The influence of substituents (R) at N1 atom of furan-2-carbaldehyde thiosemicarbazones {(C4H3O)HC 2N3-N(H)-C1(S)N1HR} on bonding, nuclearity, H-bonded networks of copper(I) comp

Article abstract of DOI:10.1016/j.poly.2012.08.014

The chemistry of copper(I) halides (CuX) with furan-2-carbaldehyde-N ¹-substituted thiosemicarbazones {(C₄H₃O) HC²N³N²H-C¹(S)N¹HR, Hftsc-N¹HR} in presence o

Full text of DOI:10.1016/j.poly.2012.08.014

Polyhedron 47 (2012) 134–142
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
The influence of substituents (R) at N1 atom of furan-2-carbaldehyde
thiosemicarbazones {(C4H3O)HC2@N3–N(H)–C1(@S)N1HR} on bonding,
nuclearity, H-bonded networks of copper(I) complexes
a
a
b
c
Tarlok S. Lobana a, , Rekha Sharma , Geeta Hundal , A. Castineiras , Ray Jay Butcher
⇑
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, India
b Departamento De Quimica Inorganica, Facultad de Farmacia, Universidad de Santiago, 15782 Santiago, Spain
c 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 chemistry of copper(I) halides (CuX) with furan-2-carbaldehyde-N1-substituted thiosemicarbazones
{(C4H3O)HC2@N3N2H–C1(@S)N1HR, Hftsc-N1HR} in presence of triphenyl phopshine is described. For
methyl and ethyl substituents (R) at N1 atom, and with X = I, Br, Cl, the halogen-bridged dimers, namely,
Article history:
Received 23 January 2012
Accepted 6 August 2012
Available online 16 August 2012
[Cu2(
However, the presence of phenyl substituent at N1 has favored a three coordinate complex, [CuI(
Hftsc-N1HPh)2] 7, and with copper(I) bromide/and chloride, it has formed sulfur-bridged dimers, [Cu2X2(-
1-Hftsc-N1HPh)2( -S-Hftsc N1HPh)2] (X = Br 8, Cl 9). In the latter three complexes (7–9), the Ph3P ligand
l-X)2(g
1-S-Hftsc-N1HR)2(PPh3)2] (R, X: Me, I, 1, Br 2, Cl 3; Et, I 4, Br 5, Cl 6) have been obtained.
g
1-S-
Keywords:
Furane-2-carbaldehyde-N1-methyl
thiosemicarbazone
g
l
did not take part in coordination. All these complexes have been characterized with the help of elemental
analysis, IR, 1H NMR spectroscopy and X-ray crystallography (1–3, 5, 7 and 9). The bonding and nuclearity
of complexes has been found to vary with the substituents at N1 atom. The intermolecular interactions
have formed one dimensional (1, 9) and two dimensional (2, 3 and 5) networks.
Ó 2012 Elsevier Ltd. All rights reserved.
Three-coordinated monomers
S-bridged dimer
Copper(I) halides
Triphenylphosphine
Iodide-bridged dimer
1. Introduction
Recently, the chemistry of copper(I) halides with thiophene-2-
carbaldehyde thiosemicarbazones has been reported [25,26]. The
Thiosemicarbazones {R1R2C2(@N3)N2HC(@S)N1H2} are versatile
N, S donor ligands with potential to bind to a metal via one or more
donor atoms. The importance of thiosemicarbazones lies in their
structural diversity [1–8], ion-sensing ability [9–12], metal extrac-
tion properties [13,14] and pharmacological properties [15–18].
Thiosemicarbazones containing heterocyclic rings at C2 carbon like
pyrrole or thiophene or pyridine are extensively studied, however,
thiosemicarbazones having furan ring is less studied for their inter-
actions with the metals. Only a few complexes, namely, [Ni(ftsc)2]
[19], [Ni(mftsc)2] (mftsc = anion of 5-methyl-2-furanaldehyde
substituents at C2 and N1 atoms influenced the bonding and nucle-
arity of copper(I) halide complexes. Herein we describe the effect
of substituents at N1 atoms of furan-2-carbaldehyde thiosemicar-
bazones as shown in Chart 2. Triphenyl phosphine has been used
as co-ligand as it helps to solubilize the reaction contents and also
helps in the formation of crystals. The products have been charac-
terized by IR and 1H NMR spectroscopies, and several of them by X-
ray crystallography.
2. Materials and techniques
thosemicarbazone)
[20],
[CuI(Hftsc)(Ph3P)]2
[21a],
[CuCl(HftscMe)]2 [21b], [Cu(ftsc)2] [22], [CuCl2(Hftsc)] [23],
[Ag(Hftsc)(Ph3P)]2(NO3)2 [7] and [Ga(ftscMe)Me2] (ftscMe = fur-
an-2-carbaldehyde-N-methyl-thiosemicarbazonate) [24] are struc-
turally characterized. The furan based neutral thiosemicarbazones
Copper(I) halides were prepared by the reduction of CuSO4Á5H2-
O using SO2 in the presence of NaX (X = Cl, Br, I) in distilled water
[27]. The N1-methyl-thiosemicarbazide, N1-ethyl-thiosemicarba-
zide, N1-phenyl-thiosemicarbazide and Ph3P were procured from
Aldrich Sigma Ltd. Thiosemicarbazone ligands were prepared by
condensation of furanaldehyde with respective thiosemicarbazides
as previously reported [1,25,26]. The elemental analysis for C, H
and N were carried out using a thermoelectron FLASHEA1112 ana-
lyzer. The melting points were determined with a Gallenkamp
electrically heated apparatus. The I.R spectra of the ligands and
the complexes were recorded in the range, 4000–400 cmÀ1 (using
KBr pellets) on the FTIR-SHIMADZU 8400 Fourier Transform
have shown two types of bonding modes, namely,
g
1-S (mode A)
[21],
l
-S (mode B) and N3, S-chelation-cum-S-bridging (mode C)
[7], however, in anionic form it has shown N3, S-chelation (mode
D) [22] (Chart 1).
⇑
Corresponding author. Tel.: +91 93175 98845; fax: +91 183 2258820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.08.014

T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
135
2.1.4. Synthesis of [Cu2(l-I)2(g
1-S-Hftsc-N1HEt)2(Ph3P)2] (4)
R
N3
S
S
N3
S
S
Yield, 73%, m.p. 205–207 °C. Anal. Calc. for C52H52Cu2I2N6S2O2-
M
P2: C, 48.04; H, 4.60; N, 6.47. Found: C, 48.24; H, 4.33; N, 6.27%.
M
M
M
M
C
IR data (KBr, cmÀ1):
m
(N–H), 3264m, 3252m, (–NHEt + N2H);
m
m
(C–
(C–
M
A
D
B
H), 3087m, 3010m, 2879m;
m(C@N) + m(C–C), 1565s, 1530s;
N), 1075s, 1033s, 925s; (C@S), 867s;
m
m
(P–CPh), 1093(s). 1H NMR
Chart 1. Bonding modes.
(CDCl3, d ppm): 12.24s (s, 1H, N2H), 8.17 (s, 1H, C2H), 7.31–7.69
(m, 18H, C6H, 3Ph, N1H), 6.76 (d,1H, C4H), 6.50 (dd, 1H, C5H),
3.63 (m, 2H, CH2), 1.33 (t, 3H, CH3).
5
4
S
1
2
3
6
NH
C
2.1.5. Synthesis of [Cu2(l-Br)2(g
1-S-Hftsc-N1HEt)2(Ph3P)2] (5)
2
C
3
N
1
O
NHR
Yield, 71%, m.p. 198–200 °C. Anal. Calc. for C52H52Cu2Br2N6S2O2-
H
I
P2: C, 51.78; H, 4.31; N, 6.97. Found: C, 51.66; H, 4.24; N, 6.83%. IR
R =
furan-2-carbaldehyde thiosemicarbazone (Hftsc-NH2)
H
data (KBr, cmÀ1):
m
(N–H), 3260 m, 3242 m, (–NHEt + N2H);
m
m
(C–H),
(C–N),
furan-2-carbaldehyde-N1-methyl thiosemicarbazone (Hftsc-N1HMe)
furan-2-carbaldehyde-N1-ethyl thiosemicarbazone (Hftsc-N1HEt)
Me
3095m, 3014m, 2877m;
m
(C@N) +
m
(C–C), 1570s, 1539s;
m
1056s, 1030s, 931s; (C@S), 866s;
m
(P–CPh), 1094(s). 1H NMR
Et
(CDCl3, d ppm): 12.51 (s, 1H, N2H), 8.19 (s, 1H, C2H), 7.31–7.65
(m, 18H, C6H, 3Ph, N1H), 6.74 (d,1H, C4H), 6.51 (dd, 1H, C5H),
3.69 (m, 2H, CH2), 1.31 (t, 3H, CH3).
furan-2-carbaldehyde-N1-phenyl thiosemicarbazone(Hftsc-N1HPh)
Ph
Chart 2.
2.1.6. Synthesis of [Cu2(l-Cl)2(g
1-S-Hftsc-N1HEt)2(Ph3P)2] (6)
Spectrophotometer and on Pye–Unicam SP-3-300 spectrophotom-
eter. The 1H NMR spectra were recorded on a JEOL AL300 FT spec-
trometer at 300 MHz in CDCl3 with TMS as the internal reference.
Yield, 69%, m.p. 180–182 °C. Anal. Calc. for C52H52Cu2Cl2N6S2O2-
P2: C, 55.91; H, 4.65; N, 7.52. Found: C, 55.69; H, 4.69; N, 7.63%. IR
data (KBr, cmÀ1):
m
(N–H), 3265m, 3245m, (–NHEt + N2H);
m
m
(C–H),
(C–N),
3098m, 3017m, 2876m;
m
(C@N) +
m
(C–C), 1575s, 1539s;
m
1056s, 1033s, 935s; (C@S), 862s;
m
(P–CPh), 1092(s). 1H NMR
2.1. Synthesis of complexes
(CDCl3, d ppm): 12.50 (s, 1H, N2H), 8.18 (s, 1H, C2H), 7.31–7.63
(m, 18H, C6H, 3Ph, N1H), 6.74 (d,1H, C4H), 6.49 (dd, 1H, C5H),
3.67 (m, 2H, CH2), 1.32 (t, 3H, CH3).
2.1.1. Synthesis of [Cu2(l-I)2(g
1-S-Hftsc-N1HMe)2(Ph3P)2] (1)
To copper(I) iodide (0.025 g, 0.131 mmol) dissolved in acetoni-
trile (15 mL), the HftscMe ligand (0.024 g, 0.131 mmol) was added
and the contents were stirred for 3–4 h. It formed yellow precipi-
tate and to the precipitate, the co-ligand Ph3P (0.034 g,
0.131 mmol) was added and after stirring for 5–10 min, it formed
a yellow solution. Slow evaporation of the solution at room tem-
perature gave yellow crystals. Yield, 74%, m.p. 205–207 °C. Anal.
Calc. for C50H48Cu2I2N6S2O2P2: C, 41.21; H, 3.78; N, 6.61. Found:
2.1.7. Synthesis of [CuI(g
1-S-Hftsc-N1HPh)2] (7)
To copper(I) iodide (0.025 g, 0.131 mmol) in acetonitrile
(15 mL), the ligand HftscPh (0.034 g, 0.131 mmol) was added,
and the contents were stirred for 3–4 h. It formed yellow precipi-
tates and addition of Ph3P (0.034 g, 0.131 mmol) followed by stir-
ring for 5–10 min formed a yellow solution, which on slow
evaporation at room temperature yielded brown crystals. Yield,
34%, m.p. 170–172 °C. Anal. Calc. for C24H22O2S2CuI: C, 42.32; H,
3.23; N, 12.34. Found: C, 42.24; H, 3.26; N, 12.34%. IR data (KBr,
C, 41.19; H, 3.52; N, 6.19%.). IR data (KBr, cmÀ1):
3143m, 3129m; (–NHMe + N2H),
(C–H), 3010m, 2983m, 2822m;
(C–N), 1066s, 1039s, 936s;
m(N–H), 3310m,
m
m
m
(C@N) +
(C@S), 865s;
m(C–C), 1550s, 1520s; m
m
(P–CPh), 1094(s). 1H NMR (CDCl3, d ppm): 12.23
cmÀ1):
2987m, 2979m;
1014s, 928s;
m
(N–H), 3290s, 3122m, 3107m, (–NHPh + N2H);
m(C–H),
(s, 1H, N2H), 8.19 (s, 1H, C2H), 7.36–7.67 (m, 18H, C6H, 3Ph,
N1H), 6.75 (d,1H, C4H), 6.51 (dd, 1H, C5H), 3.21 (d, 2H, CH3).
Complexes 2–6 were prepared by the same method.
m
(C@N) + (C–C), 1550s, 1530s; (C–N), 1076s,
m
m
m
(C@S), 867m. 1H NMR (CDCl3, d ppm): 12.24 (s, 1H,
N2H), 8.98 (s, 1H, C2H), 8.29 (s, 1H, C6H), 7.28–7.56 (m, 6H, Ph,
N1H), 6.83 (d, 1H, C4H), 6.53 (dd, 1H, C5H),. Complexes 8 and 9
were prepared similarly.
2.1.2. Synthesis of [Cu2(l-Br)2(g
1-S-Hftsc-N1HMe)2(Ph3P)2] (2)
2.1.8. Synthesis of [Cu2Br2(l g
-S-Hftsc-N1HPh)2( 1-S-Hftsc-
Yield, 65%, m.p. 210–212 °C. Anal. Calc. for C50H48Cu2Br2N6S2O2-
N1HPh)2]Á2CH3CN (8)
P2: C, 50.98; H, 4.08; N, 7.14. Found: C, 50.38; H, 3.99; N, 7.41%. IR
data (KBr, cmÀ1): (N–H), 3315m, 3146m, 3120m (–NHMe + N2H);
m
Brown crystals. Yield, 42%, m.p. 205–207 °C. Anal. Calc. for C52-
m
m
(C–H), 3016m, 2990m, 2843m;
m
(C@N) +
m
m
(C–C), 1560s, 1529s;
H50Cu2Br2N14O4S4: C, 39.12; H, 3.13; N, 12.28. Found: C, 39.20;
(P–CPh), 1092(s). 1H
H, 3.12; N, 12.29%. IR data (KBr, cmÀ1):
m
(N–H), 3292s, 3115m,
(C–H), 2983m, 2972m; (C@N) + (C–C),
(C–N), 1067s, 1012s, 928s;
(C@S), 865m. 1H
(C–N), 1060s, 1029s, 935s;
m
(C@S), 863s;
NMR (CDCl3, d ppm): 11.58 (s, 1H, N2H), 8.22 (s, 1H, C2H), 7.37–
7.65 (m, 18H, C6H, 3Ph, N1H), 6.72 (d,1H, C4H), 6.51 (dd, 1H,
C5H), 3.19 (d, 2H, CH3).
3100m, (–NHPh + N2H);
1560s, 1529s;
m
m
m
m
m
NMR (CDCl3, d ppm): 12.43 (s, 1H, N2H), 8.78 (s, 1H, C2H), 7.69
(s, 1H, C6H), 7.24–7.59 (m, 6H, Ph, N1H), 6.75 (d, 1H, C4H), 6.54
(dd, 1H, C5H).
2.1.3. Synthesis of [Cu2(l-Cl)2(g
1-S-Hftsc-N1HMe)2(Ph3P)2] (3)
Yield, 69%, m.p. 202–205 °C. Anal. Calc. for C50H48Cu2Cl2N6S2O2-
2.1.9. Synthesis of [Cu2Cl2(l g
-S-Hftsc-N1HPh)2( 1-S-Hftsc-
P2: C, 55.14; H, 4.41; N, 7.72. Found: C, 55.26; H, 4.48; N, 7.62%. IR
N1HPh)2]Á2CH3CN (9)
data (KBr, cmÀ1):
m
(N–H), 3316m, 3148m, 3122m (–NHMe + N2H);
Brown crystals. Yield, 35%, m.p. 203–205 °C. Anal. Calc. for C52-
m
m
(C–H), 3016m, 2976m, 2832m;
m
(C@N) +
m
m
(C–C), 1555s, 1529s;
H50Cu2Cl2N14S4O4: C, 49.52; H, 3.97; N, 15.55. Found: C, 49.49; H,
(C–N), 1056s, 1029s, 938s;
m(C@S), 862s;
(P–CPh), 1092(s). 1H
3.87; N, 15.54%. IR data (KBr, cmÀ1):
m
(N–H), 3293s, 3122m,
(C–H), 2987m, 2986m; (C@N) + (C–C),
(C–N), 1076s, 1020s, 928s;
(C@S), 863m. 1H
NMR (CDCl3, d ppm): 12.20 (s, 1H, N2H), 8.84 (s, 1H, C2H), 7.64
NMR (CDCl3, d ppm): 12.56 (s, 1H, N2H), 8.17 (s, 1H, C2H), (C2H),
7.37–7.68 (m, 18H, C6H, 3Ph, N1H), 6.75 (d,1H, C4H), 6.50 (dd,
1H, C5H), 3.20 (d, 2H, CH3).
3117m, (–NHPh + N2H);
1555s, 1530s;
m
m
m
m
m

136
T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
R
P)2] 1. The thio-ligand, Hftsc-N1H2 (R = H) with copper(I) iodide
also yielded a similar dimer, [Cu2( -I)2(
1-S-Hftsc-N1H2)2(Ph3P)2]
S
l
g
S
PPh3
S
X
X
CH3CN
C
NH
R
+
CuX
[21]. Both these dimers are similar to those formed with thio-
phene-2-carbaldehyde- and thiophene-2-carbaldehyde-N1-methyl
thiosemicarbazones [21,25]. Other copper(I) halides with furan-2-
carbaldehyde-N1-methyl/ethyl-thiosemicarbazones have also
Cu
Cu
Ph3P
C
N
NHR
O
Ph3P
H
R
S
R = Me, X = I, 1; Br, 2: Cl, 3
R = Et, X = I, 4; Br, 5: Cl, 6
yielded halide bridged dimers, [Cu2(l-X)2(g
1-S-Hftsc-N1HR)2(Ph3-
Scheme 1.
P)2] (R, X: Me, Br, 2; Me, Cl, 3; Et, I, 4; Et, Br, 5; Et, Cl, 6) (Scheme 1).
Complexes 2–6 are similar to the corresponding thiophene-2-carb-
aldehyde-N1-methyl (or ethyl) thiosemicarbazones [25]. It is re-
marked here that theoretically it has been demonstrated that the
halogen-bridging is a favored mode of bonding in copper-thiosem-
icarbazone chemistry unless halogen is engaged in some sort of
hydrogen bonding with a solvent or water from the system [21,26].
Another thio-ligand, namely, furan-2-carbaldehyde-N1-phenyl
thiosemicarba-zone (Hftsc-N1HPh), has shown a different coordi-
nation behavior. Two types of products have been isolated, namely,
S
C
NH
S
R
+
CuX
C
NHPh
N
O
H
Ph3P
I
R
a three coordinate complex, [CuI(
g
1-S-HftscPh)2] 7, and sulfur-
R
1-X)2( -S-Hftsc-N1HPh)2(
l
1-S-Hftsc-N1-
X
S
S
S
S
bridged dimers, [Cu2( g
g
Cu
Cu
Cu
HPh)2]Á2CH3CN (X = Br, 8; Cl, 9) (Scheme 2). The mixing ratios were
same as for 1–6, but Ph3P did not show coordination to CuI metal
center. It is an unusual behavior and may be attributed to the pres-
ence of phenyl substituent at N1 atom. Thus basically in complexes
7–9, the copper(I) halides are bonded to two thio-ligands and one
halogen, CuX(Hftsc-N1HPh)2, which probably dimerise through
sulfur for X = Br, Cl (8, 9) and remain three coordinated for X = I
(7). In comparison, thiophene-2-carbaldehyde-N1-phenyl thio-
semicarbazone (Httsc-N1HPh) was found to form with copper(I)
iodide three coordinate monomer and its sulfur-bridged dimer in
the same unit cell. On the other hand with copper(I)chloride and
bromide, it formed three coordinate complexes as shown in
Scheme 3 [25]. Thus furan and thiophene based thio-ligands
showed different behavior for phenyl substituent at N1 atom.
R
R
S
X
S
R
7
R
X=Br, 8; Cl, 9
Scheme 2.
(s, 1H, C6H), 7.26–7.60 (m, 6H, Ph, N1H), 6.70 (d, 1H, C4H), 6.65 (dd,
1H, C5H).
2.2. .X-ray data collection, structure solution and refinement
The data were collected on a Siemens P4 diffractometer using
XSCANS [28] for 1 and 3, on a Bruker SMART CCD 1000 for 2, an auto-
matic Enraf-Nonius CAD-4 diffractometer and Xcalibur for 5, 9 and
Ruby, Gemini for 7. All these diffracometers are equipped with
The presence of m
(N–H) bands in the ranges 3265–3316 cmÀ1
(due to –N1HR) and 3242–3100 cmÀ1 due to ÀN2HÀ in IR spectra
of complexes revealed that neutral ligand is coordinated to the
graphite monochromated MoK radiation (k = 0.71073 Å). Data
a
copper center. The thioamide bands due to
m(C@S) undergo low en-
ergy shifts at 862–867 cmÀ1 in complexes (free ligands, 880–
were collected and refined on Siemens XSCANS and data reduction
was done by SHELXTL-PC [29] for 1 and 3. The data were processed
with SAINT [30], corrected using SADABS for 2 [31] and solved and
refined by SHELXL-97, in 2 and 7 [32] for 2 and XCAD-49 and SHELXL
97 [33] for 5 and 9.
887 cmÀ1). In complexes 1–6, the appearance of
m
PÀCPh) bands
in the ranges 1092À1095 cmÀ1 indicate coordinated Ph3P ligand.
-
3.2. Molecular structures (1–3, 5, 7 and 9)
3. Results and discussion
The crystallographic data, important bond parameters of com-
pounds 1–3, 5, 7, 9 and its comparison with literature are given
in Tables 1–4. The molecular structures of representative com-
plexes (1, 7 and 9) are given in Figs. 1–3. Complexes 1–3, 5 and 9
crystallized in triclinic system with space group P1, whereas com-
plex 7 crystallized in monoclinic group with space group P21/c.
3.1. General comments on synthesis
ꢀ
Scheme 1 shows the formation of complexes. Furan-2-carbalde-
hyde-N1-methyl thiosemicarbazone (Hftsc-N1HMe) with copper(I)
iodide in acetonitrile with Ph3P as co-ligand has yielded an iodide
These complexes are divided into three categories: (i) halogen-
bridged dinuclear complex, [Cu2(
l
-I)2(g
1-S-Hftsc-N1HMe)2(Ph3-
bridged dimers, [Cu2(l-X)2(g
1-S-HL)2(Ph3P)2] (HL = Hftsc-N1HMe,
X
Cu
S
R
S
R
PPh3
X = Cl, Br
R
S
C
R
S
NH
R
+
CuX
I
S
S
I
NHPh
C
N
S
S
Cu
Cu
+
H
Cu
S
S
I
S
R
R
R
R
Scheme 3.

T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
137
Table 1
A comparison of important parameters (bond length, Å; bond angle, °) of dinuclear-copper(I) complexes.
R1, R2, R3a
CuÀS
IÀCuÀI
CuÀIÀCu
Cu. . .Cu
Ref.
Comparison of iodo-bridged dimers with different R1, R2, R3
2.3017(2)
99.43(2)
80.57(2)
3.5043
[37]
H3C
C
H3C
, H
2.3098(2)
97.28(3)
82.72(3)
3.606(1)
2.9786
[37]
[38]
H3C
C
H
, H
2.3399(9)
111.91(3)
68.087(16)
C
H
, H
2.331(4)
109.28(7)
70.72(7)
3.097(4)
3.3509
3.2213
3.377
[39]
[21]
[25]
[25]
[21]
[25]
N
H
C
C
C
C
C
C
H
H
H
H
H
H
, H
2.3284(8)
2.3306(4)
2.3214(14)
2.340(9)
106.819(15)
107.06(2)
73.571(13)
72.934(6)
76.971(1)
67.999(16)
71.80(2)
S
S
S
O
O
, H
, Me
, Et
, H
103.029(18)
112.001(16)
108.20(2)
2.9808(8)
3.187
2.3336(13)
, Me
Comparison of sulfur-bridged dimers with different R1, R2, R3
R1, R2, R3 (X)
CuÀS
SÀCuÀS
CuÀSÀCu
Cu. . .Cu
Ref.
2.2833(3), 2.5955(4)
100.738(12)
69.89(11)
2.8060(3)
[36]
O
C
H
, Me
(Cl)
2.2829(5), 2.7583(5)
2.2641(9), 2.8006 (10)
99.546(15)
104.16(3)
80.454(15)
75.84(3)
3.276
3.141
This paper
[36]
O
C
H
, Ph (Cl)
S
C
H
, Me
(Cl)
2.2961(9), 2.6553(11)
97.33(3)
82.67(3)
3.281
[25]
S
C
H
, Ph (I)
a
R1R2@NNHC(@S)NHR3.
Hftsc N1HEt) 1–3, 5, (ii) three coordinated monomer, [CuI(
g
l
1-S-
-S-
1-S-Hftsc-N1HPh)2] 9. Complexes 1–3, 5 are halo-
[Cu2(
l
-X)2(
g
1-S-HL)2(Ph3P)2] (HL = Hftsc-N1HMe, X = I 1 (Fig. 1);
-X)2Cu core in all
Hftsc-N1HPh)2]
Hftsc-N1HPh)2(
7
and (iii) sulfur-bridged dimer, [Cu2Cl2(
Br, 2; Cl, 3: Hftsc-N1HEt, Br 5). The central Cu(
l
g
these complexes is parallelogram with unequal CuÀX bond dis-
gen bridged dimers. Here one halogen atom, one thione sulfur and
one P donor of PPh3 appear to have formed a three-coordinate unit
which dimerizes via halogen to form halogen bridged dimers
tances (Table 4).
It can be observed that if we keep the ligand constant as for
example in complexes of Hftsc-N1HMe, the CuÀS bond distances

138
T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
Table 2
Important bond parameters of three-coordinated complexes, [CuX(Htsc)2].
R1, R2 (R3)a
X
I
CuÀS
2.2269(7)
2.2321(7)
CuÀX
2.5441
XÀCuÀS
119.62(3)
SÀCuÀS
121.42(2)
Ref.
[35]
C
,
(H)
I
2.2367(7)
2.2422(8)
2.5479(4)
2.5876(5)
2.4207(4)
2.295(3)
123.83(2)
123.53(3)
122.45(3)
121.73(9)
119.96(12)
109.88(3)
112.63(3)
116.13(3)
116.21(10)
121.10(6)
This paper
[25]
O
, H
, H
, H
, H
(Ph)
I
2.2526(9)
2.2613(9)
S
(Ph)
Br
Cl
Cl
2.2201(8)
2.2387(7)
[25]
S
(Ph)
2.214(3)
2.234(3)
[25]
S
(Ph)
2.223(3)
2.226(4)
2.3055(3)
[36]
, H
(Me)
a
R1R2@NNHC(@S)NHR3.
Table 3
Crystallographic data of complexes.
1
2
3
Empirical formula
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C
50H48Cu2I2N6O2P2S2
C50H48Br2Cu2N6O2P2S2
triclinic
C50H48Cl2Cu2N6O2P2S2
triclinic
triclinic
P1
ꢀ
ꢀ
ꢀ
P1
P1
10.901(5)
10.963(5)
11.797(5)
102.748(5)
105.557(5)
96.144(5)
1303.8(10)
2
10.4280(8)
10.8034(8)
12.9144(10)
113.8490(10)
91.9000(10)
106.6370(10)
1256.43(17)
1
10.7050(10)
10.9210(10)
12.571(2)
68.600(10)
89.300(10)
69.570(10)
1271.1(3)
1
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g cmÀ3
l
)
1.62
2.185
1.557
2.629
1.423
1.132
(Mo) (mmÀ1
)
k (MoK
F(000)
T (K)
Reflections collected
Reflections observed [I > 2
Parameters
a
) (Å)
0.71069
632
295(2)
5076
4392
310
0.71073
596
110(2)
14352
5127
0.71073
560
295(2)
4590
2526
r
(I)]
298
298
R
0.0292
0.0980
1.136
0.0249
0.0616
1.051
0.0666
0.2290
0.998
Rw (all data)
Goodness-of-fit (GOF) on F2
5
7
9
Empirical formula
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C
52H52Br2Cu2N6O2P2S2
C24H22CuIN6O2S2
monoclinic
P21/c
16.657
9.282
19.705
90
108.37
90
C52H50Cl2Cu2N14O4S4
triclinic
P1
triclinic
P1
ꢀ
ꢀ
10.9430(9)
11.1806(9)
12.6450(10)
112.156(8)
90.369(7)
109.116(8)
1338.86(19)
1
11.2973(5)
11.9516(5)
12.4961(4)
93.951(3)
108.277(3)
112.057(4)
1451.07(10)
1
a
(°)
b (°)
c
(°)
V (Å3)
2891.4
4
1.565
Z
Dcalc (g cmÀ3
l
)
1.496
2.469
1.443
1.025
(Mo) (mmÀ1
)
1.999

T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
139
Table 3 (continued)
1
2
3
k (MoK
F(000)
T (K)
Reflections collected
Reflections observed [I > 2
Parameters
a
) (Å)
0.71073
612
200(2)
14770
8342
0.71073
1352
123(2)
22196
9598
0.71073
648
200(2)
22532
9582
r
(I)]
308
325
352
R
0.0377
0.1027
1.010
0.0413
0.0930
0.921
0.0320
0.0769
0.891
Rw (all data)
Goodness-of-fit (GOF) on F2
Table 4
Important bond parameters (bond lengths (Å) and bond angles (°)).
[Cu2(
l
-I)2(
g
1-S-HftscMe)2(Ph3P)2] 1
2.3336(13)
2.2642(12)
2.7010(12)
2.7341(9)
Cu(1)ÀS(1)
Cu(1)ÀP(1)
Cu(1)ÀI(1)
Cu(1)ÀI(1)#1
S(1)ÀC(24)
N(1)ÀN(2)
N(2)ÀC(24)
P(1)ÀCu(1)ÀS(1)
P(1)ÀCu(1)ÀI(1)
S(1)ÀCu(1)ÀI(1)
P(1)ÀCu(1)ÀI(1)
I(1)ÀCu(1)ÀI(1)#1
Cu(1)ÀI(1)ÀCu(1)
C(24)ÀS(1)ÀCu(1)
118.35(4)
112.24(3)
96.11(3)
106.10(3)
108.20(2)
71.80(2)
1.693(3)
1.377(4)
1.339(5)
110.58(12)
[Cu2(l
-Br)2(
g
1-S-HftscMe)2(Ph3P)2] 2
2.2933(6)
Cu(1)ÀS(1)
Cu(1)ÀP(1)
Cu(1)ÀBr(1)
P(1)ÀCu(1)ÀS(1)
P(1)ÀCu(1)ÀBr(1)
S(1)ÀCu(1)ÀBr(1)
P(1)ÀCu(1)ÀBr(1)
Br(1)ÀCu(1)ÀBr(1)#1
Cu(1)ÀBr(1)ÀCu(1)
C(6)ÀS(1)ÀCu(1)
112.50(2)
2.2344(6)
2.4904(4)
2.6179(4)
1.704(2)
1.376(2)
1.353(3)
112.487(19)
116.590(18)
107.429(19)
97.397(11)
82.603(11)
112.84(8)
Cu(1)ÀBr(1)#1
S(1)ÀC(6)
N(1)ÀN(2)
N(2)ÀC(6)
Fig. 1. Structure of iodide bridged dimer [Cu2(
(complexes 2, 3 and 5 have similar structures).
l-I)2(g 1
1-S-HftscMe)2(Ph3P)2]
[Cu2(l
-Cl)2(
g
1-S-HftscMe)2(Ph3P)2] 3
2.226(2)
P(1)ÀCu
S(1)ÀCu
ClÀCu
P(1)ÀCuÀS(1)
P(1)ÀCuÀCl
S(1)ÀCuÀCl
P1 ÀCu ÀCl
ClÀCuÀCl
113.16(9)
117.14(8)
115.66(8)
104.53(8)
93.44(7)
86.56(7)
112.7(3)
2.292(2)
2.353(2)
2.573(2)
1.336(10)
1.383(8)
Bond angles around each copper atom in these complexes lie in
the range, 71.80–118.35°, representing distorted tetrahedral
geometry in these complexes. In complexes of Hftsc-N1HMe, the
ClÀCu
C(19)ÀN(2)
N(2)ÀN(3)
C(19)ÀS(1)
CuÀClÀCu
angle CuÀXÀCu at halogen atom of the central core, Cu(
l-X)2Cu,
1.692(8)
C(19)ÀS(1)ÀCu
increases with the decrease in size of the halogen atom (X = I,
71.80° 1; Br, 82.603° 2; Cl, 86.56° 3) and opposite is the trend for
the bond angle XÀCuÀX at Cu metal center (X = I, 108.20(2)° 1;
Br, 97.397(11)° 2; Cl, 93.44(7)° 3).
[Cu2(l
-Br)2(
g
1-S-HftscEt)2(Ph3P)2] 5
2.2866(8)
CuÀS
CuÀP
CuÀBr
PÀCuÀS
109.71(3)
117.03(2)
116.68(2)
107.60(2)
96.827(14)
83.173(14)
113.97(9)
2.2361(7)
2.4887(5)
2.6005(5)
1.697(2)
1.375(3)
1.334(3)
PÀCuÀBr
SÀCuÀBr
PÀCuÀBr
BrÀCuÀBr#1
CuÀBrÀCu
C(6)ÀSÀCu
CuÀBr#1
SÀC(6)
Table 1 shows variations in the bond parameters of iodo-
bridged dinuclear complexes. The CuÀS distances show variation
by changing the substituents at C2 carbon. In case of the iodo-
bridged dimers, the CuÀS distance is less with the aliphatic substi-
tuent at C2 (Me, H, 2.3017(2); Me, Me, 2.3098(2) Å) of thiosemicar-
bazone than the aromatic or heterocyclic substituents and is
probably due to the +I effect of methyl groups. With R1, R2 = Me,
H and Me, Me, the angle at copper (IÀCuÀI) is much smaller than
with R1 = furan, pyrrole, thiophene or phenyl groups. The CuÁ Á ÁCu
separation varies with R1, R2 substituents phenyl = furan < pyr-
role < thiophene < dimethyl < methyl. A change of substituent at
N1 atom also influences the bond parameters. For example, in case
of thiophene-2-carbaldehyde thiosemicarbazone, the CuÀS dis-
tance increases as H is changed by methyl group (2.3284(3) Å, H;
2.3306(4) Å, Me), however, the reverse is true for furanaldehyde
thosemicarbazone (2.340(9) Å, H; 2.336(18) Å, Me). The same
trend is observed with CuÁ Á ÁCu separation.
N(1)ÀN(2)
N(2)ÀC(6)
[CuI(g
1-S-HftscPh)2] 7
IÀCu
2.5479(4)
2.2367(7)
2.2422(8)
1.706(3)
1.706(3)
S(1B)ÀCuÀS(1A)
S(1B)ÀCuÀI
109.88(3)
123.83(2)
126.27(2)
109.64(10)
109.80(9)
CuÀS(1B)
CuÀS(1A)
S(1A)ÀCuÀI
S(1A)ÀC(6A)
S(1B)ÀC(6B)
C(6A)ÀS(1A)ÀCu
C(6B)ÀS(1B)ÀCu
[Cu2Cl2(
l
-S-HftscPh)2(
g
1-S-HftscPh)2] 9
CuÀS(1A)
2.2617(4)
2.2829(5)
2.3306(4)
2.7583(5)
1.6843(15)
1.3757(17)
1.3436(18)
S(1A)ÀCuÀS(1B)
108.223(16)
120.942(16)
120.547(15)
103.356(15)
99.546(15)
99.483(14)
110.72(5)
CuÀS(1B)
S(1A)ÀCuÀCl
CuÀCl
S(1B)ÀCuÀCl
CuÀS(1B)#1
S(1A)ÀC(6A)
N(1A)ÀN(2A)
N(2A)ÀC(6A)
S(1A)ÀCuÀS(1B)#1
S(1B)ÀCuÀS(1B)#1
ClÀCuÀS(1B)#1
C(6A)ÀS(1A)ÀCu
#1
Àx, Ày, Àz.
There is one sulfur-bridged dimer, namely, complex, [Cu2Cl2(l-
S-Hftsc-1HPh)2(
g
1-S-Hftsc-N1HPh)2]Á2CH3CN 9. Here CuI is bonded
vary in the order, 1 (2.3336(13)) > 2 (2.2933(6)) > 3 (2.292(3)) Å
due to the electronegativity differences of halogen atoms.
Keeping the halogen constant, for example, in complexes of
copper(I) bromide, CuÀS bond distance decreases when methyl
substituent at N1 (2: 2.2933(6) Å) is replaced by the bulkier ethyl
group (5: 2.2866(8) Å) and it is attributed to the higher positive
inductive effect of ethyl group leading to the strengthening of
the Cu–S bond. The CuÀX and CuÀP bond distances in complexes
1, 3 and 5 are close to the literature value [25,26].
to one Cl, and two S donor atoms in species, CuCl(Hftsc-N1HPh)2,
which has dimerised via thione sulfur (Fig. 2). One bridging CuÀS
distance in Cu(l-S)2Cu core is much longer 2.7583(5) Å than the
other (2.2829(5) Å). The former distance is more than the sum of
ionic radii of Cu+ and S2À, 2.61 Å [34]. Unlike the methyl or ethyl
substituents, the phenyl group has prevented PPh3 coordination.
It appears that the negative inductive effect of phenyl at N1 atom
lowers Lewis basicity of S donor atom and copper(I) bonded to

140
T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
Fig. 2. Structure of sulfur-bridged dimer [Cu2Cl2(
l
-S-Hftsc-N1HPh)2(
g
1-S-Hftsc-N1HPh)2]Á2CH3CN 9.
Only complex 7 is three coordinate. Here Cu is bonded to two S
atoms of two thio-ligands and one iodide. The CuÀS bond lengths
are 2.2367(7), 2.2422(8) Å. The bond angles around copper ranges,
109.88–126.27°, indicates distorted planar geometry. Comparison
of some important bond parameters of three-coordinated mono-
mers is given in Table 2. The three coordinate complexes have been
formed: (i) with copper(I) iodide for Ph, Ph (R1, R2) at C2 carbon
[35], (ii) with copper(I) halides for thiophene and hydrogen (R1,
R2) at C2 along with phenyl (R3) at N1 atom [25], (iii) with copper(I)
chloride for phenyl and hydrogen (R1, R2) at C2 along with methyl
(R3) at N1 atom [36] and with copper(I) iodide for furan and hydro-
gen (R1, R2) at C2 along with phenyl (R3) at N1 atom [This work].
The CuÀS bond distance increases in order: R1, R2: benzophe-
none < furan < thiophene (iodide halogen). The XÀCuÀS angles
vary in close range, 119–124, while SÀCuÀS angles have range,
109–122°.
Fig. 3. Structure of [CuI(g
1-S-HftscPh)2] 7.
more electronegative Cl then prefers to pick up two S atoms of
thio-ligands with subsequent dimerization. The bond angles
around each copper atom lie in range, 108.22–120.94°. A compar-
ison of important bond parameters of sulfur-bridged dimers with
3.3. Packing of complexes (H-bonding networks)
The intermolecular H-bonding is an interesting feature of these
complexes. In complex 1, one of the methyl hydrogen at N1 atom is
intermolecularly connected with the furan ring, namely H2-
CHÁ Á Ápfuran (2.772 Å) interaction. Additionally, the CHfuranÁ Á Ápph
(2.855, 2.803 Å) H-bonding leads to the formation of H-bonded
1D polymer (Fig. 4). However, the more electronegative bromine
atom in 2 has changed the H-bonding pattern. The bromine-hydro-
gen (BrÁ Á ÁHCPh, 2.838 Å) H-bonding generated a 1D polymer along
formula, [Cu2X2(l-S-Htsc)2(g
1-S-Htsc)2] is given in Table 1. Keep-
ing R1, R2 and halogen constant (R1, C5H5O; R2, H; X = Cl), angle at
sulfur has been markedly changed when methyl group (R3) at N1 is
replaced by phenyl group (Me, 69.89(11)°, Ph, 80.454(5)°). This in-
crease in angle at sulfur also increases the CuÁ Á ÁCu separation (Me,
2.8060(3) Å; Ph, 3.276 Å). The steric hindrance by bulkier phenyl
group may be the reason for this change.
the a-axis, which is further engaged in CHPhÁ Á Á
p, 2.537 Å H-bond-
Fig. 4. Packing network of [Cu2(l-I)2(g
1-S-HftscMe)2(Ph3P)2] 1.

T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
141
Fig. 5. Packing network of dinuclear complex, [Cu2(l-Br)2(g
1-S-HftscMe)2(Ph3P)2] 2.
of dimer (Fig. 6). No other interaction is found in this complex. In
complex 9, the phenyl substituent at N1 interacts intermolecularly
with the chlorine atom via CH(Ph)Á Á ÁCl, 2.879 Å to yield a 1D poly-
mer (Fig. 7). Two layers of acetonitrile molecules are present above
and below the 1D layer and are held in position by H-bonding be-
tween amino hydrogen and nitrogen of acetonitrile .i.e. PhN1HÁ Á ÁN,
2.249 Å interaction.
3.4. Solution phase studies
The 1H NMR spectra reveal downfield shift in N2H signals in
complexes 1–9 vis-à-vis the free ligands (HftscMe, d 10.80 ppm;
HftscEt, d 10.84 ppm; HftscPh, 11.36 ppm) and it reveals coordina-
tion of neutral ligands to the copper metal center in each complex.
Further, the C2H signals of free ligands (HftscMe, d 7.86 ppm; Hfts-
cEt, d 7.87 ppm; HttscPh, d 9.29 ppm) undergo downfield shifts in
complexes 1–6 {d 8.17–8.89 ppm} and upfield shift in 7–9 (d
8.78–8.98 ppm). The ring protons of Ph3P, which appeared in the
range, d 7.29–7.53 ppm, have obscured N1HR2 proton signals in
these complexes. The methyl protons of –N1HCH3 appear as a dou-
blet in the range, d 3.19–3.20 ppm in complexes 1–3. The ethyl pro-
Fig. 6. Packing network of three coordinate complex, [CuI(g
1-S-HftscPh)2] 7.
ing along b axis to form a 2D polymer (Fig. 5). Complexes 3 and 5
exhibited similar type of H-bonding.
In complex 7, there is only intermolecular, {PhN1HÁ Á Á
p(Ph),
2.721, 2.824 Å} interaction present, which results in the formation
Fig. 7. Packing network of [Cu2Cl2(
l
-S-HftscPh)2(
g
1-S-HftscPh)2]Á2CH3CN 9.

142
T.S. Lobana et al. / Polyhedron 47 (2012) 134–142
tons of –N1HC2H5 group appear as two sets, one multiplet (d 3.63–
3.69 ppm, CH2); and one triplet (d 1.31–1.33 ppm, CH3) in com-
plexes 4–6. The phenyl protons of –N1HC6H5 appear in the range,
d 7.24–7.60 ppm in 7–9, which also incorporate –N1H protons. It
is pointed out here that the solution phase studies appear to be
in line with the solid state studies.
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4. Conclusion
Furan-2-carbaldehyde thiosemicarbazones {(C4H3O)HC2@N3–
N(H)–C1(@S)N1HR} with methyl/ethyl (HftscMe/HftscEt) substitu-
ents at N1 nitrogen have favored halogen-bridged dinuclear
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complexes with copper(I) halides (X = Cl, Br, I), namely, [Cu2(
l-
X)2(g
1-S-L)2(PPh3)2], a behavior similar to that of N1-substituted
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bromide, namely, [Cu2X2(g l-S-HL)2], where no PPh3
1-S-HL)2(
was coordinating and this is unlike that shown by thiophene-2-
carbaldehyde-N1-phenyl-thiosemicarbazone [25].
Acknowledgements
Financial assistance from CSIR (Scheme No.: 01(1993)/05/EMR-
II), New Delhi is gratefully acknowledged.
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Appendix A. Supplementary data
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CCDC 860067–860072; contains the supplementary crystallo-
graphic data for 1–3, 5, 7 and 9. 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 http://dx.doi.org/
10.1016/j.poly.2012.08.014.
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