Heterocyclic thioamides of copper(I): Synthesis and crystal structures of copper complexes with 1,3-imidazoline-2-thiones in the presence of triphenyl phosphine

Article abstract of DOI:10.1016/j.poly.2007.11.036

Reaction of copper(I) chloride with 1,3-imidazoline-2-thione (imzSH) in the presence of Ph₃P in 1:2:2 or 1:1:2 (M:L:PPh₃) molar ratios yielded a compound of unusual composition, [Cu₂(imzSH)(PPh₃)₄Cl₂] · CH₃OH (1), whose X-ray crystallography has shown that its crystals consist of four coordinated [CuCl(1κS-imzSH)(PPh₃)₂] (1a), and three coordinated [Cu(PPh₃)₂Cl] (1b) independent molecules in the same unit cell. In contrast, crystals of complexes of copper(I) bromide/iodide are formed by single molecules of [CuBr(1κS-imzSH)(PPh₃)₂] · H₂O (2) and [CuI(1κS-imzSH)(PPh₃)₂] (3), respectively, similar to molecule 1a. The related ligand, 1,3-benzimidazoline-2-thione (bzimSH) formed a complex [CuBr(1κS-bzimSH)(PPh₃)₂] · CH₃COCH₃ (4), similar to 2. The formation of 1a and 1b has been also revealed by NMR spectroscopy. The NMR spectra of 2-4 also showed weak signals indicating formation of compounds similar to 1b. It reveals that the lability of the Cu-S bond varies in the order: Cl ? Br ～ I. Weak interactions {e.g. C-H?π electrons of ring, -NH?halogens/oxygen, C-H?halogens/oxygen, π?π (between rings)} have played an important role in building 2D chains of complexes 1-4.

Full text of DOI:10.1016/j.poly.2007.11.036

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 1008–1016
www.elsevier.com/locate/poly
Heterocyclic thioamides of copper(I): Synthesis and crystal structures
of copper complexes with 1,3-imidazoline-2-thiones in the presence
of triphenyl phosphine
Tarlok S. Lobana *, Razia Sultana, Geeta Hundal
Department of Chemistry, Guru Nanak Dev University, Amritsar, Punjab 143 005, India
Received 17 September 2007; accepted 28 November 2007
Available online 24 January 2008
Abstract
Reaction of copper(I) chloride with 1,3-imidazoline-2-thione (imzSH) in the presence of Ph3P in 1:2:2 or 1:1:2 (M:L:PPh3) molar
ratios yielded a compound of unusual composition, [Cu2(imzSH)(PPh3)4Cl2] Á CH3OH (1), whose X-ray crystallography has shown that
its crystals consist of four coordinated [CuCl(1jS-imzSH)(PPh3)2] (1a), and three coordinated [Cu(PPh3)2Cl] (1b) independent molecules
in the same unit cell. In contrast, crystals of complexes of copper(I) bromide/iodide are formed by single molecules of [CuBr(1jS-
imzSH)(PPh3)2] Á H2O (2) and [CuI(1jS-imzSH)(PPh3)2] (3), respectively, similar to molecule 1a. The related ligand, 1,3-benzimidazo-
line-2-thione (bzimSH) formed a complex [CuBr(1jS-bzimSH)(PPh3)2] Á CH3COCH3 (4), similar to 2. The formation of 1a and 1b
has been also revealed by NMR spectroscopy. The NMR spectra of 2–4 also showed weak signals indicating formation of compounds
similar to 1b. It reveals that the lability of the Cu–S bond varies in the order: Cl ꢀ Br ꢁ I. Weak interactions {e.g. C–HÁ Á Áp electrons of
ring, –NHÁ Á Áhalogens/oxygen, C–HÁ Á Áhalogens/oxygen, pÁ Á Áp (between rings)} have played an important role in building 2D chains of
complexes 1–4.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: 1,3-Imidazoline-2-thione; Copper(I); Tetrahedral complexes
1. Introduction
dazoline-2-thione (III, mimzSH) has formed complexes of
different nuclearity with coinage metals (Cu, Au), namely,
Pyridine-2-thione (I, py2SH, Chart 1) bearing the func-
tional group, –N(H)–C(@S)– M –N@C(–SH)–, a simplest
prototype of heterocyclic thioamides with a six-membered
ring has shown diverse bonding properties both in the neu-
tral and in anion forms leading to the formation of mono-
mers, dimers, oligomers and polymers [1–8]. Among the
heterocyclic thioamides with five membered rings, the
1,3-imidazoline-2-thione (II, imzSH) with the functional
group, –N(H)–C(@S)–N(H)– M –N@C(–SH)–N(H)–, rep-
resents the simplest compound, but its coordination chem-
istry with coinage metals is surprisingly unknown [1–8].
However, its methyl derivative, namely, 1-methyl-1,3-imi-
monomers
[Cu(mimzSH)3](NO3)
[9],
[Cu(mim-
zSH)(PPh3)2Br] [10], dimers [Cu2(mimzSH)4X2] {X = Cl,
[11]; SCN, [12]}, [Cu2(mimzSH)6](BF4)2 [13], [Cu2(mim-
zSH)5](SO4) Á 3H2O [14], and
a polymer {Cu(mim-
zSH)(CN)}n [15]. As anion, mimzSÀ has formed a
monomer [Au(mimzS)(PCy3)] [16], a tetramer [Cu4(mim-
zS)4] [17], and a mixed valent oligomer [CuI10Cu2II(mim-
zS)12(NCMe)4] [18]. The closely allied heterocyclic
thioamide, namely, 1,3-benzimidazoline-2-thione (IV,
bzimSH) and its nitro derivative (bzimSH-7-NO2)
have also formed monomeric [Cu(bzimSH)(PPh3)2Cl] Á
acetone [19a], [Cu(bzimSH-7-NO2)(PPh3)2Cl] [19a],
[Cu(bzimSH)(PPh3)2I] Á CH3CN Á CH3OH Á 2.7H2O [19b]
dimeric [Cu2Cl2(bzimSH)2(m-tolyl3P)2] [20], and tetrameric
[Cu4(bzimSH)10](ClO4)4 Á 14H2O complexes [21]. As
*
Corresponding author. Tel.: +91 183 22 57604; fax: +91 183 22 58820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.11.036

T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
1009
2.2. Synthesis of complexes
H
N
5
5
4
4
9
6
2
H1N
3
2.2.1. [Cu2(1jS-imzSH)(PPh3)4Cl2] Á CH3OH (1)
To solution of copper(I) chloride (0.025 g,
S
MeN
NH
NH
HN
7
a
2
N
H
8
0.25 mmol) in acetonitrile was added a solution of 1,3-
imidazoline-2-thione (0.025 g, 0.25 mmol) in acetonitrile,
followed by stirring for 1 h at room temperature and
to the white precipitates formed was added Ph3P
(0.132 g, 0.50 mmol) and stirred until a clear solution
was obtained. The crystalline fibers formed were redis-
solved in MeOH and a layer of CHCl3 was spread over
it. The slow evaporation of solution at room tempera-
ture formed colorless crystals of 1. The complex is solu-
ble in chloroform, dichloromethane and acetonoirile
S
S
S
I, pySH
III, mimzSH
II, imzSH
IV, bzimSH
Chart 1.
RN
M
NH
RN
M
NH
(56%,
m.p.
135–138 °C).
Anal.
Calc.
for
S
S
C76H68Cl2Cu2ON2P4S: C, 66.18; H, 4.93; N, 2.03.
Found: C, 66.36; H, 4.90; N, 1.63%. Main IR peaks
(KBr, cmÀ1): 3363 s, m(O–H); 3118–3092
m m(N–
V
VI
H) + m(C–H)Ph; 2988 w, 2862 m m(C–H); 1581 s, 1481
s m(C–N) + d(C–H); 1217 s m(C–S); 1093 s m(P–CPh).
1H NMR data (CDCl3, d ppm): 7.23 t (C4,5H, imzSH),
7.37 m (o-H), 7.33 m (p-H), 7.25–7.27 m (m-H) (Species
1a), 7.67 m (o-H), 7.55 m (p-H), 7.46 m (m-H) (Species
1b). 31P NMR (CDCl3): À3.42 (Species 1a), 30.74 (Spe-
cies 1b) ppm. Dd(dcomplex À dPPh3) = 1.28 (Species 1a);
35.44 (Species 1b).
Chart 2. Models of bonding.
neutral ligands, monomers and dimers exhibited modes V
(1jS) and VI (l-1j2S) modes of bonding (Chart 2).
Recently, we have reported that reaction of 1,3-imidaz-
olidine-2-thione (imzdSH), a saturated analogue of imzSH
(II, Chart 1) with copper(I) bromide/iodide (2:1 molar
ratio, L:M) has formed novel linear polymers, {Cu6(l3-
1j3S-imzdSH)4(l-1j2S-imzdSH)2(l-I)2I4}n, {Cu6(l3-1j3S-
imzdSH)2(l-1j2S-imzdSH)4(l-X)4X2}n, (X = Br, I), as well
as dimers, {Cu2(l-1j2S-imzdSH)2(g1-S-imzdSH)2Br2} and
{Cu2(l-1j2S-imzdSH)(1jS-imzdSH)3Cl2} [7,8]. It was
desired to carry out similar reactions of copper(I) halides
with the unsaturated 1,3-imidazoline-2-thione (II, imzSH,
Chart 1) and benzimidazoline-2-thione (IV, bzimSH) for
obtaining polymeric compounds. The products of these
reactions are reported herein.
Compound 2 was prepared similarly. Here crystals were
grown from the reaction solvents (CH3CN–CHCl3) when
allowed to evaporate slowly.
2.2.2. [CuBr(1jS-imzSH)(PPh3)2] Á H2O (2)
Complex 2 is soluble in chloroform, dichloromethane
and acetonoirile (73%, m.p. 155–157 °C). Anal. Calc. for
C39H36BrCuN2OP2S: C, 59.58; H, 4.58; N, 3.56. Found:
C, 60.31; H, 4.41; N, 3.12%. Main IR peaks (KBr, cmÀ1):
3396 s, m(O–H); 3137 w, 3138 m m(N–H); 3001–3070 w
m(C–H)Ph; 2983 w, 2904 w m(C–H); 1581 s, 1477 s m(C–
1
2. Experimental
N) + d(C–H); 1216 s m(C–S); 1083 s, m(P–CPh). H NMR
data (CDCl3, d ppm): 6.74 t (C4,5H), 10.9 b (NH), 7.66 m
(o-H), 7.54 m (p-H), 7.47 m (m-H) [CuBr(PPh3)2], 7.41 m
(o-H), 7.33 m (p-H), 7.27 m (m-H) (2). 31P NMR (CDCl3):
d = À4.3, Dd(dcomplex À dPPh3), 0.40 (2) ppm. Crystals were
grown from CH3CN–CHCl3 mother liquor. Compound 3
was prepared similarly.
2.1. Materials and techniques
Copper(I) halides were prepared by reducing an aqueous
solution of CuSO4 Á 5H2O using SO2 in the presence of
NaX (X = Cl, Br, I) in water [22]. The reagents, 1,3-imidaz-
oline-2-thione, benz-1,3-imidazoline-2-thione and Ph3P,
were procured from Aldrich Chemicals Ltd. and used as
such. C, H and N analysis were obtained with Thermoelec-
tron FLASHEA1112 CHNS analyzer. The IR spectra were
recorded using KBr pellets in the range 4000–200 cmÀ1 on
Pye-Unicam SP-3-300 spectrophotometer. The melting
points were determined with a Gallenkamp electrically
2.2.3. [CuI(1jS-imzSH)(PPh3)2] (3)
Complex 3 is soluble in chloroform, dichloromethane
and chloroform (71%, m.p. 205–207 °C). Anal. Calc. for
C39H34ICuN2P2S: C, 57.46; H, 4.17; N, 3.44. Found: C,
57.24; H, 4.15; N, 3.14%. Main IR peaks (KBr, cmÀ1):
3145 w, m(N–H); 3070 w, 3051 w m(C–H)Ph; 2981 w, 2958
w m(C–H); 1577 s, 1473 s m(C–N) + d(C–H); 1184 s m(C–
1
heated apparatus. H NMR spectra were recorded on a
1
JEOL AL-300 FT spectrometer operating at a frequency
of 300 MHz in CDCl3 with TMS as the internal reference.
The 31P NMR spectra were recorded on a Bruker ACP-300
spectrometer operating at a frequency of 121.5 MHz, using
CDCl3 with H3PO4 as the external reference.
S); 1091 s m(P–CPh). H NMR data (CDCl3, d ppm): 6.79
t (C4,5H), 7.68 m (o-H), 7.64 m (p-H), 7.54 m (m-H)
[CuI(PPh3)2], 7.47 m (o-H), 7.39 m (p-H), 7.27 m (m-H)
(3). 31P NMR (CDCl3), À5.1, Dd(dcomplex À dPPh3),
À0.4 ppm 3.

1010
T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
Table 1
Crystallographic data for compounds 1–4
1
2
3
4
Empirical formula
Formula weight
T (K)
C76H68C12Cu2N2OP4S
1379.27
295(2)
C39H36BrCuN2OP2S
784.13
295(2)
0.71073
C39H34CuIN2P2S
815.12
295(2)
0.71073
C46H42BrCuN2OP2S
874.25
295(2)
0.71073
˚
Wavelength (A)
0.71073
Crystal system
Space group
a (A)
triclinic
monoclinic
P21/n
9.623(1)
monoclinic
P21/n
9.441(2)
monoclinic
P21/c
13.099(1)
ꢀ
P1
˚
9.992(1)
˚
b (A)
17.6240(10)
19.902(2)
22.005(2)
17.6510(10)
19.554(2)
19.856(3)
18.737(2)
17.407(1)
˚
c (A)
a (°)
b (°)
c (°)
84.18(1)
87.50(1)
78.26(1)
3412.8(5)
90
96.61(1)
90
3712.8(6)
90
92.64 (1)
90
3661.7(1)
90
97.81(9)
90
4232.6(6)
3
˚
V (A )
Z
2
4
4
4
Dcalc (Mg mÀ3
)
1.342
0.872
0.2 Â 0.2 Â 0.1
1.49–29.97
13816
1.403
1.839
1.479
1.614
1.372
1.621
Absorption coefficient (mmÀ1
Crystal size (mm)
h Range (°)
Reflection collected
)
0.2 Â 0.1 Â 0.1
0.2 Â 0.1 Â 0.1
0.2 Â 0.2 Â 0.1
1.48–25.50
1.46–25.50
1.60–25.50
7105
7258
8235
Unique reflections [Rint
Final R indices [I > 2r(I)]
R indices (all data)
]
12811 [0.0320]
R1 = 0.0452, wR2 = 0.1090
R1 = 0.0713, wR2 = 0.1211
6674 [0.0383]
R1 = 0.0535, wR2 = 0.1227
R1 = 0.1388, wR2 = 0.1645
6824 [0.0423]
R1 = 0.0529, wR2 = 0.1155
R1 = 0.1282, wR2 = 0.1534
7877 [0.0441]
R1 = 0.0698, wR2 = 0.1778
R1 = 0.1454, wR2 = 0.2409
2.2.4. [CuBr(1jS-bzimSH)(PPh3)2] Á CH3COCH3 (4)
To suspension of copper(I) bromide (0.025 g,
atoms were refined anisotropically, and hydrogen atoms
were assigned calculated positions. Scattering factors from
the International Tables for X-ray crystallography were
used [24]. Data reduction, structure solution, refinement
and molecular graphics were performed using SHELXTL-PC
[25] and WINGX [26]. For compound 2, the imidazole ring
showed disorder in terms of having unusual bond distances
and slightly higher thermal parameters. The disorder could
not be resolved and the structure was refined by adding fol-
lowing restraints on bond distances involving the group
(C37–N1, C37–N2 1.373(3), C38–N1, C38–N2 1.440(3),
a
0.17 mmol) in acetone was added a solution of benz-1,3-
imidazoline-2-thione (0.026 g, 0.17 mmol) in acetone, fol-
lowed by stirring for 2 h at room temperature and to the
white precipitates formed was added PPh3 (0.091 g,
0.34 mmol) and contents stirred until a clear solution was
obtained. The slow evaporation of solution at room tem-
perature formed colorless crystals of 4. This complex is sol-
uble in chloroform, acetonitrile and dichloromethane
(72%, m.p. 228–231 °C). Anal. Calc. for C46H42BrCu-
N2OP2S: C, 63.05; H, 4.79; N, 3.20. Found: C, 62.97; H,
4.51; N, 2.90%. Main IR peaks (KBr, cmÀ1): 3110–
3041m, m(N–H) + m(C–H)Ph; 2958 w, 2854 m m(C–H);1608
w, 1604 w m(C–N) + d(C–H); 1155 s m(C–S); 1091 m m(P–
˚
C38–C39 1.336(3) and C37–S1 1.703(3) A, respectively).
Hydrogens of water molecule could not be located from
the difference Fourier map and have not been included in
the model. All other hydrogens were fixed geometrically
and were not refined. The cell and refinement parameters
are summarized in Table 1.
1
CPh). H NMR data (CDCl3,d ppm): 11.2 bs (NH) 7.64–
7.71 m (o-H, p-H), 7.55 m (m-H) [CuBr(PPh3)2], 7.47 m
(o-H), 7.35 m (p-H), 7.22–7.30 m (m-H, C4À7H, bzimzSH)
(4). 31P NMR (CDCl3), 30.84 [CuI(PPh3)2], À3.6 (4);
Dd(dcomplex À dPPh3), 35.54 [CuI(PPh3)2], 1.10 ppm 4.
3. Results and discussion
3.1. Synthesis and infrared spectroscopy
2.3. X- ray crystallography
Reactions of 1,3-imidazoline-2-thione (imzSH) with
copper(I) halides in 2:1 molar ratio did not yield polymers
similar to that formed by 1,3-imidazolidine-2-thione men-
tioned in introduction [7,8]. There was a change in color
from colorless to green (probably due to CuII) when solu-
tion was left in open for several days and no crystalline
product could be isolated. The addition of triphenyl phos-
phine (Ph3P) yielded crystalline products. Thus the reaction
of copper(I) chloride with imzSH in the presence of Ph3P in
1:2:2 or 1:1:2 (M:L:PPh3) molar ratios yielded a compound
of unusual composition, [Cu2(imzSH)(PPh3)4Cl2] Á CH3OH
The data for compounds 1–4 were collected at 294(1) K
on a Siemens P4 diffractometer. The h-2h technique was
used to measure the intensities up to a maximum of
2h = 5°, with graphite-monochromatised Mo Ka radiator
˚
(k = 0.71073 A). Cell parameters were refined in the h
range, 12–20° using XSCANS [23]. The data were corrected
for Lorentz and polarization factors. An empirical psi
absorption correction was applied. The structure was
solved by the direct methods and refined by full matrix
least squares methods based on F2. All non-hydrogen

T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
1011
Fig. 1. Two crystallographically independent molecules of [CuCl(1jS-imzSH)(PPh3)2] Á [CuCl(PPh3)2] (1) and their partial labeling scheme. Solvent
molecule and the hydrogen atoms have been removed for clarity.
Fig. 2. The structure of [CuBr(1jS-imzSH)(PPh3)2] Á H2O (2) with numbering scheme.
(1), whose X-ray crystallography has shown that its crys-
tals consists of four coordinated [CuCl(1jS-
bztz2SH)2(PPh3)2] A and ][CuCl(1jS-bztz2SH)(PPh3)2] B
in the unit cell, resulted from the reaction of CuCl(PPh3)3
with benzo-1,3-thiazoline-2-thione in 1:2 molar ratio in
CH3CN–MeOH, each having a tetrahedral geometry [27].
The main characteristic IR peaks of complexes of 1,3-
imidazoline-2-thione (imzSH) and benz-1,3-imidazoline-2-
thione (bzimSH) are listed in the experimental section.
The m(N–H) peak of free imzSH at 3118–3092(m) cmÀ1
undergoes low energy shifts to 3002–3145 cmÀ1 in com-
plexes 1–3. In complex 4, the m(N–H) and m(C–H)Ph signals
merge in the region, 3110–3041 m cmÀ1. The most signifi-
cant diagnostic peak due to m(C@S) in the free imzSH
ligand at 1232 cmÀ1 shifts to low energy region 1217–
1184 cmÀ1 in its complexes 1–3. Similarly, the m(C@S) peak
of the free bzimSH ligand at 1177 (s) cmÀ1 undergoes low
imzSH)(PPh3)2] (1a) and three coordinated [Cu(PPh3)2Cl]
(1b) independent molecules in the same unit cell (vide
infra). In contrast, crystals of complexes of copper(I) bro-
mide/iodide are formed by single molecules of
[CuBr(1jS-imzSH)(PPh3)2] Á H2O (2) and [CuI(1jS-
imzSH)(PPh3)2] (3), respectively, similar to molecule 1a.
A related ligand, 1,3-benzimidazoline-2-thione (bzimSH)
formed the complex [CuBr(1jS-bzimSH)(PPh3)2] Á CH3-
COCH3 (4), similar to mononuclear complexes, [Cu(1jS-
bzimSH)(PPh3)2Cl] Á acetone and [Cu(1jS-bzimSH-7-
NO2)(PPh3)2Cl] [19a]. In the literature, dealing copper-het-
erocyclic thioamide chemistry, the only analogous forma-
tion
of
two
independent
molecules
[Cu(1jS-

1012
T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
energy shift to 1155 (s) cmÀ1 in 4. The shifts in m(C@S)
peaks in all the complexes is attributed to the weakening
of C@S bond due to the coordination of thione sulfur to
the metal center. In all the complexes, the presence of
m(P–CPh) occurred in the range, 1083–1093 cmÀ1. The pres-
ence of methanol and water in complexes 1 and 2 has been
detected by the presence of m(O–H) at 3363 (1, methanol)
and 3396 (2, water).
3.2. Crystal structures of complexes 1–4
Complex 1 crystallized in triclinic system with space
ꢀ
group P1, while complexes 2, 3 and 4 crystallized in mono-
clinic system with space groups P21/n (2, 3) and P21/c (4).
The atomic numbering schemes of complexes 1, 2, 3 and 4
are shown in Figs. 1–4, packing diagram in Figs. 5–8 and
selected bond lengths and angles are given in Table 2.
3.2.1. Complex [CuCl(1jS-
Fig. 3. The structure of [CuI(1jS-imzSH)(PPh3)2] (3) with numbering
imzSH)(PPh3)2] Á [CuCl(PPh3)2] (1)
scheme.
Complex
1
has four coordinated [CuCl(1jS-
imzSH)(PPh3)2] (1a) and three coordinated [Cu(PPh3)2Cl]
(1b) independent molecules in the same unit cell (Fig. 1).
In molecule 1a, Cu is bonded to two P atoms of PPh3,
one S atom of imzSH, and one Cl atom with bond angles
around copper in the range, ca. 100–125° (Table 2). It
reveals distorted tetrahedral geometry. In molecule 1b,
Cu is bonded to two P atoms of PPh3, and one Cl atom
with bond angles around copper in the range, ca. 114–
128° and geometry is distorted trigonal planar. The P–
Cu–P angle in 1b [127.76(3)°] is higher than that in 1a
[124.49(3)°] due to less steric crowding in the trigonal pla-
nar geometry. This P–Cu–P angle in 1a is higher than
122.4° in analogous complex [CuL(PPh3)2Cl] (L = 1, 3- thi-
azolidine-2-thione) [28]. The Cu–S bond distance,
˚
2.3643(10) A, in molecule 1a is comparable with literature
˚
values {2.381–2.418 A} [28,29]. The Cu–Cl bond distance
˚
2.4272(9) A in cÀomplex 1aÀis less than sum the of ionic radii
of Cu+ and Cl (Cu , Cl , 2.58 A) [30]. The Cu–P bond
+
˚
˚
distances, 2.2976(8), 2.2815(9) A in 1a are expectedly
longer than 2.2695(9), 2.2720(8) A in three coordinated
1b, which are similar to Cu–P distances in the analogous
complexes [29,31].
˚
3.2.2. Structures of complexes 2–4
In complex 2, Cu is bonded to two P atoms of Ph3P
ligands, one S atom of the 1,3-imidazoline-2-thione, and
one bromine atom. Similar is binding pattern in complexes
Fig. 4. The structure of [CuBr(1jS-bzimSH)(PPh3)2] Á CH3COCH3 (4) with partial numbering scheme and the solvent.

T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
1013
Fig. 5. Crystal structure of complex 1 showing the alternate 1D linear chains of molecule 1a and molecule 1b. These two independent chains are further
linked to each other due to edge-to-edge p. . .p and C–H. . .p interactions forming a 2D network.
Fig. 6. Packing diagram of compound 2 showing formation 2D structure due to H-bonding and edge-to-edge p. . .p interactions.
˚
3 and 4 (Figs. 2–4). The angles around Cu lie in the ranges
100.47(7)–128.77(7)°, 102.09(10)–125.06(8)° and 103.64(9)–
122.21(8)° in complexes 2, 3 and 4, respectively, with P(2)–
Cu–P(1) being the largest, and P–Cu–X {X = Br, I} being
the smallest. The P–Cu–P angles in complexes 1a, 2–4 are
124.49(3), 128.77(7), 125.06(8) and 122.21(8)°, respectively,
and are influenced by the steric and intra- and inter-molec-
ular hydrogen bonding interactions. This reveals a dis-
torted tetrahedral geometry around each copper atom in
mononuclear complexes. The Cu–S bond distances lie in
distances lie in the range, 2.2819(17)–2.326(3) A, in com-
plexes 2–4, similar to the distances found in complex 1a.
The Cu–Br and Cu–I bond distances are less than the
sum of the ionic radii of Cu+ and XÀ (Cu+, BrÀ, 2.73;
+
À
˚
Cu , I , 2.97 A) [30].
3.3. Packing networks of complexes 1–4
The packing diagram of 1 (Fig. 5) shows alternate 1D
linear chains of molecule 1a and molecule 1b. Molecule
1a forms these linear chains due to methanol. . .chlorine
(O1SÁ Á ÁCl 1i) and phenylene C. . .S (C29. . .Sii) intermolecu-
˚
close range 2.344(3)–2.373(2) A in complexes 2–4 and are
˚
comparable with 2.3643(10) A in molecule 1a. The Cu–P

1014
T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
Fig. 7. Crystal structure of compound 3 showing pleated sheet like 2D structure.
Fig. 8. Packing diagram of compound 4 showing the formation of a 2D H-bonded network in the bc plane.
lar and imidazole. . .methanol (N1Á Á ÁO1S), and imidaz-
ole. . .chlorine (N2Á Á ÁCl1) intramolecular H-bonding inter-
actions. Molecule 1b is linearly chained due to C74. . .Cl2
H-bonding interactions. These two independent chains
are further linked to each other to form a 2D network
due to edge-to-edge p. . .p interactions between rings A
(C13–C18) and I (C52–C57) and rings G (C40–C45) and
(N1Á Á ÁO1) to form the parallel linear chains. These chains
are further linked to each other via edge-to-edge pÁ Á Áp
˚
interactions (3.582 A) resulting in 2D structure.
In complex 3, the terminal iodine atom is engaged in
intramolecular H-bonding with imino hydrogen (N1Á Á ÁI1)
(Fig. 7). The molecules are linked to each other by means
of intermolecular H-bonding, C27Á Á ÁI1ii and C38–
˚
˚
E (C25–C30), with distances of 3.319 and 3.502 A, respec-
H38Á Á Áring (C25–C30) (3.858(8) A) C–HÁ Á Áp interactions
tively, and also due to C–H. . .p interaction between
centroid of ring C (C13–C18) and methanol C1S with a
to form zig-zag chains. These linear chains are further
linked to each other by means of N2Á Á ÁI1i and C–HÁ Á Áp
interactions between C22–H22Á Á Áring (C25–C30) (3.659(9)
˚
distance of 3.688 A (Table 3).
˚
Complex 2 involves intramolecular H-bonding between
imino nitrogen of imidazole and bromine atom (N2Á Á ÁBr)
(Fig. 6). Water molecule is present in the crystal lattice
and is engaged in intermolecular H-bonding with bromine
atom (O1. . .Br) and with imino nitrogen of imidazole ring
A) to form a pleated sheet like 2D structure.
In complex 4, there is intramolecular H-bonding
between imino hydrogen of imidazole and bromine atom
(N1Á Á ÁBr). These molecules are further linked to each other
by means of C5–H5Á Á ÁBr H-bonding to form a 1D zig-zag

T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
1015
Table 2
Table 3
˚
˚
Bond lengths (A) and bond angles (°) for compounds 1–4
Hydrogen bonds (A) for complexes 1–4
˚
˚
1a
Cu1–S1
Cu(1)–P(1)
Cu(1)–P(2)
Cu(1)–Cl(1)
P(1)–Cu(1)–S(1)
P(2)–Cu(1)–S(1)
P(1)–Cu(1)–Cl(1)
P(2)–Cu(1)–Cl(1)
No.
D–HÁ Á ÁA
d(DÁ Á ÁA) (A)
d(HÁ Á ÁA) (A)
\D–H. . .A (°)
2.3643(10)
2.2976(8)
2.2815(9)
2.4272(9)
102.60(4)
111.40(3)
110.81(4)
100.17(3)
S(1)–C(37)
N(2)–C(37)
N(1)–C(37)
1.703(4)
1.399(5)
1.341(5)
1
N2Á Á ÁCl1
N1Á Á ÁOlS
O1SÁ Á ÁCl1i
C29Á Á ÁS1ii
C74Á Á ÁCl2ii
3.080(4)
2.711(6)
3.035(4)
3.779(4)
3.723(4)
2.15
2.01
2.09
2.88
2.92
156
159
160
162
145
S(1)–Cu(1)–Cl(1)
P(2)–Cu(1)–P(1)
C(37)–S(1)–Cu(1)
106.43(3)
124.49(3)
109.13(12)
2
3
N1Á Á ÁO1
N2Á Á ÁBr
C15Á Á ÁS1i
N1Á Á ÁI1
2.693(12)
3.228(7)
3.801(9)
3.744(8)
3.809(8)
3.758(10)
3.909(9)
3.218(7)
3.664(13)
3.492(13)
2.975(12)
2.00
2.40
2.98
2.92
3.17
2.92
3.49
2.40
2.80
2.73
2.21
136
162
148
162
132
150
136
159
154
140
147
1b
Cu(2)–Cl(2)
Cu(2)–P(3)
Cu(2)–P(4)
2.2112(10)
2.2695(9)
2.2720(8)
Cl(2)–Cu(2)–P(4)
P(3)–Cu(2)–P(4)
Cl(2)–Cu(2)–P(3)
114.41(4)
127.76(3)
117.80(4)
N2Á Á ÁI1i
C36Á Á ÁS1
C27Á Á ÁI1ii
N1Á Á ÁBr
C5Á Á ÁBri
C11Á Á ÁO1ii
N2Á Á ÁO1iii
4
2
Cu–S(1)
Cu–P(1)
Cu–P(2)
Cu–Br
P(1)–Cu–S(1)
P(2)–Cu–S(1)
P(1)–Cu–Br
P(2)–Cu–Br
2.366(2)
S(1)–C(37)
N(2)–C(37)
N(1)–C(37)
1.703(3)
1.367(3)
1.366(3)
2.2819(17)
2.2862(18)
2.5312(11)
106.06(7)
100.47(7)
103.14(5)
104.80(6)
For 1 (i) x À 1, +y, +z; (ii) x + 1, +y, +z.
S(1)–Cu–Br
P(1)–Cu–P(2)
C(37)–S(1)–Cu
114.01(7)
128.77(7)
108.4(3)
For 2 (i) x À 1, +y, +z.
For 3 (i) x À 1, y, z; (ii) 3/2 À x, y À 1/2, 1/2 À z.
For 4 (i) x, Ày + 1/2, +z À 1/2; (ii) x, Ày + 1/2, +z + 1/2; (iii) x, +y À 1,
+z.
3
Cu–S(1)
Cu–P(1)
Cu–P(2)
2.344(3)
2.309(2)
2.291(2)
S(1)–C(37)
N(2)–C(37)
N(1)–C(37)
1.643(10)
1.352(10)
1.380(11)
Cu–I(1)
2.6729(11)
102.09(10)
103.61(9)
103.54(6)
105.44(6)
(PPh3)2] Á [CuCl(PPh3)2] (1) showed two sets of PPh3 sig-
nals which revealed the formation of [CuCl(1jS-
imzSH)(PPh3)2] (1a) (7.25–7.27 ppm) and [Cu(PPh3)2Cl]
(1b) (7.46–7.67 ppm, PPh3) in the solution state. Similarly
complexes [CuBr(1jS-imzSH)(PPh3)2] Á H2O (2) and
[CuI(1jS-imzSH)(PPh3)2] (3) showed one set of PPh3 sig-
nals in the regions 7.27–7.41 and 7.27–7.47 ppm, respec-
tively, and another set of weak PPh3 signals in the
regions, 7.47–7.68 ppm showed the formation of com-
pounds, namely, Cu(PPh3)2Br and Cu(PPh3)2I similar to
1b. Complex [CuBr(1jS-bzimSH)(PPh3)2] Á CH3COCH3
(4) showed one set of signals due to PPh3 in the region,
7.22–7.47 ppm similar to complexes 1a, 2 and 3 and
another set of PPh3 signals in the region, 7.55–7.64 ppm
due to {Cu(PPh3)2Br}. The peaks due to benzimidazoline
ring merged with the PPh3 protons in 7.22–7.64 ppm {cf.
peaks due to free bzimSH ligand 7.23 m (2H, C4,7H) and
7.15 m (2H, C5,6H) in dmso-d6}. Complexes 2 and 4
showed broad signal due to NH protons (10.2, 2, 10.4, 4
ppm). The NH proton signals could not be identified in
complexes 1 and 3 due to broadening.
P(1)–Cu–S(1)
P(2)–Cu–S(1)
P(1)–Cu–I(1)
P(2)–Cu–I(1)
S(1)–Cu–(I)
P(2)–Cu–P(1)
C(37)–S(1)–Cu
118.30(8)
125.06(8)
115.3(3)
4
Cu–S(1)
Cu–P(1)
Cu–P(2)
Cu–Br
P(1)–Cu–S(1)
P(2)–Cu–S(1)
P(1)–Cu–Br
P(2)–Cu–Br
2.373(2)
2.277(2)
2.326(3)
2.5144(13)
103.64(9)
109.42(9)
110.11(7)
102.89(7)
S(1)–C(1)
N(1)–C(1)
N(1)–C(2)
1.690(8)
1.345(11)
1.371(10)
S(1)–Cu–Br
P(1)–Cu–P(2)
C(1)–S(1)–Cu
108.05(7)
122.21(8)
107.2(3)
chain along c-axis (Fig. 8). Acetone as a solvent of crystal-
lization is present in crystal lattice and is involved in inter-
molecular H-bonding N2Á Á ÁO1(solvent) along the chains.
C11–H11Á Á ÁO1 weak H-bonds between phenylene C and
the solvent helps to form a 2D network in the bc plane.
3.4. NMR spectroscopy
The 31P NMR spectra of compounds 1–4 showed signals
at À3.42 (1a), À4.30 (2), À5.10 (3) and À3.60 ppm (4) with
coordination shifts (Dd) of 1.28, 0.40, À0.40 and 1.10
3 ppm, respectively. In literature similar shifts in cop-
per(I)–phosphine-heterocyclic thioamide complexes have
been observed [29,32]. The signal due to [CuCl(PPh3)2]
(1b) has been identified at 30.74 ppm. Compound 4 showed
additional signal at 30.84 ppm, attributed to the formation
of species [Cu(PPh3)2Br], however, compounds 2 and 3 did
not show the formation of similar species [Cu(PPh3)2Br]
and [Cu(PPh3)2I] in solution state.
The 1H NMR of ligand 1,3-imidazoline-2-thione
(imzSH) in DMSO shows a singlet at 6.65 ppm due to
equivalent ring (C4H, C5H) protons. When this ligand
coordinates to the metal via its S electrons, ring protons
become magnetically inequivalent and thus two expected
doublets due to C4H, C5H protons merge into an
unresolved triplet. Each of complexes 1–3 showed a
triplet at a low field (7.23, 1; 6.74, 2; 6.79 ppm, 3). Interest-
ingly, NMR spectrum of complex [CuCl(1jS-imzSH)

1016
T.S. Lobana et al. / Polyhedron 27 (2008) 1008–1016
[11] J.R. Creighton, D.J. Gardiner, A.C. Gorvin, C. Gutteridge, A.R.W.
4. Supplementary material
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(1985) 195.
CCDC 658223, 658224, 658225 and 658226 contain the
supplementary crystallographic data for 1, 2, 3 and 4.
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.
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