Synthesis, spectroscopy and structures of halogen and sulfur-bridged dinuclear silver(I) complexes with N1-substituted thiophene-2-carbaldehyde thiosemicarbazone

Article abstract of DOI:10.1016/j.poly.2009.01.041

The reactions of silver(I) halides (Cl or Br) with thiophene-2-carbaldehyde N¹-methyl thiosemicarbazone (HttscMe) in the presence of Ph₃P (1:1:1 molar ratio) yield halogen-bridged dimers, [Ag₂(μ-X)₂(η¹

Full text of DOI:10.1016/j.poly.2009.01.041

Polyhedron 28 (2009) 1103–1110
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, spectroscopy and structures of halogen and sulfur-bridged
dinuclear silver(I) complexes with N1-substituted thiophene-2-carbaldehyde
thiosemicarbazone
a
b
Tarlok S. Lobana a, , Rekha Sharma , Ray J. Butcher
*
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India
b Department of Chemistry, Howard University, Washington, DC 20059, USA
a r t i c l e i n f o
a b s t r a c t
The reactions of silver(I) halides (Cl or Br) with thiophene-2-carbaldehyde N1-methyl thiosemicarbazone
Article history:
(HttscMe) in the presence of Ph3P (1:1:1 molar ratio) yield halogen-bridged dimers, [Ag2(l-X)2(g
1-S-
Received 6 November 2008
Accepted 26 January 2009
Available online 13 February 2009
HttsMe)2(PPh3)2] (X = Cl, 1; Br, 2). The use of 2,20-bipyridine in lieu of Ph3P in the reaction of silver(I) chlo-
ride with HttscMe yields the sulfur-bridged dimer, [Ag2(
l
-S-HttscMe)2(
g
1-HttsMe)2] ꢀ 2CHCl3 3. The
substituents have altered the nature of bridge between the two silver atoms. The AgꢀꢀꢀAg separation
(3.4867(5) Å) in complex 3 is less than that in the halogen-bridged dimers (3.734(4) Å 1; 3.746(5) Å 2).
Unlike PPh3 the co-ligand 2,20-bipyridine did not coordinate to the silver center, but was necessary for
crystallization in the reaction with the thio-ligand. NMR spectroscopy revealed that the complexes
remained unchanged in the solution state (CDCl3).
Keywords:
Silver(I) halides
Thiophene-2-carbaldehyde N1-methyl
thiosemicarbazone
Complexes
Ó 2009 Elsevier Ltd. All rights reserved.
Sulfur-bridged dimer
Halogen-bridged dimer
1. Introduction
dine ligands, with the objective of observing the effect of the
methyl substituent at N1 on the nature of the products. These com-
Among coinage metals (Cu, Ag and Au), the chemistry of cop-
per(I) and copper(II) with N,S-donor ligands based on thiosemicar-
bazones {R1R2C@N–N(H)–C(@S)–NR3R4} has received considerable
attention in recent years [1–14]. However, thiosemicarbazone
chemistry of silver/gold salts is limited [7,15–23]. It is pointed
out here that the chemistry of silver(I) halides with other N,S-do-
nors is also poorly described in the literature [24–35,40], and most
of the complexes reported are with ionic silver(I) salts [36]. There
is interest in silver(I) chemistry due to its structural diversity,
supramolecular chemistry luminescent/conducting properties, bio-
logical and pharmacological activities, such as antimicrobial, anti-
fungal properties and metal based drugs [37–39,41].
Recently, from this laboratory, it was reported that silver(I) ha-
lides with thiosemicarbazones having R1, R2 substituents such as,
Ph, H; Ph, Me or Me, Me formed only halogen-bridged dimers,
while heterocyclic ring substituents such as: pyrrole, H; thiophene,
H and pyridine, Ph, yielded only sulfur-bridged dimers (Chart 1)
[15,16].
plexes were characterized by elemental analysis, IR, NMR spectros-
copy (1H and 31P) and X-ray crystallography.
S
1
2
NH
C
3
N
C2
1
S
NHMe
H
I
2. Experimental
2.1. Materials and techniques
Sodium chloride, sodium bromide, thiophene-2-carbaldehyde,
3-methyl thiosemicarbazide and triphenylphosphine were pro-
cured from Aldrich Chemicals Ltd. and were used as received.
The silver(I) halides (X = Cl, Br) were freshly prepared by reacting
silver(I) nitrate with sodium chloride or bromide in methanol.
Thiophene-2-carbaldehyde N1-methyl thiosemicarbazone was pre-
pared by refluxing thiophene-2-carbaldehyde and 3-methylthose-
micarbazide in methanol for 8–10 h. C, H and N analyses were
obtained with a Thermoelectron FLASHEA1112 CHNS analyzer.
Infrared spectra were recorded from KBr pellets in the range
In continuation of our interest in silver(I) halide-thiosemicarba-
zone chemistry, we report in this paper the results of the reaction
of silver(I) halides with thiophene-2-carbaldehyde N1-methyl thio-
semicarbazone (Structure I) in the presence of Ph3P or 2,20-bipyri-
* 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 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.01.041

1104
T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
P
X
P
P
S
S
P
S
S
X
X
S
1
C
2
NH
R1
Ag
Ag
Ag
Ag
3
N
2
C
1
NHR3
X
R2
R1, R2 = Ph, H; Ph, Me;
Me, Me
R1
R3 = H
=
=
,
,
S
H
N
H
H
N
R2
Chart 1.
4000–200 cmꢁ1 on a Pye-Unicam SP-3-300 spectrophotometer.
Melting points were determined with an electrically heated Gal-
lenkamp apparatus. 1H NMR were recorded on a JEOL AL-300 FT
spectrometer operating at a frequency of 300 MHz using CDCl3 as
the solvent with TMS as an internal standard. 31P NMR spectra
were recorded on a Bruker ACP-300 spectrometer operating at a
frequency of 121.5 MHz with H3PO4 as an external standard with
d = 0.
ture was stirred for 2 h. The white precipitates that formed were
filtered to remove acetonitrile, and to the white solid suspended
in chloroform was added the solid HttscMe ligand (0.027 g,
0.13 mmol). The contents were stirred for a further period of
10 min and the yellow colored clear solution thus formed was al-
lowed to crystallize. Slow evaporation at room temperature
yielded crystals of [Ag2(l-Br)2(g
1-S-HttsMe)2(PPh3)2] (2) (2 yel-
low, 69%, m.p. 195–198 °C). Anal. Calc. for C50H48Ag2Br2N6P2S4: C,
46.47; H, 3.92; N, 6.92. Found: C, 46.28; H, 3.70; N, 6.47%. IR data
2.2. Synthesis of the complexes
(KBr, cmꢁ1):
m
(N–H) 3345(s);
(C–H)Me 2753(w); (C@N) +
(C–N) 1029(s); m
(C@S) 853(s). 1H
m
(–NH–) 3150(m);
m(C–H)Ph
2975(m);
1532(m);
m
m
m
m
m
(C@C) 1632(m), 1555(m),
2.2.1. [Ag2(
l
-Cl)2(
g
1-S-HttsMe)2(PPh3)2] (1)
(P–CPh) 1094(s);
To AgCl (0.025 g, 0.17 mmol) suspended in acetonitrile (15 mL)
was added solid Ph3P (0.046 g, 0.17 mmol), and the reaction mix-
ture was stirred for 2 h. The white precipitates that formed were
filtered to remove acetonitrile, and to the white solid suspended
in chloroform was added the solid HttscMe ligand (0.035 g,
0.17 mmol). The contents stirred for a further period of 10 min
and the yellow colored clear solution thus formed was allowed
to crystallize. Slow evaporation at room temperature yielded crys-
NMR (CDCl3, d ppm): 11.59s (–N2H), 8.61s (C2H), 7.32–7.52m
(C4,6H + 15H, PPh3 + N1H), 7.06dd (C5H), 3.23d (–CH3). 31P NMR
(CDCl3, d ppm): 6.2,
D
d (d complex ꢁ d ligand) 10.9.
2.2.3. [Ag2Cl2( -S-HttscMe)2(
l
g
1-S-HttscMe)2] ꢀ 2CHCl3 (3)
To AgCl (0.025 g, 0.17 mmol) suspended in acetonitrile (15 mL)
was added solid 2,20-bipyridine (0.034 g, 0.17 mmol) and the reac-
tion mixture was stirred for 2 h. The light purple precipitates that
formed were filtered to remove acetonitrile, and to the purple pre-
cipitates suspended in chloroform was added the solid ligand
HttscMe (0.035 g, 0.17 mmol). The contents were stirred for a
further period of 10 min and the solution was allowed to crystal-
lize. Slow evaporation at room temperature yielded crystals of
tals of [Ag2(l-Cl)2(g
1-S-HttsMe)2(PPh3)2] (1) (1 yellow, 72%, m.p.
175–177 °C). Anal. Calc. for C50H48Ag2Cl2N6P2S4: C, 49.26; H,
4.35; N, 6.92. Found: C, 49.67; H, 4.0; N, 6.95%. IR data (KBr, cm
ꢁ1):
m
(N–H) 3340(s);
H)Me 2733(w); (C@N) +
(P–CPh) 1093(s); (C–N) 1031(s);
m
(–NH–) 3160(m);
m(C–H)Ph 2951(m); m(C–
m
m
m(C@C) 1620(m), 1565(m), 1530(m);
m
m
(C@S) 854(s). 1H NMR (CDCl3,
[Ag2Cl2(l-S-HttscMe)2(g
1-S-HttscMe)2] (3) (yellow, 65%, decom-
posed at 180–185 °C). Anal. Calc. for C28H36Ag2Cl8N12S8: C, 27.86;
d ppm): 12.42s (–N2H), 8.66s (C2H), 7.32–7.52m (C4,6H + 15H,
PPh3 + N1H), 7.05dd (C5H), 3.23d (–CH3). 31P NMR (CDCl3, d
H, 3.20; N, 19.0. Found: C, 27.23; H, 2.90; N, 19.4%. IR data (KBr,
ppm): 10.5,
2.2.2. [Ag2(
D
d (d complex ꢁ d ligand) 14.7.
cmꢁ1):
m
(N–H) 3347(s);
(C–H)Me 2757(w); (C@N) +
(C–N) 1029(s); m
(C@S) 854(s). 1H NMR (CDCl3, d ppm): 11.68s
m(–NH–) 3142(m);
m(C–H)Ph 2981(m);
m
m
m
m
(C@C) 1638(m), 1566(m), 1530(m);
l
-Br)2(
g
1-S-HttsMe)2(PPh3)2] (2)
To AgBr (0.025 g, 0.13 mmol) suspended in acetonitrile (15 mL)
was added solid Ph3P (0.035 g, 0.13 mmol), and the reaction mix-
(–N2H), 8.56s (C2H), 7.86sb (N1H) 7.32–7.39m (C4,6H), 7.06dd
(C5H), 3.24d (–CH3).
NH
S
PPh3
S
X
X
R3 = Me
Ag
Ag
Ph3P
S
NH
2
1
C
X = Cl, 1; Br, 2
NH
2
C
1
3
N
NHR3
S
Ph P
3
NH
AgX +
+
H
3 = H
X
S
S
PPh3
R
Ag
Ag
Ph3P
X
X = Cl 4 [15]
HN
NH
NH
S
2
1
C
Cl
S
S
NH
AgCl
+ 2, 2'-bipyridine
+
2
C
1
3
N
Ag
Ag
S
NHMe
S
S
Cl
H
HN
HN
3
Scheme 1.

T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
1105
Table 1
Crystallographic data of complexes 1–3.
Empirical formula
M
T (K)
C50H48Ag2Cl2N6P2S4
1209.80
100(2)
C50H48Ag2Br2N6P2S4
1298.70
100(2)
C28H36Ag2Cl8N12S8
1296.51
200(2)
Crystal system
Space group
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/n
Unit cell dimensions
a (Å)
b (Å)
c (Å)
10.7279(13)
16.153(2)
14.9158(18)
90.00
10.8211(8)
16.3962(13)
14.8555(11)
90.00
15.6035(10)
9.9952(5)
17.5911(11)
90.00
a
(°)
b (°)
102.864(2)
90.00
2519.8(5)
2
1.594
1.155
102.868(2)
90.00
2569.5(3)
2
1.679
2.583
109.667(7)
90.00
2583.5(3)
2
1.667
1.531
c
(°)
V (Å3)
Z
Dcalc (g cmꢁ3
)
l
(mmꢁ1
)
Reflections collected
Unique reflections
Rint
6680
6217
0.0399
5088
15505
6299
0.0520
4991
18520
8418
0.0449
6138
Reflections with [I > 2
r(I)]
Final R indices [I > 2
r(I)]
R = 0.0506, wR = 0.0977
R = 0.0648, wR = 0.1246
R = 0.0960, wR = 0.1993
2,20-bipyridine in lieu of Ph3P in the reaction of silver(I) chloride
3. X-ray crystallography
with HttscMe yielded [Ag2(
l
-S-HttscMe)2(
g
1-HttsMe)2] ꢀ 2CHCl3
3. There was no coordination by 2,20-bipyridine in this reaction.
Reactions of silver(I) halides with thiosemicarbazones in the ab-
sence of Ph3P or 2,20-bipyridine yield insoluble complexes. Thus
the presence of the co-ligand is necessary to get crystalline
compounds.
The data for 1 and 2 were measured on a Bruker AXS SMART
APEX CCD diffractometer. Data were reduced and corrected for
absorption using SMART and SAINT [42]. 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 (structure solution, refinement and some
molecular graphics). All non-hydrogen atoms were refined aniso-
tropically. All hydrogen atoms were placed in calculated positions
and were refined with an isotropic displacement parameter 1.5
(methyl) or 1.2 (all others) times that of the adjacent carbon or
oxygen atom.
It was reported earlier that thiophene-2-carbaldehyde thiosem-
icarbazone (Httsc, R3 = H) with silver(I) chloride formed a sulfur-
bridged complex, [Ag2Cl2(
l
-S-Httsc)2(Ph3P)2] ꢀ 2CH3CN
4 [15],
and the replacement of one hydrogen at the N1 nitrogen with a
methyl group has changed the nature of bonding from sulfur-
bridging (4) to halogen-bridging (1 and 2). Complex 3 shows S-
bridging, as in 4, and probably is dominated by the presence of four
A prismatic crystal of complex 3 was mounted on an automatic
Enraf–Nonius CAD-4 diffractometer equipped with a graphite
monochromator and Mo Ka radiation (k = 0.71073 Å). The unit cell
dimensions and intensity data were measured at 200 K. The struc-
ture was solved by direct methods and refined by full matrix least
squares based on F2 with anisotropic thermal parameters for non-
hydrogen atoms using XCAD-49 (data reduction), and SHELXL (absorp-
tion correction, structure solution refinement and molecular
graphics) [43]. The thiophene rings of the terminally bonded
HttscMe ligand in complex 3 are disordered and the data is 99%
complete to a theta value of 25° (2h of 50°), which meets the crite-
rion. The reason for the 90% completion figure is that data was col-
lected out to a theta value of 32.51°, but at this angle the data is
incomplete due to the shape of the detector (this is normal for area
detector data).
Table 2
Bond lengths (Å) and bond angles (°).
[Ag2(l-Cl)2(
g
1-HttsMe)2(Ph3P)2] 1
2.4258(8)
Ag(1)–P(1)
Ag(1)–S(1)
Ag(1)–Cl(1)
C(2)–S(1)
C(2)–N(2)
C(2)–N(1)
N(2)–N(3)
1.700(3)
1.348(4)
1.322(4)
1.379(4)
2.5693(8)
2.6335(8)
2.6493(8)
3.734(4)
112.32(3)
114.88(3)
109.81(3)
121.58(3)
Ag(1)–Cl(1)
Ag–Ag#1
P(1)–Ag(1)–S(1)
P(1)–Ag(1)–Cl(1)
S(1)–Ag(1)–Cl(1)
P(1)–Ag(1)–Cl(1)
S(1)–Ag(1)–Cl(1)
Cl(1)–Ag(1)–Cl(1)
Ag(1)–Cl(1)–Ag(1)
C(2)–S(1)–Ag(1)
105.84(3)
90.15(2)
89.85(2)
109.00(11)
[Ag2(l-Br)2(
g
1-HttsMe)2(Ph3P)2] 2
2.4414(11)
Ag(1)–P(1)
Ag(1)–S(1)
Ag(1)–Br(2)
Ag(1)–Br(2)
Ag–Ag#1
P(1)–Ag(1)–S(1)
P(1)–Ag(1)–Br(2)
S(1)–Ag(1)–Br(2)
P(1)–Ag(1)–Br(2)
C(2)–S(1)
C(2)–N(2)
C(2)–N(1)
N(2)–N(3)
1.699(5)
1.361(5)
1.324(6)
1.374(5)
2.5625(12)
2.7357(5)
2.7422(5)
3.746(5)
113.10(4)
122.13(3)
105.60(3)
108.68(3)
4. Results and discussion
4.1. Synthesis
S(1)–Ag(1)–Br(2)
Br(2)–Ag(1)–Br(2)
Ag(1)–Br(2)–Ag(1)
C(2)–S(1)–Ag(1)
112.08(3)
93.717(15)
86.284(15)
109.38(15)
Scheme 1 gives a pictorial representation of formation of the sil-
ver(I) halide complexeswith thiophene-2-carbaldehyde N1-methyl-
thiosemicarbazone (HttscMe). To silver(I) chloride suspended in
acetonitrile was added triphenylphosphine, and the contents were
stirred for 2 h, which formed white precipitates. The ligand HttscMe
was added to these precipitates suspended in chloroform and stirred
for 10 min. The clear solution was allowed to evaporate at room
[Ag2(l-S-HttscMe)2(
g
1-HttsMe)2] ꢀ 2CHCl3
3
Ag–S(1B)
Ag–Cl
2.5168(7)
Ag–S(1A)
2.6259(8)
1.721(3)
1.722(3)
1.327(4)
108.46(2)
96.24(2)
100.25(8)
83.76(2)
2.5770(8)
2.5969(7)
3.4867 (5)
111.31(2)
109.49(2)
S(1A)–C(2A)
S(2A)–C(7A)
N(1A)–C(2A)
Cl–Ag–S(1A)
S(1A)–Ag–S(1A)
C(2A)–S(1A)–Ag
Ag–S(1A)–Ag
Ag–S(1A)
Ag–Ag#1
S(1B)–Ag–Cl
S(1B)–Ag–S(1A)
Cl–Ag–S(1A)
S(1B)–Ag–S(1A)
temperature, which formed crystals of the stoichiometry, [Ag2(
Cl)2(
1-S-HttsMe)2(PPh3)2] 1. A similar reaction with silver(I)
bromide yielded [Ag2( -Br)2(
1-S-HttsMe)2(PPh3)2] 2. The use of
l-
116.71(2)
113.94(2)
g
l
g

1106
T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
S-donor atoms in this dimer, and this also enhances the argento-
philicity with a relatively short AgꢀꢀꢀAg contact.
The presence of two
(due to –N1HR) and 3142–3160 cmꢁ1 (due to –N2H) in complexes
m
(N–H) bands in the ranges 3340–3347 cmꢁ1
Fig. 1. ORTEP drawing of [Ag2(l-Cl)2(g
1-HttsMe)2(Ph3P)2], 1, showing thermal ellipsoids at the 50% probability level.
Fig. 2. ORTEP drawing of [Ag2(l-Br)2(g
1-HttsMe)2(Ph3P)2], 2, showing thermal ellipsoids at the 50% probability level.

T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
1107
Table 3
Comparison of bond parameters of dimers 1–8.
R1, R2, R3 (No.)
Ag–S
Ag–X
Ag–X–Ag
X–Ag–X
90.15(2)
AgꢀꢀꢀAg
Ref.
Ag(
l-X)2Ag cores
2.5693(8)
2.6335(8); 2.6493(8)
89.85(2) (Cl)
3.734(4)
this work
, H
S
Me (1)
, H
2.5625(12)
2.507(2)
2.7357(5); 2.7422(5)
2.6454(7); 2.8378(7)
86.284(15) (Br)
82.24(2) (Br)
93.717(15)
97.75(2)
3.746(5)
this work
[16]
S
Me (2)
Me, Me
3.6089(9)
H (5)
Me
,
2.5881(6)
2.5851(8)
2.5927(6)
2.7252(3); 2.7914(3)
2.6254(8); 2.7056(8)
2.7210(3); 2.8115(3)
78.004(8) (Br)
78.01(2) (Cl)
101.997(8)
101.99(2)
3.4722(3)
3.3558(5)
3.3023(3)
[16]
[16]
[15]
H (6)
H (7)
H (8)
Me
,
H
,
73.2.27(8) (Br)
Ag–S–Ag
106.721(8)
S–Ag–S
Ag(l-S)2Ag cores
, H
2.5967(11); 2.6259(12)
2.611(2); 2.876(2)
2.5771(12)
2.520(2)
83.77(3) (Cl)
68.33(6) (Cl)
96.23(3)
3.4867(5)
this work
[15]
S
Me (3)
, H
111.67(6)
3.0902(15)
S
H (4)
R1R2C@NNHC(@S)NHR3.
Fig. 3. ORTEP drawing of [Ag2(
l
-S-HttscMe)2(
g
1-HttsMe)2] ꢀ 2CHCl3 3, showing thermal ellipsoids at the 50% probability level.

1108
T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
1–3 supports the coordination of HttscMe as a neutral ligand. The
(N–H) band of the –N1HR group showed a high-energy shift in the
complexes vis-à-vis the free ligand (3326 cmꢁ1). The most charac-
Ag angles are close to 90° (90.15(12), 89.85(2)° 1; 93.717(15),
86.284(15)° 2), while similar cores of complexes 5–8 form parallel-
ograms (Table 3). In complex 3, two bridging sulfurs, one terminal
sulfur and one terminal chloride atom are coordinated to the sil-
teristic thioamide band due to m(C@S) lies in the range 852–854 cm
ꢁ1 in complexes 1–3 and is at a somewhat low energy region (free
ver(I) centers. The central core Ag(l-S)2Ag is a parallelogram (S–
ligand, 860 cmꢁ1). This indicates the coordination of sulfur to the
Ag–S, Ag–S–Ag, 109.49°, 83.76°). The geometries around each sil-
ver atom in complexes 1–3 can be treated as distorted tetrahedral.
The Ag–X–Ag and X–Ag–X or Ag–S–Ag and S–Ag–S bond angles
vary in a complementary fashion, the larger the angle at the bridg-
ing halogen/sulfur, the greater is the AgꢀꢀꢀAg contact. The AgꢀꢀꢀAg
separation (3.487 Å) in sulfur-bridged complex 3 is close to twice
the sum of the van der Waal’s radius of silver atoms (3.40 Å [44])
and this separation is less than that (3.734(4) Å for 1; 3.746(5) Å
for 2) in the halogen-bridged dimers.
silver center. The m(P–CPh) bands in complexes 1 and 2 at 1093
and 1094 cmꢁ1, respectively, support the presence of coordinated
triphenylphosphine in these complexes [15,16].
4.2. Structures of the complexes
The crystallographic data and important bond parameters
(bond lengths and bond angles) of complexes 1–3 are given in Ta-
bles 1 and 2, respectively. The molecular structures along with the
numbering scheme are given in Figs. 1–3, respectively. All the
three complexes crystallized in the monoclinic crystal system with
space group P21/n.
4.4. H-bonded networks
Scheme 2 shows the intra-molecular interactions in complexes
1 and 2. Complex 4 has S-bridging and the imino group is H-
bonded to the terminal chlorine. The presence of the methyl group
at the N1 atom modulates the bonding property of HttscMe, prob-
ably by way of higher steric crowding if it was in a sulfur-bridged
dimer. This paves way for halogen-bridging and the imino group
now H-bonds to this halogen (N2HꢀꢀꢀCl, 2.45 Å 1; N2HꢀꢀꢀBr, 2.614 Å
2). The two chloro-bridged dimeric units of 1 are interconnected
4.3. Structures of the dimers 1–3
Complexes 1 and 2 have similar structures. In each complex, sil-
ver(I) is coordinated to two bridging halogen atoms, one terminal S
atom and one terminal P atom. The central Ag(l-X)2Ag cores of
these dimers are almost square planar as the X–Ag–X and Ag–X–
1
N2
1
2
NHMe
H2N
H
N
H
C
C
S
Cl
X
X
S
Ag
Ag
Ag
Ag
S
4 [15]
X = Cl, 1; Br, 2
Scheme 2.
Fig. 4. Packing diagram of [Ag2(l-Cl)2(g
1-HttsMe)2(Ph3P)2] 1.

T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
1109
Fig. 5. Packing diagram of [Ag2(l-Br)2(g
1-HttsMe)2(Ph3P)2] 2.
Fig. 6. Packing diagram of [Ag2(
l
-S-HttscMe)2(
g
1-HttsMe)2] ꢀ 2CHCl3 3.
via phenyl hydrogen–chlorine (CHPhꢀꢀꢀCl#1, 2.852 Å) and phenyl
mine, (H2CHꢀꢀꢀBr, 2.972 Å) interactions, which form a H-bonded
linear chain. Two linear chains are connected via phenyl hydro-
gen–bromine (CHPhꢀꢀꢀBr#1, 2.996 Å) interaction and form a H-
bonded 2D polymer (Fig. 5).
The imino hydrogen atom of terminal as well as bridging li-
gands forms a strong intra-molecular H-bond with the chlorine
hydrogen–
p, (CHPhꢀꢀꢀ
p, 2.626 Å) interactions to form a linear chain
along the a-axis (Fig. 4). Two such linear chains are further inter-
connected by a phenyl hydrogen–chlorine (CHPhꢀꢀꢀCl#2, 2.778 Å)
interaction which forms a H-bonded 2D polymer. In the dimer 2,
two units are H-bonded via MeN1H–
p (2.768 Å) and methyl-bro-

1110
T.S. Lobana et al. / Polyhedron 28 (2009) 1103–1110
atom (–N2HterꢀꢀꢀCl, 2.38 Å; –N2HbriꢀꢀꢀCl, 2.35 Å) in complex 3. Two
dimeric units are interconnected via the imino hydrogen of a ter-
minal ligand of one unit and the sulfur atom of a bridging ligand
of the second unit (–N2HterꢀꢀꢀSbri, 2.71 Å), which forms a linear
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Acknowledgement
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CCDC 705112–705114 contains the supplementary crystallo-
graphic data for 1–3, respectively. 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: de-
posit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.poly.2009.01.041.
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