Solvothermal Syntheses, Crystal Structures, and Thermal Properties of New Manganese Thioantimonates(III): The First Example of the Thermal Transformation of an Amine-Rich Thioantimonate into an Amine-Poorer Thioantimonate

Article abstract of DOI:10.1021/ic034970+

Two new neutral thioantimonates(III) were first prepared by the reaction of elemental manganese, antimony, and sulfur in tren (tren = tris(2-aminoethyl)amine, C₆H₁₈N₄) at 140 °C. In the amine-rich compound [Mn(tren)]₂Sb₂S ₅ (1) the trigonal SbS3 pyramids are connected via common corners (S(3)) into the tetradentate [Sb₂S₅]^4- anion. Four S atoms have bonds to the manganese atoms of the [Mn(tren)²⁺] cations. A special structural feature is the large Sb-S(3)-Sb(a) angle of 134°. Density functional calculations clearly demonstrate that this large angle results from the steric interactions between the two Mn(tren) subunits. In the crystal structure of the amine-poorer compound [Mn(tren)] ₂Mn₂Sb₄S₁₀ (2), MnS₄ tetrahedra and SbS₃ pyramids are linked via common corners and edges to form a new heterometallic [Mn₂Sb₄S₁₀] core. The [Mn(C₆H₁₈N₄)²⁺] cations are located at the periphery of the core and are bound to the [Mn₂Sb ₄S₁₀] unit via two S atoms. The thermal behavior of both compounds was investigated using simultaneous thermogravimetry (TG), differential thermoanalysis, and mass spectroscopy. The amine-richer compound 1 decomposes in three steps upon heating. After the first TG step an intermediate phase is formed, which was identified as the amine-poorer compound 2 by X-ray diffraction. Reaction of compound 2 at 140 °C with an excess of tren forms the amine-rich compound 1.

Full text of DOI:10.1021/ic034970+

Inorg. Chem. 2004, 43, 2914−2921
Solvothermal Syntheses, Crystal Structures, and Thermal Properties of
New Manganese Thioantimonates(III): The First Example of the Thermal
Transformation of an Amine-Rich Thioantimonate into an Amine-Poorer
Thioantimonate
Michael Schaefer, Christian Na1ther, Nicolai Lehnert, and Wolfgang Bensch*
Institut fu¨r Anorganische Chemie der Christian-Albrechts UniVersita¨t Kiel, Olshausenstrasse 40,
D-24098 Kiel, Germany
Received August 15, 2003
Two new neutral thioantimonates(III) were first prepared by the reaction of elemental manganese, antimony, and
sulfur in tren (tren ) tris(2-aminoethyl)amine, C6H N ) at 140 °C. In the amine-rich compound [Mn(tren)] Sb2S5
18
4
2
4-
(1) the trigonal SbS3 pyramids are connected via common corners (S(3)) into the tetradentate [Sb2S5] anion.
Four S atoms have bonds to the manganese atoms of the [Mn(tren)2+] cations. A special structural feature is the
large Sb−S(3)−Sb(a) angle of 134°. Density functional calculations clearly demonstrate that this large angle results
from the steric interactions between the two Mn(tren) subunits. In the crystal structure of the amine-poorer compound
[Mn(tren)] Mn2Sb4S10 (2), MnS4 tetrahedra and SbS3 pyramids are linked via common corners and edges to form
2
a new heterometallic [Mn2Sb4S10] core. The [Mn(C6H N )2+] cations are located at the periphery of the core and
18
4
are bound to the [Mn2Sb4S10] unit via two S atoms. The thermal behavior of both compounds was investigated
using simultaneous thermogravimetry (TG), differential thermoanalysis, and mass spectroscopy. The amine-richer
compound 1 decomposes in three steps upon heating. After the first TG step an intermediate phase is formed,
which was identified as the amine-poorer compound 2 by X-ray diffraction. Reaction of compound 2 at 140 °C with
an excess of tren forms the amine-rich compound 1.
Introduction
of the materials. Such a removal of the structure-directing
amines is a prerequisite for the preparation of porous
compounds with accessible empty space. On the other hand,
the emission of the structure-directing molecules may lead
to a rearrangement of the building units, forming materials
with a higher degree of condensation. A few years ago we
started to prepare new chalgogenidometalates on the basis
The solvothermal syntheses of chalcogenidometalates in
the presence of amines as structure-directing molecules has
become of increasing interest. One major goal in this field
is the development of strategies for a more rational construc-
tion of their structures to prepare new compounds such as,
e.g., open framework chalcogenidometalates with organic
molecules acting as space fillers and/or charge balancing ions
or condensed frameworks with interesting physical proper-
ties. Open frameworks should exhibit dramatically different
physical and chemical properties compared to the well-
established oxidic counterparts. Many thio and seleno
compounds with interesting structural features were prepared
during the past decade,1-14 but in all cases the structure-
directing molecules could not be removed without a collapse
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* Author to whom correspondence should be addressed. Fax: +49 (0)-
431/880-1520. E-mail: wbensch@ac.uni-kiel.de.
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2914 Inorganic Chemistry, Vol. 43, No. 9, 2004
10.1021/ic034970+ CCC: $27.50 © 2004 American Chemical Society
Published on Web 03/30/2004

New Manganese Thioantimonates(III)
of antimony. Several primary SbSx building blocks are known
for such compounds which can be used for the construction
of thioantimonate frameworks. In continuing work we started
to investigate whether it is possible to incorporate transition-
metal (TM) atoms into thioantimonate networks. The idea
was to compensate the high negative charge of the thio-
antimonate anions by the TM ions, thus yielding charge
neutral networks, and to alter the physical and chemical
properties of such compounds to influence their optical and
magnetic properties. According to this idea, we successfully
synthesized a series of compounds with composition Mn2-
Sb2S5‚L (L ) 1,3-diaminopropane (dap), methylamine (ma),
ethylamine (ea), ethylenediamine (en))15,16 showing a layered
structure with pores within the layers. But in most cases the
usage of, e.g., bi- or tridentate amines as the solvents leads
to the formation of isolated TM(amine)zn+ complexes.17-20
Such complexes were found to act as suitable structure
directors, but the TMn+ ions are not bound to the SbxSym-
units and no frameworks are formed. Another idea was to
alter the physical and chemical properties of thioantimonates
by the integration of TMn+ ions into the framework, i.e.,
changing the optical and magnetic properties. But application
of bi- or tridentate amines as the solvents17-20 often formed
isolated TM(amine)zn+ complexes. Such complexes were
found to act as suitable structure directors, but the TMn+
ions are not bound to the SbxSym- units. Very recently we
demonstrated that TMn+ ions can be integrated into thio-
antimonate frameworks using an amine such as tren (tren )
tris(2-aminoethyl)amine) which leaves one or two coordina-
tion sites free at the TMn+ ions, enabling bond formation to
the SbxSy network.21,22 For instance, [Fe(tren)]FeSbS4 is a
mixed-valent compound.23 The Fe3+ ion is part of a protein
analogous [2FeIII-2S] cluster encapsulated within the thio-
antimonate anion, whereas the Fe(tren)2+ cation has one bond
to a S atom of the anion. Other exciting examples for the
successful incorporation of TMn+ ions are [Co(tren)]Sb2S4
and [Ni(tren)]Sb2S4.24 In [Co(tren)]Sb2S4 a two-dimensional
thioantimonate(III) network is found with different SbxSx
rings. The Co(tren)2+ cations are bound to the anion via one
S atom and are located in the cavities of Sb10S10 rings. In
[Ni(tren)]Sb2S4 the SbS3 pyramids are interconnected to form
a one-dimensional thioantimonate(III) chain. The Ni(tren)2+
cations have bonds to two S atoms of the anion, yielding a
NiSb2S3 heteroring. During our systematical exploration of
the Mn-Sb-S-tren system, we synthesized the two title
compounds [Mn(tren)]2Sb2S5 (1) and [Mn(tren)]2Mn2Sb4S10
(2). Formally, compound 1 can be regarded as amine-rich
and 2 as an amine-poor sample. Following the ideas of
Na¨ther et al.,25-28 compound 1 was thermally decomposed
in a directed way to form compound 2. This is the first
example in thioantimonate(III) chemistry showing that
thermal decomposition reactions are a promising technique
for the synthesis of new compounds. The reaction is of
special interest because the degree of condensation increases
on going from compound 1 to compound 2 and offers a
synthetic approach for the modification of chalcogenido-
metalate frameworks. In addition, the solvothermal syntheses
of chalcogenidometalates are normally performed using the
elements as starting materials and an excess of amines. Very
often mixtures of different compounds are obtained, and the
synthesis of metal-rich compounds is difficult to achieve.
In such cases thermal decomposition reactions can be an
alternative tool for the preparation of large amounts of new
compounds which cannot be prepared in solution or which
are always obtained as mixtures. Furthermore, the reverse
reaction from 2 to 1 was also successful, demonstrating that
even complex compounds can be used as starting materials
for the synthesis of thioantimonates(III). In compound 1 an
unusual large angle around a S atom joining two Sb centers
of 134° is observed. Density functional calculations are
performed to gain insight into whether electronic or sterical
effects are responsible for the enlarged angle. In the present
paper we report the syntheses, crystal structures, and thermal
reactions of the two new manganese thioantimonates(III).
The results of the theoretical calculations undertaken for
compound 1 are also presented.
Experimental Section
Synthesis of 1. Orange-colored plates of [Mn(tren)]2Sb2S5 were
synthesized using elemental Mn (54.9 mg, 1 mmol), Sb (121.76
mg, 1 mmol), and S (80 mg, 2.5 mmol) in 95% tren (5 mL, 33.4
mmol). The mixture was heated to 140 °C for 7 days in a Teflon-
lined steel autoclave with an inner volume of approximately 30
mL and cooled within 3 h to room temperature. The product was
filtered off, washed with acetone, and stored under vacuum. The
yield based on Mn is about 60%. As byproducts [Mn(tren)(trenH)]-
21
SbS4 and crystalline Sb were identified by X-ray diffraction
(XRD). C, H, N, S Anal. Found for selected crystals: C, 17.2; H,
4.4; N, 13.2; S, 18.0. Calcd: C, 17.9; H, 4.5; N, 13.9; S, 19.9.
Synthesis of 2. [Mn(tren)]2Mn2Sb4S10 was obtained from el-
emental Mn (54.9 mg, 1 mmol), Sb (121.76 mg, 1 mmol), and S
(80 mg, 2.5 mmol) in an aqueous solution of 40% tren (5 mL,
13.4 mmol) at 140 °C in a Teflon-lined steel autoclave (∼30 mL).
After 7 days the mixture was cooled within 3 h to room temperature,
and the orange-colored squares were filtered off, washed with
acetone, and stored under vacuum. The yield based on Mn is about
80%. Besides the title compound an unknown amorphous phase
and crystalline Sb were observed by XRD. C, H, N, S Anal. Found
for selected crystals: C, 10.8; H, 2.8; N, 8.4; S, 23.6. Calcd: C,
10.9; H, 2.8; N, 8.5; S, 24.3.
(15) Bensch, W.; Schur, M. Eur. J. Solid State Inorg. Chem. 1996, 33,
1149.
(16) Schur, M.; Bensch, W. Z. Naturforsch. 2002, 57b, 1.
(17) Bensch, W.; Na¨ther, C.; Sta¨hler, R. Chem. Commun. 2001, 477.
(18) Sta¨hler, R.; Na¨ther, C.; Bensch, W. Eur. J. Inorg. Chem. 2001, 1835.
(19) Sta¨hler, R.; Bensch, W. Z. Anorg. Allg. Chem. 2002, 628, 1657.
(20) Sta¨hler, R.; Na¨ther, C.; Bensch, W. Acta Crystallogr., Sect. C 2001,
57, 26.
Crystal Structure Determination. All data were collected using
an imaging plate diffraction system (IPDS) from Stoe & Cie
(21) Schaefer, M.; Engelke, L.; Bensch, W. Z. Anorg. Allg. Chem. 2003,
629, 1912.
(22) Schaefer, M.; Bensch, W. Solid State Sci. 2003, 5, 1135.
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Chem. 2003, 629, 532.
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394.
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Inorganic Chemistry, Vol. 43, No. 9, 2004 2915

Schaefer et al.
Table 1. Crystallographic Data for 1 and 2
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 1 and 2a
1
2
1
Sb-S(1)
Sb-S(3)
Mn-S(2)
Mn-N(2)
Mn-N(4)
2.3980(8)
2.4725(5)
2.7036(8)
2.250(3)
2.341(3)
Sb-S(2)
Mn-S(1)
Mn-N(1)
Mn-N(3)
2.3589(7)
2.5006(9)
2.334(3)
2.280(3)
cryst syst
a/Å
b/Å
c/Å
orthorhombic
triclinic
8.420(2)
9.900(2)
11.430(2)
101.11(3)
105.27(3)
91.76(3)
898.6(3)
P1h
8.6313(4)
18.988(1)
16.410(1)
90
90
90
2689.5 (2)
Pbcn
20
R/deg
â/deg
Sb-S(3)-Sbb
134.06(5)
102.90(2)
173.82(8)
104.29(8)
105.52(8)
97.97(8)
S(1)-Sb-S(2)
S(2)-Sb-S(3)
N(1)-Mn-S(2)
N(2)-Mn-S(2)
N(3)-Mn-S(2)
N(4)-Mn-S(2)
98.07(3)
107.79(3)
98.97(8)
86.33(7)
86.37(7)
174.07(8)
γ/deg
S(1)-Sb-S(3)
N(1)-Mn-S(1)
N(2)-Mn-S(1)
N(3)-Mn-S(1)
N(4)-Mn-S(1)
V/Å3
space group
T/°C
20
Z
8
1
density(calcd)/g cm-3
µ/mm-1
1.991
3.31
403.08
0.0290
0.0726
2.439
4.92
1319.85
0.0202
0.0526
2
mol wt
Sb(1)-S(1)
Sb(1)-S(3)
Sb(2)-S(4)
Mn(1)-S(1)
Mn(2)-S(2)
Mn(2)-S(4)c
Mn(1)-N(1)
Mn(1)-N(3)
2.3962(9)
2.4831(9)
2.466(1)
2.4805(9)
2.4693(9)
2.4953(9)
2.326(2)
2.269(2)
Sb(1)-S(2)
Sb(2)-S(3)
Sb(2)-S(5)
Mn(1)-S(2)
Mn(2)-S(4)
Mn(2)-S(5)
Mn(1)-N(2)
Mn(1)-N(4)
2.4196(8)
2.4673(9)
2.365(1)
2.836(1)
2.569(1)
2.478(1)
2.243(2)
2.284(3)
R1 for Fo > 4σ(Fo)a
wR2 for all reflnsb
a R1 ) ∑||Fo| - |Fc|/∑|Fo. b wR2 ) [∑[w(Fo - Fc )2]/∑[w(Fo )2]]1/2
.
2
2
2
(graphite-monochromated Mo KR radiation, λ ) 0.71073 Å). The
measurements were carried out at 293 K. The structure solutions
were performed using SHELXS-97.29 The structure refinements
were done against F2 using SHELXL-97.30 For compound 1 a
numerical absorption correction was applied using X-Red31 and
X-Shape.32 All non-hydrogen atoms were refined anisotropically.
The hydrogen atoms were positioned with idealized geometry and
refined with individual isotropic displacement parameters using the
riding model. The crystals of compound 2 were always non-
merohedrically twinned, which was seen by the inspection of the
reciprocal space using the program recipe from Stoe & Cie. The
reflections of both individuals were indexed and integrated sepa-
rately using the programs recipe and twin.33 Crystal data and results
of the structure refinement as well as selected bond lengths and
angles are found in Tables 1 and 2.
Long Sb-S Bonds
3.565(1)
3.897(2)
Sb(1)-Sb(2)d
Sb(2)-S(2)d
Sb(1)-S(4)d
3.676(1)
Sb(1)-S(3)-Sb(2)
S(1)-Sb(1)-S(3)
S(3)-Sb(2)-S(4)
S(4)-Sb(2)-S(5)
N(1)-Mn(1)-S(1)
N(2)-Mn(1)-S(1)
N(3)-Mn(1)-S(1)
N(4)-Mn(1)-S(1)
108.17(4)
92.72(4)
95.87(4)
94.17(4)
173.47(7)
100.69(7)
107.86(7)
97.04(8)
S(1)-Sb(1)-S(2)
S(2)-Sb(1)-S(3)
S(3)-Sb(2)-S(5)
Mn(1)-S(2)-Mn(2)
N(1)-Mn(1)-S(2)
N(2)-Mn(1)-S(2)
N(3)-Mn(1)-S(2)
N(4)-Mn(1)-S(2)
97.19(4)
91.73(4)
94.26(4)
114.53(4)
99.52(8)
83.03(7)
87.70(8)
175.84(8)
a Estimated standard deviations are given in parentheses. b Symmetry
code 1 - x, y, 0.5 - z. c Symmetry code 2 - x, 1 - y, 1 - z. d Symmetry
code 1 - x, 1 - y, 1 - z.
Crystallographic data (excluding structure factors) for the
structures reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre (CCDC) as Supplementary
Publication Nos. CCDC 213776 (1) and CCDC 213777 (2). Copies
of the data can be obtained free of charge on application to the
CCDC, 12 Union Rd., Cambridge CB2 1 EZ, U.K. [fax, +44-(0)-
1223-336033; e-mail, deposit@ccdc.cam.ac.uk].
X-ray Powder Diffraction. The X-ray powder patterns were
recorded in transmission geometry using a Stoe Stadi-P diffracto-
meter with a position-sensitive detector (PSD) (Cu KR radiation,
λ ) 1.540598 Å).
Thermal Behavior. Differential thermal analysis (DTA)-
thermogravimetry (TG)-mass spectrometry (MS) measurements
were performed simultaneously using the STA-409CD with Skim-
mer coupling from Netzsch, which is equipped with a quadrupole
mass spectrometer, QMA 400 (max 512 amu), from Balzers. The
MS measurements were performed in analogue and trend scan
mode. All measurements were corrected according to buoyancy and
current effects and were performed using heating rates of 4 K/min
in Al2O3 crucibles under a dynamic helium atmosphere (flow rate
75 mL/min, purity 4.6).
Elemental Analysis. These investigations were performed using
a EuroEA elemental analyzer from Eurovector.
Density Functional Calculations. Spin-unrestricted density
functional theory (DFT) calculations using Becke’s three-parameter
hybrid functional with the correlation functional of Lee, Yang, and
Parr (B3LYP)34 were performed with the program package Gaussian
98.35 The applied LanL2DZ basis set uses Dunning/Huzinaga full
double-ú (D95)36 basis functions on first-row and Los Alamos
effective core potentials plus double-ú (DZ) functions on all other
atoms.37 The structure of the discrete dimer [Mn(tren)]2Sb2S5 (cf.
Figure 1) was fully optimized in C1 symmetry. The higher symmetry
(34) (a) Becke, A. D. Phys. ReV. A 1988, 38, 3098. (b) Becke, A. D. J.
Chem. Phys. 1993, 98, 1372. (c) Becke, A. D. J. Chem. Phys. 1993,
98, 5648.
(35) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. A., Jr.;
Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels,
A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone,
V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;
Clifford, S.; Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R.
L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara,
A.; Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; Johnson, B. G.;
Chen, W.; Wong, M. W.; Andres, J. L.; Head-Gordon, M.; Replogle,
E. S.; Pople, J. A. Gaussian 98, revision A.11; Gaussian, Inc.:
Pittsburgh, PA, 1998.
(29) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure Deter-
mination; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(30) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(31) Stoe & Cie. X-Red32 V 1.11 Software; Stoe & Cie GmbH: Darmstadt,
Germany, 1998.
(32) Stoe & Cie. X-Shape V 1.03 Software; Stoe & Cie GmbH: Darmstadt,
Germany, 1998.
(33) Stoe & Cie. IPDS Program Package, V. 2.89; Stoe & Cie GmbH:
Darmstadt, Germany, 1998.
(36) Dunning, T. H., Jr., Hay, P. J., Schaefer, H. F., III, Eds.; Plenum:
New York, 1976.
(37) (a) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 270, 299. (b)
Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284.
2916 Inorganic Chemistry, Vol. 43, No. 9, 2004

New Manganese Thioantimonates(III)
trigonal pyramid.15-20,22-24,41-51 The S(3) atom is located on
a 2-fold axis, and the two SbS3 pyramids are connected via
this S atom, forming the unusual tetradentate [Sb2S5]4- anion.
We note that the [Sb2S5]4- anion was observed in only a
few compounds,15,16,51 but never acting in such a manner as
a multidentate ligand. The other four S atoms of the anion
are bound to the two Mn atoms, forming two four-membered
MnSbS2 rings which are almost coplanar to each other (mean
deviation from least-squares plane 0.0331 Å, angle between
the planes 0.8°). We note that four-membered MnSbS2 rings
are rare and only a few examples exist.15,16,22,44
The Mn-N bonds vary between 2.250(3) and 2.341(8)
Å. The longer bonds are in trans positions to the Mn-S
bonds. The Mn-S distances range from 2.5006(9) to 2.7036-
(8) Å. The S(1) atom is within the distorted rectangular plane
of the octahedron, and the elongation of the Mn-S(1) bond
is due to sterical requirements (Table 2, Figure 1). A shorter
Mn-S(2) distance would lead to strong repulsive interactions
between N(2)H2 and S(2), which is energetically not
favorable.
Figure 1. Crystal structure of 1 with labeling. Hydrogen atoms are omitted
for clarity.
of the crystal structure has not been used in the calculations to
fully explore the geometric flexibility of the dimer independent of
crystal packing effects, etc. As described in the Results and
Discussion, this leads to slight distortions which are due to the
formation of extra hydrogen bonds in the gas phase, but no severe
changes of the overall structure occur. From experiment it is known
that the magnetic interaction between the two high-spin Mn2+ ions
(both S ) 5/2) through the [Sb2S5]4- bridge is weak. For the
calculations, the ferromagnetical coupling scheme giving rise to a
total spin of S ) 5 for the dimer has been used. The calculated
second derivatives show that the optimized structure represents a
global minimum. Restricted potential energy surface (PES) scans
along the Sb-S-Sb angle, where S is the central bridging sulfur,
have also been performed with B3LYP/LanL2DZ for both the
X-ray- and the DFT-optimized structures. In addition, the depen-
dence of the above-mentioned Sb-S-Sb angle on the bulkiness
of the coordinated fragment (here Mn(tren)) has been studied.
Accordingly, structures have been calculated for the anion [Sb2S5]4-
as well as the hypothetical models [(Ni(NH3)2]2Sb2S5 and [Ni-
(tma)2]2Sb2S5 (tma ) trimethylamine) with sterically less demanding
metal(ligand) units bound to [Sb2S5]4-. These calculations have been
performed in C1 symmetry using B3LYP/LanL2DZ. Nickel(II) was
chosen in these calculations, because it has a lower coordination
number than Mn(II) and it has a closed-shell (S ) 0) electron
configuration. The obtained structures of the [Sb2S5]4- unit in the
Ni(II)-ammonia and the Ni(II)-tma complexes are comparable
to that of [Mn(tren)]2Sb2S5, whereas [Sb2S5]4- itself has a linear
structure due to the strong Coulomb repulsion of the terminal
negative charges.
The Sb-S distances between 2.3589(7) and 2.4725(5) Å
are similar with the data for SbS3 units reported in the
literature. The S-Sb-S angles are in the typical range from
98.07(9)° to 107.79(3)°. A highly interesting feature of the
anion is the very large Sb-S(3)-Sb(a) angle of 134.06(5)°
(Figure 1). Normally, the angles around S atoms are in the
range from 90° to 110°. A detailed analysis of the geometry
demonstrates that an angle about S(3) which is in the typical
range would bring the two Mn(tren) units too close together.
We note that the actual geometry yields a short intra-
molecular H‚‚‚S distance of 2.541(1) Å (N(2)H2‚‚‚S(2a)
angle 154.34°). The [Mn(tren)]2Sb2S5 molecules are stacked
onto each other along [100], and due to the glide plane the
orientation of neighbored rods shows an up-down alternation
along [001] (see Figure 2). Between adjacent molecules
intermolecular H‚‚‚S separations ranging from 2.582(1) to
3.018(1) Å indicate hydrogen bonding.
The amine-poorer compound [Mn(tren)]2Mn2Sb4S10 (2)
crystallizes in the triclinic space group P1h with one formula
unit in the unit cell. Two crystallographically independent
Mn, two Sb, and five S atoms are found (Figure 3 and Table
2). Mn(1) is coordinated by four N atoms of the tren ligand
and two S atoms of the anion in a distorted octahedral
environment, Mn(1)N4S2 (Figure 3). The Mn(2) atom is
surrounded by four S atoms, forming a distorted tetrahedron,
Results and Discussion
The amine-rich compound [Mn(tren)]2Sb2S5 (1) crystallizes
in the orthorhombic space group Pbcn with eight formula
units in the unit cell. The crystallographically independent
manganese atom is surrounded by four nitrogen atoms of
the tren ligand and two sulfur atoms of the anion within a
distorted octahedron, MnN4S2 (Figure 1 and Table 2). The
Mn(tren) complex and its derivatives have been known and
studied for a long time, and some transition metal compounds
were synthesized in the past.38-40 The Sb atom has short
bonds to three S atoms, forming the well-known SbS3
(41) Wang, X.; Liebau, F. J. Solid State Chem. 1994, 111, 385.
(42) Powell, A. V.; Paniagua, R.; Vaqueiro, P.; Chippindale, A. M. Chem.
Mater. 2002, 14, 1220.
(43) Powell, A. V.; Boissiere, S.; Chippindale, A. M. J. Chem. Soc., Dalton
Trans. 2000, 4192.
(44) Pfitzner, A.; Kurowski, D. Z. Kristallogr. 2000, 215, 373.
(45) Powell, A. V.; Boissie`re, S.; Chippindale, A. M. Chem. Mater. 2000,
12, 182.
(46) Sheldrick, W. S.; Ha¨usler, H.-J. Z. Anorg. Allg. Chem. 1988, 557,
105.
(47) Oliver-Fourcade, J.; Izghouti, L.; Philippot, E. ReV. Chim. Min. 1981,
(38) Sime, R. J.; Dodge, R. P.; Zalkin, A.; Templeton, D. H. Inorg. Chem.
1971, 10, 537.
(39) Ciampolini, M.; Nardi, N. Inorg. Chem. 1966, 5, 41.
(40) Ellermeier, J.; Bensch, W. Transition Met. Chem. (Dordrecht, Neth.)
2002, 27, 763.
18, 207.
(48) Graf, H. A.; Scha¨fer, H. Z. Naturforsch. 1972, 27b, 735.
(49) Cordier, G.; Scha¨fer, H. ReV. Chim. Min. 1981, 18, 218.
(50) Do¨rrscheidt, W.; Scha¨fer, H. Z. Naturforsch. 1981, 36b, 410.
(51) Sta¨hler, R.; Bensch, W. J. Chem. Soc., Dalton Trans. 2001, 2518.
Inorganic Chemistry, Vol. 43, No. 9, 2004 2917

Schaefer et al.
Figure 4. Arrangement of the [Mn(tren)]2Mn2Sb4S10 molecules in the
structure. The H atoms and disordered C atoms are omitted for clarity.
Figure 2. Arrangement of [Mn(tren)]2Sb2S5 in the structure. H atoms are
omitted for clarity.
2.4805(9) Å for Mn(1)-S(1) and 2.836(1) Å for Mn(1)-
S(2). The S(2) atom is located in the distorted rectangular
plane of the octahedron, and a shorter Mn(1)-S(2) bond has
several consequences. The interatomic separation between
S(2) and N(2) would be shortened, leading to repulsive
interactions, and the Mn(2)-S(2) bond length would be
enlarged to weaken this bond (Table 2, Figure 3). The Mn-
(2)-S bonds have distances 2.4693(9)-2.569(1) Å similar
with the reported distances for interconnected MnS4
tetrahedra.52-54 The [Mn(tren)]2Mn2Sb4S10 molecules are
stacked along [001] in a way that a layerlike arrangement is
formed (Figure 4). Several relatively short intermolecular
S‚‚‚N separations may be regarded as weak hydrogen
interactions (N-H‚‚‚S distances between 2.501(3) and
2.7879(5) Å).
Figure 3. Crystal structure of 2 with labeling. Hydrogen atoms are omitted
for clarity.
Mn(2)S4. The two Sb atoms form typical SbS3 trigonal
pyramids. The structure of 2 is formed by the interconnection
of these primary building units. The Sb(1)S3 unit shares a
common edge with the Mn(1)N4S2 octahedron to form an
almost planar four-membered ring, Mn(1)Sb(1)S2 (mean
deviation from the best plane 0.0137 Å). Further condensa-
tion of the Sb(1)S3 unit occurs via common corners with
the Sb(2)S3 pyramid and the Mn(2)S4 tetrahedron. In
addition, the Mn(2)S4 tetrahedron and the Sb(2)S3 pyramid
have a common corner (S(4)), yielding a puckered six-
membered heteroring (Mn(2)Sb2S3). The remaining part of
the structure is generated by the center of inversion, and three
further four-membered rings are formed. The mean deviation
from the best plane for Mn(2a)Sb(2)S2 is 0.1511 Å. The angle
between Mn(1)Sb(1)S2 and Mn(2a)Sb(2)S2 is about 76.7°.
Some special features of [Mn(tren)]2Mn2Sb4S10 should be
highlighted here: The S(2) atom is connected to three metal
atoms (two Mn atoms and one Sb atom). Five four-membered
heterorings and a six-membered heteroring are essential parts
of the structure. In addition, neglecting the organic ligands,
the structure consists of a [Mn2Sb4S10] core formed by the
interconnection of the MnS4 tetrahedra and the SbS3 pyra-
mids. This core may be viewed as a complex tetradentate
ligand which is bound to two further Mn2+ ions, and such a
manganese(II)-thioantimonate(III) core is very unusual and
has never been reported before.
The Sb-S bond lengths are between 2.365(1) and 2.4831-
(1) Å, with S-Sb-S angles ranging from 91.73(4)° to 97.19-
(4)° both being in agreement with the data reported in the
literature.
Thermoanalytical Investigations. On heating compound
1 at 4 °C/min to 350 °C, two strong endothermic events are
observed at peak temperatures of about Tp1 ) 233 °C and
Tp2 ) 298 °C in the DTA curve. They are accompanied by
three steps in the TG curve (Figure 5). The total mass loss
amounts to 27.2%. In the gray residue, elemental Sb, Sb2S3,
and MnS were identified with XRD. Small amounts of
organic residue were also found (CHNsum 2.7%). The mass
change during the first step suggests that the tren molecule
is emitted in a well-defined way. To support this assumption,
MS spectra were measured simultaneously during the thermal
decomposition reactions. In agreement with our assumption
up to 270 °C the fragment of tris(2-aminoethyl)amine (m/z
) 99) could be detected. To acquire more information about
this well-defined emission of one tren molecule in another
run, the DTA-TG experiment was stopped after the first
step. The X-ray powder pattern of the green-colored inter-
(52) Bronger, W.; Bo¨ttcher, P. Z. Anorg. Allg. Chem. 1972, 390, 1.
(53) Bronger, W.; Balk-Hardtdegen, H.; Schmitz, D. Z. Anorg. Allg. Chem.
1989, 574, 99.
(54) Bronger, W.; Bo¨hmer, M.; Schmitz, D. Z. Anorg. Allg. Chem. 2000,
626, 6.
The Mn-N bond lengths range from 2.243(2) to 2.326-
(2) Å, with the longer bonds being in trans positions to the
Mn-S bonds. The Mn(1)-S distances are very different:
2918 Inorganic Chemistry, Vol. 43, No. 9, 2004

New Manganese Thioantimonates(III)
Figure 7. Comparison of the crystal structure (top) and the fully optimized
structure (B3LYP/LANL2DZ) (bottom) of [Mn(tren)]2Sb2S5. Hydrogen
atoms involved in hydrogen bridges are shown as white spheres; all others
are omitted for clarity.
Figure 5. DTA, TG, and MS curves for [Mn(tren)]2Sb2S5 (Tp ) peak
temperature; m/z ) 34 (H2S); m/z ) 99 (tren)).
Table 3. Comparison of Experimental and Calculated Geometric
Parameters of [Mn(tren)]2Sb2S5
param
X-raya
2.3980 2.514 Sb-S3-Sbb
2.3589 2.553
2.4725 2.579 H2N(2)-S(2)
2.5006 2.537 H1N(3)-S(2)
2.7036 2.658 H2N(2)b-S(2)b
2.3980 2.546 H1N(3)b-S(2)b
2.3589 2.500
opta
param
X-raya
134
opta
123
Sb-S(1)
Sb-S(2)
Sb-S(3)
Mn-S(1)
Mn-S(2)
Sbb-S(1)b
Sbb-S(2)b
Sbb-S(3)
hydrogen bonds
3.077
2.670
2.541
2.670
2.64
2.54
2.36
2.47
2.4725 2.627
Mnb-S(1)b 2.5006 2.689
Mnb-S(2)b 2.7036 2.570
a Bond lengths in angstroms, angles in degrees. b Symmetry code 1 -
x, y, 0.5 - z.
thermal decomposition is complex due to redox reactions
leading to the formation of elemental Sb.
Figure 6. DTA, TG, and MS curves for [Mn(tren)]2Mn2Sb4S10 (Tp ) peak
temperature; m/z ) 34 (H2S); m/z ) 99 (tren)).
Synthetic Aspects. On the basis of the results of the
thermal decomposition reaction of compound 1, the amine-
poorer compound [Mn(tren)]2Mn2Sb4S10 (50 mg, 0.038
mmol) was used as the source in a solvothermal synthesis
by applying 2 mL of tren and heating the mixture at 140
°C. After 14 days compound 1 was obtained in a good yield
as a crystalline powder along with an unknown crystalline
product.
Density Functional Calculations. The obtained structure
of [Mn(tren)]2Sb2S5 from DFT calculations is shown in
Figure 7, right, and key structural parameters are compared
to experimental parameters in Table 3. The overall structure
calculated with DFT is quite similar to the experimentally
determined one (Figure 7, left). Bond lengths of the Mn2-
Sb2S5 subunit are in general obtained about 0.1 Å too long,
which is not unusual for heavy atoms in nonrelativistic
calculations. In the crystal structure, the two MnSbS2 planes
(MnSbS(1)S(2) and the symmetry-related plane in Figure 7)
are planar and parallel to each other, resulting in an effective
C2 symmetry of the molecule (vide supra). In contrast, the
calculated structure is only of C1 symmetry (Experimental
Section). This is due to the formation of new hydrogen
bridges in the gas phase as indicated in Table 3 that lead to
a distortion of the structure. In particular, the Mn(a)Sb(a)S-
(1a)S(2a) square is somewhat distorted from planarity,
mediate showed the reflections of compound 2 together with
some weak reflections of elemental Sb. According to the
MS data during the second decomposition, tren and H2S are
released (Figure 5). Therefore, we suggest that [Mn-
(tren)]2Sb2S5 decomposes during the first step in the follow-
ing way: 2[Mn(tren)]2Sb2S5 f [Mn(tren)]2Mn2Sb4S10
+
2tren. An interesting structural aspect is that the structure of
2 can be constructed using two [Mn(tren)]MnSb2S5 fragments
which in turn may be obtained by the removal of one tren
molecule from compound 1. We note that the thermal
transformation of compound 1 in 2 is not complete because
elemental Sb is formed during the reaction.
Figure 6 shows the thermal decomposition of [Mn-
(tren)]2Mn2Sb4S10 at 4 °C/min until 350 °C. One strong
endothermic event occurs at Tp ) 307 °C. The experimental
mass loss of 21.3% is in agreement with that expected for
the removal of both tren ligands (-∆m(tren)theo ) 22.2%).
Additional mass spectroscopy demonstrates that the thermal
decomposition of 2 is accompanied by the emission of tren
and H2S. In the gray residue, elemental Sb, Sb2S3, and MnS
could identified with XRD and small amounts of organic
residues were also found (CHNsum 2.4%). Formally, the
reaction can be described as [Mn(tren)]2Mn2Sb4S10 f 4MnS
+ 3Sb + Sb2S3 + 3H2S + 2tren. We stress here that the
Inorganic Chemistry, Vol. 43, No. 9, 2004 2919

Schaefer et al.
geometry of the complex. To further explore the relationship
between the Sb-S(3)-Sb(a) angle and the steric demand
of the coordinated metal fragment, calculations have been
performed on smaller, hypothetical systems. Geometry
optimization of the sterically less crowded model [Ni-
(NH3)2]2Sb2S5 leads to an overall structure that is comparable
to [Mn(tren)]2Sb2S5, but with an Sb-S-Sb angle of only
113°. This further supports the conclusion that the large value
of the Sb-S-Sb coordinate in [Mn(tren)]2Sb2S5 is due to
steric strain. It also shows that the overall geometric structure
of [TM(L)]2Sb2S5 complexes (TM ) transition metal; L )
ligand(s)) as shown in Figure 7 is independent of the
paramagnetism of Mn(II). The obtained structure of [Ni-
(NH3)2]2Sb2S5 shows severe distortions due to strong hy-
drogen bonds between the terminal (negatively charged)
sulfur atoms of the [Sb2S5]4- subunit and NH3 groups
coordinated to Ni. To further explore this point, calcula-
tions have been performed on the model compound [Ni-
(tma)2]2Sb2S5, where no such hydrogen bonds can be formed.
Indeed, this leads to a much more open structure where the
Ni(tma)2 subunits are rotated away from each other and the
Sb-S-Sb angle decreases further to 103°.
Conclusions
The major aim of our work is the understanding of the
influence of different parameters which determine the product
formation under solvothermal conditions. In addition, the
structure-property relationship is another important part of
our investigations. The final goal of the work is the
optimization of the syntheses to reach a state where a more
directed synthesis of thioantimonates(III) is possible. In the
present paper we demonstrated that the solvothermal route
allows the preparation of TMn+-containing thioantimonates-
(III). Furthermore, we showed that the directed thermal
decomposition of a suitable precursor material such as [Mn-
(tren)]2Sb2S5 is a new synthetic approach in thioantimonate-
(III) chemistry. It must be noted that normally the starting
thioantimonates(III) are fully destroyed during such thermal
reactions. Hence, the observation that a well-crystallized new
compound is formed by applying the directed thermal
decomposition is unique in the field of thioantimonate(III)
chemistry. In further experiments we presented evidence that
the product of the thermal reaction can be used as a starting
material for the synthesis of thioantimonate(III) compounds.
In the present case the solvothermal treatment of [Mn-
(tren)]2Mn2Sb4S10 with tren leads to a full conversion into
the starting compound [Mn(tren)]2Sb2S5. This is the first
example that even complex thioantimonates(III) can be used
as sources for the synthesis of new compounds. Further
experiments are under way to find suitable new starting
compounds for the synthesis of thioantimonates with a high
Mn:Sb ratio.
Figure 8. PES scans along the central Sb-S-Sb angle of [Mn(tren)]2Sb2S5
for the crystal structure (top) and the fully optimized structure (bottom).
allowing the H2N(2)-S(2a) bridge to become extremely
short (only 2.36 Å). This leads to a more open structure in
the calculation (see Figure 7) as compared to experiment.
Correspondingly, the Sb-S(3)-Sb(a) angle is reduced from
134° in the crystal structure to 123° in the calculation. This
observation leads to the hypothesis that the large value of
the Sb-S(3)-Sb(a) angle in compound 1 is related to the
steric demand of the coordinated Mn(tren) subunit. To
quantitatively estimate the energetics along the Sb-S(3)-
Sb(a) coordinate, restricted PES scans have been performed
for both the experimental and the calculated structures of
[Mn(tren)]2Sb2S5. Importantly, the PES for the crystal
structure presented in Figure 8 shows that an Sb-S(3)-Sb-
(a) angle of 130-140° represents the actual energy minimum
along this coordinate when all other geometric parameters
are fixed. This is in very good agreement with the experi-
mental value of 134°. Furthermore, the energy required for
an enlargement of this angle to even 150° is still below 10
kcal/mol, which shows that this is an energetically soft
coordinate. A decrease of the Sb-S(3)-Sb(a) angle below
130° is very unfavorable due to steric interactions between
the two Mn(tren) subunits. The PES for the optimized
structure is qualitatively identical (Figure 8), but the mini-
mum is shifted to 123° in accordance with the more open
In the theoretical calculations using crystal structures of
several [TM(L)]2Sb2S5 complexes (vide supra), evidence is
presented that the structure obtained for [Mn(tren)]2Sb2S5
represents a general structural motif for such [TM(L)]2Sb2S5
systems. This is due to the formation of strong hydrogen
2920 Inorganic Chemistry, Vol. 43, No. 9, 2004

New Manganese Thioantimonates(III)
Supporting Information Available: Tables of atomic coordi-
nates, isotropic and anisotropic displacement parameters, and full
bond lengths and angles including details of the structure deter-
mination. This material is available free of charge via the Internet
at http://pubs.acs.org.
bonds, which form a bridge between a Mn(tren) unit and an
opposed sulfur.
Acknowledgment. This work has been supported by the
State of Schleswig-Holstein and the Deutsche Forschungs-
gemeinschaft (DFG). We also thank Inke Jess for the
acquisition of the single-crystal data and Jan Greve for the
thermal measurements.
IC034970+
Inorganic Chemistry, Vol. 43, No. 9, 2004 2921