Mono- and di-nuclear complexes of thiosemicarbazones with copper(I): Synthesis, spectroscopy and structures

Article abstract of DOI:10.1016/j.poly.2009.08.028

Reactions of copper(I) halides with a series of thiosemicarbazones, namely, benzaldehyde thiosemicarbazone (R¹R²C{double bond, long}N-NH-C({double bond, long}S)-NH₂, R¹ = Ph, R² = H; Hbtsc), 2-benzoyl

Full text of DOI:10.1016/j.poly.2009.08.028

Polyhedron 28 (2009) 3899–3906
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Mono- and di-nuclear complexes of thiosemicarbazones with copper(I): Synthesis,
spectroscopy and structures
a
a
b
c
Tarlok S. Lobana a, , Sonia Khanna , Geeta Hundal , Ray J. Butcher , Alfonso Castineiras
*
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
b Department of Chemistry, Howard University, Washington, DC 20059, USA
c Departamento De Quimica Inorganica, Facultad de Farmacia, Universidad de Santiago, 15782 Santiago, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of copper(I) halides with a series of thiosemicarbazones, namely, benzaldehyde thiosemicarba-
zone (R1R2C@N–NH–C(@S)–NH2, R1 = Ph, R2 = H; Hbtsc), 2-benzoylpyridine thiosemicarbazone (R1 = Ph,
Received 20 April 2009
Accepted 31 August 2009
Available online 10 September 2009
R
2 = py; Hbpytsc), and acetone thiosemicarbazone (R1 = R2 = Me; Hactsc), in the presence of PPh3 has
formed dimeric complexes, viz. sulfur bridged [Cu2(
[Cu2( -I)2(
1-S-Hbtsc)2(PPh3)2] (2), and heterobridged [Cu2(
as well as mononuclear complexes [CuX(
l
-S-Hbtsc)2Br2(PPh3)2]Á2H2O (1), iodo-bridged
l
g
l g l-Br)(PPh3)2] (3),
3-S,N3-Hactsc)( 1-Br)(
g
1-S-Hbpytsc)(PPh3)2]ÁCH3CN (X = Br, 4; Cl, 5). Complexes 1,
Keywords:
Copper(I)
Thiosemicarbazones
Heterobridging
Di-nuclear complexes
2, 4 and 5 involve thiosemicarbazone ligands in
g
1-S bonding mode while in compound 3, ligand acts
in N3, S-chelation-cum-S-bridging mode (
l
3-S,N3 mode). The intermolecular interactions such as,
N2HÁ Á ÁX, HN1HÁ Á ÁX (X = S, Br, Cl), CHÁ Á Á
p interactions lead to 2D networks. All the complexes have been
characterized with the help of elemental analyses, IR, 1H, and 31P NMR spectroscopy, and single crystal X-
ray crystallography. The role of a solvent in alteration of nuclearity and bonding modes of complexes has
been highlighted.
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
2. Materials and techniques
Metal complexes of thiosemicarbazone ligands have shown var-
iable bonding properties and structural diversity along with prom-
ising biological implications, and ion sensing abilities [1–18].
Recently, thiosemicarbazone chemistry of copper(I) halides has
been explored and in neutral form, they have exhibited different
Copper(I) halides were prepared by reducing an aqueous solu-
tion of CuSO4Á5H2O with SO2 in the presence of NaX (X = Cl, Br, I)
in H2O [32]. Ph3P was procured from Aldrich Chemicals Ltd. and
used as such. 2-Benzoylpyridine thiosemicarbazone (Hbpytsc)
and acetone thiosemicarbazone (Hactsc) were prepared using liter-
ature methods [25,33]. C, H and N analysis were obtained with
Thermoelectron FLASHEA1112 CHNS analyzer. Infrared spectra
were recorded as KBr pellets in the range 4000–200 cmÀ1 on Pye
– Unicam SP-3-300 spectrophotometer. The melting points were
determined with a Gallenkamp electrically heated apparatus. 1H
NMR were recorded on a JEOL AL-300 FT spectrometer operating
at a frequency of 300 MHz using CDCl3 as solvent with TMS as
internal reference. 31P NMR spectra were recorded on a Bruker
ACP-300 spectrometer operating at a frequency of 121.5 MHz with
H3PO4 as external reference set at zero value.
bonding modes:
g l
1-S (mode A), 2-S (mode B), N3, S-chelation
(mode C), N3, S-chelation-cum-S-bridging (mode D) [19–30], and
in the anionic form, there is only N2, S-chelation-cum-S-bridging
(mode E) [31] (Chart 1).
In reactions of benzaldehyde thiosemicarbazone with copper(I)
halides, for X = I a tetrahedral complex, [CuI(
for X = Br, both [CuBr(
1-S-Hbtsc)(PPh3)2] and a bromo-bridged di-
mer, [Cu2( -Br)2(
1-S-Hbtsc)2(PPh3)2] and for X = Cl, a sulfur
bridged dimer, [Cu2( -S-Hbtsc)2Cl2 (PPh3)2] were formed in CH3CN
g
1-S-Hbtsc)(PPh3)2],
g
l
g
l
solvent [24]. These reactions studied using acetonitrile–chloroform
mixture, have yielded new products for X = I, Br, which are re-
ported in this paper. Using the acetonitrile–dichloromethane mix-
ture for the ligands, Hbpytsc and Hactsc, new complexes of
copper(I) have been obtained.
2.1. Synthesis of complexes
2.1.1. [Cu2(l-I)2(g
1-S-Hbtsc)2(PPh3)2](1)
Chart 2 shows the ligands along with their abbreviations used.
All these complexes have been characterized by elemental analy-
sis, spectroscopy (IR, 1H, 31P NMR) and X-ray crystallography.
To a solution of copper(I) iodide (0.025 g, 0.13 mmol) in CH3CN
(10 mL) was added Hbtsc (0.023 g, 0.13 mmol), and contents were
stirred for 45 min and to the resulting yellow solid was added PPh3
(0.034 g, 0.13 mmol), and CHCl3 (5 mL) and the clear solution was
allowed to slowly evaporate at room temperature which yielded
yellow colored crystals. M.p. 220–222 °C, yield, 65%. Anal. Calc.
* Corresponding author. Fax: +91 183 2 258820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.08.028

3900
T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
NH2
NH2
C
S
C
S
N3
N3
N2
S
S
Cu
Cu
Cu
Cu
Cu
Cu
S
Cu
Cu
Cu
(A)
(B)
(D)
(E)
(C)
Chart 1.
dNH2 +
1060s, 958s;
7.34–7.73m (PPh3 + Ph + N1H2), 8.59sb (–N1H2); 8.24s (–C2H),
11.97s (–N2H). 31P NMR (CDCl3, dmso-d6,
ppm): 30.29,
À3.05 ppm, d(dcomplex À dligand) = 35.6, 1.65 ppm. Complex is
poorly soluble in CHCl3 and CH3CN.
m
(C@C) 1583m, 1544s, 1477s;
m(C@S) 850s, 811s; m(C–N)
(P–CPh) 1093s. 1H NMR (CDCl3, dmso-d6, d ppm):
R1 =
R2 =
Me
Me
m
S
H
1
C
R1
R2
N2
1
3
N
d
C2
NH2
D
H
N
2.1.3. [Cu2(l3-S,N-Hactsc)(l-Br)(g
1-Br)(PPh3)2] (3)
Hbtsc
Hbtsc = benzaldehyde thiosemicarbazone
Hbpytsc
Hactsc
To a solution of CuBr (0.025 g, 0.174 mmol) in CH3CN (10 mL),
was added solid PPh3 (0.046 g, 0.174 mmol) and the stirring was
continued until the formation of white solid, followed by addition
of Hactsc ligand (0.023 g, 0.174 mmol). To this mixture, 5 mL of
CH2Cl2 (5 mL) was added and the contents were stirred for a fur-
ther period of 10 min. On slow evaporation, pale yellow crystals
Hbpytsc = 2-benzoylpyridine thiosemicarbazone
Hactsc = acetone thiosemicarbazone
Chart 2.
H
Me
PPh3
for C52H48Cu2I2N6P2S2: C, 49.41; H, 3.80; N, 6.65. Found: C, 49.63;
H, 3.58; N, 6.55%. IR data (KBr, cmÀ1):
(N–H) 3425s, 3252m
(–NH2–) 3180m, 3138m (–NH–); (C–H) 3051sh, 3018m;
(C@N) + dNH2 + (C@C) 1628s, 1477m, 1431s; (C–S) 817s, 848s
(thioamide moiety); (C–N) 1024s, 1065s;
(P–CPh) 1092s. 1H
3
Br
S
½[CuBr(PPh3)]4
CH3CN + CH2Cl2
Br
2
C
N
1
C
2
N
Cu
m
Cu
N3
Me
1
m
S
Ph3P
NH2
m
m
m
m
m
3
NMR (CDCl3, dmso-d6, d ppm): 6.52–6.85m (PPh3 + Ph), 7.01sb,
PPh3
7.56sb (–N1H2); 7.34s (–C2H), 10.87s (–N2H). 31P NMR (CDCl3,
dmso-d6,
d
ppm): À4.63 ppm,
D
d(dcomplex À dligand) = 0.07 ppm.
Cu
Complex is poorly soluble in CHCl3 and CH3CN.
PPh3
X
H
S
1
2
2PPh3
+ CuX
S
1
2
3
N
2.1.2. [Cu2(
l
-S–Hbtsc)2Br2(PPh3)2]Á2H2O (2)
H
N
C
C
1
N
N
C
CH3CN/CH2Cl2
It was prepared by method used for complex 1. M.p.
182 À 185 °C, yield 70%. Anal. Calc. for C52H52Br2Cu2N6O2P2S2: C,
51.74; H, 4.31; N, 6.96. Found: C, 51.96; H, 4.14; N, 7.05%. IR data
NH2
H
Br 4; Cl 5
(KBr, cmÀ1):
m
(O–H) 3686m, 3504m, 3442s;
m(N–H) 3307s,
Scheme 2.
3211m (–NH2–) 3163m (–NH–); (C–H) 3053s;
m
m(C@N) +
S
C
R
S
2PPh3
I
PPh3
NH
2 CuI +
2
Cu
Cu
CH3CN -CHCl3
C
NH2
N
I
S
R
Ph3P
H
1
CH3CN
4PPh3
CHCl3
-2PPh3
I
2
Cu
S
R
Ph3P
PPh3
R
S
2 PPh3
Br
PPh3
Br
S
S
NH
C
Cu
R
CuBr +
2
2
Cu
CH3CN/ CHCl3
C
NH2
N
Ph3P
H
2
Scheme 1.

T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
3901
were formed. M.p. 178–180 °C, yield 64%. Anal. Calc. for
C40H39Br2Cu2N3P2S: C, 50.96; H, 4.14; N, 4.45. Found: C, 50.63; H,
4.21; N, 4.45%. Main IR peaks (KBr, cmÀ1):
(N–H) 3418s, 3238s
(–NH2–), 3155s (–NH–); (C@N) + dNH2 + (C@C) 1604s, 1548s,
1477s; (C–N) 1068s; (P–CPh
63.62; H, 4.35; N, 7.17%. Main IR peaks (KBr, cmÀ1):
3412s, 3209s (–NH2–) 3136b (–NH–); (C@N) + dNH2 +
1585s, 1550s, 1466s; (C@S) 835s (thioamide moiety);
1070s, 1028s;
(P–CPh) 1092s. 1H NMR (CDCl3, d ppm) 7.23–
7.61m (PPh3 + C4H), 7.78td (C5, 6H), 8.66sb (–N1H2), 8.81d (C7H),
13.82s (–N2H). 31P NMR (CDCl3,
ppm): À4.05 ppm,
d(dcomplex À dligand) = 0.65 ppm. Complex is partially soluble in
CHCl3 and CH3CN.
m
m
(N–H)
(C@C)
m
m
m
m
m(C–N)
m
m
m
(C@S) 810s (thioamide moiety);
m
m
)
1095s. 1H NMR (CDCl3, d ppm) 2.01s, 2.03s (CH3); 7.22–7.67m
d
(PPh3 + –N1H2), 10.24s (–N2H). 31P NMR (CDCl3, d ppm):
D
À4.18 ppm,
D
d(dcomplex À dligand) = 0.52 ppm. Complex is partially
soluble in CHCl3 and CH3CN.
2.1.5. [Cu(
g
1-S-Hbpytsc)Cl(Ph3P)2]ÁCH3CN (5)
2.1.4. [Cu(
g
1-S-Hbpytsc)Br(Ph3P)2]ÁCH3CN (4)
It was prepared by method used for complex 4. M.p. 160–
162 °C, yield 60%. Anal. Calc. for C49H42ClCuN4P2SÁCH3CN: C,
66.52; H, 4.89; N, 7.60. Found: C, 66.69; H, 5.14; N, 7.54%. Main
To a solution of CuBr (0.025 g, 0.17 mmol) in CH3CN (10 mL),
was added solid Hbpytsc ligand (0.045 g, 0.17 mmol) and PPh3
(0.092 g, 0.34 mmol) in CH2Cl2 (5 mL), followed by stirring for a
period of 10 min. Yellow colored crystals were formed by the slow
evaporation of the solution. M.p. 185–187 °C, yield 71%. Anal. Calc.
for C49H42BrCuN4P2SÁCH3CN: C, 63.39; H, 4.66; N, 7.25. Found: C,
IR peaks (KBr, cmÀ1
3110sb (–NH–); (C@N) + dNH2 +
(C@S) 837s (thioamide moiety);
1092s. 1H NMR (CDCl3, d ppm) 7.22–7.48m (PPh3 + Ph + N1H2),
)
m
(N–H) 3412s, 3200s (–NH2–) 3122w,
(C@C) 1599s, 1550s, 1500s;
(C–N) 1068s, 1028s; (P–CPh
m
m
m
m
m
)
Table 1
Crystallographic details of complexes 1–5.
1
2
3
Empirical formula
Molecular mass
T (K)
C52H48Cu2I2N6P2S2
1263.90
100(2)
C52H52Br2Cu2N6O2P2S2
1205.96
295(2)
C40H39Br2Cu2N3P2S
942.64
200(2)
Crystal system
Space group
a (Å)
monoclinic
P21/c
11.107(2)
16.064(3)
14.158(3)
90
94.585(3)
90
2518.0(8)
2
triclinic
triclinic
ꢀ
ꢀ
P1
P1
9.521(5)
8.7740(8)
9.1096(17)
14.387(2)
76.072(14)
72.481(10)
64.010(15)
977.7(2)
b (Å)
c (Å)
10.771(8)
13.764(5)
102.29(6)
103.09(5)
98.67(8)
1313.6(11)
1
1.524
a
(o)
b (o)
c
(o)
V (Å3)
Z
1
D (mg/m3)
1.667
2.260
1.601
3.299
l
(mmÀ1
)
2.516
F(0 0 0)
1256
612
474
Crystal size (mm3)
h Range for data collection (°)
Index ranges
0.19 Â 0.08 Â 0.08
1.84–26.42
À13 6 h 6 13
0 6 k 6 20
À0 6 l 6 17
21722
0.20 Â 0.20 Â 0.18
0.35 Â 0.31 Â 0.26
4.49–30.53
À12 6 h 6 11
À12 6 k 6 12
À20 6 l 6 16
13 381
12–20
0 6 h 6 11
À12 6 k 6 12
À16 6 l 6 16
5146
Reflections collected
Independent reflections (Rint
Final R indices
)
5171 (0.0370)
0.0300, 0.0574
4835 (0.0619)
0.0796, 0.2396
7921 (0.0260)
0.0295, 0.0571
[I > 2r(I)]
R1, wR2
4
5
Empirical formula
Molecular mass
T (K)
C51H45BrCuN5P2S
965.37
100(2)
C51H45ClCuN5P2S
920.91
295(2)
Crystal system
Space group
a (Å)
triclinic
P1
triclinic
P1
9.633(1)
13.627(1)
18.463(1)
94.41(1)
ꢀ
ꢀ
9.6003(6)
13.5226(8)
18.2422(11)
95.266(1)
92.469(1)
105.447(1)
2267.4(2)
2
b (Å)
c (Å)
a
(o)
b (o)
92.75(1)
c
(o)
105.03(1)
2328.0(3)
2
1.314
0.681
V (Å3)
Z
D (mg/m3)
1.414
1.521
l
(mmÀ1
)
F(0 0 0)
992
956
Crystal size (mm3)
0.53 Â 0.46 Â 0.15
1.12–28.28
À12 6 h 6 12
À17 6 k 6 18
À24 6 l 6 24
23 683
0.20 Â 0.10 Â 0.10
1.55–25.50
0 6 h 6 11
À16 6 k 6 15
À22 6 l 6 22
9230
h Range for data collection (o)
Index ranges
Reflections collected
Independent reflections (Rint
)
11 199 (0.0224)
0.0355, 0.0914
8675 (0.0332)
0.0435, 0.1037
Final R indices I > 2 (I)] R1, wR2
r

3902
T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
7.55d (C4H), 7.78 td (C5, 6H), 8.80d (C7H), 9.18sb (–N1H2), 13.77s
lides with thiosemicarbazones, and the addition of chloroform has
changed both the nuclearity and nature of bridge-bonding be-
tween two copper centers.
(–N2H). 31P NMR (CDCl3, d ppm): À3.61 ppm,
D
d(dcomplex
À
dligand) = 1.09 ppm. Complex is soluble in CHCl3 and hot CH3CN.
Complex 5 was prepared similarly.
2-Benzoylpyridine thiosemicarbazone with copper(I) bromide/
chloride in presence of two moles of PPh3 in acetonitrile-dichloro-
methane mixture yielded tetrahedral complexes, [CuX(g
1-S-
3. X-ray crystallography
Hbpytsc)(PPh3)2]ÁCH3CN (Br 4; Cl 5). The use of one mole of PPh3
in this reaction system did not give crystalline products. Di-nuclear
Suitable light yellow crystals of complexes 2 and 5 were
mounted on a Siemens P4 diffractometer and the h–2h technique
was used to measure the intensities, up to a maximum of
complex [Cu2Br(l
-Br)(N3, S-Hactsc)(PPh3)2] (3) has been obtained
by reacting copper(I) bromide with PPh3 in CH3CN followed by
addition of acetone thiosemicarbazone (Hactsc) along with dichlo-
romethane (5 mL) (Scheme 2).
2h = 50° with graphite monochromatised Mo
Ka radiation
(k = 0.71073 Å) Unit cell dimensions and data were collected at
295(2) K using XSCANS [34]. The data were corrected for Lorentz
IR spectroscopy of all the complexes confirmed the presence of
the individual ligands via their
m
(N–H),
m(C–N), m(C@C), m(C@N),
and polarization factors. An empirical
w absorption correction
and (P–C) vibrational modes. The
m
m
(C@S) thioamide bands are lo-
was applied. The structure was solved by the direct methods and
refined by full matrix least squares methods based on F2 using
SIR-92 and SHELXL-97 [35a]. All non-hydrogen atoms were refined
anisotropically. All hydrogen atoms were attached geometrically
riding on their respective carrier atoms with Uiso being 1.5, 1.2
and 1.2 times the Uiso of their carrier methyl, methylene and aro-
matic carbon atoms, respectively. Scattering factors from the Inter-
national Tables for X-ray crystallography were used [36]. Data
reduction, structure solution, refinement and molecular graphics
were performed using SHELXTL-PC [35b] and WINGX [37]. In complex
2, oxygen of water molecule is highly disordered and the disorder
could not be resolved thus this oxygen has a high ADP max/min ra-
tio. The hydrogens of water molecule were located from difference
Fourier map with great difficulty and were not refined. They were
fixed at a distance 0.950(3) Å with a thermal parameter 1.2 times
that of oxygen O1.
cated at 770–837 cmÀ1, which suggests (in agreement with the X-
ray data) a significant weakening of the C@S double bond in all
complexes.
4.2. Crystal structures
Complexes 2, 3–5 crystallized in triclinic crystal systems with
ꢀ
space group P1, while complex 1 crystallized in monoclinic crystal
Suitable crystals of complex 4 were mounted on Bruker AXS
SMART APEX CCD diffractometer; complex 1 on Bruker SMART
CCD-1000 diffractometer and 3 on Oxford Diffraction Gemini dif-
fractometer, with graphite monochromatised Mo K
a radiation
(k = 0.71073 Å). The unit cell dimensions and intensity data were
measured at 100(2) K (1, 4) and 200(2) K (3). Data were reduced
and corrected for absorption using SMART and SAINT (1, 4) [37] or CRY-
SALIS RED (3) [38]. The structures were solved by direct methods and
refined by full matrix least squares based on F2 with anisotropic
thermal parameters for non-hydrogen atoms using SHELXTL (struc-
ture solution, refinement and some molecular graphics) (1, 4)
[35] and CRYSALIS RED (3) [38]. The structure 3 solves and is well be-
haved in P1 with no restraints needed and gives an excellent R (less
Fig. 1. Molecular structures of complex [Cu2(l-I)2(Hbtsc)2(PPh3)2] 1.
ꢀ
than 3%). In P1, the structure can be partially solved and there are
signs of the rest of molecule but the R is high (>16%) and all atoms
have to be severely restrained in order to refine it.
4. Results and discussion
4.1. Synthesis and Infrared spectroscopy
Reaction of copper(I) iodide with Hbtsc in acetonotrile–chloro-
form mixture (2:1 v/v) in presence of one or two moles of PPh3 has
invariably formed an iodo-bridged dimer, [Cu2(l-I)2(g
1-S-
Hbtsc)2(Ph3P)2] 1 (Scheme 1). This reaction in CH3CN alone in pres-
ence of one/two moles of PPh3 yielded rather a mononuclear com-
plex, [CuI(
system as used for complex 1, copper(I) bromide has yielded a
sulfur-bridged di-nuclear complex, [Cu2( -S-Hbtsc)2(
1-Br)2
(Ph3P)2]Á2H2O 2, unlike a bromo-bridged dimer, [Cu2(
-Br)2(g1
S-Hbtsc)2(Ph3P)2] 6, and a mononuclear complex [CuBr(
1-S-
g
1-S-Hbtsc)(PPh3)2] [24]. Using the similar solvent
l
g
l
-
g
Hbtsc)(PPh3)2] obtained in CH3CN in presence of one/two moles
of PPh3, respectively [24]. The behavior of copper(I) chloride was
unchanged in mixed solvents [24]. The formation of 1 and 2 high-
lights the importance of medium used for reactions of copper(I) ha-
Fig. 2. Molecular structure of complex [Cu2(l-S-Hbtsc)2Br2(PPh3)2]Á2H2O 2.

T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
3903
systems with P21/n space group. Table 1 represents the crystallo-
graphic details. Bond parameters and hydrogen bonding data are
given in Supplementary data.
in the Table 2. The variation of bond parameters related to the cen-
tral cores is listed as follows:
In di-nuclear complex, [Cu2(
(Fig. 1), sulfur atoms and PPh3 ligands occupy trans positions
across the central Cu( -I)2Cu core while in [Cu2(
-S-Hbtsc)2(g1
Br)2(PPh3)2]Á2H2O 2, bromine and PPh3 ligands occupy trans
positions across the central Cu( -S)2Cu core (Fig. 2). The unequal
l-I)2(g
1-S-Hbtsc)2(PPh3)2]
1
CuÁ Á ÁCu (R1, R2): Me, H > Me, Me > thiophene, H > furan,
H ꢀ phenyl, H.
l
l
-
Cu–I–Cu: Me, H > Me, Me > thiophene, H > phenyl, H > furan, H.
I–Cu–I: Me, H < Me, Me < thiophene, H < phenyl, H < furan, H.
l
It is apparent that Cu–I–Cu and I–Cu–I bond angles vary in a
complementary fashion. Generally, CuÁ Á ÁCu contact is found to be
longer with smaller substituents vis-à-vis bulkier groups at C2
Cu–S or Cu–I distances of central cores of complexes 1 and 2, form
parallelograms. From Table 2, it can be seen that CuÁ Á ÁCu contact
{2.9786 Å} in 1 is shortest among other iodo-bridged dimers listed
Table 2
Selected bond distances (Å) and bond angles (o).
I
Cu
Cu
I
Complex (R1, R2)
Cu–S
Cu–I
CuÁ Á ÁCu
Cu–I–Cu
I–Cu–I
2.3399(9)
2.6351(6)
2.6850(5)
2.9786
68.087(16)
111.913(16)
[this work]
, H
1
Me, Me [30]a
Me, H [30]b
2.3017(17)
2.3098(16)
2.3505(9)
2.6130(7)
2.8020(8)
2.6324(8)
2.8202(10)
2.6466(4)
2.8171(5)
3.5043(0)
3.606(1)
80.57(2)
99.43(2)
82.72(3)
75.586(14)
97.28(3)
3.2247(6)
104.414(14)
c
,
,
H
H
[24]
S
2.3401(9)
2.6507(7)
2.6797(6)
2.9808(8)
67.999(16)
112.001(16)
d
[24]
O
S
Cu
Cu
S
Cu–S
Cu–Br
CuÁ Á ÁCu
3.200
Cu–S–Cu
83.68(12)
S–Cu–S
2.393(4)
2.405(3)
2.473(2)
96.32(12)
[this work]
,H
2
2.3769(6)
2.4039(6)
2.4851(4)
2.4786(4)
3.0087(5)
3.2329(6)
77.998(18)
84.88(2)
102.002(18)
95.12(2)
, H
, H
[24]e
N
H
2.3922(6)
2.3986(6)
f
[24]
S
S
Cu
Cu
Br
Cu–S
Cu–Br
CuÁ Á ÁCu
2.8151(5)
Cu–S–Cu
Cu–Br–Cu
68.606(15)
3 Me, Me[this work]
2.3576(6)
2.4597(6)
2.344(8),
2.426(9)
2.4591(5)
2.4978(6)
2.488(5)
2.488(5)
71.482(19)
2.771(5)
71.03(2)
67.68(15)
6 [39]g
6
a
b
c
d
e
f
[Cu2(
[Cu2(
[Cu2(
[Cu2(
[Cu2(
[Cu2(
l
l
l
l
l
l
-I)2(
-I)2(
-I)2(
-I)2(
g
g
g
g
1-S-Hactsc)2 (PPh3)2].
1-S-Hmtsc)2 (PPh3)2].
1-S-Httsc)2(PPh3)2].
1-S-Hftsc)2(PPh3)2].
-S-Hptsc)(
-S-Httsc)(
-Br)(l3-S,N-Hcptsc)CuBr(PPh3)].
g
1-Br)2(PPh3)2]Á2H2O.
g
1-Br)2 (PPh3)2]Á2H2O.
g
[(Ph3P)Cu(
l

3904
T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
[24,27,30]. Here it can be concluded that the CuÁ Á ÁCu separations,
3.20–3.23 Å in sulfur bridged dimers {( -S)2}, decrease to
2.77–2.82 Å in hetero-bridged dimers {( -S)( -Br)}, and a further
decrease (2.504(1) Å) occur in triply-bridged dimer with {(
I)2( -S)}core of [(Ph3P)Cu( -I)2( -S-Haptsc)Cu(PPh3)] (Hap-
l
l
l
l-
l
l
l
tsc = acetophenone thiosemicarbazone) [40].
In each of mononuclear complexes, [CuX(
g
1-S-Hbpytsc)
(PPh3)2]ÁCH3CN (X = Br 4; Cl 5 Fig. 4), the copper atom is bonded
to a terminal halogen atom, a sulfur atom of Hbpytsc ligand and
two phosphorous atoms from two triphenylphosphine ligands
forming a distorted tetrahedral about copper atom. The pyridyl
group is not coordinating and remains as a pendant group as in
[CuX(
g
1-S-Hpytsc) (PPh3)2]ÁCH3CN (X = Cl, Br) [24]. The Cu–S,
Cu–P and Cu–X distances are similar to the literature reports
[24], except the bond angles. The variation of bond angles relative
to the substituents at C2 carbon vary as follows:
Fig. 3. Molecular Structure of [Cu2(l3-S,N-Hactsc)(l-Br)Br(PPh3)2] (3).
P–Cu–P: Ph, Ph > Ph, Py > py, H.
S–Cu–X; Br: Ph, Ph > Ph, py > py, H.
Cl:Ph, py > py, H > Ph, py.
carbon. The bond parameters of sulfur bridged dimer 2 are analo-
gous to that of sulfur bridged di-nuclear complex [Cu2(
l
-S-
Httsc)(g
1-Br)2(PPh3)2]Á2H2O
(Httsc = thiophene-2-carbaldehyde
thiosemicarbazone) (Table 2). Water molecules engage in hydro-
gen bonding with bromine atoms, and thus paving way for sulfur
bridging [24]. The bond angles at copper atoms reveal a distorted
tetrahedral geometry in complexes 1 and 2.
The S–Cu–X and P–Cu–X bond angles are complementary to
each other (Table 3).
4.3. Packing arrangements
Complex [Cu2(
l
3-S,N-Hactsc)(
l
-Br)(
g
1-Br)(PPh3)2]Á3 has cen-
tral core, Cu( -Br)(l-S)Cu with heterobridging and two copper
l
Both di-nuclear complexes 1 and 2 did not show any intramo-
lecular interactions. In complex 1, two dimers are linked to each
other via intermolecular imino hydrogen–sulfur hydrogen bonding
(–N2HÁ Á ÁS), resulting in a linear polymeric chain along a axis. Two
atoms are under different coordination environments (Fig. 3). The
central {Cu(l-S)(l-Br)Cu} core has unequal Cu–S and nearly equal
Cu–Br distances. The Hactsc ligand thus adopts N3, S-chelation-
cum-S-bridging mode, which is similar to that in analogous
chains are further linked to each other via CHÁ Á Á
p interactions
complex, [(Ph3P)Cu(l-Br)(l3-S,N-Hcptsc)CuBr(PPh3)] 6 (Hcptsc =
(along b axis) among phenyl rings of PPh3 and Hbtsc (2.831,
3.330, and 3.252 Å), and this process results in a 2D network in
ab plane (see Supplementary data). Complex 2 has two water mol-
ecules per dimer, which form intermolecular –N2HÁ Á ÁO, OHÁ Á ÁN2
and C20–H20Á Á ÁO1 hydrogen bonds within each dimer. The dimers
are further forming a one dimensional ribbon along b axis due to
C8–H8Á Á ÁO1 H-bonds (Fig. 5).
cyclopentanone thiosemicarbazone) [39]. This type of coordination
mode is rare in copper(I)-thiosemicarbazone chemistry [29]. The
angles at bridged sulfur and bridged bromine atoms are much
shorter relative to the angles in symmetrically sulfur or bromo-
bridged dimers (Table 2) [24]. The bond angles at Cu(1) range from
85.2° to 126.9° and at Cu(2) from 95.6° to 114.5°, revealing a dis-
torted tetrahedral geometry. The CuÁ Á ÁCu separation, 2.8151(5) Å
in 3 is slightly longer than 2.771(5) Å in 6 [39], but shorter than
those in bromo or sulfur bridged dimers reported in literature
The packing pattern of 3 reveals the absence of any intramolec-
ular interactions in the molecule. The terminal bromine forms
–HN1HÁ Á ÁBr and –N2HÁ Á ÁBr intermolecular hydrogen bonds. The
bridging bromine forms BrÁ Á ÁHN1H and BrÁ Á ÁHCH2 (3.169 Å) inter-
molecular hydrogen bonds. These interactions lead to the forma-
tion of 1D polymeric chain. This network is extended in 2D via
CH–
p (phenyl–phenyl) interactions (3.139, 2.817 Å) (Fig. 6).
Complex [CuBr(
g
1-S-Hbpytsc)(PPh3)2]ÁCH3CN (4) exhibits intra-
molecular hydrogen bonding interactions between amino-bromine
(BrÁ Á ÁHN1H) and imino-pyridyl nitrogen (—N2H Á Á Á Np4yridyl) atoms.
Acetonitrile molecules are engaged in intermolecular hydrogen
bonding with bromine (NCCH2HÁ Á ÁBr) and amino hydrogen atoms
(CH3CNÁ Á ÁHN1H), and form H-bonded dimers. These dimers are
further linked via intermolecular hydrogen bonding between coor-
dinated sulfuratom and phenyl hydrogen of Hbpytsc ligand (SÁ Á ÁHPh
,
2.928 Å) leading to the 2D network in ab plane (Fig. 7). Complex 5
shows similar packing interactions (see Supplementary data).
5. Solution state studies
The 1H NMR spectra of complexes 1–5 reveal the presence of –
N2H, –N1H2, methyl and ring proton signals generally at low field
relative to their corresponding free ligands. The methyl protons
of Hactsc ligand in 3 are non-equivalent {d 2.01 and 2.03 ppm}
are marginally shifted relative to the free ligand (d 1.90–
2.32 ppm). Complexes 1, 3–5 complexes displayed a single peak
in their 31P NMR spectra. This shows that the complexes remain in-
Fig. 4. Molecular Structure of [CuCl(
atoms are not shown for clarity (complex 4 has a similar structure).
g
1-S-Hbpytsc)(PPh3)2]ÁCH3CN (5) Hydrogen

T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
3905
Table 3
A comparison of bond distances (Å) and bond angles (o) of mononuclear complexes 4 and 5 with related complexes.
Complex
X
Cu–S
Cu–X
P–Cu–P
S–Cu–X
P–Cu–X
Br
2.3693(5)
2.4609(3)
122.31(2)
110.636(15)
104.706(16)
106.067(15)
4 [This work]
5 [This work]
,
,
N
N
Cl
2.3850(8)
2.3337(9)
122.56(3)
109.14(3)
106.02(3)
106.26(3)
Br
Cl
Br
2.3542(17)
2.3606(8)
2.4142(13)
2.4863(12)
2.3757(7)
2.5475(8)
131.56(4)
126.00(3)
122.39(5)
112.38(4)
106.21(3)
107.76(4)
99.49(6)
105.27(6)
[28]a
[28]b
,
,
102.55(3)
106.96(3)
105.11(4)
106.40(4)
[24]c
[24]d
,
H
H
N
Cl
2.4063(6)
2.4097(6)
120.92(2)
108.43(2)
104.71(2)
108.65(2)
,
N
a
b
c
[CuBr(
g
1-S-Hbztsc)(PPh3)2].
g
1-S-Hbztsc)(PPh3)2].
[CuCl(
[CuBr(
g
1-S-Hpytsc)(PPh3)2].
g
1-S-Hpytsc)(PPh3)2].
d
[CuCl(
Fig. 5. C8–H8Á Á ÁO1 H-bonds forming a 1D ribbon along b axis in complex 2.
Fig. 6. Packing diagram of [Cu2Br(l-Br)(l
3-N3,S-Hactsc)(PPh3)2] (3).
tact in solution state. However, complex 2 showed a signal at d
30.29 ppm with coordination shift of 35.6 ppm supporting sulfur
bridging [24,27]. This complex, in addition showed a signal at d
À3.05 ppm which has been rationalized as due to change of sulfur
bridging to bromo-bridging in solution phase, in line with previous
observations [24,27].

3906
T.S. Lobana et al. / Polyhedron 28 (2009) 3899–3906
Fig. 7. Packing diagram of [CuBr(
g
1-S-Hbpytsc)(PPh3)2]ÁCH3CN (4) (complex 5 shows similar packing pattern).
[10] M.A. Ali, A.H. Mirza, A.M.S. Hossain, M. Nazimuddin, Polyhedron 20 (2001)
6. Conclusion
1045.
[11] D.X. West, M.M. Salberg, G.A. Bain, A.E. Liberta, J.-V. Martinez, S.H. Ortega,
Transition Met. Chem. 21 (1996) 206.
[12] E.W. Ainscough, A.M. Brodie, J.D. Ransford, J.M. Waters, J. Chem. Soc., Dalton
Trans. (1991) 2125.
[13] M. Baldini, M.B. Ferrari, F. Bisceglie, G. Pelosi, S. Pinelli, P. Tarasconi, Inorg.
Chem. 42 (2003) 2049.
[14] E.W. Ainscough, A.M. Brodie, J.D. Ransforsd, J.M. Waters, J. Chem. Soc., Dalton
Trans. (1991) 1737.
The solvent has played an important role in deciding the bond-
ing and nuclearity of the complexes with copper(I) halides. For
example, formation of mononuclear complex [CuI(
Hbtsc)(PPh3)2] in CH3CN [24] versus iodo-bridged dimer [Cu2(
I)2(
1-S-Hbtsc)2(PPh3)2] 1 in CH3CN–CHCl3 mixture. Similar is
the case of formation of bromo-bridged dimer [Cu2( -Br)2(
1-S-
Hbtsc)2(PPh3)2] in CH3CN to sulfur-bridging dimer [Cu2( -S-
g
1-S-
l-
g
l
g
[15] M.B. Ferrari, F. Bisceglie, G. Pelosi, P. Tarasconi, R. Albertini, G.G. Fava, S. Pinelli,
J. Inorg. Biochem. 89 (2002) 36.
l
[16] M.E. Hossain, M.N. Alam, J. Begum, M.A. Ali, M. Nazimuddin, F.E. Smith, R.C.
Hynes, Inorg. Chim. Acta 249 (1996) 247.
[17] D.X. West, A.M. Stark, G.A. Bain, A.E. Liberta, Transition Met. Chem. 21 (1996)
289.
[18] M.B. Ferrari, F. Bisceglie, G. Pelosi, P. Albertini, P.P. Dall’Aglio, A. Bergamo, G.
Sava, S. Pinelli, J. Inorg. Biochem. 98 (2004) 301.
Hbtsc)2Br2(PPh3)2] (2) in CH3CN–CHCl3. The addition of chloroform
has changed both the nuclearity and nature of bridge-bonding be-
tween two copper centers. Another interesting feature is formation
of heterobridged dimer [Cu2Br(
l-Br)(l
3-N3, S-Hactsc)(PPh3)2] 3.
[19] T.S. Lobana, Rekha, B.S. Sidhu, A. Castineiras, E. Bermejo, T. Nishioka, J. Coord.
Chem. 58 (2005) 803.
Acknowledgements
[20] T.S. Lobana, Rekha, R.J. Butcher, Transition Met. Chem. 29 (2004) 291.
[21] H.G. Xeng, D.X. Zeng, X.Q. Xin, W.T. Wong, Polyhedron 16 (1997) 3499.
[22] M.B. Ferrari, G.G. Fava, M. Lanfranchi, C. Pellizzi, P. Tarasconi, Inorg. Chim. Acta
181 (1991) 253.
[23] R.D. Pike, A.B. Wiles, T.A. Tronic, Acta. Crystallogr. E62 (2006) m347.
[24] T.S. Lobana, Rekha, R.J. Butcher, A. Castineiras, E. Bermejo, P.V. Bharatam,
Inorg. Chem. 45 (2006) 1535.
Financial assistance from CSIR, New Delhi (F.No.9/254(159)/
2005-EMR-I) and research facilities to one of us (Sonia) by the uni-
versity are gratefully acknowledged.
Appendix A. Supplementary data
[25] S. Lhuachan, S. Siripaisarnpipat, N. Chaichat, Eur. J. Inorg. Chem. (2003)
263.
[26] G. Argay, A. Kalman, L. Parkanyl, V.M. Laovac, I.D. Braski, P.N. Radivojsa, J.
Coord. Chem. 51 (2000) 9.
[27] T.S. Lobana, Rekha, A.P.S. Pannu, G. Hundal, R.J. Butcher, A. Castineiras,
Polyhedron 26 (2007) 2621.
[28] T.S. Lobana, S. Khanna, R.J. Butcher, A.D. Hunter, M. Zeller, Polyhedron 25
(2006) 2755.
[29] T.S. Lobana, R. Sharma, G. Bawa, S. Khanna, Coord. Chem. Rev. 253 (2009)
977.
CCDC 658222, 683848, 727897, 727898, and 666763 contain
the supplementary crystallographic data for 1, 2, 3, 4 and 5. These
data can be obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.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.2009.08.028.
[30] T.S. Lobana, S. Khanna, R.J. Butcher, Z. Anorg. Allg. Chem. 633 (2007) 1820.
[31] L.A. Ashfield, A.R. Cowley, J.R. Dilworth, P.S. Donnely, Inorg. Chem. 43 (2004)
4121.
[32] G. Brauer, Handbook of Preparative Chemistry, 2nd ed., vol. 2, Academic Press,
New York, 1965.
References
[33] T.S. Lobana, A. Sanchez, J.S. Casas, A. Castineiras, J. Sordo, M.S. Garcia-Tasende,
E.M. Vazquez-Lopez, J. Chem. Soc., Dalton Trans. (1997) 4289.
[34] XSCANS, Siemens Analytical X-ray Instruments Inc., Madison, WI, USA, 1994.
[35] (a) G.M. Sheldrick, Acta Crystallogr. A46 (1990) 467;
(b) G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112.
[36] International Tables for X-ray Crystallography, vol. C, Kluwer, Dordrecht, The
Netherlands, 1995.
[37] Bruker, SMART and SAINT. Area Detector Control and Integration Software, Bruker
Analytical X-ray Instruments Inc., Madison, Wisconsin, USA, 1997.
[38] Wingx, L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[39] T.S. Lobana, P. Kumari, R.J. Butcher, Inorg. Chem. Commun. 11 (2008) 11.
[40] T.S. Lobana, S. Khanna, R.J. Butcher, A.D. Hunter, M. Zeller, Inorg. Chem. 46
(2007) 5826.
[1] D.X. West, S.B. Padhye, P.B. Sonaware, Struct. Bond. (Berlin) 76 (1991) 4.
[2] M.J.H. Campbell, Coord. Chem. Rev. 15 (1975) 279.
[3] S. Padhye, G.B. Kauffman, Coord. Chem. Rev. 63 (1985) 127.
[4] D.X. West, A.E. Liberta, S.B. Padhye, R.C. Chilate, P.B. Sonaware, A.S. Kumbhar,
R.G. Yerande, Coord. Chem. Rev. 123 (1993) 49.
[5] J.S. Casas, M.S. Garcia-Tasende, J. Sordo, Coord. Chem.Rev. 209 (2000) 197.
[6] D.R. Smith, Coord. Chem. Rev. 164 (1997) 575.
[7] R.K. Mahajan, I. Kaur, T.S. Lobana, Talanta 59 (2003) 101.
[8] D.X. West, J.J. Ingram, N.M. Kozub, G.A. Bain, A.E. Liberta, Transition Met. Chem.
21 (1996) 213.
[9] E.W. Ainscough, A.M. Brodie, J.D. Ransford, J.M. Waters, J. Chem. Soc., Dalton
Trans. (1997) 1251.