G.S. Sivagurunathan et al. / Polyhedron 65 (2013) 316–321
317
monochromated Mo K
corrected for absorption using the SADABS program and
a
radiation (k = 0.71073 Å). Data were
-scan
3. Results and discussion
x
technique was used for data collection [16,17]. The structures
were solved by SIR97 [18] and were refined by full matrix least
squares with SHELXL-97 [19]. All the non-hydrogen atoms were
refined anisotropically and the hydrogen atoms were fixed
geometrically. ORTEP-3 program was used for drawing the molecular
plots [20].
3.1. Characterization of thallium sulfide
3.1.1. Powder XRD analysis
Fig. 1 shows the powder XRD patterns of Tl S . The prepared
compound shows two prominent signals (Fig. 1A) at 2h = 32.83°
and 23.05° which agreed well with the JCPDS No. 43-1067 for
4
3
Tl
heating of the film at 300 °C converted it to Tl
The converted thin film, Tl showed an intense signal at
h = 29.45°, in agreement with the JCPDS No. 29-1344 and the
two prominent signals at 2h = 32.83°(220) and 23.05° (ꢀ211)
characteristic of Tl totally vanished on heating at 300 °C. In this
study, on heating Tl to 300 °C the PXRD pattern showed increase
in intensity of 32.83° and 23.05° signals compared to that at room
temperature as shown in Fig. 1. The signal corresponding to Tl S at
h = 29.45° did not appear at 300 °C. Therefore, the present inves-
tigation reveals that the bulk Tl is stable up to 300 °C and does
not transform to Tl S.
4
S
3
. An earlier report on thin films of Tl
4
S
3
indicated that the
2
S completely [6].
2
.2. Synthesis of the complexes and non conventional solvothermal
2
S
preparation of thallium sulfide
2
2.2.1. Preparation of thallium(III) chloride
4 3
S
S
4 3
Thallium(III) chloride was prepared by the oxidation of thal-
lium(I) chloride with chlorine [14]. Thallium(I) chloride (0.24 g,
mmol) was added with 15 mL of acetonitrile under stirring.
1
2
Chlorine gas was passed through the suspension with continuous
stirring, thallium(III) chloride being completely soluble in acetoni-
trile a clear solution was formed after some time. After the forma-
tion of thallium(III) chloride, nitrogen gas was passed through the
acetonitrile solution in order to remove excess chlorine gas.
Thallium(III) chloride in solid state decomposes at ꢁ40 °C and
hence the acetonitrile solution was used as such in the preparation
of the complexes. Yield of thallium(III) chloride as acetonitrile
solution was found to be 82%.
2
4 3
S
2
3.1.2. EDX, HRTEM analysis
EDX of Tl is shown in Fig. 2. The metal sulfide obtained
4 3
S
shows spherical nature of the particles and EDX confirmed the
presence of thallium and sulfur. HRTEM and SAED of the sample
are shown in Fig. 3. The spherical nature of the particles is con-
firmed by the TEM micrographs and the particles are in the range
of 20 nm.
2
.2.2. Synthesis of tris (cyclohexylmethyldithiocarbamato)
thallium(III)(1)
Cyclohexylmethyl amine (0.4 mL, 3 mmol) in acetonitrile
3.2. Characterization of the dithiocarabamate precursors
(
25 mL) and carbon disulfide (0.24 mL, 3 mmol) in acetonitrile
were mixed under ice cold condition (5 °C) to obtain yellow dith-
3.2.1. Infrared spectral studies
iocarbamic acid solution. To the freshly prepared dithiocarbamic
acid solution acetonitrile solution of TlCl (0.34 g, 1 mmol) was
3
added drop by drop with constant stirring for about an hour. An or-
ange yellow solid separated from the mixture which was filtered,
washed with acetonitirle and dried in air. The separated compound
was recrystallized from toluene. Yield: 78%; mp:196 °C.
Table 1 lists important spectral and cyclicvoltammetric data. In
the IR spectra of the compounds, the characteristic thioureide
ꢀ1
stretching bands are observed at 1471 cm for Tl(chmdtc)3 (1)
ꢀ1
ꢀ1
1468 cm for Tl(chedtc)3 (2) and 1448 cm for Tl(dchdtc)3 (3)
respectively. The stretching band of (3) is significantly lower than
those observed in (1) and (2) due to the steric effect of two bulky
2.2.3. Synthesis of tris(cyclohexylethyldithiocarbamato)thallium(III)(2)
Cyclohexylethylamine (0.45 mL, 3 mmol in acetonitrile 25 mL),
carbon disulfide (0.24 mL, 3 mmol) and TlCl
3
(0.34 g, 1 mmol) were
used and the procedure as described in 2.3.2 was followed. Yield:
6
8%; mp: 180 °C.
2.2.4. Synthesis of tris(dicyclohexyldithiocarbamato)thallium(III)(3)
Dicyclohexylamine (0.59 mL, 3 mmol in acetonitrile 25 mL),
carbon disulfide (0.24 mL, 3 mmol) and TlCl
3
(0.34 g, 1 mmol) were
used and a procedure as described in 2.3.2 was followed. Yield:
7
0%; mp: 242 °C.
4 3
2.2.5. Preparation of Tl S by nonconventional solvothermal
decomposition of [Tl(chmdtc)
3
]
A
mixture of tris(cyclohexylmethyldithiocarbamato) thal-
lium(III) (0.7 g) as a clear solution in chloroform (100 mL) was
heated with diethylenetriamine (2 mL) at 60 °C for 45 min. Black
Tl
chloroform in a drop of dodecylamine and was dried in air. Yield:
1%. Similar procedure was adopted for the preparation of Tl
from compounds (2) and (3). Yields of Tl from (2) and (3) are
9% and 75% respectively. The ease of formation of thallium sulfide
4 3
S obtained was decanted from chloroform, washed with ether,
7
4 3
S
4 3
S
6
was found to be very high for (3) compared to the other two
compounds.
4 3
Fig. 1. Powder XRD patterns of Tl S , (A) at room temperature, (B) at 300 °C).