Coordination chemistry of [methyl-3-(4-benzyloxyphenyl)methylene] dithiocarbazate with divalent metal ions: Crystal structures of the N,S Schiff base and of its bis-chelated nickel(II) complex

Article abstract of DOI:10.1007/s11243-011-9499-6

The condensation of 4-benzyloxybenzaldehyde with S-methyldithiocarbazate (SMDTC) yielded the Schiff base methyl-3-[(4-benzyloxyphenyl)methylene] dithiocarbazate (HL) that, upon reaction with different metal ions, afforded bis-chelated complexes, ML_2<

Full text of DOI:10.1007/s11243-011-9499-6

Transition Met Chem (2011) 36:531–537
DOI 10.1007/s11243-011-9499-6
Coordination chemistry of [methyl-3-(4-
benzyloxyphenyl)methylene]dithiocarbazate with divalent metal
ions: crystal structures of the N,S Schiff base and of its bis-chelated
nickel(II) complex
•
M. Al-Amin A. A. Islam M. Tofazzal H. Tarafder
•
•
M. Chanmiya Sheikh M. Ashraful Alam
•
Ennio Zangrando
Received: 22 March 2011 / Accepted: 26 April 2011 / Published online: 15 May 2011
ꢀ Springer Science+Business Media B.V. 2011
Abstract The condensation of 4-benzyloxybenzaldehyde
with S-methyldithiocarbazate (SMDTC) yielded the Schiff
base methyl-3-[(4-benzyloxyphenyl)methylene] dithiocar-
bazate (HL) that, upon reaction with different metal ions,
afforded bis-chelated complexes, ML2 [where M=Ni(II),
Cu(II), Zn(II), Cd(II) or Pd(II)]. The ligand and all the metal
complexes were characterized by physico-chemical and
spectroscopic methods. The Schiff base and its bis-chelated
Ni(II) complex were characterized also by single crystal
X-ray analyses. The crystallographic results show that the
Schiff base exists in thione tautomeric form with the dith-
iocarbazate fragment adopting an EE configuration with
respect to the C=N bond of the group. In the NiL2 complex,
the metal is chelated by two mononegatively charged Schiff
bases coordinating via the b-nitrogen and thiolate sulfur
anion, generated in situ during the complexation process,
and adopts a distorted square planar geometry.
Introduction
Bidentate Schiff bases of S-methyl dithiocarbazate
(SMDTC) or S-benzyl dithiocarbazates (SBDTC) and their
bivalent metal complexes have received considerable atten-
tion in the field of medical science for their antibacterial,
antifungal, antiviral, antitumour, and anticancer activities
[1–6]. Dithiocarbazic acid and its derivatives exhibit
intriguing coordination and geometric variations with diva-
lent metal ions thus affecting its biocidal activities [1–11].
Dithiocarbazate and carbazole compounds are known to
exhibit good hole transporting properties, and their charge
transfer metal complexes can create freecarriers in the visible
region through the photocarrier generation process [12].
For example, the bis-chelated Ni(II) complex of a biden-
tate Schiff base, S-methyl-b-N-(N-ethyl-3-carbazolyl)meth-
ylenedithiocarbazate, showed strong two photon absorptions
and distinct optical limiting response [7]. Lately, a four
coordinate Zinc(II) complex, bis[benzyl N-(indol-3-ylmeth-
ylene)hydrazine carbodithioato] zinc (BHCZ), showed
enhanced acceleration of the rate of wound healing encloser
in rats as compared with intrasite as positive control [13]. As
part of our continued interests in this area, we report herein
the synthesis of a new bidentate NS Schiff base derived from
the condensation of SMDTC with 4-benzyloxybenzaldehyde
and its metal complexes. The crystal structures of the Schiff
base and its NiII complex have been solved.
Electronic supplementary material The online version of this
article (doi:10.1007/s11243-011-9499-6) contains supplementary
material, which is available to authorized users.
M. A.-A. A. A. Islam Á M. Ashraful Alam
Department of Chemistry, Rajshahi University of Engineering
and Technology, Rajshahi, Bangladesh
M. T. H. Tarafder (&)
Department of Chemistry, Rajshahi University, Rajshahi,
Bangladesh
e-mail: ttofazzal@yahoo.com
Experimental
M. Chanmiya Sheikh
Department of Chemistry, Toyama University, Toyama, Japan
Physical measurements
E. Zangrando (&)
Dipartimento di Scienze Chimiche e Farmaceutiche,
All the reagents and solvents were of Analar grade. The
reagents were used without further purification, but the
`
Universita di Trieste, Trieste, Italy
e-mail: ezangrando@units.it
123

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Transition Met Chem (2011) 36:531–537
solvents were purified by standard methods [14]. Chemicals:
4-hydroxybenzaldehyde, hydrazine hydrate (99.99%),
nickel(II) acetate tetrahydrate, copper(II) acetate mono
hydrate, zinc(II) acetate dihydrate, cadmium(II) nitrate tet-
rahydrate, palladium(II) chloride (Fluka Chemica, Switzer-
land), methyl iodide, carbon disulfide, potassium hydroxide
(Merck India). Solvents: dimethyl sulphoxide (Fluka),
dimethyl formamide (Fluka), acetone, ethanol, chloroform
(Merck, India). The ligand precursor, 4-benzyloxybenzal-
dehyde, was prepared following the literature report [15].
IR spectra (4,000–225 cm-1) were obtained as CsI
pellets using a Perkin-Elmer, Spectrum 100 FT-IR spec-
trometer, (USA). 1H NMR (0-12 ppm) and 13C NMR
(0–200 ppm) spectra were recorded on a JNM 400 MHz
and on a 100 MHz spectrometer, respectively, in CDCl3
(and in some cases d6-DMSO) using TMS as internal
standard. Mass spectra were obtained on a JEOL-JMS-
D300 mass spectrometer (scan range, mass-to-charge (m/e)
ratio 0-750), Venture Business Laboratory, University of
Toyama (Japan), and C, H, N, and S microanalyses with a
Perkin-Elmer 2,400 II organic elemental analyzer (USA).
Magnetic measurements were made on a magnetic sus-
ceptibility balance (Sherwood Scientific, UK), and molar
conductance measurements with a heavy-duty conductiv-
ity/temperature meter (Extech Instruments, USA, model
No. 407303). The UV–visible absorptions were scanned on
a T60 UV–VIS spectrophotometer (PG Instruments, UK)
between 200–800 nm using 10-5 M solution in chloroform
and PdL2 in DMF.
Table 1 Crystallographic data of the Schiff base HL and of NiL2
complex
HL
NiL2
Empirical formula
fw
C16H16N2OS2
316.43
C32H30N4NiO2S4
689.55
Crystal system
Space group
Triclinic
P 1
Triclinic
P 1
˚
a, A
5.5670(9)
8.8350(10)
16.578(2)
103.075(10)
94.718(10)
90.924(10)
791.04(18)
2
10.4790(12)
12.1740(12)
13.8850(15)
91.523(11)
70.117(13)
74.065(15)
1587.6(3)
2
˚
b, A
˚
c, A
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V, A
Z
Dcalcd (g cm-3
)
1.328
1.442
l(Mo-Ka) (mm-1
)
3.044
3.633
F(000)
332
716
h range (ꢁ)
2.75–63.41
12944
3.41–63.63
27617
No. of reflns collcd
No. of indep reflns
Rint
2491
4890
0.051
0.075
No. of reflns (I [ 2r(I))
No. of refined params
Goodness-of-fit (F2)
R1, wR2 (I [ 2r(I))
2018
2426
191
390
1.010
0.883
0.0470, 0.1296
0.190, -0.234
0.0452, 0.1088
0.250, -0.265
3
˚
Residuals, e/A
X-ray crystallography
was added to a hot solution of SMDTC (0.976 g, 8 mmol)
in absolute ethanol (20 mL).The mixture was refluxed for
30 min, then the orange crystalline solid was filtered off,
washed with hot ethanol, and dried under vacuum over
anhydrous CaCl2. The compound was dissolved in boiling
chloroform (50 mL) and allowed to cool down. Orange
powdered solid was obtained after 1 h. The compound
containing 0.2 g was dissolved in refluxing ethanol
(50 mL), the suspended solid was separated by filtration,
and allowed to stand overnight. Fifty mg of the orange
crystalline material was redissolved in boiling ethanol
(30 mL) and allowed to stand at room temperature, when
after 3 days, flat orange single crystals suitable for X-ray
crystallography were obtained.
Data collections [16] for the crystal structures reported
were carried out at room temperature by using a Kap-
paCCD2000 detector mounted on an FR591 rotating anode
˚
equipped with Cu-Ka radiation (k = 1.5418 A). Cell
refinement, indexing, and scaling of all the data sets were
performed using the programs Denzo and Scalepack [17].
The structures were solved by direct methods and sub-
sequent Fourier analyses [18] and refined by the full-matrix
least-square method based on F2 with all observed reflec-
tions [18]. Hydrogen atoms were placed at calculated
positions. Graphical representation drawings were done
with ORTEP-3 for Windows [19]. All the calculations were
performed using the WinGX System, Ver 1.80.05 [20].
Crystal data and details of data collections and refinements
are summarized in Table 1.
Synthesis of metal complexes, ML2
A solution of Ni(OAc)2. 4H2O (0.06 g, 0.25 mmol) in
absolute ethanol (10 mL) was added to a boiled solution
of the ligand (0.158 g, 0.5 mmol) in the same solvent
(40 mL). The mixture was refluxed for 30 min, then the
brown precipitate, which had appeared was filtered off,
Synthesis of the Schiff base, HL
The S-methyldithiocarbazate (SMDTC) was prepared as
previously reported [3]. A solution of 4-benzyloxybenzal-
dehyde (1.61 g, 7.59 mmol) in absolute ethanol (30 mL)
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Transition Met Chem (2011) 36:531–537
533
H
H
O
washed with hot ethanol, and dried under vacuum over
anhydrous CaCl2. Brown single crystals were obtained by
crystallization from a mixture of chloroform and absolute
ethanol (80/5, v/v) at room temperature after 23 days.
The copper(II) and cadmium(II) complexes were pre-
pared following the same procedure and same molar
ratio using Cu(OAc)2.H2O and Cd(NO3)2.4H2O. The zinc
complex was prepared by dissolving 0.25 mmol of
Zn(OAc)2.2H2O in 60% aqueous ethanol (10 mL). Brown
microcrystals of the copper(II) complex were obtained by
crystallization from a mixture of chloroform and toluene
(80/10, v/v) after 21 days, while the zinc(II) and cad-
mium(II) complexes were reprecipitated from chloroform
and toluene. The palladium(II) complex was prepared by
dissolving 0.125 mmol of PdCl2 in methanol (50 mL), and
the product was recrystallized from DMF.
K2CO3
CH2Br+HO
CHO
acetone, ref.
CHO
benzylbromide
4-hydroxybenzaldehyde
4-benzyloxybenzaldehyde
EtOH, ref.
SMDTC
13
12
16
H
H
6
5
11
H
14
13
14
10
4
7
H
C
12
11
O
C
3
1
15
H
CH3
N N
8
9
H
15
16
MII
S
10
O
6
2
EtOH, ref.
HL
7
S
5
H
8
4
C
N
CH3
3
9
S
S
C
N
M
N
C
S
S
2
N
C
CH3
1
H
H
H
O
ML2
Scheme 1 Synthesis of the Schiff base and of metal complexes,
MIIL2 (M=Ni, Cu, Zn, Cd, and Pd)
Results and discussion
The condensation of 4-benzyloxybenzaldehyde with
S-methyl dithiocarbazate (SMDTC) in absolute ethanol
gave the Schiff base, HL, which on further reactions with
metal ions in absolute ethanol [for Ni(II), Cu(II), Zn(II),
and Cd(II)] or methanol [Pd(II)] resulted in the formation
of the corresponding four coordinated complexes
(Scheme 1). The Lasign’s test (halogen test) indicated the
absence of chloride ions in the Pd(II) complex, suggesting
the uni-negative bidentate complexation by the Schiff base.
All the compounds were soluble in noncoordinating
organic solvents such as CHCl3, DMF, and DMSO. How-
ever, PdL2 was not soluble in chloroform. The room tem-
perature molar conductance values at 10-5M solution of
the complexes in CHCl3 (PdL2 in DMF) are in the range,
6.2–9.8 ohm-1 cm2 mol-1, revealing nonelectrolytic nat-
ure of the complexes [21]. The elemental analyses
(Table 2) and mass spectroscopic data (Table 3) obtained
by LRMS (low resolution mass spectroscopy) and HRMS
(high resolution mass spectroscopy) are in good agreement
with the corresponding molecular formulae.
stretching mode [23]. However, two medium to weak bands
at 519–400 and 373–256 cm-1, were tentatively assigned to
the m(M–N) and m(M–S) stretching modes, respectively.
The 1H NMR and 13C NMR data of the Schiff base and
its complexes are reported in Table 3. The Schiff base
showed a broad singlet at d 10.51 for the imide proton
of [=N–NH-C(=S)-SCH3] moiety. On the other hand, the
absence of this resonance in all the spectra of the com-
plexes suggests that coordination of the ligand, taken place
through the thiolate sulfur, was accompanied by the
deprotonation of the Schiff base via the thioenol form.
The ligand had another singlet at d7.84 for the azomithine
proton [2, 22], which was downfield shifted in the com-
plexes, indicating that the coordination of the ligand
occurred through its azomithine nitrogen [23]. The ligand
showed 13C NMR signals at d 17.69, 203.0, 161.14, and
70.12 ppm for the C-1, C-2, C-3, and C-10 carbons,
respectively, while the C-1 and C-10 carbon signals were
shielded in the complexes as compared with the ligand
[23]. The C-3 (azomithine) carbon signal was shifted to the
downfield in the complexes as compared with the ligand
[23]. The C-2 (C=S) carbon resonance was not detected in
the spectra of the complexes, most probably due to a very
low intensity caused by dilute solution. The carbons of
aromatic rings in the ligand and in the metal complexes
showed signals in the range, d 114.40–146.38 ppm.
The IR absorption frequencies are listed in Table 2. The
medium intensity IR band at 3,118 cm-1 in the spectrum of
the free Schiff base, assigned to the m(N–H) stretching
frequency, was absent upon complexation suggesting that
the ligand undergoes coordination through the thiolate
anion [21–23]. The Schiff base presented strong bands at
1,603 and 1,095 cm-1 for the m(C=N) and m(C=S) stretches,
respectively [22, 23]. The absence of m(C=S) band in the
complexes also supported the aforesaid contention of thio-
late binding with the metals [22]. As for the azomithine
m(C=N) band, there were slight changes upon coordination
(Table 2), compared to the free ligand. The ligand exhibited
a medium to strong band at 1,033 cm-1 for the m(N–N)
The UV–visible spectrum of the Schiff base showed
a medium to weak intensity absorption band at 249 nm,
a very strong intensity band at 317-321 nm and a medium
to strong intensity band at 349 nm (Table 2), correspond-
ing to the p ? p* (aromatic), p ? p* (C=N), and n ? p*
(C=S) transitions, respectively [23, 24]. The complexes
exhibited intra-ligand charge-transfer transitions in the
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534
Transition Met Chem (2011) 36:531–537
Table 2 Elemental analyses, magnetic moment, molar conductance, and UV–visible data
Comp Color
M.p. Yield IR
(ꢁC) (%)
UV
%
C
Km (X-1
cm-1
mol-1
)
m(C=N) m(C=N) kmax (log e)
H
N
S
HLa
Orange
179 46
236 66
1603vs 1033 m 249 (1.5); 321–317
(9.9); 349 (4.0)
60.7 (60.7)
8.8 (8.8)
NiL2 Brown
CuL2 Brown
1601s
1033 m 385 (1.5); 350 (2.5);
327.4 (2.3); 266 (2.8);
261-251 (9.9)
55.8 (55.7) 4.4 (4.4) 8.1 (8.1) 18.6 (18.6) 6.2
55.4 (55.4) 4.4 (4.4) 8.1 (8.1) 18.5 (18.5) 7.8
190 75
1604s
1038 m 400 (0.9); 360.6 (2.5);
266 (1.9); 251.4 (1.7)
ZnL2 Pale yellow 206 70
CdL2 Yellow 168 46
1596vs 1042 m 378 (2.8); 361 (3.6); 331 55.2 (55.2) 4.4 (4.3) 8.1 (8.1) 18.6 (18.4) 6.3
(3.67); 266 (2.2)
1598s
1036 m 373 (2.7); 364.8 (3.9);
355.8–350.2 (9.9); 341
(9.9); 269 (2.3)
51.7 (51.7) 4.0 (4.0) 7.5 (7.5) 17.1 (17.2) 6.9
PdL2 Orange-red 244 72
1601s
1031 m 394 (0.6); 335 (0.9); 290 52.3 (52.1) 4.3 (4.1) 7.5 (7.6) 17.3 (17.4) 9.8
(0.78); 256 (7.4).
a
For HL m(N–H) and m(C=S) IR bands at 3118 m, 1095sh
Table 3 1H NMR, 13C NMR, and mass spectral data
Comp. 1H NMR
13C NMR
Mass by EI? method (m/z)
Low mass
High massa
HL
2.66 (s, 3H, CH3), 5.11 (s, 2H, CH2O), 7.0 17.69 (C1), 203 (C2), 161.14 (C3),
& 7.67 (dd, 2H, H-6,8 & H-5,9), 70.12 (C10), 115.28, 127.47, 128.18,
7.33–7.72 (m, 5H, C6H5-), 7.84 (s, 1H, 128.67, 129.54, 132.64, 140.24,
–CH=N–), 10.51 (bs, 1H,=N–NH–). 145.09 (aromatic).
316 [M?],
316.0666
(316.0704)
269 [C15H13ON2S]?,
268 [C15H12ON2S],
243 [C15H15OS]?,
210 [C9H10N2S2],
92 [C7H8], 91 [C7H7]?,
65 [C5H5]?
NiL2 2.61 (s, 3H, CH3), 5.12 (s, 2H, CH2O),
6.97 & 7.84 (dd, 2H, H-6,8 & H-5,9),
7.71 (m, 5H, C6H5-), 7.61 (s, 1H, –
CH=N–).
688 [M?],
688.0629
(688.0605)
601 [C30H28N2NiO2S3]?, 510
[C18H18N4NiO2S4]?, 420
[C17H18N2NiOS3]?, 330, 268,
209, 91, 65.
CuL2
692 [M?],
693.0269
(693.0648)
605 [C30H28N2CuOS3]?, 555
[C23H18N4CuOS4]?, 493
[C26H22CuO2S2]?
ZnL2 2.59 (s, 3H, CH3), 5.13 (s, 2H, CH2O),
6.90 & 8.14 (dd, 2H, H-6,8 & H-5,9),
16.34 (C1), 182.77 (C2), 164.82 (C3), 694 [M?],
70.16 (C10), 115, 124.21, 127.43,
7.34–7.43 (m, 5H, C6H5-), 8.43 (s, 1H, 128.29, 128.7, 131.35, 135.95, 140.21
694.0625
(694.0543)
647 [C31H27N4ZnO2S3]?, 588
[C25H24N4ZnOS4]?, 268, 210, 92,
65.
–CH=N–).
154.76 (aromatic).
CdL2 2.65 (s, 3H, CH3), 5.11 (s, 2H, CH2O),
6.99 & 7.67 (dd, 2H, H-6,8 & H-5,9),
7.34–7.42 (m, 5H, C6H5-), 7.94 (s, 1H, 128.16, 128.64, 129.65, 136.29,
17.58 (C1), 185.31 (C2), 161.21 (C3), 744 [M?],
70.09 (C10), 115.25, 125.71, 127.46,
744.0493
(744.0285)
716 [C30H26N4CdO2S4]?, 656
[C30H28N2CdO2S3]?, 569
[C28H26CdO2S2]?
–CH=N–).
146.38 (aromatic).
PdL2 2.50 (s, 3H, CH3), 5.19 (s, 2H, CH2O),
7.14 & 7.81 (dd, 2H, H-6,8 & H-5,9),
17.69 (C1), 179.72 (C2), 163.40 (C3), 735 [M?],
69.40 (C10), 115.21, 127.74, 127.78,
736.1118
(736.0286)
658 [C26H25N4PdO2S4]?, 631
[C25H24N4PdOS4]?, 601
[C23H18N4PdOS4]?, 493
[C16H12N4PdS4]?, 330, 268, 91,
65.
7.35–7.48 (m, 5H, C6H5-), 8.63 (s, 1H, 127.98, 128.47, 129.96, 140.24,
–CH=N–). 145.09 (aromatic).
a
Mass of the corresponding compound shown in parenthesis below the mass to charge ratio
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Transition Met Chem (2011) 36:531–537
535
range 266–269, 327–335, and 350-365 nm, for the p ? p*
(aromatic), p ? p* (C=N), and n ? p* (C=S) transitions,
respectively [21, 23]. The complexes showed a medium
intensity band at 373–400 nm for the S ? M charge
transfer transition, indicating the coordination of the Schiff
base to the metal atom via the thiolate sulfur [21]. The
diamagnetic nature of the Ni(II) and Pd(II) complexes,
consistent with the d8 configuration, suggests a square
planar geometry [22], although d8 metal ions in this
coordination environment are expected to exhibit three
C12
C13
C14
C10
C11
C6
C5
C7
C15
C16
O1
C4
C3
C8
C9
N1
N2
C2
1
1
1
1
1
1
transitions for A1g ? A2g, A1g ? B1g, and A1g ? Eg
transitions [24]. However, such transitions are usually not
observed since the strong S ? M LMCT bands with
ligands containing chalcogen donor atoms masks the
expected d–d bands [23]. The diamagnetic Zn(II) and
Cd(II) complexes, consistent with the d10 metal ion con-
figuration, do not show d-d transitions as well. The Cu(II)
complex has magnetic moment of 1.80 B.M. (Table 2)
corresponding to a single electron spin [22].
S2
S1
C1
Fig. 1 ORTEP diagram of the Schiff base with atom numbering
scheme
˚
Table 4 Selected bond distances (A) in HL compared to the corre-
spondent values in the two ligands of NiL2
HL
NiL2
Description of the crystal structures
Ligand A
Ligand B
N(1)–N(2)
N(1)–C(2)
N(2)–C(3)
S(2)–C(1)
S(2)–C(2)
S(1)–C(2)
1.386(2)
1.328(3)
1.275(3)
1.792(3)
1.748(2)
1.666(2)
1.405(4)
1.282(5)
1.305(5)
1.789(5)
1.746(5)
1.716(5)
1.413(4)
1.300(5)
1.316(5)
1.789(5)
1.747(5)
1.706(5)
The ORTEP diagram of the Schiff base HL along with the
atom numbering scheme is shown in Fig. 1, and selected
bond lengths and angles are given in Table 4. In solid state,
the dithiocarbazate group adopts an EE configuration with
respect to the C=N bond of the benzylidene group. The
ligand is in its thione tautomeric form with S(1)-C(2) bond
˚
length of 1.666(2) A. The benzaldehyde dithiocarbazate
´
˚
fragment is almost planar [max deviation = 0.044 A], while
the dihedral angle between the benzyloxy and phenyl ring is
of 79.31(6)ꢁ. In the crystal, the molecules are interconnected
˚
by N–H…S hydrogen bonds (N…S = 3.379 A, N–H…S
angle of 147ꢁ) to form centrosymmetric dimers (Fig. 2). The
arrangement is similar to that observed for the benzyl-3-
(3-phenylprop-2-enylidene)dithiocarbazate earlier reported
[25]. Finally, no p–p interaction among aromatic rings is
present in the crystal packing.
N1
S1
The ORTEP diagram of NiII complex, NiL2 along with the
atom numbering scheme, is shown in Fig. 3, and a selection
of bond lengths and bond angles are given in Table 5. With
respect to the free ligand, a rotation about the C2-N1 is
required to allow the N,S coordination to the metal. As
derived from the spectral and magnetic study, the complex is
monomeric with a slightly distorted square planar geometry.
The two Schiff bases, in their deprotonated imino thiolate
form, are coordinated to the Ni(II) centre via the azomithine
nitrogen and thiolate sulfur atoms in a trans-planar configu-
ration. This coordination geometry is the most frequent for
this type of ligand, although Ni complexes with cis config-
uration have been also reported. [7, 28, 29] In the cited
complexes, the cis configuration appears stabilized by p–p
stacking interactions occurring between the aromatic rings.
Fig. 2 HL dimer formation through NH…S interactions
In the present complex, the two ligands are crystallog-
raphy independent with variation for bond lengths and
angles within their e.s.d.’s, the most evident difference
being the mutual orientation of phenyl rings within each
unit. In fact, each phenyl ring form an angle of 4.8(2) and
24.5(2)ꢁ with the adjacent semicarbazate fragment, indi-
cating an electron delocalization system in the former, that
123

536
Transition Met Chem (2011) 36:531–537
Fig. 3 ORTEP diagram of
the NiII complex with atom
numbering scheme
C15
C16
C14
O1
C8
C11
C7
C13
C12
C9
C3
S4
C10
S3
C6
C22
N3
C4
C21
N2
C5
N4
N1
C2
Ni
C24
C29
C28
C23
C1
S1
C30
C25
S2
C32
C33
C34
C26
C27
O2
C31
C36
C35
˚
Table 5 Selected bond distances (A) and angles (ꢁ) for complex
NiL2
conts/retrieving.html or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (?44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at doi:
XXXXXX.
Ni–N(2)
1.911(3)
1.906(4)
85.95(12)
93.52(12)
94.55(12)
Ni–S(1)
2.1673(13)
2.1767(13)
86.21(12)
178.79(15)
167.38(6)
Ni–N(4)
Ni–S(3)
N(2)–Ni–S(1)
N(4)–Ni–S(1)
N(2)–Ni–S(3)
N(4)–Ni–S(3)
N(2)–Ni–N(4)
S(1)–Ni–S(3)
Acknowledgments The authors MAAAI and MAA thank the
Department of Chemistry RUET for lab facilities and MCS the
Department of Chemistry, Toyama University, for analytical facili-
ties. MTHT is grateful for a UGC grant and EZ thanks MIUR (PRIN
Nꢁ 2007HMTJWP_002) for financial support.
could justify the differences in bond angles observed
between the dithiocarbazate groups. On the other hand, the
angle between the benzyloxy and phenyl ring is compara-
ble in the two ligands (of 58.2(1) and 54.7(2)ꢁ).
The square planar coordination geometry shows slight
distortions having not coplanar atoms with the two five-
membered chelating rings that form a dihedral angle of
27.17(19)ꢁ. The Ni–S bond distances (of 2.1673(13),
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