Synthesis, characterization and thermal decomposition of thiourea complexes of antimony and bismuth triiodide

Article abstract of DOI:10.1007/s10973-005-6959-2

The thiourea complexes of antimony and bismuth triiodide were synthesized by a direct reaction of antimony and bismuth triiodide with thiourea powder at room temperature. The formula of the complex is MI₃[SC(NH ₂)₂]₃(M=Sb, Bi). The crystal structure of the complexes belongs to monoclinic system and the lattice parameters are a=1.4772 nm, b=1.6582 nm, c=2.0674 nm and β=90.81° for SbI ₃(SC(NH₂)₂)₃ and a=1.4009 nm, b=2.0170 nm, c=2.0397 nm and β=90.84° for BiI₃[SC(NH ₂)₂]₃. The infrared spectra reveal that the trivalent antimony or bismuth ion is coordinated by the nitrogen atom, not the sulfur atom of the thiourea. Thermal analysis shows that there are two times structure rearrangements or phase transformation in the complexes from 100 to 170°C. Springer-Verlag 2006.

Full text of DOI:10.1007/s10973-005-6959-2

Journal of Thermal Analysis and Calorimetry, Vol. 86 (2006) 3, 775–781
SYNTHESIS, CHARACTERIZATION AND THERMAL DECOMPOSITION
OF THIOUREA COMPLEXES OF ANTIMONY AND BISMUTH TRIIODIDE
1
G. Q. Zhong , S. R. Luan , P. Wang , Y. C. Guo , Y. R. Chen and Y. Q. Jia
4
2
3
4
4*
1
College of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, P. R. China
Department of Chemistry, Yancheng Teacher’s College, Yancheng 224002, P. R. China
2
3
4
Department of Chemistry, Nanyang Teacher’s College, Nanyang 473061, P. R. China
Department of Chemistry, East China University of Science and Technology, Shanghai 200237, P. R. China
The thiourea complexes of antimony and bismuth triiodide were synthesized by a direct reaction of antimony and bismuth triiodide
with thiourea powder at room temperature. The formula of the complex is MI [SC(NH (M=Sb, Bi). The crystal structure of the
complexes belongs to monoclinic system and the lattice parameters are a=1.4772 nm, b=1.6582 nm, c=2.0674 nm and β=90.81° for
SbI (SC(NH [SC(NH . The infrared spectra reveal that
and a=1.4009 nm, b=2.0170 nm, c=2.0397 nm and β=90.84° for BiI
3
2 2 3
) ]
3
2
)
2
)
3
3
2 2 3
) ]
the trivalent antimony or bismuth ion is coordinated by the nitrogen atom, not the sulfur atom of the thiourea. Thermal analysis
shows that there are two times structure rearrangements or phase transformation in the complexes from 100 to 170°C.
Keywords: characterization, solid–solid synthesis, thermal decomposition, thiourea complex of Sb and Bi
Introduction
triiodide: First, 2.0880 g (4.155 mmol) SbI and
3
0
.9489 g (12.47 mmol) SC(NH ) were weighed and
2 2
Solid–solid reaction is a simple synthetic method and
has been used in inorganic synthesis. The solid com-
plexes of transition metal ions and various organic
ligands were synthesized through solid–solid reac-
tion [1]. By comparison, the solid complexes of main
group metal ions are less reported [2–4]. Especially,
the solid–solid reaction synthesis of complexes of an-
timony and bismuth is rare. The complexes of some
main group elements [5], such as antimony and bis-
muth, can possess a certain biological function [6–8].
To synthesize new complexes of antimony and bis-
muth will be interesting not only for main group ele-
ment chemistry, but also bioinorganic chemistry.
Since many inorganic salts of antimony and bismuth
are easily hydrolyzed in aqueous solution [9], to syn-
thesize solid complexes of antimony or bismuth
through reaction in aqueous solution may be difficult.
However, such complexes can be easily prepared by
solid–solid reaction [10, 11]. Here, we report a
solid–solid reaction synthetic process of the thiourea
complexes of antimony and bismuth triiodide, the re-
sults of indexing to the powder X-ray diffraction pat-
terns of the complexes, their far-infrared spectra and
thermal decomposition.
well mixed. With careful grinding in an agate mortar,
the mixture’s color was red at first, then gradually be-
came yellow. The mixture was kept being grounded at
room temperature for about 2 h, then dried in a vac-
uum desiccator over phosphorus pentoxide for a
week. The product was a yellow powder and does not
absorb moisture in the air. Synthesis of the thiourea
complex of bismuth triiodide: 1.9962 g (3.385 mmol)
BiI and 0.7731 g (10.156 mmol) SC(NH ) were
3 2 2
weighed. Then, the synthetic process was performed
according to the above-mentioned procedure. At first,
no reaction was observed. After adding a few of abso-
lute methanol, the black mixture turned red. After
drying, a red powder was obtained, which does not
absorb moisture.
The powder X-ray diffraction patterns for the
products were recorded by a D/max-YB X-ray
diffractometer, CuKα1 radiation at room temperature.
The results of indexing to the powder X-ray diffrac-
tion patterns are shown in Tables 1 and 2. The far-in-
frared spectra of the complexes and thiourea were re-
corded by a Nicolet 5D-FT spectrometer and potas-
sium bromide disk technique. The far-infrared spectra
are shown in Fig. 1.
Thermal studies were performed by SDT Q600
V5.0 Thermal Analyzer (Simultaneous DSC-TGA Q
Series, TA Instruments, US.), in the air, with a heat-
Experimental
–
1
ing rate of 10°C min , the reference α-Al
The sample mass was 4.976 mg for the complex of an-
O .
2 3
Antimony triiodide, bismuth triiodide and thiourea
used in the experiments are analytical grade reagents.
Synthesis of the thiourea complex of antimony
timony and 2.292 mg for that of bismuth. The TG and
*
Author for correspondence: yqjiac@online.sh.cn
1
388–6150/$20.00
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands
©
2006 Akadémiai Kiadó, Budapest

ZHONG et al.
3 2 2 3
Table 1 The experimental and calculated results for powder X-ray diffraction pattern of SbI [SC(NH ) ] .
(
Monoclinic: a=1.4772 nm, b=1.6582 nm, c=2.0674 nm, β=90.81°)
h, k, l
d
exp/nm
d
cal/nm
I/I
0
h, k, l
d
exp/nm
d
cal/nm
I/I
0
1
02
0.8418
0.6986
0.6743
0.6458
0.5528
0.5163
0.4935
0.4471
0.4350
0.4191
0.3854
0.3672
0.3562
0.3448
0.3329
0.3281
0.3220
0.3175
0.3095
0.3037
0.2930
0.2864
0.2800
0.2741
0.2656
0.2614
0.2574
0.2525
0.8413
0.6986
0.6746
0.6467
0.5527
0.5168
0.4934
0.4470
0.4335
0.4191
0.3858
0.3676
0.3559
0.3448
0.3325
0.3279
0.3219
0.3176
0.3091
0.3039
0.2930
0.2866
0.2801
0.2741
0.2656
0.2615
0.2571
0.2525
14
61
40
100
12
24
43
19
22
21
25
44
25
39
11
21
57
58
46
87
42
9
–451
–263
056
0.2457
0.2428
0.2389
0.2351
0.2313
0.2240
0.2200
0.2185
0.2171
0.2147
0.2115
0.2072
0.2048
0.1987
0.1925
0.1897
0.1822
0.1810
0.1768
0.1757
0.1720
0.1682
0.1607
0.1585
0.1497
0.1459
0.1332
0.1296
0.2453
0.2427
0.2389
0.2351
0.2314
0.2240
0.2199
0.2185
0.2171
0.2146
0.2116
0.2072
0.2046
0.1987
0.1925
0.1895
0.1822
0.1810
0.1769
0.1756
0.1720
0.1683
0.1607
0.1586
0.1497
0.1459
0.1333
0.1297
15
10
12
24
10
12
16
13
14
14
12
13
15
29
18
13
19
13
9
–
201
2
0
0
0
0
10
22
30
04
14
–362
–337
–238
–265
–157
–347
–633
437
–
–
302
231
124
115
330
–634
712
–
–
–
411
43
225
16
422
13
1
–281
419
1
–448
–572
376
4
–
–
–
152
342
501
–368
–169
–391
–619
851
9
8
1
45
12
7
–
–
316
127
15
27
23
17
18
27
–680
578
12
8
3
26
–
–
227
137
595
7
598
8
1
63
–599
8
DTA curves of the complexes are shown in Fig. 2.
The possible thermal decomposition processes, the
experimental and calculated results for the thermal
analysis are summarized in Table 3. To check the py-
rolysis reactions, the relative contents of Sb and Bi in
the intermediates were also determined. First, a cer-
tain amount (253.5 mg) of the Sb complex or that
uct in the alumina crucible was heated at another cor-
responding temperature for 10 min followed by re-
peating the above procedure. The intermediates in
three steps of the thermal decomposition process of
the complex were analyzed. The analysis results are
given in Table 3.
(
207.9 mg) of the Bi complex was placed in an alu-
mina crucible and heated in a muffle furnace. After
the furnace temperature rose to a corresponding tem-
perature, the sample was kept in the furnace for
Results and discussion
The indexing to the powder X-ray diffraction patterns
of the resultants shows that all the diffraction peaks in
each pattern can be readily indexed by a set of lattice
parameters according to monoclinic system.
As Tables 1 and 2 show, the largest relative deviation
between the calculated and measured spacing is less
than 0.3%. This indicates that the resultant is a single
1
0 min. The mass loss of the sample was measured
and about 50 mg pyrolysis product was taken to deter-
mine the relative content of Sb or Bi in the product.
Antimony was determined by iodimetry and bismuth
by EDTA and the standard zinc chloride solution
back titration, respectively. Then, the residual prod-
776
J. Therm. Anal. Cal., 86, 2006

THIOUREA COMPLEXES OF ANTIMONY AND BISMUTH TRIIODIDE
tion number of the trivalent antimony and bismuth ion
can be six [9]. Therefore, the trivalent antimony or
bismuth ion can also be coordinated by three donor at-
oms from the thiourea, except for three iodine anions.
Thiourea can coordinate to the metal ion through ei-
ther the sulfur or the nitrogen atom. In most cases, the
metal ion is coordinated by the sulfur atom. Only in a
few metal thiourea complexes [13, 14], the metal ion
is coordinated by the nitrogen atom. IR spectra can
distinguish which donor atom (sulfur or nitrogen
atom) coordinates to the metal ion. If the metal ion is
coordinated by the sulfur atom, there must be the ab-
sorption peak from the stretching vibration of the
–
1
M–S bond in 200–300 cm region [14]. As Fig. 1
shows, in the infrared spectrum of thiourea, the ab-
–
sorption peak at 488 (or 467 cm ) can be assigned to
1
–
1
the N–C–N deformation vibration, 413 cm to the
–
N–C–S deformation vibration, and 631 cm to the
1
C=S rocking vibration [12]. The absorption peaks at
–
73 and 111 cm are from the lattice vibration in the
1
1
thiourea [15]. There is no absorption peaks from 200
–
1
to 300 cm in the infrared spectra of the complexes.
This is an important evidence for the absence of the
Sb–S and Bi–S bond. This demonstrates that the
thiourea molecule coordinates to the antimony or bis-
muth ion through the nitrogen atom. We find that the
main peaks in the infrared spectrum of the thiourea
also appear in the infrared spectrum of the complexes,
but some peaks shift. For example, in the antimony
complex, the N–C–N deformation vibration shifts
–
1
–1
–1
from 488 cm
(or 467 cm ) to 503 cm
–
or 459 cm ), the N–C–S deformation vibration shifts
1
(
–
1
from 413 to 391 cm and the C=S rocking vibration
–
shifts from 631 to 594 cm , and in the bismuth com-
1
plex, the N–C–N deformation vibration shifts from
–
88 cm (or 467 cm ) to 501 cm (or 459 cm ), the
1
–1
–1
–1
4
N–C–S deformation vibration shifts from 413 to
–
93 cm and the C=S rocking vibration shifts from
1
3
–
31 to 593 cm . The shifts can be attributed to the co-
1
6
ordination between the antimony or bismuth ion and
the nitrogen atom of thiourea. The formation of the
coordination bond between the antimony or bismuth
ion and the nitrogen atom must affect the bonding be-
tween the nitrogen and carbon atom in the thiourea
and lead to the variation of the vibration frequency of
the chemical bonds containing the carbon and nitro-
gen atom. In the IR spectra of the gaseous molecule of
the antimony triiodide (or bismuth triiodide), there
Fig. 1 The far-infrared spectra of A – SC(NH
2 2
) ;
B – SbI [SC(NH ) ; C – BiI [SC(NH ) ]
3 2 3 2 2 3
2
]
3
phase compound with monoclinic symmetry.
The crystal structure of antimony and bismuth
triiodide belongs to hexagonal system (JCPDS7-273
and 7-269). Thiourea belongs to orthorhombic system
(
JCPDS31-1934). However, the crystal structure of
–
1
–1
are 4 absorption peaks: u =186.5 cm (or 145.8 cm )
s
the resultants belongs to neither the hexagonal system
nor the orthorhombic system, but the monoclinic sys-
tem. Besides, the color of the resultants are also very
different from that of the reactants. Obviously, the
resultants must be new compounds.
–
and u =147 cm (or 115.2 cm ) from the symmetric
1
–1
as
and antisymmetric stretching vibration of the Sb–I
–1
–
1
(
or Bi–I bond), δ =74 cm (or 90.2 cm ) and
s
–1 –1
δas=54.3 cm (or 71 cm ) from the symmetric and
antisymmetric deformation vibration for SbI3
Some stable complexes composed of transition
metal salt and thiourea are known [12]. The coordina-
(
or BiI ), respectively [14]. The absorption peaks of
3
J. Therm. Anal. Cal., 86, 2006
777

ZHONG et al.
Table 2 The experimental and calculated results for powder X-ray diffraction pattern of Bi
3
[SC(NH
2
)
2
]
3
.
(
Monoclinic: a=1.4009 nm, b=2.0170 nm, c=2.0397 nm, β=90.84°)
h, k, l
d
exp/nm
d
cal/nm
I/I
0
h, k, l
d
exp/nm
d
cal/nm
I/I
0
2
0
1
0
3
00
03
32
14
00
0.7008
0.6794
0.5199
0.4941
0.4662
0.4418
0.4371
0.4215
0.3998
0.3582
0.3386
0.3295
0.3189
0.3108
0.2959
0.2778
0.2743
0.2688
0.2630
0.2595
0.2539
0.7004
0.6798
0.5196
0.4943
0.4669
0.4418
0.4366
0.4222
0.3998
0.3585
0.3385
0.3297
0.3193
0.3106
0.2958
0.2777
0.2742
0.2687
0.2630
0.2594
0.2539
100
79
22
74
6
028
364
0.2472
0.2395
0.2323
0.2258
0.2232
0.2202
0.2182
0.2104
0.2082
0.2052
0.1995
0.1933
0.1895
0.1865
0.1819
0.1787
0.1635
0.1593
0.1539
0.1395
0.2472
0.2397
0.2323
0.2257
0.2231
0.2202
0.2182
0.2103
0.2080
0.2052
0.1996
0.1933
0.1895
0.1865
0.1819
0.1787
0.1636
0.1593
0.1538
0.1394
12
8
–601
621
19
15
8
–347
–427
464
–
223
15
19
16
9
14
12
9
2
3
0
0
23
02
15
44
193
–642
094
15
7
24
9
–
341
–376
393
13
17
7
4
0
2
02
62
35
24
46
57
58
11
8
259
–169
439
7
–
–
–
–
–
325
442
316
512
354
6
646
7
568
6
8
–658
920
6
18
25
6
0
65
926
5
–
363
18
BiI and SbI can be found in the thiourea complexes.
3 3
by the nitrogen atom in the thiourea complexes of an-
timony and bismuth triiodide.
As Fig. 1. shows, there is a shoulder peak on the left
–
side of the strong absorption at 151 cm in the IR
1
The sulfur atom is not coordinated to the central
metal ion in the complex may be explained by the ef-
fective ionic radius of metal ion and iodine anion.
spectrum of the thiourea complex of SbI . The shoul-
3
–
1
der at 188 cm may be from the symmetric stretching
–
vibration (u =186.5 cm ) of the Sb–I bond. The ab-
1
3+
3+
–
The effective ionic radius of the Sb , Bi and I is
0.76, 1.03 and 2.20 , respectively [16]. The effective
ionic radius of the iodine anion is much larger than that
of the antimony or bismuth ion. The covalent radius
(1.03 ) of the sulfur atom is also much larger than that
s
–
1
sorption peak at 151 cm is attributed to the overlap
of the absorption peaks from the antisymmetric
–
stretching vibration (u =147 cm ) of the Sb–I bond
1
as
–
and that from the lattice vibration (u=173 cm ). As
1
–
for the absorption peak at 59 cm , it may be assigned
1
3+
(0.75 ) of the nitrogen atom. When the smaller Sb
3+
to the antisymmetric deformation vibration
1
or Bi ion is surrounded by three huge iodine anions,
due to the steric hindrance, the thiourea molecule can
only coordinate to the central metal ion through a do-
nor atom with small ionic radius. This is why the nitro-
gen atom, not the sulfur atom coordinates to the anti-
mony or bismuth ion in the complexes.
–
(
δ =54.3 cm ) of SbI . Similarly, in the infrared
as
3
spectrum of the bismuth complex, the peak at
–
55 cm is due to the overlap of the absorption peaks
1
1
from the symmetric stretching vibration (us=
–
45.8 cm ) of the Bi–I bond and that from the lattice
1
1
–
1
–1
vibration (u=173 cm ) and the peak at 115 cm is at-
tributable to the overlap of the absorption peaks from
the antisymmetric stretching vibration (uas=
Table 3 gives the possible thermal decomposi-
tion reactions of the complexes. As Fig. 2A shows,
there is an endothermic peak at 106.7°C in DTA
curve of the thiourea complex of antimony triodide
before the beginning of thermal decomposition.
This may be attributable to the structure rearrange-
ment in the coordination sphere of the complex. Be-
cause structure rearrangement does not lead to any
mass loss, but needs certain energy. Then, a small en-
–
1
1
15.2 cm ) of BiI and that from the lattice vibration
3
–
u=111 cm ). The absorption peak at 61 cm is as-
1
–1
(
signed to the antisymmetric deformation vibration
–
71 cm ) of BiI . From these assignments, it can be
1
(
3
concluded that the antimony or bismuth ion both
bonds directly to the iodine anion and is coordinated
778
J. Therm. Anal. Cal., 86, 2006

THIOUREA COMPLEXES OF ANTIMONY AND BISMUTH TRIIODIDE
mic peaks in DTA curve. Perhaps the first endother-
mic peak at 106.7°C in DTA curve corresponds to the
structure rearrangement in the coordination sphere
and the second endothermic peak at 121.3°C corre-
sponds to the phase transformation in the complex
crystal. The first mass loss of the thiourea complex of
SbI
dothermic peak in DTA curve. This is due to the loss
of HI and SC(NH ) from the complex. The experi-
3
happens at about 175°C corresponding to an en-
2
2
mental mass loss (28.3%) is very close to the theoreti-
cal one (27.91%). The check experiment supports this
conclusion. After the sample of the Sb complex is
heated at 260°C for 10 min, the mass loss (26.8%) of
the sample is close to the theoretical mass loss
(
27.91%) of the Sb complex. As Table 3 shows, the
composition of the pyrolysis product in this step may
be SbI [S ]. If this composition is reasonable,
the theoretical content of Sb in SbI [S C N H ] will
C N H
2 2 4 7
2
2
2
2
4
7
be 23.1%. The check experiment indicates that the
relative content (21.8%) of Sb in the pyrolysis prod-
uct determined by chemical method is close to the
theoretical content of Sb in SbI [S C N H ]. When
2 2 2 4 7
Fig. 2 TG and DTA curves of A – SbI
B – BiI [SC(NH
3
[SC(NH
2
)
2
]
3
and
temperature is over 267.5°C, all the ligands, iodine at-
oms and partial antimony atoms will be eliminated
from the complex. The elimination reaction needs the
energy and leads to the endothermic peak at 315°C in
DTA curve. The experimental and theoretical mass
losses are 60.85% and 60.42%, respectively.
The check experiment demonstrates that the mass loss
of the sample is 58.8% at 360°C and the relative con-
tent of Sb in the pyrolysis product is 98.9%.
This shows that the pyrolysis product is the metal an-
timony. The residual antimony metal will be volatil-
ized gradually with increasing temperature. Lastly, no
residue can be found.
3
2 2 3
) ]
dothermic peak in DTA curve appears at 121.3°C,
again. Because there is not any corresponding mass
loss of the sample in the TG curve, it can be attribut-
able to another structure rearrangement or phase
transformation in the solid complex. Another experi-
ment also demonstrates, indeed, no mass loss of the
sample of the Sb complex occurs below 125°C. After
the sample of the Sb complex is heated at 125°C for
1
0 min, the relative content (16.6%) of Sb in the sam-
ple is very close to the theoretical content (16.67%) of
Sb in the complex. Interestingly, it is found that the
solid sample is softened at 125°C. Perhaps, this is an
evidence for the phase transformation in the complex.
Furthermore, as above mentioned, the sulfur atom of
thiourea can not coordinate to the antimony or bis-
muth ion due to steric hindrance. However, heating a
sample may overcome this steric hindrance effect.
Therefore, when increasing temperature, the atom co-
ordinating to the Sb ion may change from the nitrogen
atom to the sulfur atom. This leads to the structure re-
arrangement in the coordination sphere of the com-
plex. Of course, the phase transformation can also
lead to an endothermic effect, but not a mass loss.
However, it seems to be impossible that the phase
transformations of the complex crystal can occur two
times in such a small temperature range (100 to
Figure 2B also shows two endothermic peaks at
124.1 and 164.8°C in DTA curve, before the begin-
ning of thermal decomposition of the thiourea com-
plex of bismuth triodide. Similarly, the endothermic
peaks can also be attributed to the structure rearrange-
ment in the coordination sphere of the complex or the
possible phase transformation in the complex crystal.
The check experiments confirm the conclusion. After
the sample is heated at 150°C in a muffle furnace, no
mass loss of the sample can be found and the relative
content (25.3%) of Bi in the sample is very close to
the percentage content (25.56%) of Bi in the complex.
The first mass loss of the sample is mainly from elimi-
nation of the NH and thiourea molecules and corre-
3
sponds to the endothermic peak at 214.3°C in DTA
curve. The experimental mass loss (20.78%) consists
very well with the theoretical one (20.69%).
The check experiment shows, if the sample is heated
at 245°C for 10 min, the mass loss of the sample will
be 23.3%. This is slightly larger than the theoretical
1
20°C). Since there are three thiourea molecules in
one complex molecule, the substitution of the sulfur
atoms for the nitrogen atoms in the coordination
sphere must carry out gradually with increasing tem-
perature. This explains why there are two endother-
J. Therm. Anal. Cal., 86, 2006
779

ZHONG et al.
Table 3 Thermal dccomposition data of SbI
3
[SC(NH
2
)
2
]
3
and BiI
3
2 2 3
[SC(NH ) ]
Mass loss/%
Reaction
DTA/°C
W
exp
W
theor
SbI
3
2 2 3
[SC(NH ) ]
↓
↓
↓
structural rearrangement
106.7 (endo)
(125°C)
[Sb]
0.0*
16.56%**
16.67%**
SbI
structural rearrangement
SbI [SC(NH
–HI, –SC(NH
3 2 2 3
[SC(NH ) ]
↓
121.2 (endo)
3
2 2 3
) ]
↓
↓
↓
2
)
2
224.9 (endo)
(250°C)
[Sb]
28.89
27.91
26.8*
21.8%**
23.1%**
60.42
SbI
2
2 2 2
[SC(NH ) ]NHSCNH
↓
↓
↓
↓
0
↓
–I
2
, –SC(NH
2
)
2
315.0 (endo)
60.85
2
–SCNH NH, –0.3Sb
(360°C)
[Sb]
58.8*
98.9%**
100%**
11.67
.7Sb
–0.7Sb
11.68
BiI
3
2 2 3
[SC(NH ) ]
↓
↓
↓
structural rearrangement
124.1 (endo)
(150°C)
[Bi]
0.0*
25.3%**
25.56%**
BiI
structural rearrangement
BiI [SC(NH
–2SC(NH
3 2 2 3
[SC(NH ) ]
↓
164.8 (endo)
3
2 2 3
) ]
↓
↓
↓
2
)
2
, –NH
3
214.3 (endo)
(245°C)
[Bi]
20.78
20.69
23.3*
33.4%**
32.2%**
66.53
3
BiI (HNCS)
↓
↓
↓
↓
0
↓
↓
0
–HNCS, –1.5I
–0.5Bi
2
324.7 (endo)
66.30
(390°C)
[Bi]
68.7*
99.3%**
100%**
9.07
.5Bi
–0.37Bi
+0.195O
420.6 (exo)
9.06
.065Bi
2
O
3
3.86
3.70
*
**
The percentage mass loss of the sample measured in the check experiment, the relative content of Sb or Bi in the intermediate
measured in the check experiments
loss (20.69). In this case, the composition of the py-
rect. Then, there is a larger mass loss in TG curve.
The sample will lose HNCS, iodine and partial bis-
muth atoms. The break of the Bi–I bond in the com-
plex and the volatilization of the HNCS, iodine and
bismuth atoms from the sample need a certain energy,
hence, this corresponds to an endothermic peak at
324.7°C. The check experiment confirms that the
rolysis product may be BiI (HNCS), hence, the per-
3
centage content of Bi in the product will be 32.2%.
As Table 3 shows, the relative content of Bi in the py-
rolysis product determined by chemical method is
3
3.4%. This demonstrates that the composition of the
product in the above pyrolysis reaction may be cor-
780
J. Therm. Anal. Cal., 86, 2006

THIOUREA COMPLEXES OF ANTIMONY AND BISMUTH TRIIODIDE
mass loss (68.7%) of the sample in this step is close to
References
the theoretical mass loss (66.53%) and the relative
content of Bi in the product is 99.3%. This indicates
that the pyrolysis product must be metal Bi. We have
also noted that the product displays metal luster. Over
1
2
3
4
H. Oki and K. Otsuka, Bull. Chem. Soc. Jpn.,
9 (1976) 1841.
4
R. A. Siddiqui, P. Raj, A. K. Saxena and S. K. Dixit,
Synth. Reac. Inorg. Met.-org. Chem., 26 (1996) 1189.
G. R. Willey, L. T. Daly, P. P. Meehan and
4
00°C, the residual bismuth can be oxidized by oxy-
gen in air. The oxidation reaction leads to an exother-
mic effect, so, there is an exothermic peak in DTA
curve. The partial Bi will volatilize gradually with
increasing temperature. Last, the thermal decomposi-
tion product is a yellow residue (Bi O ).
M. G. B. Drew, J. Chem. Soc. Dalton Trans., (1996) 4045.
M. S. Singh and K. P. Rao, Synth. Reac. Inorg. Met.-org.
Chem., 29 (1999) 541.
O
3
2
5 G. Cantos, C. L. Barbieri, M. Iacomini, P. A. J. Gorin and
L. R. Travassos, Biochem. J., 289 (1993) 155.
2
3
6
7
8
J. Kaloustian, A. M. Pauli, G. Pieroni and H. Portugal,
J. Therm. Anal. Cal., 70 (2002) 963.
L. Xi, L. Yi, W. Jun, L. Huigang and Q. Songsheng,
J. Therm. Anal. Cal., 67 (2002) 589.
Conclusions
N. N. Greenwood and A. Earnshaw, Chemistry of the
nd
Elements (2 Ed.), Reed Educational and
The new solid thiourea complexes of antimony and
bismuth can be synthesized through a direct solid re-
action between antimony or bismuth triiodide and
thiourea powders. The formula of the complex is
Professional Publishing Ltd. (1997) p. 553.
Y. C. Guo, S. R. Luan, Y. R. Chen, X. S. Zang, Y. Q. Jia,
G. Q. Zhong and S. K. Ruan, J. Therm. Anal. Cal.,
68 (2002) 1025.
9
SbI [SC(NH ) ] or BiI [SC(NH ) ] . The crystal
3 2 2 3 3 2 2 3
structure of the two complexes belongs to monoclinic
system. The far-infrared spectra of the complexes re-
veal that there is no Sb–S or Bi–S bond in the com-
plexes and the Sb or the Bi ion are not only bonded di-
rectly to the iodine anion, but also coordinated to the
nitrogen atom of thiourea. The thermal analysis indi-
cates that there may be structure rearrangement in the
coordination sphere and phase transformation in the
10 R. R. Jia, Y. X. Yang, Y. R. Chen and Y. Q. Jia, J. Therm.
Anal. Cal., 76 (2004) 157.
1 A. Yamaguchi, R. P. Penland, S. Mizushima, T. J. Lane,
C. Curran and J. V. Quagliano, J. Am. Chem. Soc.,
0 (1958) 527.
1
8
1
1
2 R. Rivest, Can. J. Chem., 40 (1962) 2234.
3 K. Nakamoto, Infrared and Raman Spectra of Inorganic
and Coordination Compounds, John Wiley & Sons Inc.,
rd
1978 (3 Ed.).
range from 100 to 120°C for SbI
3
[SC(NH
2
)
2
]
3
and in
14 D. M. Adams and J. B. Cornell, J. Chem. Soc.(A),
(1967) 884.
5 R. D. Shannon, Acta Crystallogr., Sect. A.: 32 (1976) 751.
the range from 120 to 160°C for BiI [SC(NH ) ] , re-
3 2 2 3
1
spectively. The check experiments confirm the ther-
mal decomposition process of the Sb and the Bi com-
plex and the occurrence of structure rearrangement or
phase transformation.
Received: February 10, 2005
Accepted: August 10, 2006
DOI: 10.1007/s10973-005-6959-2
J. Therm. Anal. Cal., 86, 2006
781