2.343(9) S(2)-Pd(1)-P(1)
N(1)—N(2)
1.406(6) S(2)-Pd(1)-Cl(1)
N(1)—C(29) 1.287(1) P(1)-Pd(1)-Cl(1)
N(2)—C(25) 1.278(9) C(25)-N(2)-N(1)
C(25)—S(2)
C(25)—S(1)
S(1)—C(26)
1.738(7) S(2)-C(25)-S(1)
1.750(7) N(2)-C(25)-S(1)
1.798(1) C(25)-S(1)-C(26)
C(26)—C(27) 1.432(7) S(1)-C(26)-C(27)
C(27)—C(28) 1.173(8) C(26)-C(27)-C(28)
The palladium-nitrogen bond length in the metalla-
cycle, 2.098(0) Å, is longer than the predicted single
bond value of 2.011 Å, based on the sum of covalent
radii for nitrogen (sp2) and palladium, 0.701 and 1.31 Å,
respectively,23 reflecting the trans influence of the phos-
phorus atom.24 The Pd-P bond distance, 2.255(7) Å, is
shorter than the sum of the single bond radii of palla-
dium and phosphorus (2.41 Å), suggesting partial dou-
ble bond character similar to the others reported ear-
lier.25,26 The Pd—Cl bond length, 2.343(9) Å, is consis-
tent with Pd—Cl distances found in related species.26,27
The highest deviation from the least squares plane in
Pd(II) coordination environment was observed for P(1)
atom by 0.325 Å. The angles of N(1)-Pd(1)-P(1) and
S(2)-Pd(1)-Cl(1) have not the ideal value of 180°
(171.47° and 178.06°). The other four angles subtended
at the Pd(II) ion all deviate from the values expected for
an ideal square-planar geometry (See Table 2). Com-
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© 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2010, 28, 221— 228

Mixed Ligand Palladium(II) Complex with Schiff Base
parison between bond angles of [PdCl(PPh3)L] complex
with those of other related square-planar palladium(II)
complexes of similar ligands22 shows that the distortion
is a common phenomenon in square-planar-Pd(II) com-
plexes of NS donor ligands.
Figure 2.
π…π interactions are evident on the Hirshfeld sur-
face as a large flat region across the molecule, which is
most clearly visible on the curvedness surfaces. The
pattern of red and blue triangles on the same region of
the shape index surface is another characteristic of π…π
interactions. Blue triangles represent convex regions
due to ring carbon atoms of the molecule inside the sur-
face, while red triangles represent concave regions due
to carbon atoms of the π-stacked molecule above it. As
mentioned above, over the plane of the molecule, in-
spection of the adjacent red and blue triangles on the
shape index surfaces and large flat region on the curv-
edness surfaces of [PdCl(PPh3)L] shows the π…π stack-
ing (see the regions labeled 1 in Figure 2) in which the
shortest one has the distance of 3.672 Å formed between
C(7)—C(12) π-rings with symmetry code (x, y, z). By
using breakdown of fingerprint plot technique, we can
decompose fingerprint plots to highlight intermolecular
contacts. This disintegration allows the separation of
contributions from different interaction kinds, which
commonly overlap in the full fingerprint or difficulty,
has been recognized in 3D maps.
Decoding of intermolecular interactions: Hirshfeld
surface and fingerprint plot
Exploring crystal lattice with Hirshfeld surfaces and
fingerprint plots produced with CrystalExplorer com-
puter program using the structural information obtained
from X-ray diffraction determination is presented in this
section. Particular attention is given to 3D shape and
curvature surfaces and breakdown of fingerprint plots
which provide a concise summary of the intermolecular
interactions occurring in the crystal by mapping the
fraction of points on the corresponding Hirshfeld sur-
face as a function of the closest distances from the point
to nucleus interior (di) and exterior (de) to the surface.
The Hirshfeld surfaces for [PdCl(PPh3)L] are shown in
Figure 2 Hirshfeld surface of [PdCl(PPh3)L], mapped with
shape index (a) and curvedness property (b) in two orientations.
The molecular structures have been added right hand to the
Hirshfeld surface maps for presenting more clear geometry.
Figure 3 Fingerprint plots for [PdCl(PPh3)L] resolved into C—
H…π (a) and N…π contacts (b). The full fingerprint appears be-
neath each decomposed plot as a grey shadow.
Chin. J. Chem. 2010, 28, 221— 228
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225

Takjoo et al.
FULL PAPER
Figure 3 showed highlighting separately the C—
H…π and N…π intermolecular contacts on fingerprint
plot.
fingerprint is shown in grey π…π and C—H…S inter-
molecular interactions link the infinite sheet to form a
three-dimensional network to be shown in Figure 8.
To provide a context, the outline of the full finger-
print is shown in grey. The C—H…π interaction formed
between C(22)—H(22A) and C(19)—C(24) phenyl
rings of triphenylphosphine with the bond length 2.860
Å, constitutes an intermolecular dimer (Figure 4). Each
dimer interacts with a neighboring dimeric unit by N…π
interactions between the N(2) atoms and phenyl rings of
S-allyl dithiocarbazate Schiff bases, 3.636 Å, to form a
one dimensional chain (see the region labelled (b) in
Figure 5).
Figure 4 Dimer unit formed via the C—H…π interactions.
Figure 6 Selective highlighting of Cl…H and H…Cl contacts
on the dnorm surface and fingerprint plot of [PdCl(PPh3)L]. The
full fingerprint appears beneath each decomposed plot as a grey
shadow.
Figure 5 A view shows assemblage of [PdCl(PPh3)L] via C—
H…π interactions and formation of dimer unit (a) and N…π con-
tacts and connection of dimer unit (b) which have made 1D chain
and finally, Cl…H interactions (c) that link parallel chains to
make an infinite sheet.
In the same manner, Figure 6 represents the selective
highlighted C—H…Cl intermolecular contacts on dnorm
surface16 and fingerprint plot, C(20)—H(20A)…Cl(1)
2.948 Å. The shortest distances have been normalized
with respect to the van der Waals radii of the atoms. In
the color scale, blue regions have no contacts shorter
than the van der Waals radii, red regions are closer than
the van der Waals radii and white regions are a distance
equal to the sums of appropriate radii. Cl…H interac-
tions connect the one dimensional chains to create an
infinite sheet (Figure 5). Figure 7 illustrates selective
highlighted weak C—H···S intermolecular contacts on
fingerprint plot of title complex, C(22)—H(22A)…S(1)
3.047 Å. To provide a context, the outline of the full
Figure 7 Fingerprint plot for [PdCl(PPh3)L] resolved into C—
H…S contacts. The full fingerprint appears beneath each decom-
posed plot as a grey shadow.
Conclusion
In conclusion, we have prepared NS-donor bidentate
226
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© 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2010, 28, 221— 228

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9
S-allyldithiocarbazate Schiff base ligand and its
[PdCl(PPh3)L] mixed ligand complex, as first example
of complexation of Pd(II) with S-allyl dithiocarbazate
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Acknowledgements
The authors are grateful to Ferdowsi University of
Mashhad and Northeast Normal University of China for
providing the possibilities of doing this research.
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