Syntheses and structures of [M{In(SC{O}Ph)4}2] (M = Mg and Ca): Single molecular precursors to MIn2S4 materials

Article abstract of DOI:10.1021/ic060993n

The compounds [Mg{In(SC{O}Ph)₄}₂] (1) and [Ca(H ₂O)_x{In(SC{O}Ph)₄}₂]·yH ₂O (x = 0, y = 1, 2 major product; x = 1, y = 0, 2a minor product; x = 2, y = 2, 2b minor product) have be

Full text of DOI:10.1021/ic060993n

Inorg. Chem. 2006, 45, 8258−8263
Syntheses and Structures of [M
{
In(SC
{
O
}
Ph)4}
2] (M
)
Mg and Ca):
Single Molecular Precursors to MIn2S4 Materials
Lu Tian, Wei Hoon Lye, Theivanayagam C. Deivaraj, and Jagadese J. Vittal*
Department of Chemistry, National UniVersity of Singapore, 3 Science DriVe 3, Singapore 117543,
Singapore
Received June 5, 2006
The compounds [Mg
1, y 0, 2a minor product; x
M(SC Ph)2 (M Mg and Ca) prepared in situ in the molar ratio 1:2. The structures of 1, 2a, and 2b have been
determined by X-ray crystallography. The structure of 1 consists of two tetrahedral [In(SC
Ph)4]- anions
sandwiching the MgII metal ions through six carbonyl O atoms. The coordination geometry at the MgII metal atom
{In(SC{O
}Ph)4}2] (1) and [Ca(H2O)x
{In(SC{O}Ph)4} ]‚yH2O (x ) 0, y ) 1, 2 major product;
2
x
)
)
)
2, y 2, 2b minor product) have been synthesized by reacting InCl3 and
)
{O
}
)
{O}
is distorted octahedral with an O6 donor set. The structures of 2a and 2b consist of two [In(SC{O}
Ph)4]- anions
sandwiching the CaII metal ion through five and four carbonyl O atoms, and the octahedral coordination at the CaII
centers is completed by one and two aqua ligands, respectively. Two aqua ligands and two lattice water molecules
form a H-bonded water chain in the channel created by [Ca{In(SC{O}Ph)4}2] molecules in the crystal structure of
2b. The thermal decomposition of 1 and 2 indicated the formation of the corresponding MIn2S4 materials, and this
was confirmed by X-ray powder diffraction patterns.
Introduction
donors.1 These donor sites enable the incorporation of hard
and soft metal centers into a coordination compound, as
illustrated by the clawlike [M(SC{O}Ph)3]- metalloligand
complexes (Me4N)[A{M(SC{O}Ph)3}2] (A ) NaI and KI and
M ) CdII and HgII).2 In these complexes, two [M(SC-
{O}Ph)3]- anions sandwich an alkali metal ion. The CdII or
HgII atoms have a trigonal-planar MS3 coordination environ-
ment, and the alkali-metal ions have an octahedral AO6 core.2
Subsequently, we have studied the tetrahedral [In(SC{O}Ph)4]-
anions as metalloligands to bind to various alkali-metal ions
to form [A(MeCN)x{M(SC{O}Ph)4}] (A ) LiI, NaI, and KI
and M ) GaIII and InIII; x ) 0-2), which are one-dimensional
coordination polymers.9 In a continuation of our investiga-
tions on the chemistry of metal thiocarboxylate compounds,
we report MgII and CaII complexes of [In(SC{O}Ph)4]-
anions in this paper. The syntheses and structures of [Mg-
{In(SC{O}Ph)4}2] (1) and [Ca(H2O)x{In(SC{O}Ph)4}2]‚
yH2O (x ) 0, y ) 1, 2; x ) 1, y ) 0, 2a; x ) 2, y ) 2, 2b)
are described. Such II-III2-VI4 materials have potential
For more than a decade, we have been interested in the
development of the chemistry of metal thiocarboxylate
complexes. The interest derives from their fascinating
structural chemistry1-4 and from the fact that many of them
can be used as single molecular precursors for the low-
temperature synthesis of bulk metal sulfides, thin films, and
nanoparticles.5-8 Monothiocarboxylates (RC{O}S-) represent
an interesting class of ligands with both hard and soft
* To whom correspondence should be addressed. E-mail: chmjjv@
nus.edu.sg. Fax: 65-6779-1691.
(1) (a) Sampanthar, J. T.; Deivaraj, T. C.; Vittal, J. J.; Dean, P. A. W. J.
Chem. Soc., Dalton Trans. 1999, 4419. (b) Burnett, T. R.; Dean, P.
A. W.; Vittal, J. J. Can. J. Chem. 1994, 72, 1127. (c) Vittal, J. J.;
Dean, P. A. W. Polyhedron 1998, 17, 1937. (d) Dean, P. A. W.; Vittal,
J. J.; Craig, D. C.; Scudder, M. L. Inorg. Chem. 1998, 37, 1661.
(2) (a) Deivaraj, T. C.; Dean, P. A. W.; Vittal, J. J. Inorg. Chem. 2000,
39, 3071. (b) Vittal, J. J.; Dean, P. A. W. Inorg. Chem. 1993, 32,
791.
(3) Vittal, J. J.; Dean, P. A. W. Inorg. Chem. 1996, 35, 3089.
(4) Devy, R.; Vittal, J. J.; Dean, P. A. W. Inorg. Chem. 1998, 37, 6939.
(5) (a) Shang, G.; Hampden-Smith, M. J.; Duesler, E. N. Chem. Commun.
1996, 1733. (b) Shang, G.; Kunze, K.; Hampden-Smith, M. J.; Duesler,
E. N. Chem. Vap. Deposition 1996, 2, 242. (c) Nyman, M. D.;
Hampden-Smith, M. J.; Duesler, E. N. Chem. Vap. Deposition 1996,
2, 171.
(7) (a) Deivaraj, T. C.; Park, J.-H.; Afzaal, M.; O’Brien, P.; Vittal, J. J.
Chem. Mater. 2003, 15, 2383. (b) Deivaraj, T. C.; Park, J.-H.; Afzaal,
M.; O’Brien, P.; Vittal, J. J. Chem. Commun. 2001, 2304.
(6) (a) Nyman, M. D.; Jenkins, K.; Hampden-Smith, M. J.; Kodas, T. T.;
Duesler, E. N.; Rheingold, A. L.; Liable-Sands, M. L. Chem. Mater.
1998, 10, 914. (b) Nyman, M. D.; Hampden-Smith, M. J.; Duesler,
E. N. Inorg. Chem. 1997, 36, 2218.
(8) (a) Deivaraj, T. C.; Lin, M.; Loh, K. P.; Yeadon, M.; Vittal, J. J. J.
Mater. Chem. 2003, 13, 1149. (b) Lin, M.; Loh, K. P.; Deivaraj, T.
C.; Vittal, J. J. Chem. Commun. 2002, 1400.
(9) Deivaraj, T. C.; Lye, W. H.; Vittal, J. J. Inorg. Chem. 2002, 41, 3755.
8258 Inorganic Chemistry, Vol. 45, No. 20, 2006
10.1021/ic060993n CCC: $33.50
© 2006 American Chemical Society
Published on Web 08/26/2006

Single Molecular Precursors to MIn2S4 Materials
Table 1. Crystallographic Data and Refinement Parameter for 1, 2a, and 2b
1
2a
2ba
chemical formula
C56H40In2Mg O8S8
C56H42CaIn2O9S8
C56H48CaIn2O12S8
fw
1351.40
monoclinic
-50
1383.58
monoclinic
-50
1439.24
tetragonal
-50
cryst syst
T, °C
λ, Å
space group
a, Å
b, Å
c, Å
â, deg
V, Å3
Z
0.710 73
P21/c
0.710 73
P21/c
0.710 73
P41212
19.0741(7)
11.1258(4)
26.6374(10)
90.422(2)
5652.7(4)
4
1.588
1.175
R1 ) 0.0529
13.811(3)
30.544(7)
16.527(4)
112.998(6)
6418(3)
4
1.434
1.108
R1 ) 0.1288
19.5247(7)
19.5247(7)
15.8951(7)
90
6059.4(4)
4
1.578
1.180
R1 ) 0.0314
D
calcd, g cm-3
µ, mm-1
final R indicesb
[I > 2σ(I)]
wR2 ) 0.1382
R1 ) 0.0643
wR2 ) 0.3291
R1 ) 0.1598
wR2 ) 0.0689
R1 ) 0.0338
R indices
(all data)
wR2 ) 0.1432
wR2 ) 0.3480
wR2 ) 0.0698
2
2
4
a Flack parameter, -0.04(2). b R1 ) (∑||Fo| - |Fc||)/∑|Fo|; wR2 ) [∑w(Fo - Fc )/∑wFo ]1/2
.
Table 2. Selected Bond Distance (Å) and Angle (deg) Ranges in 1, 2a, and 2b
1 (M ) Mg)
2a (M ) Ca)
2b (M ) Ca)
Bond Distance Range
In-S
M-O
S-C
O-C
2.453(2)-2.512(2)
2.006(4)-2.060(4)
1.716(6)-1.755(6)
1.213(6)-1.234(6)
2.441(6)-2.514(4)
2.28(1)-2.32(1)
1.70(2)-1.76(2)
1.21(2)-1.24(2)
2.461(1)-2.488(1)
2.312(3)-2.363(3)
1.742(4)-1.763(4)
1.218(4)-1.232(4)
Bond Angle Range
S-In-S
88.75(5)-124.23(8)
85.6(2)-93.5(2)
174.7(2)-176.9(2)
85.9(2)-113.9(2)
155.6(4)-168.8(4)
92.5(2)-128.2(1)
79.4(4)-103.7(4)
164.4(4)-170.3(3)
87.8(5)-109.0(5)
137.2(9)-164.7(9)
106.02(3)-108.71(4)
78.2(2)-122.9(1)
156.7(1)-172.8(2)
91.3(1)-100.9(1)
161.1(3)-170.0(3)
cis O-M-O
trans O-M-O
C-S-In
C-O-M
applications in optoelectronics.10 These compounds have also
been investigated as single-source precursors for MIn2S4
materials. The literature on the heterobimetallic compounds
containing InIII is limited. A Cambridge Structural Database
(version 5.27, May 2006) search reveals that there are only
four structures containing both MgII and InIII.11-14 In one
structure, the two metals are bridged by fluorine atoms11 and
the other three are salts. However, there is no report on the
structures containing CaII and InIII, and hence compound 2
and its hydrated forms are unique, and probably they
represent the first series of heterobimetallic compounds
containing both CaII and InIII.
Experimental Section
Figure 1. Molecular structure of 1 with its numbering scheme.
All reactions and manipulations were carried out under an
atmosphere of dry N2 via standard Schlenk techniques. The starting
materials thiobenzoic acid (Alfa Aesar, 90%), MgO (Merck, 97%),
Ca(OH)2 (GCE, 97%), and InCl3 (Aldrich, 98%) were obtained
commercially and used as received. The yields are reported with
respect to InIII salts. The elemental analyses were performed in the
microanalytical laboratory in the Department of Chemistry, National
University of Singapore. 13C{1H} NMR spectra of the compounds
were recorded on a Bruker ACF 300-MHz spectrometer. Thermo-
gravimetric (TG) analyses were performed (under a N2 atmosphere)
using a SDT 2960 TGA apparatus with a sample size of 8-10 mg
per run. X-ray powder diffraction patterns were obtained using a
(10) Sirimanne, P. M.; Sonoyama, N.; Sakata, T. J. Solid State Chem. 2000,
154, 476.
(11) Neumuller, B.; Gahlmann, F. Z. Anorg. Allg. Chem. 1993, 619, 718.
(12) Pietryga, J. M.; Jones, J. N.; Mullins, L. A.; Wiacek, R. J.; Cowley,
A. H. Chem. Commun. 2003, 2072.
(13) Partha, P. P.; Thomas, B. R.; Scott, R. W. J. Am. Chem. Soc. 1993,
115, 3316.
(14) Werner, B.; Kra¨ter, T.; Neumu¨ller, B. Z. Anorg. Allg. Chem. 1995,
621, 346.
Inorganic Chemistry, Vol. 45, No. 20, 2006 8259

Tian et al.
Figure 2. Ball-and-stick diagram showing the molecular structure of 2a.
Figure 3. Ball-and-stick diagram showing the molecular structure of 2b.
Bruker D5005 X-ray diffractometer equipped with Cu KR radiation.
The accelerating voltage and current were 40 kV and 40 mA,
respectively. The IR spectra (KBr pellet) were recorded using a
3.36. Found: C, 45.10; H, 4.29. Because of the hygroscopic nature,
the elemental analysis is not very accurate and not consistent with
the proposed formula for 2b.
FTS 165 Bio-Rad FTIR spectrometer in the range 4000-400 cm-1
.
X-ray Crystallography. Single crystals were obtained during
the synthesis. The diffraction experiments were carried out at -50
°C on a Bruker SMART CCD diffractometer with a Mo KR sealed
tube. The program SMART15 was used for collecting frames of data,
indexing reflection, and determining lattice parameters, SAINT15
for integration of the intensity of reflections and scaling, SADABS16
for absorption correction, and SHELXTL17 for space group and
structure determination and least-squares refinements on F 2. One
of the thiobenzoate ligands in 2a was found to be disordered. Two
disordered phenyl rings (70:30) were resolved. The positional and
isotropic thermal parameters of all of the H atoms of the water
molecules in 2b were refined in the model. The relevant crystal-
lographic data and refinement details are compiled in Table 1, and
selected bond distance and angle ranges are given in Table 2.
[Mg{In(SC{O}Ph)4}2] (1). Thiobenzoic acid (0.25 mL, 2.12
mmol) was deprotonated by MgO (0.043 g, 1.06 mmol) in MeOH
(10 mL). To this yellow turbid solution of Mg(SC{O}Ph)2 was
added InCl3 (0.120 g, 0.53 mmol) in MeOH (10 mL). The mixture
was stirred for about 30 min, the solvent was evaporated under
vacuum to get a creamy yellow product, which was washed with
diethyl ether, and the residue was extracted into dichloromethane.
The CH2Cl2 filtrate was concentrated and layered with hexane. A
white crystalline precipitate started forming almost immediately.
The flask was then allowed to stand in the refrigerator at 5 °C.
Colorless needlelike crystals of 1 appeared the following day, which
were suitable for X-ray diffraction studies. Yield: 0.24 g (68%).
Anal. Calcd for 1, C56H40In2MgO8S8 (mol wt 1351.40): C, 49.77;
H, 2.98; S, 18.98. Found: C, 49.45; H, 2.79; S, 19.22. 13C {1H}
NMR (CDCl3): δ 128.2 (m-C), 128.9 (o-C), 133.8 (p-C), 137.8
(ipso-C), 209.1 (PhCOS). IR data (cm-1): 1589 (s, CdO), 1568
(s, CdO), 1212 (s, Ph-C), 932 (s, C-S), 652 (s, δ(SCO)). ESI-
MS (acetone) at 50 °C: m/z 663.2 ([In(SC{O}Ph)4]-, 15%), 137.4
(PhC{O}S-, 100%).
[Ca(H2O)x{In(SC{O}Ph)4}2]‚yH2O (x ) 0, y ) 1, 2; x ) 1, y
) 0, 2a; x ) 2, y ) 2, 2b) can be obtained under different
experimental conditions. Compound 2 was synthesized via a
synthetic strategy similar to that of 1 except that Ca(OH)2 was used
instead of MgO. Colorless blocklike crystals of 2 were obtained as
the major product, but it became opaque after 1 day in the mother
liquid. However, very long thin rodlike crystals of 2a were obtained
as a minor product along with 2, which were suitable for single-
crystal X-ray diffraction experiments. Yield of 2: 58%. Anal. Calcd
for 2, C56H42CaIn2O9S8 (mol wt 1385.19): C, 48.56; H, 3.06; S,
18.52. Found: C, 48.20; H, 3.53; S, 18.05. 13C {1H} NMR
(CDCl3): δ 128.2 (m-C), 129.0 (o-C), 133.7 (p-C), 138.1 (ipso-
C), 209.0 (PhCOS). IR data (cm-1): 1587 (s, CdO), 1553 (s, Cd
O), 1210 (s, Ph-C), 937 (s, C-S), 652 (s, δ(SCO)). ESI-MS
(acetone) at 50 °C: m/z 663.1 ([In(SC{O}Ph)4]-, 65%), 137.3
(PhC{O}S-, 100%). TG weight loss: expected, 1.3%; found, 1.2%.
Anal. Calcd for 2a, C56H42CaIn2O9S8 (mol wt 1385.19): C, 48.56;
H, 3.06; S, 18.52. Found: C, 48.08; H, 3.65; S, 18.36. Another
minor product 2b was obtained as follows. After the reaction
mixture was stirred for about 30 min, the solvent was evaporated
under vacuum to get a creamy yellow product, which was washed
several times with MeOH and deionized water. The MeOH filtrate
afforded single crystals of [Ca(H2O)2{In(SC{O}Ph)4}2]‚2H2O. Anal.
Calcd for 2b, C56H48CaIn2O12S8 (mol wt 1439.24): C, 46.73; H,
Results and Discussion
Synthesis. Compounds 1 and 2 were prepared by a simple
reaction between the metal salts and appropriate amounts of
the corresponding alkaline-earth metal salt of thiobenzoate
anions prepared in situ in a MeOH solvent, as shown in eqs
1 and 2.
MO or M(OH)2 + 2PhC{O}SH f M(SC{O}Ph)2 +
xH2O (x ) 1 or 2) (1)
4M(SC{O}Ph)2 + 2InCl3 f [M{In(SC{O}Ph)4}2] +
3MCl2 (M ) Mg and Ca) (2)
The compounds are soluble in CH2Cl2, CHCl3, and (Me)2-
CO but insoluble in MeCN, MeOH, and EtOH. The
desolvated compounds are found to be very stable, and no
apparent decomposition occurred when they were left at room
temperature in air. Compound 2 with a variable number of
water molecules has been isolated. Upon prolonged exposure
to humid air, 2a and 2b with more water in the lattice and
(15) SMART & SAINT Software Reference manuals, version 5.0; Bruker
Analytical X-ray Systems, Inc.: Madison, WI, 2000.
(16) Sheldrick, G. M. SADABS a software for empirical absorption
correction, version 2.03; University of Go¨ttingen: Go¨ttingen, Ger-
many, 2001.
(17) SHELXTL Reference Manual, version 6.1; Bruker Analytical X-ray
Systems, Inc.: Madison, WI, 2000.
8260 Inorganic Chemistry, Vol. 45, No. 20, 2006

Single Molecular Precursors to MIn2S4 Materials
Figure 4. (a and b) Two views of the H-bonded water chain inside the channel created by [Ca{In(SC{O}Ph)4}2] in 2a. Color code: red, O; green, CaII;
brown, InIII; yellow, S; black, C; white, H. (c) Perspective view of the water chain. All C-H hydrogen atoms are omitted for clarity.
Table 3. Selected H-Bonding Parameters in 2ba
Table 4. Pyrolysis and TG Results for 1 and 2
D-H‚‚‚A
d(D-H)
d(H‚‚‚A)
DHA
d(D‚‚‚A)
temp
range
residue wt
residue wt
O5-H5A‚‚‚O7a
O5-H5B‚‚‚O6b
O6-H6‚‚‚O4
O7-H7‚‚‚S2
0.77(2)
0.78(2)
0.76(2)
0.78(2)
2.12(3)
2.01(2)
2.07(1)
2.71(3)
153(6)
165(3)
173(4)
150(2)
2.830(3)
2.772(5)
2.830(3)
3.407(4)
(°C) in obsd (calcd) in pyrolysis
TG
product of
decomposition
compd
(%) in TG
(%)
1
194-412 46.7 (46.2)
412-585 28.6 (28.3)
28.9a
“[MgIn2S3(SC{O}Ph)2]”
MgIn2S4 (01-070-2893)
anhydrous 2
“[CaIn2S3(SC{O}Ph)2]”
CaIn2S4 (00-31-0272)
a Symmetry operators: a, -x + 1, -y + 1, z + 1/2; b, -x + 1, -y + 1,
2
78-99
1.20 (1.30)
30.6a
1
z + /2.
181-485 47.6 (47.5)
485-624 29.9 (28.8)
a 1 and 2 were heated at 600 °C under 0.5 Torr of pressure for 6 h.
has four thiobenzoate anions bonded through the S atoms,
as shown in Figure 1. These tetrahedral anions act as a
metalloligand to sandwich a MgII metal ion. Each [In(SC-
{O}Ph)4]- anion chelates a MgII ion through three carbonyl
O atoms. In other words, each “In(SC{O}Ph)3Mg” cage is
comprised of three fused eight-membered rings. Thus, the
coordination geometry around the MgII metal atom is
distorted octahedral with an O6 donor set. The In-S distances
in 1 range from 2.453(2) to 2.512(2) Å, which are compa-
rable to the In-S distances observed in the compound (Et3-
NH)[In(SC{O}Ph)4].8a The Mg-O distances are in the range
from 2.006(4) to 2.060(4) Å. Large variations in the angles
around the InIII [88.75(5)-124.23(8)°] and MgII [85.6(2)-
176.9(2)°] metal ions are indicative of distortion from the
ideal tetrahedral and octahedral geometries, respectively. A
noncrystallographic center of inversion is present at the MgII
atom.
Figure 5. TG curves of 1 and 2.
coordination sphere were formed. This is not surprising
considering the hydrophilic nature and hydration energy
associated with CaII ions.
Structure of 1. The neutral molecule consists of two
tetrahedral [In(SC{O}Ph)4]- anions in which each InIII center
Structures of 2a and 2b. As displayed in Figure 2, the
molecular structure of 2a also contains two tetrahedral
[In(SC{O}Ph)4]- anions chelating the CaII ion through five
carbonyl O atoms. The coordination geometry at the CaII
metal atom is distorted octahedral with an O6 donor set, with
Inorganic Chemistry, Vol. 45, No. 20, 2006 8261

Tian et al.
Figure 6. Powder X-ray diffraction patterns of the decomposed products of 1 (a) and 2 (b).
the sixth position occupied by an aqua ligand. The In-S
distances in 2a are in the range 2.441 (6)-2.514(4) Å and
the Ca-O distances in the range 2.28(1)-2.32(1) Å. InIII
and CaII metal centers in 2a are also highly distorted from
tetrahedral and octahedral geometries as inferred from a wide
range of angles (Table 2).
lates can undergo a thiocarboxylic anhydride elimination
reaction to form “MS”.6b
The weight losses observed in the TG experiments agree
well with the calculated values for the formation of the
proposed intermediate “[MIn2S3(SC{O}Ph)2]” and the loss
of three S(C{O}Ph)2 molecules (Table 4). The observed
residual weight matched well with the calculated residual
weight of MgIn2S4 but slightly higher for CaIn2S4 in both
TG and pyrolysis experiments. The diffraction peaks shown
in the X-ray diffraction patterns of the residues shown in
Figure 6 can be assigned to the cubic-phase MgIn2S4 (JCPDS
01-070-2893) and the cubic-phase CaIn2S4 (JCPDS 00-31-
0272) reported in the literature.19 The mismatching of the
intensity and poor agreement in the region 2θ < 50° may
be due to a combination of both the less crystalline nature
of the compound and/or the preferred orientations of the
crystallites. The single-source precursor method appears to
be an alternative but attractive route to preparing MIn2S4
compounds, and the traditional synthetic method normally
requires very high temperatures (<900 °C).20
The structure of 2b shown in Figure 3 is very similar to
that of 2a but with a crystallographic 2-fold symmetry at
Ca1. However, only two carbonyl O atoms from each
[In(SC{O}Ph)4]- anion are bonded to the CaII ion. The
remaining two cis corners of the pseudo-octahedral geometry
at CaII are occupied by two aqua ligands. The crystal has
two lattice water molecules per formula unit.
The cis geometry at the CaII center helps the molecule
remain packed to form a channel. All of the carbonyl O
atoms and aqua ligands provide a hydrophilic environment
for the channel in which the lattice water molecules have
been trapped. Two symmetry-independent lattice water
molecules sitting in a 2-fold crystallographic special position
are alternatively bonded to the aqua ligands to generate a
H-bonded water chain in the lattice, which propagates in the
c direction, as shown in Figure 4. Selected H-bonding
parameters are tabulated in Table 3. It may be noted that
the lattice water molecules are further H-bonded to a carbonyl
oxygen, O4, and a sulfur atom, S2, thereby stabilizing the
structure.
Conclusions
We have shown that [In(SC{O}Ph)4]- can be used as a
metalloligand to bind to MgII and CaII ions and isolated 1
and 2, which are molecular compounds unlike the alkali-
metal derivatives of [In(SC{O}Ph)4]-.4 In solution, [Ca{In-
(SC{O}Ph)4}2] can easily be hydrated because of the nature
of the CaII ions, and two different hydrated crystalline forms
were isolated. Of these, 2b has an interesting channel created
by [Ca{In(SC{O}Ph)4}2], trapping a single-stranded H-
bonded water chain in the lattice. Thermal decomposition
of these compounds led to the formation of MIn2S4 and was
confirmed by the power X-ray diffraction patterns of the
residues. On the basis of our investigations, 1 and 2 are useful
precursors to the MIn2S4 materials. Further use of these
Thermogravimetry and Pyrolysis. Metal chalcogenide
compounds with composition II-III2-VI4 (where II )
divalent metal, III ) trivalent metal, VI ) chalcogen) are
the potential materials for optoelectronics applications.18
Compounds 1 and 2 described here have the correct ratio of
metals to serve as precursors for MIn2S4 compounds; hence,
the thermal decompositions of 1 and 2 have been investigated
using TG and are presented in Figure 5, and the results are
summarized in Table 4. TG curves show that the inception
of weight loss occurs at 194 and 181 °C for 1 and 2,
respectively. They decompose in two distinct steps in the
temperature regions of 194-585 and 181-620 °C, respec-
tively, and the final residues are expected to be MIn2S4.
Hampden-Smith et al. have shown that metal thiocarboxy-
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8262 Inorganic Chemistry, Vol. 45, No. 20, 2006

Single Molecular Precursors to MIn2S4 Materials
Supporting Information Available: Crystallographic data in
CIF format and ORTEP diagrams of 1, 2a, and 2b. This material
is available free of charge via the Internet at http://
pubs.acs.org.
precursors to make nanoparticles and thin films is under
investigation.
Acknowledgment. We acknowledge the financial support
of the National University of Singapore (Grant R143-000-
283-112).
IC060993N
Inorganic Chemistry, Vol. 45, No. 20, 2006 8263