Microwave-assisted synthesis of In(SPh)3 and its use as precursor for the self-assembly of two new one-dimensional indium thiolate-dipyridyl compounds

Article abstract of DOI:10.1016/j.inoche.2010.11.010

Tris(benzenethiolato)indium(III) (In(SPh)₃) has been facilely prepared in high yield of 95.0% by a microwave-assisted solvothermal reaction of indium and diphenyl disulphide in methanol in 15 min. The combination of In(SPh)₃ as precursor with dipyridyl ligands of bipy (bipy = 4,4′-bipyridine) and dpp (dpp = 1,3-di(4-pyridyl)propane) in methanol at ambient conditions yielded two new compounds, namely In(SPh)₃(bipy) (1) and In(SPh)₃(dpp) (2), respectively. Single-crystal X-ray crystallographic studies reveal that in both the structures, the five-coordinated In(III) ions in nearly perfect trigonal-bipyramidal geometry are interconnected by the bifunctional dipyridyl ligands to form one-dimensional chains. Their thermal properties have been investigated.

Full text of DOI:10.1016/j.inoche.2010.11.010

Inorganic Chemistry Communications 14 (2011) 265–267
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Microwave-assisted synthesis of In(SPh)3 and its use as precursor for the
self-assembly of two new one-dimensional indium thiolate-dipyridyl compounds
Jian-Rong Li a,b, Zai-Lai Xie a, Bing Hu a, Xiao-Ying Huang a,
⁎
a
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, the Chinese Academy of Sciences, Fuzhou, Fujian 350002, PR China
b
Graduate School of the Chinese Academy of Sciences, Beijing 100049, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Tris(benzenethiolato)indium(III) (In(SPh)3) has been facilely prepared in high yield of 95.0% by a microwave-
assisted solvothermal reaction of indium and diphenyl disulphide in methanol in 15 min. The combination of
In(SPh)3 as precursor with dipyridyl ligands of bipy (bipy=4,4′-bipyridine) and dpp (dpp=1,3-di(4-
pyridyl)propane) in methanol at ambient conditions yielded two new compounds, namely In(SPh)3(bipy) (1)
and In(SPh)3(dpp) (2), respectively. Single-crystal X-ray crystallographic studies reveal that in both the
structures, the five-coordinated In(III) ions in nearly perfect trigonal–bipyramidal geometry are
interconnected by the bifunctional dipyridyl ligands to form one-dimensional chains. Their thermal
properties have been investigated.
Received 2 October 2010
Accepted 3 November 2010
Available online 11 November 2010
Keywords:
Microwave-assisted
Synthesis
Metal thiolate
Precursor
© 2010 Elsevier B.V. All rights reserved.
Crystal structure
Metal thiolates are important starting materials for preparing
crystalline metal chalcogenides [1,2], coordination compounds [3] and
nanomaterials [4–6]. Normally, tris(benzenethiolato)indium(III), name-
ly In(SPh)3 could be prepared either by the reaction of InCl3 with thiolate
natrium in methanol [7] or one-step reaction of indium and diphenyl
disulphide in refluxing toluene [8]. The former involves multi-step
reactions, while the latter takes hours. Green et al. described a direct
electrochemical synthesis of In(SPh)3, but theyield was low [9]. From the
commercial application of view, it is much needed to develop new facile
and fast synthetic routes for important precursors such as metal
thiolates. Microwave-assisted synthesis is characterized by mild reaction
conditions, short reaction time, and high yield of products. It has been
widely used in the preparations of organic compounds [10,11] and
inorganic nanometerials [12,13]. Recently, it also shows promising in
synthesizing some crystalline metal-organic frameworks [14,15]. Herein
we demonstrate that In(SPh)3 can be obtained readily by microwave-
assisted synthesis and its use as precursor for the self-assembly of
two one-dimensional indium compounds, namely In(SPh)3(bipy) (1)
and In(SPh)3(dpp) (2) (bipy=4,4′-bipyridine, dpp=1,3-di(4-pyridyl)
propane). The crystal structures and thermal properties of compounds 1
and 2 are investigated.
Note that the previous synthetic methods usually involve a reflux
process and take several hours [8,16]. By contrast, the microwave-
assisted solvothermal reaction applied here produced the resulting
compound In(SPh)3 only in 15 min, indicating that microwave heating
is an efficient method for synthesizing In(SPh)3. Anal. (%) Calc. for In
(SPh)3, C18H15InS3: C, 48.88, H, 3.42. Found: C, 48.85, H, 3.45. IR (KBr
pellet, cm−1) for In(SPh)3: 1574(s), 1474(s), 1437(s), 1384(s), 1080
(m), 1022(s), 1006(s), 808(s), 732(vs), 694(s), 684(vs).
Compound 1 was obtained by a solution method. The bipy
(0.091 g, 0.5 mmol) was dissolved in methanol (5 mL) and then
added to a solution of In(SPh)3 (0.222 g, 0.50 mmol) in methanol
(10 mL). The reactants were mixed by shaking until homogeneous
and a larger number of colorless needle-like crystals of 1 formed
rapidly and were collected after filtration in the yield of 71% (0.212 g).
A procedure similar to that used for 1 was employed to prepare
compound 2 except that dpp (0.099 g, 0.5 mmol) was used instead of
bipy. Colorless needle-like crystals of 2 were obtained in the yield of
60% (0.192 g) after standing the reaction solvent for about 30 min.
In(SPh)3 was obtained by microwave-assisted solvothermal reaction
of diphenyl disulphide (3.27 g, 15 mmol), indium powder (1.14 g,
10 mmol) and methanol (15 mL) at 120 °C for 15 min using a Biotage
Initiator Microwave Synthesizer. Light white powders of In(SPh)3
(4.19 g, yield: 95%) was isolated by evaporating methanol in vacuum.
Scheme 1. The contrast between the microwave heating and conventional heating for
the synthesis of In(SPh)3, and its use as precursor for the self-assembly of two new one-
dimensional indium thiolate-dipyridyl compounds.
⁎
Corresponding author. Tel./fax: +86 591 83793727.
E-mail address: xyhuang@fjirsm.ac.cn (X.-Y. Huang).
1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2010.11.010

266
J.-R. Li et al. / Inorganic Chemistry Communications 14 (2011) 265–267
Table 1
conventional and the microwave-assisted syntheses, as well as the
synthesis of compounds 1 and 2, are illustrated in Scheme 1.
Summary of crystallographic data and structure refinement details for compounds 1
and 2.
The single crystals of compounds 1 and 2 suitable for single-crystal
X-ray diffraction were isolated from the reactions of dipyridyl ligands
(bipy for 1 and dpp for 2), In(SPh)3 and methanol in sealed thick-walled
Pyrex tubes in 90 °C for three days [17]. The X-ray crystallographic
analyses reveal that1 and 2 belongto the triclinic space group of P–1 and
monoclinic space group of P21/n, respectively. The crystallographic data
and structural refinement details are depicted in Table 1. The
crystallographically asymmetric unit of compound 1 consists of one
unique In3+ ion, three [SPh]− groups, and one bipy ligand (Fig. S1). Each
In3+ ion is five coordinated to three sulfur atoms from three [SPh]−
groups occupyingthe equatorial positions, and two nitrogen atomsfrom
two bipy liagnds in apically opposite positions, resulting in a trigonal–
bipyramidal geometry (Fig. 1a). As shown in Table S1, the In–S bond
lengths range from 2.4429(13) to 2.4606(13) Å and the S–In–S angles
are in the range of 114.04(4)–124.65(5)°, whereas the In–N bond
lengths are 2.406(3)Å and 2.429(3) Å withN–In–N angles of 178.70(8)°,
respectively. The three SPh− groups and one In3+ ion form a neutral [In
(SPh)3] unit and these units are inter-linked by bipy ligands to form an
infinite chain along the c axis. The indium and three sulfur are almost co-
planar (∑(S–In-S)=360°), with theindium atom lying 0.08 Å out of the
plane defined by sulfur atoms. The asymmetric unit of structure 2
contains one unique In3+ ion, three [SPh]− groups, and one dpp ligand
(Fig. S2). It features a one-dimensional chain along the [10-1] direction
constructed by the 1, 3-di(4-pyridyl)propane ligands bridging the In
(SPh)3 units(Fig. 1b). However, the rigid bipy ligand results in a linear
chain in 1, while the flexible dpp ligand leads to a zigzag chain. There
exist one and two weak non-classical intra-chain hydrogen bonds in 1
and 2, respectively, between the sulfur atoms and the C–H groups (in 1,
C(26)···S(3) 3.473(4) Å, 128.3°; in 2, C(23)···S(3) 3.467(4) Å 127.3°; C
(29)···S(2)i, 3.467(4) Å, 124.7°, symmetry code, i: x+1/2, −y+1/2,
z–1/2). Interestingly, there are face-to-face π–π interactions between
the phenyl ring of the SPh ligand and the pyridine ring within the chain
in both 1 and 2, as detailed in Table 2 and Scheme 2. In compound 1, the
inter-chain interaction is van der Waals force only. Whereas in 2, the
inter-chain π–π stacking interactions results in a 2-D network
perpendicular to the [101] direction, in which the distance of centric
of the two pyridine rings is 3.89 Å (Fig. S4 and Table 2). The 2-D
networks further stack on top of each other into a three-dimensional
structure through van der Waals interaction. It should be pointed out
that the previous studies have shown that indium thiolates are
Lewis acid and are easy to react with neutral and anionic donors
[8,18]. However, the reported compounds mostly are monomolecular
1
C
2
Empirical formula
Crystal size (mm)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
α (°)
β (°)
28H23InN2S3
C31H29InN2S3
0.20×0.16×0.15
Monoclinic
P21/n
15.018(8)
11.196(5)
18.658(10)
90
105.610(6)
90
3022(3)
4
1.101
0.71073
1304
2.03 to 27.46
22,758
6900
0.28×0.15×0.13
Triclinic
P−1
11.213(5)
11.543(5)
11.842(6)
78.90(2)
70.676(19)
65.918(16)
1317.5(11)
2
1.154
0.71073
604
2.25 to 27.45
10,362
5990
γ (°)
V (Å3)
Z
μ (mm−1
)
λ (MoKα) (Å)
F(000)
θ range (°)
Reflections measured
Independent reflections
Observed Reflection [IN2σ(I)]
Temperature (K)
4787
293
1.509
308
5093
293
1.408
334
ρcalc (g cm−3
Parameter
Rint
)
0.0324
0.0461
R1, wR2 [IN2σ(I)]a,b
R1, wR2 [all data]
GOF
0.0410, 0.0678
0.0562, 0.0743
1.002
0.0478, 0.0842
0.0726, 0.0941
1.084
Largest diff. Peak and hole/e Å−3
0.610, −0.661
0.419, −0.706
a
R1 =∑║Fo│–│Fc║/∑│Fo
.
b
wR2 =[∑w(F2o −Fc2)2/∑w(F2o)2]0.5
.
Anal. (%) Calc. for 1, C28H23InN2S3: C, 56.19, H, 3.87, N, 4.68. Found: C,
55.90, H, 3.83, N, 4.66; for 2, C31H29InN2S3: C, 58.13, H, 4.56, N, 4.37.
Found: C, 57.80, H, 4.41, N, 4.41. IR (KBr pellet, cm−1) for 1: 1605(νs),
1575(s), 1533(m), 1488(w), 1474(s), 1459(s), 1434(s), 1412(s), 1215
(s), 1072(s), 1023(s), 1006(s), 808(s), 743(vs), 695(vs), 626(s); for 2:
1614(νs), 1576(s), 1505(m) 1474(s), 1429(s), 1384(s), 1221(s), 1083
(s), 1067(s), 1022(s), 1012(s), 811(m), 808(s), 747(vs), 735(vs), 694
(vs), 611(s). The IR spectra of the precursor In(SPh)3 and compounds
1–2 show characteristic bands of aromatic plane. Bands in the region
621–1076 cm−1 are attributed to the bending vibration of C–H group
in or out of the aromatic plane, and ring deformation absorptions of
aromatic ring. The peaks at 1412–1614 cm−1 are due to the aromatic
C–C and C–N stretching vibration absorptions. The comparison of the
Fig. 1. View of the one-dimension chain of the compounds In(SPh)3(bipy) (1) (a) and In(SPh)3(dpp) (2) (b). The intra-chain hydrogen bonds and π–π stacking are shown as dashed lines.

J.-R. Li et al. / Inorganic Chemistry Communications 14 (2011) 265–267
267
Table 2
Distances (d/Å) and angles (°) for the π–π interactions in 1 and 2.a
Compound, ring(1)···ring(2)
d[Cg(1)···Cg(2)]b
αc
βd
γe
d[Cg(1)···P(2)]f
d[Cg(2)···P(1)]g
1, C(7)–C(12)···N1, C(19)–C(23)
3.66
3.60
3.89
12.9
13.2
0
23.4
19.7
25.9
27.7
22.7
25.9
3.36
3.32
3.50
3.24
3.39
3.50
2, C(7)–C(12)···N1, C(19)–C(23)
2, C(19)–C(23)···N1, C(19)i–C(23)i···N1i; i: 2−x, 1−y, 1−z
a
For a graphical depiction of distances and angles in the assessment of π-π interactions, see Scheme 2.
Centroid–centroid distance.
Dihedral angle between the ring planes.
Angle between the centroid vector Cg(1)···Cg(2) and the normal to the plane 2.
Angle vector Cg(1)···Cg(2)(between the centroid ) and the normal to the plane 1.
Perpendicular distance of Cg(1) on ring plane 2.
b
c
d
e
f
g
Perpendicular distance of Cg(2) on ring plane 1.
In this work, we have shown that microwave-assisted synthesis is a
fast and efficient route to the preparation of In(SPh)3 precursor, and the
precursor can further react with bipy and dpp giving rise to two new
compounds 1 and 2. The two compounds feature neutral In(SPh)3 unit
bridged by dipyidyl ligands to form one-dimensional polymeric
structures. Their thermal property has been investigated.
Acknowledgement
This work was supported by grants from the National Natural
Science Foundation of China (Nos. 20771102, 20873149 and 21001104).
Scheme 2. Graphical presentation of the parameters used in Table 2 for the description
of π–π stacking.
Appendix A. Supplementary data
complex. The polymeric structures containing bifunctional ligands have
not yet been described [18–20].
CCDC Nos. 794992 and 794991 contain the supplementary
crystallographic data for compounds 1 and 2, respectively. The data
can be obtained free of charge via bhttp://www.ccdc.cam.ac.uk/conts/
retrieving.htmlN, or from the Cambridge Crystallographic Data Centre,
12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
e-mail: deposit@ccdc.cam.ac.uk. Additional structural figures, tables,
PXRD patterns, and IR spectra are available as electronic supplementary
information in the online version, at doi:10.1016/j.inoche.2010.11.010.
The purity of the as-synthesized compounds 1 and 2 were further
confirmed by the consistence of their powder X-ray diffraction patterns
(PXRD) and the simulated PXRD patterns from respective single-crystal
X-ray structures (Fig. S5). The thermal stabilities of the precursor In(SPh)3
and compounds 1–2 were examined by thermogravimetric analyses
(TGA) in a N2 atmosphere from ~25 to 450 °C in NETZSCH STA 449 F3 unit
at a heating rate of 5 °C/min with ~8 mg powder samples. As shown in
Fig. 2, the In(SPh)3 is stable up to 120 °C, and then loses weight in two
steps between 120 °C and 240 °C. The combined weight loss of two steps
is 65.7%. The TG processes of 1 and 2 are very similar and reveal one step
weight loss in the range of 220 °C–400 °C. The weight losses of 1 and 2
were 70.1% and 72.8%, respectively. The weigh losses in the TG of all the
three compounds can be ascribed to the decompositions of compounds,
leaving the inorganic In2S3 as post-TGA residue, which was confirmed by
the powder X-ray diffraction study (Fig S6, JCPDS No. 6504–59 for cubic
In2S3).
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Fig 2. TGA curves of compounds In(SPh)3, (bipy) (1) and In(SPh)3(dpp) (2).