1
7j
(ε L−1 mol−1 cm−1)]: 296 (1.07 × 10 ), 416.5 (0.6776 × 10 ).
4
4
[
CuI(η -S-Htsc) ] complexes were formed. In our curiosity to
2
2
observe the effect of Ph, py substituents at C carbons, we have
come across unusual coordination behaviour of 2-benzoylpyri-
dine thiosemicarbazone (Hbpytsc, R , R = Ph, py) during equi-
molar reactions with copper(I) iodide/bromide in the presence
and absence of triphenyl phosphine. The formation of the
halogen-bridged Cu dinuclear complexes (1, 3) in the presence
of Ph P along with the sulfur-bridged Cu dinuclear complexes
2, 4) and the novelty of 2-benzoylpyridine thiosemicarbazone to
stabilize formation of copper(II)–iodide bonds are described
X-band ESR signals: g = 3.85 and g = 2.05. This complex is
k ⊥
partially soluble in CHCl and soluble in hot CH OH. Data for 2
3
3
1
2
is given below.
II
[Cu
I
2
2
(μ-S-Hbpytsc)
2
(PPh ) ]·CH Cl (2)
3 2 2 2
I
3
Yield: orange, 0.017 g , 42%. Mp: 225–227 °C. Anal. Calcd for
C H Br Cu N S P ·CH Cl : C, 53.69; H, 4.00; N, 7.95%.
Found: C, 53.40; H, 4.21; N, 7.89%. Main IR peaks (KBr,
cm ): ν(N–H) 3485m, 3418s, 3203b (–NH ) 3121b (–NH–);
(
62
54
2
2
8
2
2
2
2
herein.
−1
2
ν(CvN) + δ(N–H) + ν(CvC) 1597s, 1506s; ν(C–N) 1107s,
1
049s, 1026s; ν(P–CPh) 1095s; ν(CvS) 833s (thioamide
Experimental section
1
moiety). H NMR (CDCl , δ, ppm) 7.23–7.51 m (PPh + Ph +
C H + N H ),7.74 (td, C , H), 8.82d (C H), 9.45sb (N H ),
1
3
3
4
1
5
6
7
1
General materials and techniques
2
2
2
4.09s (–N H–). Electronic absorption spectra [CH Cl , λ
2 2 max
Copper(I) halides were prepared by reducing an aqueous solution
of CuSO ·5H O using SO in the presence of NaX (X = Cl, Br,
−1
−1
−1
4
(
ε L mol cm )]: 355 (0.168 × 10 ).
4
2
2
8
I) in water. The ligand 2-benzoylpyridine thiosemicarbazone
was prepared by refluxing thiosemicarbazide with 2-benzoylpyri-
dine in presence of acetic acid in methanol for a period of 24 h.
The elemental general analyses (C, H and N) were obtained
using a Thermoelectron FLASHEA1112 CHNS analyzer. The IR
spectra were recorded using KBr pellets in the range
II
3
1
2
[Cu2 Br (η -N , N , S-bpytsc) ]·2CH CN (3)
2
2
3
PPh (0.045 g, 0.17 mmol) was added to a solution of copper(I)
3
bromide (0.025 g, 0.17 mmol) in CH CN, followed by stirring
for 1 h resulting in formation of a white precipitate. Solid
Hbpytsc ligand (0.031 g, 0.17 mmol) and CH Cl (5 mL) were
added to it, followed by refluxing for 10 min resulting in a clear
dark orange solution, which on slow evaporation of the solution
yielded dark green crystals of [Cu Br(η -N ,N ,S-bpytsc)] (3)
and orange crystals of [Cu Br (μ-S-Hbpytsc) (PPh ) ] (4). Data
for 3, yield, 014 g, 38%; mp. 205–207 °C. Anal. Calcd for
3
000–200 cm−1 on a FTIR-SHIMADZU 8400 Fourier transform
2
2
4
spectrophotometer and on a Pye-Unicam SP-3-300 spectro-
photometer. The UV-visible spectroscopy was done using a
SHIMADZU UV-1601PC spectrophotometer. ESR studies were
carried out using an X-band spectrometer. The melting points
were determined with a Gallenkamp electrically heated appar-
II
3
1
2
2
2
2
3 2
1
C H Cu Br N S ·2CH CN: C, 40.96; H, 3.19; N, 15.93%.
26
22
2
2
8
2
3
atus. H NMR spectra were recorded on a JEOL AL-300 FT
Found: C, 40.78; H, 4.24; N, 16.09%. Main IR peaks (KBr,
spectrometer operating at a frequency of 300 MHz in CHCl -d
3
−
1
cm ): ν(N–H) 3439s, 3271s (–NH ); ν(C–H) 3081s, 3047s;
2
with TMS as the internal reference. Cyclic voltammograms were
recorded on an Autolab Electrochemical System equipped with
PGSTAT20 apparatus driven by GPES software employing a
platinum working electrode and an SCE reference electrode. All
ν(CvN) + δ(N–H) + ν(CvC) 1601s, 1481s, 1433s; ν(C–N)
118s, 1105s, 925s; ν(C–S) 781s, 731s. Complex is partially
soluble in hot CH OH and insoluble in CH CN. Electronic
absorption spectra [CH OH, λ
1
3
3
−1
−1
−1
−
3
−1
(ε L mol cm )]: 296
max
3
solutions were 10 mmol L , and the supporting electrolyte
4
4
was 10−1 mmol L−1 of tetraethyl ammonium perchlorate.
(1.88 × 10 ), 417 (1.16 × 10 ). X-band ESR signals: g = 3.75
k
and g = 2.07. Data for 4 is given below.
⊥
II
3
1
2
2 2 3
[
Cu2 I (η -N ,N ,S-bpytsc) ]·2CH CN (1)
[
2 2 2 3 2
Cu Br (μ-S-Hbpytsc) (PPh ) ] (4)
PPh (0.045 g, 0.17 mmol) was added to a solution of copper(I)
3
Yield: orange, 0.026 g, 47%. Mp: 218–220 °C. Anal. Calcd for
C H Cu I N P S : C, 52.51; H, 3.81; N, 7.90%. Found: C,
iodide (0.025 g, 0.17 mmol) in CH CN, followed by stirring for
3
1
h resulting in formation of a white precipitate. Solid Hbpytsc
62 54
2 2 8 2 2
−1
5
2.84; H, 4.10; N, 7.98%. Main IR peaks (KBr, cm ): ν(N–H)
ligand (0.031 g, 0.17 mmol) and CH Cl (5 mL) were added to
2
2
3
419s, 3225m (−NH ) 3126s (–NH–); ν(CvN) + δNH2
+
these precipitates in CH CN, followed by refluxing for 10 min
2
3
ν(CvC) 1597s, 1585s, 1506s; ν(CvS) 833s (thioamide
resulting in a clear dark orange colored solution, which on slow
1
II
3
1
2
moiety); ν(C–N) 1100s, 1050s; ν(P–C ) 1095s. H NMR
evaporation yielded dark green crystals of [Cu I (η -N ,N ,
Ph
2
2
4
1
(
(
CDCl , δ ppm) 7.29–7.61 m (PPh + Ph + C H + N H ), 7.78
3 3 2
S-bpytsc) ] (1) along with orange crystals of [Cu I (μ-S-
2
2 2
5
6
7
2
td, C , H), 8.95d (C H), 14.03s (–N H). Electronic absorption
spectra [CH Cl , λ (ε L mol cm )]: 343 (0.176 × 10 ).
max
Hbpytsc) (PPh ) ] (2). The crystals were manually separated and
2
3 2
−1
−1
−1
4
characterized. The direct reaction of copper(I) iodide with
2
2
Hbpytsc in CH CN–CH Cl was also carried out which essen-
3
2
2
tially gave complex 1 with an enhanced yield of 75%. Data for
, yield, 0.011 g, 38%; mp. 200–202 °C). Anal. Calcd for
C H Cu I N S ·2CH CN: C, 37.00; H, 2.88; N, 14.39%.
X-ray crystallography
1
The data for compounds 1 and 3 was measured on a Bruker
AXS SMART APEX CCD diffractometer with graphite mono-
chromated Mo-Kα radiation at 100(2) K. Single crystals of 2 and
4 were mounted on an Oxford Diffraction Gemini diffractometer
equipped with graphite monochromated Mo-Kα radiation
2
6
22
2 2
8
2
3
Found: C, 36.88; H, 2.75; N, 13.93%. Main IR peaks (KBr,
−1
cm ): ν(N–H) 3269s (–NH ); ν(C–H) 3096s, 3055s; ν(CvN) +
2
δNH + ν(CvC) 1622s, 1583s, 1480s; ν(C–N) 1056s, 1107s;
2
ν(C–S) 779s, 733s. Electronic absorption spectra [CH OH, λ
3
max
4846 | Dalton Trans., 2012, 41, 4845–4851
This journal is © The Royal Society of Chemistry 2012