Unusual syntheses, structures, and electronic properties of compounds containing ternary, T3-type supertetrahedral M/Sn/S anions [M 5Sn(μ3-S)4(SnS4) 4]10- (M = Zn, Co)

Article abstract of DOI:10.1021/ic050466o

A recently discovered series of quaternary compounds of the general type [K_m(ROH)_n][M_xSn_ySe_z] (R = H, Me), containing ternary anions with [SnSe₄]^4-- coordinated transition metal centers (M = Co, Mn, Zn, Cd, Hg) has now been extended by the synthesis and characterization of the two ortho-thiostannate- coordinated species, [Na₁₀(H₂O)₃₂][M ₅Sn(μ₃-S)₄(SnS₄) ₄]·2H₂O (M = Zn (1), Co (2)). The central structural motifs of compounds 1 and 2 are highly charged [M₅Sn(μ ₃-S)₄(SnS₄)₄]^10- anions, being the first T3-type supertetrahedral ternary anions reported to date. The exposure of single crystals of 2 to a dynamic vacuum for several hours resulted in the reversible formation of a partially dehydrated, but still monocrystalline material of the composition [Na₁₀(H₂O) ₆][Co₅Sn(μ₃-S)₄-(SnS ₄)₄] (3). The loss of 28 of the 34 water molecules only slightly affects the internal structure of the ternary anion in 3 and leads to a significant compacting of the crystal structure with closer linkage of the [Co₅Sn₅S₂₀]^10- cluster units via the Na⁺ cations. Magnetic measurements on 3 show that the ground state of the Co/Sn/S cluster is S = 1/2, indicating a significant antiferromagnetic coupling between the Co centers, which has also been rationalized by DFT investigations of the electronic situation in the ternary subunits of 1-3.

Full text of DOI:10.1021/ic050466o

Inorg. Chem. 2005, 44, 5686−5695
Unusual Syntheses, Structures, and Electronic Properties of
Compounds Containing Ternary, T3-Type Supertetrahedral M/Sn/S
-
Anions [M5Sn(
µ
3-S)4(SnS4)4]10 (M
)
Zn, Co)
Christian Zimmermann,† Christopher E. Anson,† Florian Weigend,‡ Rodolphe Cle´rac,§ and
Stefanie Dehnen*,†
Institut fu¨r Anorganische Chemie der UniVersita¨t Karlsruhe (TH), Institut fu¨r Nanotechnologie,
Forschungszentrum Karlsruhe GmbH, Germany, and Centre de Recherche Paul Pascal,
CRPP-CNRS UPR 8641, 115 AVenue du Dr A. Schweitzer 33600 Pessac, France
Received March 29, 2005
A recently discovered series of quaternary compounds of the general type [Km(ROH)n][MxSnySez] (R
) H, Me),
containing ternary anions with [SnSe4]4--coordinated transition metal centers (M
)
Co, Mn, Zn, Cd, Hg) has now
been extended by the synthesis and characterization of the two ortho-thiostannate-coordinated species,
[Na10(H2O)32][M5Sn( 3-S)4(SnS4)4] 2H2O (M Zn (1), Co (2)). The central structural motifs of compounds 1 and
2 are highly charged [M5Sn(
3-S)4(SnS4)4]10- anions, being the first T3-type supertetrahedral ternary anions reported
to date. The exposure of single crystals of 2 to a dynamic vacuum for several hours resulted in the reversible
formation of a partially dehydrated, but still monocrystalline material of the composition [Na10(H2O)6][Co5Sn( 3-S)4-
(SnS4)4] (3). The loss of 28 of the 34 water molecules only slightly affects the internal structure of the ternary anion
µ
‚
)
µ
µ
10-
in 3 and leads to a significant compacting of the crystal structure with closer linkage of the [Co5Sn5S20
units via the Na+ cations. Magnetic measurements on 3 show that the ground state of the Co/Sn/S cluster is S
1/2, indicating a significant antiferromagnetic coupling between the Co centers, which has also been rationalized
by DFT investigations of the electronic situation in the ternary subunits of 1 3.
]
cluster
)
−
Introduction
Compounds with group 15/16 binary fragments coordinat-
ing to transition metal centers, M, have usually been
synthesized from salts of the binary anions of the respective
group (15 or 16). In contrast, most of the known compounds
with elemental combinations M/14/16 or M/13/16 have been
prepared using separate sources for the M, E′, and E atoms.
Recent examples include clusters, such as [Cu11In15Se16-
The formation of compounds that contain ternary heavy
atom M/E′/E frameworks, in which binary aggregates of main
group elements [E′xEy]q- (E′ or E ) group 13-15 or group
16) are stabilized by coordination to transition metal ions
Mn+, is an area of increasing research activity.1,2 This is the
result both of their multifaceted structural variety and the
interesting optoelectronic and magnetic properties of the
resulting ternary or multinary compounds that in some cases
combine the properties of the formally underlying binary
phases.3
(SePh)24(PPh3)4],4 phases containing ligand-free Cd/In/S
anions,5 such as [Cd16In64S134
]
,
and solids, such as
44- 5c
A2[MnGe4S10]‚nH2O (A ) C6H14N2, Rb, Cs; n ) 0, 2, 3),6
A2[Hg3E′2S8] (A ) K, Rb; E′ ) Ge, Sn),7 and [Mn2-
{H2N(CH2)2NH2}Sb2S5].8
* To whom correspondence should be addressed. E-mail: dehnen@
aoc.uka.de. Phone: int + 49/721-608-2850. Fax: int + 49/721-608-7021.
† Institut fu¨r Anorganische Chemie der Universita¨t Karlsruhe.
‡ Institut fu¨r Nanotechnologie.
(3) Solymar, L.; Walsh, D. Electrical Properties of Materials, 6th ed.;
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§ Centre de Recherche Paul Pascal.
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J.; Fu, H.-X. J. Am. Chem. Soc. 2002, 124, 12944-12945. (c) Li, H.;
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42, 1819-1821.
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Loose, A.; Sheldrick, W. S. Z. Naturforsch. 1997, 52b, 687-692.
(1) Feng, P.; Bu, X.; Zheng, N. Acc. Chem. Res. 2005, 38, 293-303. (b)
Bu, X.; Zheng, N.; Feng, P. Chem.sEur. J. 2004, 10, 3356-3362.
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5686 Inorganic Chemistry, Vol. 44, No. 16, 2005
10.1021/ic050466o CCC: $30.25
© 2005 American Chemical Society
Published on Web 07/13/2005

T3-Type Supertetrahedral M/Sn/S Anions
However, the syntheses of (Me4N)2[Mn2Ge4S10] from
(Me4N)4[Ge4S10],9 that of K2[HgSnTe4]10 from K4[SnTe4],
and the recently reported formation of mesoporous phases,
such as (CP)x[PtyE′4E10] (CP ) cetylpyridinium, E′ ) Ge,
Sn; E ) S, Se; x ) 1.9-2.8; y ) 0.9-1.6)11 and (CTA)2-
[M2Ge4S10] (M ) Co, Ni, Zn),12 demonstrated the synthetic
potential of group 14/16 binary anions in reactions toward
transition metal salts. The elemental combinations and
structures of these phases result in narrow band gaps or
intense photoluminescence; and such compounds have
therefore been considered potentially suitable for opto-
electronic, photosynthetic, or photocatalytic applications.11
In the course of our investigations of the reactivity and
coordination chemistry of chalcogenostannate anions, we
recently described the synthesis of a series of novel
complexes featuring discrete ternary anions of the general
type [M4(µ4-Se)(SnSe4)4]10- (M ) Co, Mn, Zn, Cd, Hg),13
being the first molecular M/Sn/Se complexes to be free of
covalently bound ligands. The coordination oligomers were
stabilized, exclusively, through coordinative interactions with
different complex counterion aggregates. These anionic
substructures were the first to show the desired transfer of
intact [SnSe4]4- ions into the coordination sphere of transition
metal ions. Recently, a series of solvent-free sulfur analogues,
K10[M4(µ4-S)(SnS4)4] (M ) Mn, Fe, Co, Zn), was also
reported; they were, however, prepared differently employing
a potassium-polysulfide flux.14
for a significant antiferromagnetic coupling between the µ3-
S-bridged CoII centers, which was confirmed by analyses of
the spin density calculated for the Co/Sn/S anion.
Experimental Methods
Starting Materials. ZnX2 (X ) Cl, Br) were purchased from
Merck, and [Co(en)3]X3 (en ) 1,2-diaminoethane; X ) Cl, Br)
were prepared according to literature procedures.15a Na4[SnS4] was
prepared by a method similar to that previously described;15b an
alternative method to provide a suitable aqueous solution of
Na4[SnS4] has been the in situ reaction of stoichiometric amounts
of SnCl4 and Na2S in water.15c All synthesis steps were performed
with strong exclusion of air and external moisture (N2 atmosphere
on a high-vacuum, double-manifold Schlenk line or Ar atmosphere
in a glovebox). THF was dried and freshly distilled prior to use;
the water was degassed. 119Sn NMR data for Na[SnS4] in D2O were
from (a) a saturated solution (68.9 ppm (s)) and (b) a solution with
a concentration of <10-3 mol L-1 (73.7 ppm (s)).
Synthesis of [Na10(H2O)32][Zn5Sn(µ3-S)4(SnS4)4]‚2H2O (1).
ZnCl2 (0.066 g, 0.50 mmol) was added to a solution of 0.170 g
(0.50 mmol) of Na4[SnS4] in 14 mL of H2O. After the mixture
was stirred for 4 h, the colorless solution was layered with 10 mL
of THF. Compound 1 crystallized as colorless needles, over the
course of 2 days. Isolation by decanting the mother liquor and the
loose precipitate and drying compound 1 leads to partial dehydra-
tion, as observed for compound 2 (vide infra). In contrast to 2,
such dehydration always resulted in X-ray amorphous material with
differing H2O content as determined from elemental analysis.
Yield: 0.119 g (0.050 mmol, 50% based on Zn).
Synthesis of [Na10(H2O)32][Co5Sn(µ3-S)4(SnS4)4]‚2H2O (2).16
[Co(en)3]Cl3 (0.160 g, 0.46 mmol) or [Co(en)3]Br3 (0.220 g, 0.46
mmol) was added to a solution of 0.170 g (0.50 mmol) of Na4[SnS4]
in 14 mL of H2O; upon the addition, the reaction mixture
immediately turned dark brown. After the mixture was stirred for
12 h, an insoluble black precipitate, containing CoS and S, was
removed by filtration. The remaining solution was layered with 14
mL of THF. Over the course of 2 days, the solution became lighter
in color upon crystallization of black blocks of 2 together with
further black precipitate, presumably further amounts of CoS and
The investigations on the [SnE4]4- anions are now
extended by the use of the lighter homologous salt Na4[SnS4].
Here, we present the syntheses and crystal structures of the
novel compounds [Na10(H2O)32][M5Sn(µ3-S)4(SnS4)4]‚2H2O
(M ) Zn (1), Co (2)) and the partial dehydration product of
2, [Na10(H2O)6][Co5Sn(µ3-S)4(SnS4)4] (3). The molecular
charge of the anions, which necessitates the statistical
distribution of five M atoms and one Sn atom over six atomic
positions within the anions, was determined from the ten
Na+ ions in all three X-ray structures and is in agreement
with the chemical analyses, the quantumchemical investiga-
tions using density functional (DFT) methods, and the
magnetic behavior of the open-shell Co compounds. The
latter was investigated by magnetic measurements of a
polycrystalline sample of compound 3. These show evidence
(15) (a) Gmelins Handbuch der Anorganischen Chemie; Verlag Chemie
GmbH: Weinheim, Germany 1964; 8. Aufl., Kobalt B. (b) Eisenmann,
B.; Hansa, J. Z. Kristallogr. 1993, 203, 299-300. (c) Schiwy, W.;
Pohl, S.; Krebs, B. Z. Anorg. Allg. Chem. 1973, 402, 77-86.
(16) Compounds with ternary Co/Sn/S anions can only be isolated when
the reactivity of the Co2+ or Co3+ ion is reduced by coordinating
ligands; en complexes are be suitable starting materials for this purpose
because they are water soluble and the ligands allow for a controlled
reaction but finally leave the coordination sphere upon reaction with
[SnS4]4-. The synthesis of compound 2 can also be carried out using
[Co(en)2X2]X (X ) Cl, Br); however, the product shows higher
crystallinity when the reaction is performed as described. This probably
results from a slower reaction rate caused by the presence of an
additional chelating en ligand to be removed during formation of 2.
In contrast, reactions of CoX2 (X ) Cl, Br) with [SnS4]4- anions lead
to quantitative formation of CoS. Complexation of these salts by
multidentate polyamines (such as tetren, C8H23N5) help to control the
reaction to produce 2, as well, but the yields are lower than those
produced via the described route. Reactions of other transition metal
salts or complexes with Na4[SnS4] produce appropriately colored
solutions in some cases (e.g., with Mn2+, Cd2+, Hg2+) but do not yield
crystalline products, which may be the result of the (larger) ionic radii
to the [SnS4]4- ion leading to an anion too large to crystallize with
Na+ counterions in the present structure type. Reactions with suitably
sized ions (e.g., Cu+, Fe3+), however, lead to redox processes under
the given reaction conditions. Variations of both the reaction conditions
and the starting materials that allow the formation of stable ternary
networks containing further transition metal ions are the focus of our
current work.
(7) Liao, J.-L.; Marking, G. M.; Hsu, K. F.; Matsushita, Y.; Ewbank, M.
D.; Borwick, R.; Cunningham, P.; Rosker, M. J.; Kanatzidis, M. G.
J. Am. Chem. Soc. 2003, 125, 9484-9493.
(8) Schur, M.; Bensch, W. Z. Naturforsch. 2002, 57b, 1-7.
(9) Yaghi, O. M.; Sun, Z.; Richardson, D. A.; Groy, T. L. J. Am. Chem.
Soc. 1994, 116, 807-808.
(10) Dhingra, S. S.; Haushalter, R. C. Chem. Mater. 1994, 6, 2376-2381.
(11) Trikalitis, P. N.; Rangan, K. K.; Kanatzidis, M. G. J. Am. Chem. Soc.
2002, 124, 2604-2613.
(12) McLachlan, M. J.; Coombs, N.; Ozin, G. A. Nature 1999, 397, 681-
684.
(13) (a) Zimmermann, C.; Melullis, M.; Dehnen, S. Angew. Chem., Int.
Ed. 2002, 41, 4269-4272. (b) Dehnen, S.; Brandmayer, M. K. J. Am.
Chem. Soc. 2003, 125, 6618-6619. (c) Melullis, M.; Zimmermann,
C.; Anson, C. E.; Dehnen, S. Z. Anorg. Allg. Chem. 2003, 629, 2325-
2329. (d) Brandmayer, M. K.; Cle´rac, R.; Weigend, F.; Dehnen, S.
Chem.sEur. J. 2004, 10, 5147-5157.
(14) (a) Palchik, O.; Iyer, R. G.; Canlas, C. G.; Weliky, D. P.; Kanatzidis,
M. G. Z. Anorg. Allg. Chem. 2004, 630, 2237-2247. (b) Palchik, O.;
Iyer, R. G.; Liao, J. H.; Kanatzidis, M. G. Inorg. Chem. 2003, 42,
5052-5054.
Inorganic Chemistry, Vol. 44, No. 16, 2005 5687

Zimmermann et al.
S. Yield: 0.132 or 0.157 g (0.056 or 0.066 mmol, 61% or 72%
based on Co used as [Co(en)3]Br3 or [Co(en)3]Cl3, respectively).
As observed with 1, drying of isolated crystals causes loss of water
molecules. The dehydration product of 2 with 28 fewer water
molecules per formula unit is still crystalline and is therefore
discussed separately (compound 3).
plates and pulverized. The resulting suspension was investigated
by means of a Perkin-Elmer Lambda 900 UV/Vis/NIR spectrometer
between 250 and 1100 nm.
Magnetic Measurements. The magnetic susceptibility measure-
ments were obtained using a Quantum Design Squid magnetometer
MPMS-XL. The samples of 3 were prepared in a glovebox under
an argon atmosphere and packed in a sealed plastic bag. The raw
data were corrected for the sample holder and the orbital diamag-
netic contributions calculated from Pascal’s constants.18 The sample
has been systematically checked for ferromagnetic impurities, which
were found to be absent by measuring the field dependence of the
magnetization at T ) 100 K and the temperature dependence of
the dc susceptibility at H ) 1000 and 10 000 Oe. Temperature-
independent paramagnetism (TIP) was systematically observed and
removed in all samples. The estimation of the TIP was determined
experimentally by consideration of the residual S ) 1/2 Curie
paramagnetism which should be a plateau in the øT versus T plot.
The observed TIP values range from 0.9 to 1.4 × 10-6 emu g-1 of
Co (1.6 to 2.5 × 10-3 emu mol-1 of Co) on the seven different
batches of 3 measured.
Synthesis of [Na10(H2O)6][Co5Sn(µ3-S)4(SnS4)4] (3). The single
crystals of a complete batch of 2 were isolated by decanting both
the mother liquor and the loose byproduct precipitate, and the
washing procedure was repeated with a THF/H2O (1/1) mixture.
The solid material (0.157 g) was then pumped with dynamic
vacuum for 5 h. The crystals changed appearance, compared to
that of the starting material, 2; a metallic luster appeared, and
cracking of the crystal surfaces was observed. The yield is
quantitative with respect to 2. The majority of the partially
dehydrated crystals were suitable for X-ray structure determination.
Although some of the individual crystals tested showed poor quality,
determination of the lattice parameters was possible in all cases;
therefore, the yield is assumed to be quantitative with respect to 2.
A reversal of the partial dehydration process is possible by addition
of a droplet of water (0.02 mL) to a sample of 3, regenerating single
crystals of 2.
Theoretical Methods. Density functional (DFT) calculations19
were performed using the program system Turbomole20 (Ridft
program,21 Becke-Perdew functional (BP86),22 basis sets of TZVP
NMR Spectroscopy. 119Sn NMR data were recorded using a
Bruker AVANCE 400 MHz spectrometer at a frequency of 142.21
MHz.
(17) (a) Sheldrick, G. M. SHELXTL, version 5.1; Bruker AXS Inc.:
Madison, 1997. (b) The observed disorder in compounds 1 and 2 can
be described as follows: Na(8) and Na(9) lie on inversion centers,
and each appeared at first to be surrounded by four further Na cations,
Na(11), Na(11′), Na(13), and Na(13′) about Na(8), and Na(12),
Na(12′), Na(14), and Na(14′) about Na(9). These were then apparently
bridged by (µ3-OH) ligands, O(28) and O(29) and O(32) and O(33),
respectively. However, the thermal parameters for Na(11) to Na(14)
were too high if they were refined with unit occupancy, and attempts
to refine the four oxygen atoms anisotropically resulted in unreasonable
thermal parameters. However, if Na(11) to Na(14) were refined at
half occupancy, their temperature factors came into line with the
ordered sodium centers in the structure. Furthermore, the four oxygen
sites could readily each be split into a pair of adjacent half atoms,
which could also then be refined normally, in each case, one bridging
to one-half of a sodium atom (e.g., Na(11)) and the other bridging to
the other sodium of the disorder pair (e.g., Na(12)), both with normal
geometries. We thus assign each of the cationic units centered at Na(8)
and Na(9) as 2-fold disordered [Na3(µ-OH2)4]3+ units. Note that if
the sodium atoms are all refined with full occupancies (i.e., assuming
no disorder), the geometries at the oxygen atoms become such that it
is necessary to assign them as triple-bridging hydroxo ligands, and
the units as [Na5(µ3-OH)4]+. The overall effect is the reduction of the
positive charge available; it does not increase it. Similarly, it was found
that refinement of Na(10) and its coordinated waters with unit
occupancy was unsatisfactory, but that Na(10) could be successfully
refined at half occupancy, together with an adjacent one-half of an
oxygen atom (O(34A) in the cif file), which made normal hydrogen-
bonding distances to adjacent ordered oxygen atoms possible, while
the oxygen atoms coordinated to Na(10) could all be split and refined
as pairs of one-half of an oxygen. It was found that the disorder at
these three sites was correlated; the disordered oxygen atoms labeled
A in the cif file, together with Na(11) and Na(12), form one set of
atoms that made sensible nonbonding contacts, while the oxygen atoms
labeled B in the cif file, with Na(10), Na(13), and Na(14), formed a
second mutually consistent set. Two further oxygen atoms, O(5),
O(19), O(23), and O(26), were also disordered, but without correlating
to either of the two above sets of atoms.
Elemental Analyses. From elemental analyses of partially dried
(i.e., partially dehydrated) samples of 1 and 2, the ratios of the
elements are as follows (referring to weight %): Na/Zn/Sn/S as
1/1.43/2.57/2.76 (1) and Na/Co/Sn/S as 1/1.28/2.57/2.74 (2). The
calculated ratios for Na10M5Sn5S20‚n(H2O) are 1/1.42/2.58/2.79 (M
) Zn, 1) and 1/1.28/2.58/2.79 (M ) Co, 2), in excellent agreement
with the experimentally observed data. Details of the analytical
procedures are available from www.ianz.govt.nz.
X-ray Diffractometry. X-ray data were collected on a Bruker
SMART Apex CCD diffractometer using graphite-monochromated
Mo KR radiation (λ ) 0.71073 Å) at T ) 200 K. Structure solution
by direct methods and full-matrix least-squares refinement against
F2 were carried out using the SHELXTL software package.17a The
non-hydrogen atoms were anisotropically refined; H atoms on the
water O atoms were not included. Initially the six metal centers in
the central octahedron, M(1-6) (M ) Co, Zn), were assigned as
the respective metal, with the four outer tin sites refined as Sn.
This resulted in significantly lower temperature factors for M(1-
6) compared to that of the other atoms in the clusters. As discussed
in more detail below, the six “metal” sites were each refined,
following the full elemental analysis for 2 which indicated a Co/
Sn molar ratio of 5/5, with composition {5/6M + 1/6Sn}, modeling
a statistical disorder of 1 Sn atom and 5 M atoms over these six
apparently equal positions. This resulted in thermal parameters
consistent with the other atoms, and no attempt was made to vary
the occupancies between the atoms or to refine the four outer Sn
sites with slight admixtures of Co or Zn.
(18) Theory and Applications of Molecular Paramagnetism; Boudreaux,
E. A., Mulay, L. N., Eds.; John Wiley & Sons: New York, 1976.
(19) (a) Parr, R. G.; Yang, W. Density Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1988. (b) Ziegler,
T. Chem. ReV. 1991, 91, 651-667.
(20) (a) Ahlrichs, R.; Ba¨r, M.; Ha¨ser, M.; Horn, H.; Ko¨lmel, C. Chem.
Phys. Lett. 1989, 162, 165-169. (b) Treutler, O.; Ahlrichs, R. J. Chem.
Phys. 1995, 102, 346-354. (c) von Arnim, M.; Ahlrichs, R. J. Chem.
Phys. 1999, 111, 9183-9190.
(21) (a) Eichkorn, K.; Treutler, O.; O¨ hm, H.; Ha¨ser, M.; Ahlrichs, R. Chem.
Phys. Lett. 1995, 242, 652-660. (b) Eichkorn, K.; Weigend, F.;
Treutler, O.; Ahlrichs, R. Theor. Chim. Acta 1997, 97, 119-124.
Two (in 1 and 2) or three (in 3) Na atoms show 2-fold disorder,
and several O atoms show 2-fold (in 1-3) or 3-fold (in 1) disorder;
in 1 and 2, one Na atom has an 0.5 site occupancy. Most of these
disordered atoms were successfully refined anisotropically, although
a few Na (3) and O atoms (2 and 3) were refined isotropically.
Further details of the single-crystal X-ray diffractometry are
summarized in Table 1 and ref 17b.
Optical Absorption Spectroscopy. Single crystals of 1 and 2
were transferred into a droplet of Nujol oil between two quartz
5688 Inorganic Chemistry, Vol. 44, No. 16, 2005

T3-Type Supertetrahedral M/Sn/S Anions
Table 1. Crystallographic and Refinement Details of 1-3 at 203 K
1
2
3
empirical formula
fw (g mol-1
H68O34Zn5Na10S20Sn5
2403.94
H68O34Co5Na10S20Sn5
2371.74
H12O6Co5Na10S20Sn5
1867.30
)
cryst color and shape
cryst size
cryst syst
space group
a (Å)
colorless needle
0.13 × 0.17 × 0.22
triclinic
black block
0.15 × 0.08 × 0.20
triclinic
black block
0.12 × 0.15 × 0.22
triclinic
P1h (No. 2)
14.8457(10)
14.8772(9)
17.5101(11)
97.402(1)
100.211(1)
103.956(1)
3633.6(4)
2
2.197
4.007
3-56
multiscan (SADABS)
0.557/0.831
18078
15329
0.0404
P1h (No. 2)
14.712(2)
14.737(2)
17.142(2)
97.298(2)
99.264(2)
103.868(3)
3507.5(8)
2
2.185
3.504
3-56
multiscan (SADABS)
0.361/0.801
17136
14651
0.0444
P1h (No. 2)
13.436(2)
13.570(2)
14.105(2)
95.770(3)
117.889(3)
98.364(3)
2206.7(6)
2
2.810
5.674
4-55
multiscan (SADABS)
0.550/0.831
8187
7622
0.0256
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
F
calc (g cm-3
)
µ(Mo KR) (mm-1
2θ range (deg)
)
abs correction type
min/Tmax
T
no. of measured reflns
no. of independent reflns
R(int)
no. of independent reflns
with I > 2σ(I)
11168
8867
4912
no. of parameters
wR2 (all data)
827
0.1593
1.003
686
0.1819
1.028
450
0.1822
1.069
S (all data)
R1 (I > 2σ(I))
0.0551
1.358/-1.484
415235
0.0625
1.718/-1.207
415234
0.0676
2.811/-1.278
415219
largest difference peak/hole [e- Å-3
CSD number
]
Scheme 1. Synthesis of 1
Scheme 2. Synthesis of 2 and 3
quality,21b relativistic effective core potentials23 (ECP) for the inner
46 electrons of Sn). Both compensation of the negative charges of
the calculated molecules and simulation of the charges of the two
H atoms per cluster unit were achieved by employing the Cosmo
model,23 which has previously turned out to be suitable for these
purposes.13 Calculations were performed without symmetry restric-
tions (C1 symmetry); therefore, convergence into local minimum
structures can be expected.
to give [Sn2S6]2- and S2-, as previously observed for the
[SnSe4]4- homologues.13
Results and Discussion
Compounds 1-3 are ionic compounds that contain the
complex ternary anions [M5Sn(µ3-S)4(SnS4)4]10- (M ) Zn,
Co) together with 10 Na+ ions as determined by X-ray
diffractometry on all three compounds. The accuracy of this
formulation was confirmed by elemental analysis of samples
of partially dehydrated compound 2 and is further underlined
by only small deviations between the structural data from
the DFT optimizations of the anionic [M5Sn5S20]10- units
and the experimental values (vide infra).
The compositions of 1-3 show that the [SnS4]4- anions
of the starting material have acted as ligands, as S2- donors,
and as a source for SnIV centers. Reactions using K4[SnSe4]
usually produce crystals of [K4(MeOH)4][Sn2Se6] as coprod-
ucts, whereas a compound like Na4[Sn2S6] did not precipitate
during the synthesis of 1 or 2. However, traces of elemental
sulfur that precipitated during the preparation of 2 on the
glass wall of the Schlenk tube indicated the occurrence of
Synthesis. The synthesis of 1, [Na10(H2O)32][Zn5Sn(µ3-
S)4(SnS4)4]‚2H2O, from Na4[SnS4] and ZnCl2 is summarized
in Scheme 1. Scheme 2 shows the reaction of Na4[SnS4] with
[Co(en)3]X3 (X ) Cl, Br) in water that yields compound 2,
[Na10(H2O)32][Co5Sn(µ3-S)4(SnS4)4]‚2H2O,16 and the revers-
ible dehydration of 2 to give compound 3, [Na10(H2O)6]-
[Co5Sn(µ3-S)4(SnS4)4]. The observation of elemental sulfur
occurring in the synthesis of 2 is consistent with the reduction
of the CoIII centers by S2- anions. The latter were available
for the reduction as well as for the formation of compounds
1 and 2, resulting from partial dimerization of [SnS4]4- anions
(22) (a) Becke, A. D. Phys. ReV. A 1988, 38, 3098-3109. (b) Vosko, S.
H.; Wilk, L.; Nusair, M. Can. J. Phys. 1980, 58, 1200-1205. (c)
Perdew, J. P. Phys. ReV. B 1986, 33, 8822-8837.
(23) Dolg, M.; Stoll, H.; Savin, A.; Preuss, H. Theor. Chim. Acta 1989,
75, 173-194.
Inorganic Chemistry, Vol. 44, No. 16, 2005 5689

Zimmermann et al.
Table 2. Distances (Å) and Angles (deg) of Ternary Anions and Counterion Aggregates in 1-3a
1 (Zn/Sn)
2 (Co/Sn)
3 (Co/Sn)
Sn-Sterm
2.3531(16)-2.3632(17)
2.3964(17)-2.4152(16)
2.3533(16)-2.3970(16)
2.3241(17)-2.3494(18)
3.706(2)-3.755(2)
2.343(3)-2.358(3)
2.381(3)-2.398(3)
2.302(3)-2.352(3)
2.281(3)-2.299(3)
3.628(4)-3.685(3)
2.349(5)-2.363(4)
2.412(4)-2.447(4)
2.318(5)-2.357(4)
2.320(4)-2.349(4)
3.706(5)-3.755(5)
Sn-(µ-S)
M-(µ-S)
M-(µ3-S)
M‚‚‚M (Oh edges)
Sterm-Sn-(µ-S)
(µ-S)-Sn-(µ-S)
(µ-S)-M-(µ-S)
(µ-S)-M-(µ3-S)
(µ3-S)-M-(µ3-S)
M-(µ-S)-Sn
105.23(6)-109.96(6)
109.38(6)-111.96(6)
101.54(6)-103.65(6)
108.43(6)-110.38(6)
114.78(6)-116.49(6)
103.22(7)-105.45(6)
104.73(6)-106.49(6)
105.87(9)-110.18(11)
108.59(9)-111.69(9)
100.20(10)-103.13(10)
108.89(10)-110.90(10)
113.73(10)-115.69(11)
103.13(11)-105.68(10)
104.82(11)-107.18(11)
106.33(15)-112.9(2)
106.26(15)-111.79(15)
102.78(16)-105.03(17)
106.81(16)-111.65(16)
113.19(15)-116.03(15)
105.40(16)-107.81(18)
105.30(16)-107.93(18)
M-(µ3-S)-M
distances within the counterion aggregate
Na‚‚‚S
Na‚‚‚O
2.843(2)-3.047(4)
2.343(9)-2.865(15)
2.793(16)-3.024(5)
2.291(18)-2.83 (4)
2.75(4)-3.24(5)
2.33(5)-2.73(6)
a
M ) Zn or Sn for 1 and M) Co or Sn for 2 and 3 in the case of the six core atoms.
the 2CoIII + S2- f S + 2CoII redox reaction. This is
consistent with the assumption of formal oxidation states CoII,
SnIV, and S2- in the ternary anions in 2 and 3, and the
analogous reaction has been observed in related reactions
of [SnSe4]4- anions. The standard redox potentials in basic
solution (pH ≈ 12 for 10-3 mol L-1 [SnS4]4-) also indicate
that the [CoIII(en)3]3+ f [CoII(en)3]2+ process should take
place (E01/2 ) -0.18 V;25a 2- f 1/8S8, E01/2 ) -0.48 V.25b
S
Crystal Structures. Compound 1 forms very small
colorless needles. Compound 2 crystallizes as black blocks
that are brownish in thin layers. The material is very air-
sensitive and decomposes upon redissolution in H2O. How-
ever, crystals of 2 could be isolated without decomposition
by rapid transfer into polyfluoroether oil for the X-ray
investigation. Attempts to isolate dry material by washing
away the coprecipitating byproducts (see Experimental
Methods) with a water/THF (1/1) mixture and then removing
the residual solvent leads to partial dehydration of 2 resulting
in the formation of black single crystals of 3.
The central structural motif of 1-3 is purely inorganic
discrete ternary anions of [M5Sn(µ3-S)4(SnS4)4]10- that are
embedded in a coordination sphere of solvated Na+ ions.
Because the structural parameters of the ternary anions in
1-3 differ only slightly, the structure of the anion in 1 is
shown as an example in Figure 1; the same numbering
scheme is used for all three clusters. Table 2 summarizes
structural parameters of the anions and the embedding
counterion aggregate.
Figure 1. Fifty percent probability thermal ellipsoid plot of the ternary
anion in 1. Note that the positions of M atoms (Zn in 1, shown here; Co in
2) and Sn(5) are statistically occupied in a 5/1 ratio; each of these six sites
was refined as a superposition of M (sof ) 0.833) and Sn (sof ) 0.167).
remaining four ∆-(M, Sn)3 faces of the M5Sn octahedron so
that four further adamantane-type cages result, two of which
have the composition [M3SnS6] and two are [M2Sn2S6]; each
of the outer Sn atoms is additionally coordinated by one
terminal sulfur ligand. The latter define the corners of a T3-
type supertetrahedron with S‚‚‚S edge distances of 11.316(2)-
11.477(3) (1), 11.180(5)-11.384(5) (2), and 11.360(7)-
11.564(9) Å (3). However, a slight deviation from tetrahedral
geometry is observed, which is reflected by the variation of
bond lengths around mean values (to a maximum of (0.022,
(0.034, and (0.018 Å in 1, 2, and 3, respectively) and by
the observed ranges of angles (maximum differences of
respective angles of 4.73° in 1, 4.30° in 2, and 6.67° in 3).
It was not possible to determine the position of the extra
Sn atom within the inner M5Sn fragment. Neither distinct
differences in the metal-sulfide distances nor an irregularity
of the thermal ellipsoids pointed to a definite Sn position,
which indicates an even statistical distribution of the Sn atom
over the corners of the octahedron. However, only by
considering a partial occupation of Sn on the Co sites (1/6
vs 5/6) was it possible to bring the values of the respective
thermal parameters into line with those of the other heavy
atoms within the cluster anion. Whereas the presence of these
“inner” Sn atoms in 1-3 can be considered certain, their
origin is still unclear. It is known that [SnS4]4- anions can
undergo hydrolysis in an aqueous solution to form complexes
In the ternary anions of 1-3, five zinc or cobalt centers
that form a square pyramid and one additional tin atom are
arranged in a slightly distorted octahedral manner, being
linked by four µ3-bridging sulfur ligands at four ∆-(M, Sn)
faces to form an inner adamantane-type M5SnS4 cage (bold
black lines in Figure 1). Four [SnS4]4- units cap the
(24) (a) Klamt, A. J. Chem. Phys. 1995, 103, 9312-9320. (b) Scha¨fer, A.;
Klamt, A.; Sattel, D.; Lohrenz, J. C. W.; Eckert, F. Phys. Chem. Chem.
Phys. 2000, 2, 2187-2193.
(25) (a) Huheey, J. E.; Keiter, E. A.; Keiter, R. L. Anorganische Chemie:
Prinzipien Von Struktur und ReaktiVita¨t, 2nd ed.; de Gruyter: Berlin,
1995; p 477. (b) Hollemann, A. F.; Wiberg, N. Lehrbuch der
Anorganischen Chemie, 100th ed.; de Gruyter: Berlin, 1985; p 543.
(c) Hollemann, A. F.; Wiberg, N. Lehrbuch der Anorganischen
Chemie, 100th ed.; de Gruyter: Berlin, 1985; p 800.
5690 Inorganic Chemistry, Vol. 44, No. 16, 2005

T3-Type Supertetrahedral M/Sn/S Anions
such as [SnS2(SH)2(OH)2]4- 25c which might transform by
ligand exchange into sulfur-free Sn anion complexes. An-
other possibility would be the formation of a larger thio-
stannate aggregate of the yet unprecedented [Sn3S10]8- type
(which can be viewed as an [SnS3]2- adduct of an [Sn2S7]6-
anion or as a fragment of a [SnS3]2- polymeric chain)26 and
its coordination to a hypothetically preformed [Zn5(µ3-S)2-
(SnS4)2]2- unit.
The terminal bonds, Sn-Sterm, are shorter by 0.044-0.054
(1), 0.042-0.046 (2), or 0.064-0.086 Å (3) than those of
the bridging sulfide ligands Sn-(µ-S). Both types of Sn-S
bonds are longer on average (to a maximum of +0.035 Å
for Sn-Sterm or +0.058 Å for Sn-(µ-S)) than the respective
ones in the discrete [M4Sn4S17]10- anions.14 This reflects the
occurrence of harder and thus more tightly coordinating Na+
ions instead of K+ in the crystal lattice.
It appears that the observation of this species, instead of
a [Co6Sn4S20]12- cluster anion stabilized by 12 Na+ ions, is
a result of the packing requirements for a given type of
cation; because of its size, this ternary anion fits perfectly
in the environment of 10 octahedrally coordinated Na+ ions,
whereas a twelve-fold charge could not be compensated
because of lack of space. Thus, the distinct steric demand
of the counterion environment results in the crystallization
of the observed type of anion, at the same time ruling out
the embedding of a different structure which has previously
been observed in the presence of K+ ions. The other type of
discrete ternary anions that have been obtained, so far, by
reacting either K4[SnSe4] or a mixture of K2S/Sn/S with
The differences between the M-(µ-S) and M-(µ3-S) bond
lengths within any one cluster ion in 1, 2, or 3 are not large.
However, the M-(µ-S) distances are longer on average than
the M-(µ3-S) distances, and a similar observation was made
with the [M4Sn4S17]10- cluster anions that have Sn-(µ-S)
bonds longer than the Sn-(µ4-S) bonds.14 The M-(µ-S)
distances are again somewhat larger on average than those
in the cited ternary anions (deviations of -0.013 to +0.052
Å). The values of the Zn-(µ3-S) bonds in 1 lie within the
range of those in the known complexes (NMe4)4[Zn10(µ3-
S)4(SPh)16] (2.301-2.306 Å),33 [Zn10(µ3-S)4(µ-SEt)12(NC7H9)4]
(2.286-2.318 Å),34 or [Zn10(µ4-S)(µ3-S)6(SO4)3(py)9]‚3H2O
(2.267-2.359 Å),35 which are the only further examples of
structurally characterized clusters with “naked” µ3-S bridges
between zinc atoms. The Co-(µ3-S) distances in structurally
related Co-S complexes vary strongly as a result of different
bonding partners at the sulfur atoms (metal or C atom),
varying coordination numbers, and different formal oxidation
states. However, distances from tetracoordinate CoII centers
to (µ3-S) or (µ-SR) ligands were reported to be 2.276-2.371
Å,37 a range that spans the observed Co-(µ3-S) bond lengths
in 2 and 3.
transition metal compounds, [M4Sn4E17]10- 13,14
not only
,
show another composition but also adopt another molecular
structure, which is based on four linked barrelane-type cages
(P1 supertetrahedron). The nature of the alkali metal ion,
together with its preferred coordination environment, seems
to be the key parameter in controlling the observed cluster
structure.
The T3 anionic cluster structure represents the topological
equivalent of a section of the Sphalerite-type structure.
This is also the case for the larger supertetrahedral Cd/In/S
clusters of the Tn family, such as [Cd4In16S35]14- (T4) or
In contrast to the complex counterion aggregates that were
observed in the related M/Sn/Se compounds, the counterion
networks in 1-3 are much less complicated because all of
the Na+ ions are octahedrally coordinated by solvent
molecules or S ligands from the ternary anions. However,
the O/S ratios of the coordination polyhedra [NaO6-nSn]
differ significantly when comparing 1 and 2 (n ) 0-2) on
one hand and 3 (n ) 4-6) on the other hand. Consequently,
the coordination spheres surrounding the anions in 1 and 2,
on one hand, and 3, on the other, are dissimilar from each
other and are thus described separately.
[Cd16In64S134]
44- (T2 arrangement of T4 clusters),5 and some
T3 chalcogenido or pnictido-bridged binary d10-metal clus-
ters, [MII10(µ3-E)4(µ-EPh)12L4] (MII ) Zn, E ) Te, L )
PnPr3;27 MII ) Cd, E ) Se, L ) PPh328), [In10(µ3-S)4(µ-S)12-
(SPh)4]6- 29 or [MII10(µ3-ESiMe3)4(µ-X)12{E(SiMe3)3}4] (MII
) Zn, Cd; E ) P, As; X ) Cl, Br, I).30 However, in contrast
to these compounds, the [M5Sn5S20]10- units in 1-3 contain
two types of metal atoms to become the first ternary
aggregates of the T3-type structure. As with the quoted Cd/
In/S anions and the [B10(S4/2)S16]6- or [In10(S4/2)S16]6- units
in the binary open framework structures of Ag10[B10S18]31
or (Me2NH2)6[In10S18],32 the anions in 1-3 do not covalently
bind to an organic ligand shell at the surface but are stabilized
by coordinative interactions within the alkali metal counterion
aggregation.
(33) Dance, I. G.; Choy, A.; Scudder, M. L. J. Am. Chem. Soc. 1984, 106,
6285-6295.
(34) Nyman, M. D.; Hampden-Smith, M. J.; Duesler, E. N. Inorg. Chem.
1996, 35, 802-803.
(35) Ali, B.; Dance, I. G.; Craig, D. C.; Scudder, M. L. J. Chem. Soc.,
Dalton Trans. 1998, 1661-1667.
(36) (a) Dance, I. G. J. Am. Chem. Soc. 1979, 101, 6264-6273. (b) Tremel,
W.; Krebs, B.; Henkel, G. Angew. Chem., Int. Ed. Engl. 1984, 23,
634-635. (c) Wie, G.; Liu, H.; Huang, Z.; Kang, B. J. Chem. Soc.,
Chem. Commun. 1989, 1839-1840. (d) Henkel, G.; Weissgraber, S.
Angew. Chem., Int. Ed. Engl. 1992, 31, 1368-1369. (e) Cecconi, F.;
Gilhardi, C. A.; Midollini, S.; Orlandini, A. Polyhedron 1986, 5,
2021-2031. (f) Barbaro, P.; Cecconi, F.; Gilhardi, C. A.; Midollini,
S.; Orlandini, A.; de Biani, F. F.; Laschi, F.; Zanello, P. J. Chem.
Soc., Dalton Trans. 1996, 4337-4344. (g) Kang, B.-S.; Wen, T.-B.;
Yu, X.-Y.; Zhang, H.-X.; Tong, Y.-X.; Su, C.-Y.; Chen, Z.-W.; Liu,
H.-Q. J. Cluster Sci. 1999, 10, 429-443.
(26) Krebs, B. Angew. Chem., Int. Ed. Engl. 1983, 22, 113-134.
(27) Eichho¨fer, A.; Fenske, D.; Pfistner, H.; Wunder, M. Z. Anorg. Allg.
Chem. 1998, 624, 1909-1914.
(28) Behrens, S.; Bettenhausen, M.; Deveson, A. C.; Eichho¨fer, A.; Fenske,
D.; Lohde, A.; Woggon, U. Angew. Chem., Int. Ed. Engl. 1996, 35,
2215-2218.
(29) Krebs, B.; Henkel, G. Angew. Chem., Int. Ed. Engl. 1991, 30, 769-
788.
(30) (a) Fuhr, O.; Fenske, D. Z. Anorg. Allg. Chem. 1999, 625, 1229-
1236. (b) Eichho¨fer, A.; Fenske, D.; Fuhr, O. Z. Anorg. Allg. Chem.
1997, 623, 762-768.
(31) Krebs, B.; Dierks, H. Z. Anorg. Allg. Chem. 1984, 518, 101-114.
(32) Cahill, C. L.; Ko, Y.; Parise, J. B. Chem. Mater. 1998, 10, 19-21.
(37) For example, see: (a) Mattes, R.; Mu¨hlenbrock, C.; Leeners, K.; Pyttel,
C. Z. Anorg. Allg. Chem. 2004, 630, 722-729. (b) Kersting, B.;
Siebert, D.; Volkmer, D.; Kolm, M. J.; Janiak, C. Inorg. Chem. 1999,
38, 3871-3882.
Inorganic Chemistry, Vol. 44, No. 16, 2005 5691

Zimmermann et al.
Na+ ions in 3 vs 17 in 2), many interatomic distances are
slightly longer within the cluster ion in 3 compared to those
in 1 (c.f. Table 2). The differences amount to a maximum
of 0.0046 Å for the Sn-(µ-S) bonds.
Second, the ternary anions approach each other more
closely as a result of the greater number of S‚‚‚Na‚‚‚S
contacts in 3 compared to the number in 2. In the latter,
only 13 Na+ ions out of the 17 coordinated by each cluster
form two Na‚‚‚S contacts each, thus bridging to adjacent
cluster anions; the remaining four Na+ ions only interact with
one S ligand and five water molecules each. In contrast, all
28 Na+ ions that surround each ternary anion in 3 bridge to
neighboring cluster anions; moreover, all show coordination
by at least four S ligands, and most by five or six S ligands,
and thus, by only two, one, or no H2O molecules. In this
way, the Na+ ions bridge between up to three Co/Sn/S anions
at once so that the ternary anions in 3 are closer to the
adjacent anionic units and show a smaller nearest S‚‚‚S
distance between two Co/Sn/S units than those in 2 (4.8 vs
5.9 Å).
Third, one observes a difference of the relative orientation
of the Co/Sn/S units in 3 compared to that in 2. In 2, all the
ternary T3-type anions have one of the large tetrahedral
(Sterm)3 faces orientated nearly parallel to the crystallographic
bc plane, with the clusters as a whole pointing alternately
above and below it. Such double layers of ternary anions
arranged “up and down” with parallel orientation of one of
their tetrahedral (Sterm)3 faces, which run through the crystal
parallel to bc, are also formed in 3, but the (Sterm)3 faces are
now inclined by ca. 12.5° away from the bc plane. The closer
approach of the cluster units in 3 might result in the
pronounced metallic luster of the dehydrated quaternary
phase, indicating some kind of inter-cluster interactions. To
explore this, we are currently preparing experiments to check
the metallic conductivity of this material.
Figure 2. View of the crystal packing in 2. Differently orientated domains
of octahedral edge- or corner-sharing [NaO6-nSn] units (n ) 0-2) are
represented by different colors (see text). Free water molecules are
represented by their O atom (red). For clarity, only one of the two disordered
orientations of the groups of three octahedra (yellow or green) is drawn in
each case.
In the isotypic 1 and 2, four domains of chains of differing
lengths are formed by trans-edge or face sharing of the
coordination octahedra around the Na+ ions. Figure 2 shows
a view of the crystal packing in 2 as an example, highlighting
the domains by different colors: Na(1)-Na(3) (blue) produce
an infinite chain parallel to the c-axis near a ) 1/2 and b )
0. Na(4)-Na(7) (gray) are linked to give chains of eight
octahedra, the ends of which share the opposing ∆3-face with
further octahedra (Na(10), pink). These [NaOxSy]10 aggregates
are positioned in the bc plane of the unit cell. Cations Na(8)
and Na(13) (green) as well as Na(9) and Na(14) (yellow)
form sets of three octahedra that connect the longer chains
around 1/2, 1/2, 0 (Na(8)) or 1/2, 1/2, 1/2 (Na(9)). Atoms
Na(13) or Na(14) are only half occupied because of a
statistical disorder of these short chains with another set of
three octahedra, involving either Na(11) or Na(12) and their
symmetry equivalents around Na(8) or Na(9), respectively.
These two triplets of octahedra each follow one of two
crossover directions, the second of which is omitted in Figure
2 for clarity. Additionally, two free water molecules are
integrated in the lattice (O(51) and O(52) in 1 and 2); they
are each hydrogen bonded to two coordinated water mol-
ecules and two S atoms with tetrahedral geometries (O‚‚‚S
distances of 3.175(7)-3.406(11) Å in 1 and 3.135(7)-
3.322(8) Å in 2 and O‚‚‚O distances of 2.623(12)-3.016(9)
Å in 1 and 2.700(14)-2.787(12) Å in 2).
Optical Absorption Behavior of 1 and 2. Figure 4 shows
the absorption spectra of compounds 1 and 2 as suspensions
in Nujol from 1100 to 250 nm, corresponding to an energy
range of 1.1-5.0 eV.
The colorless crystals of 1 do not show any UV-vis
absorption below 3 eV. The onset of absorption is observed
at 377 nm (3.3 eV) which can be assigned to the lowest
possible electronic excitation energy (i.e., the energy differ-
ence between the highest-occupied and lowest-unoccupied
molecular orbitals of the cluster anions in the solid). For 2,
a sharp onset of absorption is observed at 940 nm (1.3 eV),
again indicating the smallest possible excitation energy for
charge-transfer processes in the compound. With decreasing
wavelength, compound 2 shows significant absorption over
the whole UV-vis range with several maxima at 833, 743,
and 415 nm (1.5, 1.7, and 3.0 eV) and shoulders at 693,
463, and 387 nm (1.8, 2.7, and 3.2 eV) in accordance to its
brownish black appearance. Only little is known about the
absorption behavior of CoIIS-cluster complexes; however,
the related compound K10[Co4Sn4S17] shows an onset of
absorption at 1.8 eV, consistent with its the somewhat smaller
cluster size.14b The absorptions at higher energies are the
result of d-d transitions and are consistent with the
In the crystal structure of 3, removal of most of the water
molecules causes a rearrangement of the cluster anions within
the crystal lattice. Figure 3 shows a comparison of both the
crystal packing in 2 and 3.
Upon changing from 2 to 3 by removal of 28 water
molecules per formula unit, three distinct structural changes
are observed. First, since nearly twice as many Na+ ions are
coordinated by the S ligands from a given anionic unit (28
5692 Inorganic Chemistry, Vol. 44, No. 16, 2005

T3-Type Supertetrahedral M/Sn/S Anions
Figure 3. View of the crystal packing in 2 (left-hand side) and 3 (right-hand side) as space-filling models omitting Na+ ions and H2O molecules (top) or
as ball-stick representations (bottom). Co: black. Sn: light gray. S: yellow. Na: blue. O: red. Na‚‚‚S interactions are given as blue sticks (bottom) to show
the higher Na‚‚‚S connectivity in 3 vs 2. For clarity, Na‚‚‚O interactions are not shown, and O atoms are only drawn in the unit cell. The tetrahedral shape
of the T3-type Co/Sn/S clusters is emphasized by drawing the Sterm‚‚‚Sterm connecting lines (bold yellow).
Figure 4. Absorption spectra of 1 (dotted) and 2 (solid).
complicated UV-vis spectra of previously reported molec-
ular Co(II) complexes.37
Figure 5. øT vs T plot of a polycrystalline sample of 3 (0.010 g) measured
between 1.8 and 300 K at 1000 Oe. Solid blue and red lines correspond to
Magnetism of 3. To investigate the magnetic behavior of
the modeling approach developed in the text. The inset shows a simplified
the cobalt compound, we measured the magnetic susceptibil-
ity of a polycrystalline sample of 3. The øT vs T plot is given
in Figure 5.
topology of the magnetic interactions between the five Co(II) centers.
tions between CoII centers are present in the Co cluster.
We attempted to model the magnetic susceptibility on the
basis of the square-pyramidal arrangement of the tetrahedral
CoII centers (see inset of Figure 5) which are bridged by
µ3-S atoms. On the basis of the topology of the magnetic
pathways, the magnetic susceptibility has been calculated
using the MAGPACK program developed by Clemente-Juan
and co-workers and the following Heisenberg Hamiltonian:
H ) -2J1[S1(S2 + S3 + S4 + S5)] - 2J2(S2 + S4)(S3 +
S5).38,39 With this approach and considering (i) only S ) 1/2
Between 1.8 and 40 K, the øT product is essentially
constant at 0.35 cm3 K mol-1 in good agreement with an S
) 1/2 ground state. As the temperature increases, the øT
product begins to increase in a nonlinear manner above 40
K. This unusual temperature dependence, observed in all the
samples of 3 measured, reveals the presence of excited states
that are successively populated with increasing temperature.
This feature and the presence of a doublet ground state
strongly suggest that significant antiferromagnetic interac-
Inorganic Chemistry, Vol. 44, No. 16, 2005 5693

Zimmermann et al.
spins (solid red line in Figure 5 with J1/kB ) J2/kB ) -62(1)
K) or (ii) one S ) 1/2 (top spin of the pyramid, inset of
Figure 5) and four S ) 3/2 spins (solid blue line in Figure
5 with J1/kB ) -420(5) K and J2/kB ) -150(5) K), the
susceptibility at lower temperatures (i.e., below 90 K) was
well simulated with antiferromagnetic interactions between
the spin carriers, as confirmed by DFT calculations (T ) 0
K, see below). Nevertheless, we were not able to model,
even qualitatively, the peculiar “S” shape observed on the
øT vs T plot. This is not completely surprising considering
that the effects of spin-orbit coupling and anisotropy have
not been considered and that the symmetry of the Co5Sn
cluster is lower than the idealized scheme displayed in the
inset of Figure 5. Therefore, with five crystallographically
independent CoII centers, up to eight different magnetic
interactions must be taken into account in the model. In
practice, this cannot be done without an over-parametrization
of the model, and no attempt was made to reproduce the
experimental data over the whole temperature range and to
evaluate the antiferromagnetic interactions, quantitatively.
Figure 6. Plot of the spin density of the calculated [Co5Sn5S20]10- anion
with a calculated spin state of S ) 1/2. Spin densities (i.e., difference of
densities for R and â spins) are drawn to 0.3 e- Å-3
.
Table 3. Distances (Å) and Angles (deg) for the Calculated
Quantumchemical Investigations. Density functional
(DFT) methods were employed both to check the agreement
of the experimentally determined structural parameters with
the given sum formulas of 1-3 and to investigate the spin
situation in the Co/Sn/S cluster anions in 2 and 3. Anions
[Zn5Sn5S20]10- and [Co5Sn5S20]10- were calculated within a
simulated coordination sphere of 10 positive mirror charges,
constructed using the COSMO model.21 This method has
proved to be both necessary and suitable for DFT calculations
of highly charged ternary M/Sn/E anions.13
[M5Sn5S20]10- Anionsa
[Zn5Sn5S20]10-
[Co5Sn5S20]10-
Sn-Sterm
2.425-2.428
2.422-2.454
2.436-2.442
2.339-2.344
3.795-3.716
2.389-2.423
2.435-2.574
2.269-2.350
2.187-2.336
3.640-3.847
Sn-(µ-S)
M-(µ-S)
M-(µ3-S)
M‚‚‚M (Oh edges)
Sterm-Sn-(µ-S)
(µ-S)-Sn-(µ-S)
(µ-S)-M-(µ-S)
(µ-S)-M-(µ3-S)
(µ3-S)-M-(µ3-S)
M-(µ-S)-Sn
107.9-108.5
110.4-110.8
100.4-100.8
108.2-108.4
118.1-118.5
103.7-104.0
104.6-105.1
104.0-114.3
106.8-112.4
99.7-102.7
100.4-115.9
103.9-114.1
102.7-109.3
103.3-113.4
For M ) Zn, a diamagnetic state (S ) 0) was found, which
is consistent with its colorless appearance. For [Co5Sn5S20]10-
,
M-(µ3-S)-M
various spin states are possible. One might think of total spins
of S ) 15/2 resulting from parallel spins at all five Co atoms
(each of them contributing S ) 3/2), of S ) 1/2 (antiparallel
spins with a remaining contribution of S ) 1/2 from one of
the five Co atoms), or of values between those mentioned
above with S ) (2n + 1)/2 (n ) 1-6). Single-point DFT
calculations were carried out for all of these spin states,
starting with the high-spin case S ) 15/2, and then succes-
sively lowering the number of unpaired electrons by 2 until
S ) 1/2 was reached. By this procedure, we found solutions
with a positive gap between highest-occupied and lowest-
unoccupied molecular orbitals, thus fulfilling the aufbau
principle, for the cases S ) 15/2, S ) 9/2, S ) 3/2, and S )
1/2. After the relaxation of the structure parameters for these
four cases, the three states with antiparallel spins turned out
to be 0.5-0.8 eV more stable than the S ) 15/2 state; a
more detailed discussion of the energetic sequence is not
feasible because the effects of spin-orbit coupling are not
included in the present scalar relativistic treatment. However,
the existence of different spin states with relatively small
energy differences was also observed in the experimental
a M ) Zn or Sn for 1 and M ) Co or Sn for 2 and 3 in the case of the
six core atoms.
investigation of the temperature dependency of the magnetic
susceptibility (Figure 5).
Investigation of the spatial distribution of unpaired elec-
trons (i.e., the difference of the electronic densities of R and
â electrons, “spin density”) shows a clear localization at the
Co atoms for all four cases; in Figure 6, the calculated spin
density is plotted for the case S ) 1/2.
Because of the localized character of the spin density,
Mulliken population analyses for this quantity are expected
to give reliable results. Indeed, for S ) 15/2, S ) 9/2, and
S ) 3/2, the number of unpaired of electrons per Co atom is
2.2-2.5, in reasonable agreement with to the expected value
of 3 (for tetrahedrally surrounded CoII centers). For S ) 1/2,
we observed a significantly smaller number of unpaired
electrons (1.4) for the Co center, which is at the corner of
the cube opposite to the Sn atom (see Figure 6), together
with 2.2-2.3 unpaired electrons, as before, at the four other
Co atoms. This lower-spin situation is unprecedented to date
but may serve to rationalize the observed magnetic behavior.
To confirm the compositions of 1 and 2, we compared
the structural parameters from the calculations on the anions
with the experimental values. Table 3 summarizes the
(38) Kambe, K. J. Phys. Soc. Jpn. 1950, 5, 48.
(39) (a) Borra´s-Almenar, J. J.; Clemente-Juan, J. M.; Coronado, E.;
Tsukerblat, B. S. Inorg. Chem. 1999, 38, 6081-6088. (b) Borra´s-
Almenar, J. J; Clemente-Juan, J. M.; Coronado, E.; Tsukerblat, B. S.
J. Comput. Chem. 2001, 22, 985-991.
5694 Inorganic Chemistry, Vol. 44, No. 16, 2005

T3-Type Supertetrahedral M/Sn/S Anions
distances for the calculated anions [M5Sn5S20]10- (M ) Co,
Zn). For M ) Co, the given ranges include the data from all
optimized species.
reasonable thermal ellipsoids of the resulting Sn/M hybrid
positions, by analysis of the structural parameters in com-
parison to related compounds, and by geometry optimization
using DFT methods of respective [M5Sn5S20]10- anions.
Magnetic measurements of 3 and DFT investigations of the
[Co5Sn5S20]10- anion indicate antiferromagnetic coupling of
the µ3-S-bridged CoII centers.
Future investigations are designated to concentrate on two
topics: first, the exploration of the synthetic use of other
chalcogenotetrelate salts as well as transition metal com-
pounds for the formation and isolation of novel quaternary
compounds, and second, a detailed investigation of the
physical properties of these compounds, such as optical
characteristics and magnetism, as shown for 1-3. In this
way, we might gain a deeper insight into the formation
mechanisms and electronic situation in such quaternary
phases with discrete ternary M/E′/E anions.
Most calculated distances are somewhat greater than the
observed values, as is often found with DFT (BP86) methods.
Deviations from the experimental bond lengths are 0.03-
0.07 Å for Sn-S in 1, 0.02-0.17 Å for Sn-S in 2 or 3,
0.01-0.08 Å for Zn-S, and -0.14-0 Å for Co-S. Angles
deviate by (2° around Sn in 1, -2 to +1° around Sn in 2
or 3, (0 to -3° around Zn, -9 to +4° around Co, (0 to
-1° around S in 1, and -2 to +5° around S in 2 or 3.
Conclusions
Reactions of Na4[SnS4] with ZnCl2 or [Co(en)3]X3 (X )
Cl, Br) in water followed by layering with THF leads to the
isolation of novel quaternary compounds, [Na10(H2O)32]-
[Zn5Sn(µ3-S)4(SnS4)4]‚2H2O (1) and [Na10(H2O)32][Co5Sn-
(µ3-S)4(SnS4)4]‚2H2O (2), with unusual anionic subunits. The
reactions that lead to the formation of 1 and 2 are, therefore,
the first to prove, crystallographically, that there is a transfer
of [SnS4]4- anions into the coordination sphere of transition
metal ions. By application of dynamic vacuum to compound
2, single crystals of the partial dehydration product of 2,
[Na10(H2O)6][Co5Sn(µ3-S)4(SnS4)4] (3), were obtained. Com-
pounds 1-3 were structurally characterized by single crystal
X-ray diffraction, revealing the presence of a previously
unknown type of ternary anion: a T3-type supertetrahedron
consisting of Co (or Zn), Sn, and S atoms, the topology of
which has previously only been observed with binary clusters
of d10 metal elements. Because of the presence of 10 Na+
ions per formula unit, as was observed for all three phases,
a fifth tin atom has to be assigned to an inner cluster position,
being distributed over six positions together with five M
atoms for the overall charge neutrality of the compounds.
This has been confirmed by elemental analysis, by the
Acknowledgment. This work was financially supported
by the state of Baden-Wu¨rttemberg (Margarete von Wrangell
habilitation fellowship for S.D.), the German Science Foun-
dation (DFG), the Fonds der Chemischen Industrie, the
Universite´ de Bordeaux I, the CNRS, and the Conseil
Regional d'Aquitaine. The authors are also grateful to J. M.
Clemente-Juan for teaching and providing the MAGPACK
package and to Dr. E. Matern for recording the NMR spectra.
We thank Prof. D. Fenske for generous support of our
research activities. Provision of computational resources by
Prof. R. Ahlrichs and provision of analytical equipment by
Prof. A. K. Powell are gratefully acknowledged.
Supporting Information Available: Crystallographic data files
in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
IC050466O
Inorganic Chemistry, Vol. 44, No. 16, 2005 5695