Four new lead(II) thiolate cluster complexes - Unexpected products of a conventional synthesis

Article abstract of DOI:10.1002/ejic.200400682

The reaction of Pb(OOCCH₃)₂·3H₂O with 2.1 equiv. of HS-2,6-(CH₃)₂C₆H ₃ in ethanol/water is expected to give [Pb{S-2,6-(CH ₃)₂C₆H₃}₂]. However, we obtained an orange powder whose elemental analysis disagrees with that of the expected product and indicates small amounts of oxygen. Layering of concentrated solutions of this orange powder in dry THF with pentane under nitrogen results in the formation of a mixture of three identifiable crystalline compounds, namely [Pb₁₀{S-2,6-(CH₃) ₂C₆H₃}₂₀], [Pb ₆S{S-2,6-(CH₃)₂C₆H₃} ₁₀(C₄H₈O)₄] and [Pb ₈O₂{S-2,6-(CH₃)₂C₆H ₃}₁₂]. In contrast, fractional crystallization from dilute solutions initially yielded only yellow crystals of [Pb ₁₄O₆{S-2,6-(CH₃)₂C₆H ₃}₁₆]. Further concentration of the supernatant solution yielded, upon layering with pentane, [Pb₆S{S-2,6-(CH ₃)₂C₆H₃}₁₀(C ₄H₈O)₄] and [Pb₁₀{S-2,6-(CH ₃)₂C₆H₃}₂₀] which are almost completely separable by controlling the duration of the crystallization step and the amount of condensed pentane. Recrystallization of the crude orange powder under aerobic conditions produces pure [Pb₁₄O ₆{S-2,6-(CH₃)₂C₆H₃) ₁₆] with a yield five times higher than that under nitrogen. This shows that it is sensitive to oxidation by oxygen in solution. The structures of all four complexes have been determined by single-crystal X-ray analysis. The net formed by the six oxygen and twelve lead atoms in the center of [Pb ₁₄O₆{S-2,6-(CH₃)₂C₆H ₃}₁₆] resembles a small piece of a layer of the solid-state structure of red PbO. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejic.200400682

FULL PAPER
Four New Lead(II) Thiolate Cluster Complexes – Unexpected Products of a
Conventional Synthesis
Andreas Eichhöfer*[a]
Keywords: Cluster compounds / Lead / Sulfur / UV/Vis spectroscopy
The reaction of Pb(OOCCH3)2·3H2O with 2.1 equiv. of HS-
2,6-(CH3)2C6H3 in ethanol/water is expected to give [Pb{S-
2,6-(CH3)2C6H3}2]. However, we obtained an orange powder
whose elemental analysis disagrees with that of the expected
product and indicates small amounts of oxygen. Layering of
concentrated solutions of this orange powder in dry THF with
pentane under nitrogen results in the formation of a mixture
of three identifiable crystalline compounds, namely [Pb10{S-
2,6-(CH3)2C6H3}20], [Pb6S{S-2,6-(CH3)2C6H3}10(C4H8O)4] and
[Pb8O2{S-2,6-(CH3)2C6H3}12]. In contrast, fractional crystalli-
zation from dilute solutions initially yielded only yellow crys-
tals of [Pb14O6{S-2,6-(CH3)2C6H3}16]. Further concentration
of the supernatant solution yielded, upon layering with pen-
tane, [Pb6S{S-2,6-(CH3)2C6H3}10(C4H8O)4] and [Pb10{S-2,6-
(CH3)2C6H3}20], which are almost completely separable by
controlling the duration of the crystallization step and the
amount of condensed pentane. Recrystallization of the crude
orange powder under aerobic conditions produces pure
[Pb14O6{S-2,6-(CH3)2C6H3}16] with a yield five times higher
than that under nitrogen. This shows that it is sensitive to
oxidation by oxygen in solution. The structures of all four
complexes have been determined by single-crystal X-ray
analysis. The net formed by the six oxygen and twelve lead
atoms in the center of [Pb14O6{S-2,6-(CH3)2C6H3}16] re-
sembles a small piece of a layer of the solid-state structure
of red PbO.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
dimethylthiophenol, which was reported to yield soluble
[Pb{S-2,6-(CH3)2C6H3}2]. However, the direct reaction of
Pb(OOCCH3)2·3H2O with 2.1 equiv. of HS-2,6-(CH3)2-
C6H3 at 60 °C obviously leads not only to the expected pro-
duct [Pb{S-2,6-(CH3)2C6H3}2] but also yields lead thiolate
cluster complexes which have sulfur or oxygen atoms incor-
porated in the cluster framework, the structures of which
are reported here.
Introduction
Lead chalcogenide nanocrystals (PbS, PbSe, PbTe) have
recently attracted interest due to their unique properties.[1–3]
Size-quantization effects are strongly pronounced in these
materials because of their relatively large exciton Bohr radii.
Furthermore, the quantum size effect offers potential pho-
tonic applications. Theoretically, PbSe nanocrystals (NCs)
are predicted to have absorptive and dispersive nonlinear-
ities 1000 times larger than those of CdSe NCs of the same
size.[4] However, in contrast to the recent, distinct growth in
the chemistry of transition metal chalcogenide clusters,[5,6]
related polynuclear molecules of the heavier main group ele-
ments seem to be rather unexplored to date.[7] It is known
that the reaction of lead thiolates of the general formula
Pb(SR)2 (R = organic group) with stoichiometric amounts
of sulfur or selenium yields the corresponding lead chalco-
genides.[8] These findings suggest that nonstoichiometric re-
actions could probably lead to metastable lead chalcogen-
olato/chalcogenide cluster molecules. Therefore, we became
interested in the synthesis of lead thiolate complexes as
starting materials for the synthesis of such cluster mole-
cules. In order to avoid known solubility problems of the
mostly polymeric lead thiolates[8–10] we followed a recent
recommendation of Briand[11] concerning the use of 2,6-
Results and Discussion
In order to synthesize [Pb{S-2,6-(CH3)2C6H3}2] we used
the method of Shaw and Woods developed for the synthesis
of [Pb(S-2-CH3C6H4)2].[8] The reaction of Pb(OOCCH3)2·
3H2O with 2.1 equiv. of HS-2,6-(CH3)2C6H3 in aqueous
ethanol at 60 °C yielded an orange-red precipitate, which
was filtered and dried. The elemental analysis disagrees
with the expected product [Pb{S-2,6-(CH3)2C6H3}2] espe-
cially with respect to the low amount of sulfur, a fact which
has also been observed by Shaw et al. in the related synthe-
sis of some other lead thiolate complexes. Additionally, the
presence of small amounts of oxygen is indicated by the
analysis. Layering of concentrated solutions of the crude
product in dried THF with pentane results in the formation
of a mixture of the crystalline compounds 1–3, which could
be identified by single-crystal X-ray analysis. In contrast to
this, a solution 1/5 as concentrated in dried THF led to the
crystallization of small amounts of 4 (12% calculated for
[a] Institut für Nanotechnologie, Forschungszentrum Karlsruhe,
Postfach 3640, 76021 Karlsruhe, Germany
Fax: +49-7247-82-6368
E-mail: eichhoefer@int.fzk.de
Eur. J. Inorg. Chem. 2005, 1683–1688
DOI: 10.1002/ejic.200400682
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A. Eichhöfer,
FULL PAPER
Pb) as the only product. Evaporation of the solvents of the tion modes. Pb(2), and Pb(4) are in a distorted tetrahedral
clear supernatant yellow solution in vacuo produced a yel- geometry comprising three sulfur atoms and the stereo-
low-orange powder which was redissolved in 10 mL of chemically active inert electron pair, whilst Pb(3) is bonded
THF. Layering of this concentrated solution with pentane to six sulfur atoms in a highly distorted octahedral geome-
yielded, firstly, crystals of 2, followed by crystals of 1, with- try caused by the additional inert electron pair. Pb(1) and
out any crystals of either 3 or 4.
Pb(5) possess complex coordination environments com-
Obviously, the oxygen present in the crude orange pow- prised of either five or four sulfur atoms. A comparison of
der was in this way completely bound by 4 and thus re- the measured and calculated powder diffraction pattern of
moved from the reaction solution. However, the crystalli- 1 (Figure 2) reveals the crystalline purity of the product iso-
zation of 1 and 2 proceeds in such a way that, initially, lated by fractional crystallization, as mentioned above.
orange plate-like crystals of 2 appear, which tend to form
solidified droplets of crystalline material after the layering
process, while bundles of light-orange needles of 1 start to
grow a few days later at higher concentrations of pentane.
In this way, 1 and 2 can be nearly completely separated, as
shown by powder diffraction patterns and elemental analy-
sis (see below). The yield of 4 could be increased up to 56%
by performing the recrystallization under aerobic condi-
tions, which shows that the crude orange powder is sensitive
to oxidation by oxygen in solution.
The light-orange, plate-like needles were found to dis-
play the desired composition [Pb{S-2,6-(CH3)2C6H3}2].
Interestingly, the structure is neither polymeric, as in
[Pb(SC6H5)2]n[9] or [Pb(S-4-CH3C6H4)2]n,[10] nor trimeric, as
in [Pb3(S-2,6-iC3H7C6H3)6],[12] but is found to be oligo-
Figure 1. Molecular structure of [Pb10{S-2,6-(CH3)2C6H3}20] (1). C
meric [Pb10{S-2,6-(CH3)2C6H3}20] (1). Complex 1 crys-
and H atoms omitted for clarity. Selected bond lengths [pm] (solid
tallizes in the space group Pbcn with the molecule residing
lines): Pb(1)–S(2) 265.4(4), Pb(1)–S(1Ј) 269.1(4), Pb(1)–S(1)
on an inversion center (Figure 1). The Pb–S contacts in the
298.1(4), Pb(1)–S(3) 305.9(5), Pb(2)–S(8) 265.8(4), Pb(2)–S(3)
range of 255.8–317.5 pm have been assigned as bonds (solid
lines), similar to those observed in the lead thiolates men-
tioned above, while longer contacts have been drawn for all
molecules as dashed lines. Contacts to the next molecular
unit are larger than 500 pm, which proves the oligomeric
267.9(5), Pb(2)–S(4) 275.4(3), Pb(3)–S(7) 2788(4), Pb(3)–S(2)
280.1(4), Pb(3)–S(4) 293.6(3), Pb(3)–S(5) 303.4(3), Pb(3)–S(8)
313.1(4), Pb(3)–S(9) 317.5(4), Pb(4)–S(9) 263.3(4), Pb(4)–S(5)
272.5(4), Pb(4)–S(6) 275.0(4), Pb(5)–S(10) 255.8(5), Pb(5)–S(7)
266.4(4), Pb(5)–S(6) 278.9(5). Weak contacts [pm] (dashed lines):
Pb(5)–S(5) 355.5, Pb(1)–S(4) 362.7. Symmetry transformation for
character of 1. The lead atoms exhibit different coordina- generation of equivalent atoms: –x, y, –z + 0.5.
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Four New Lead(ii) Thiolate Cluster Complexes
FULL PAPER
Figure 2. Measured (top) and calculated (bottom) powder diffrac-
tion pattern of [Pb10{S-2,6-(CH3)2C6H3}20] (1).
The orange hexagonally shaped plates that form solidi-
fied droplets of crystalline material after the layering pro-
cess were characterized to be [Pb6S{S-2,6-(CH3)2-
C6H3}10(C4H8O)4] (2). Obviously, part of the precursor
Figure 3. Molecular structure of [Pb6S{S-2,6-(CH3)2C6H3}10-
(C4H8O)4] (2). C and H atoms omitted for clarity. Selected bond
lengths [pm] (solid lines): Pb(1)–S(6) 262.7(2), Pb(1)–S(3) 266.4(3),
thiol undergoes cleavage of the S–Aryl bond under the Pb(1)–S(4) 307.6(2), Pb(2)–S(4) 280.6(2), Pb(2)–S(2) 281.8(2),
Pb(2)–S(1) 283.5(2), Pb(2)–S(3Ј) 309.3(2), Pb(2)–S(5) 312.1(2),
given experimental conditions. Complex 2 crystallizes in the
Pb(3)–S(5) 276.0(2), Pb(3)–S(1) 283.36(8), Pb(3)–S(2Ј) 284.0(3),
¯
P1 space group with the central sulfur atom occupying an
Pb(3)–S(4) 311.3(3). Weak contacts [pm] (dashed lines): Pb(1)–S(1)
350.6, Pb(1)–S(2) 353.6, Pb(2)–O(1) 304.1(3), Pb(3)–O(2) 300.2(3).
Symmetry transformation for generation of equivalent atoms: –x +
1, –y + 2, –z + 1.
inversion center (Figure 3). The six lead atoms form an
elongated octahedron whose eight trigonal faces are
bridged by sulfur atoms, with Pb–S contacts mapped as
bonds ranging from 262.7(2) to 311.3(3) pm. The two “ax-
ial” lead atoms [Pb(1) and Pb(1Ј)] are each additionally
bonded to a thiolate ligand, while the equatorial lead atoms
[Pb(2), Pb(2Ј), Pb(3), and Pb(3Ј)] are weakly coordinated
by a THF solvent molecule (Pb–O: 300.2–304.2 pm). This
leads to an octahedral coordination geometry for Pb(2),
Pb(2Ј), Pb(3) and Pb(3Ј) which is distorted by the inert elec-
tron pair. Pb(1) and Pb(1Ј) are bonded to the five nearest
sulfur atoms [S(2)–S(5) and symmetry-equivalent atoms] in
a distorted square-pyramidal fashion with additional weak
coordination by S(1) from the bottom face [Pb(1)–S(1):
350.6 pm]. Again, a comparison of the measured and calcu-
lated powder diffraction pattern of 2 (Figure 4) reveals the
crystalline purity of the product that was isolated by frac-
tional crystallization, as mentioned above.
Yellow, triclinic-shaped blocks were identified as the
mixed
lead
oxide
thiolate
cluster
complex
Figure 4. Measured (top) and calculated (bottom) powder diffrac-
tion pattern of [Pb6S{S-2,6-(CH3)2C6H3}10(C4H8O)4] (2).
[Pb8O2{SC6H3(CH3)2}12] (3). This is even observed when
using freshly dried and distilled THF which suggests that
Pb–O units are already present in the crude orange powder,
a fact which was additionally supported by elemental analy- 2C7H8.[13] An additional “PbS-2,6-(CH3)2C6H3” unit is
¯
sis. The molecular structure of 3 (1 symmetry), which crys- bonded to these two trigonal faces through three thiolate
tallizes in the P1 space group, consists of an octanuclear ligands [S(1), S(3), S(4), and equivalent atoms] forming two
¯
lead thiolate cluster which additionally incorporates two mixed oxide/thiolate-bridged Pb4OS5 cluster units which
oxygen atoms (Figure 5). The two Pb3O units are nearly are linked at their Pb3O faces by four additional μ3-thiolate
planar [deviation of O(1) from the trigonal plane is 44 pm] ligands [S(2), S(2Ј), S(5), and S(5Ј)]. The Pb–S distances are
with an average of 220.9(2) pm for the Pb–O distances. A in the range of 256.2(3)/310.0(3) pm with eight additional
similar structural unit is found in the pentanuclear, oxygen- weaker and longer contacts between 334.9 pm [Pb(2)–S(5)]
centered lead thiolate cluster [Pb5O{S-2,4,6-(CF3)3C6H2}8]· and 361.4 pm [Pb(4)–S(4)].
Eur. J. Inorg. Chem. 2005, 1683–1688
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A. Eichhöfer,
FULL PAPER
might be due to the fact that the powder measurement was
done at room temperature in contrast to 190 K for the sin-
gle-crystal measurement, and that the needle-like crystals
preferably align in the capillary vertical to the beam.
Figure 5. Molecular structure of [Pb8O2{S-2,6-(CH3)2C6H3}12] (3).
C and H atoms omitted for clarity. Selected bond lengths [pm] (so-
lid lines): Pb(1)–O(1) 220.5(6), Pb(2)–O(1) 222.4(6) Pb(3)–O(1Ј)
219.8(7), Pb(1)–S(5) 269.4(3), Pb(1)–S(1) 289.4(3), Pb(2)–S(4)
276.9(3), Pb(2)–S(2) 282.0(3), Pb(2)–S(1) 310.0(3), Pb(3)–S(3)
279.3(3), Pb(3)–S(2) 300.4(4), Pb(3)–S(4Ј) 302.6(4), Pb(4)–S(6)
256.2(3), Pb(4)–S(3Ј) 273.8(4), Pb(4)–S(1) 275.8(3). Weak contacts
[pm] (dashed lines): Pb(1)–S(3Ј) 337.5, Pb(2)–S(5) 334.9, Pb(3)–S(5)
342.3, Pb(4)–S(4) 361.4. Symmetry transformation for generation
of equivalent atoms: –x, –y + 1, –z + 1.
Figure 6. Molecular structure of [Pb14O6{S-2,6-(CH3)2C6H3}16] (4).
C and H atoms omitted for clarity. Selected bond lengths [pm] (so-
lid lines): Pb(1)–O(2) 225.0(10) Pb(1)–O(1) 231.9(9), Pb(2)–O(1)
227.2(9), Pb(2)–O(3) 238.6(9) Pb(2)–O(1Ј) 242.1(10) Pb(2)–O(2)
269.6(10), Pb(3)–O(1Ј) 229.8(8), Pb(3)–O(3) 232.0(10), Pb(1)–S(2)
285.0(4), Pb(4)–O(2) 226.8(9), Pb(4)–O(3) 228.2(9), Pb(5)–O(3)
229.5(9), Pb(6)–O(2) 221.5(10), Pb(3)–S(3) 285.9(5), Pb(4)–S(1)
302.4(5), Pb(4)–S(2) 305.5(4), Pb(5)–S(5) 264.6(5), Pb(5)–S(1)
289.8(6), Pb(5)–S(3) 289.9(6), Pb(6)–S(6) 274.4(5), Pb(6)–S(1)
293.5(5), Pb(6)–S(4) 299.8(5), Pb(7)–S(8) 262.7(6), Pb(7)–S(7)
263.1(6), Pb(7)–S(4) 270.4(6), Pb(7Ј)–S(8) 263.5(11), Pb(7Ј)–S(4)
264.1(9). Weak contacts [pm] (dashed lines): Pb(1)–S(4) 334.2,
Pb(1)–S(6) 370.1, Pb(1)–S(8) 338.0, Pb(1)–S(3Ј) 323.2, Pb(2)–S(1)
361.1, Pb(2)–S(6) 333.6, Pb(2)–S(2Ј) 330.6, Pb(3)–S(5) 349.1,
Pb(3)–S(6Ј) 325.0, Pb(4)–S(5) 331.2, Pb(4)–S(7) 338.6, Pb(4)–S(8)
370.0, Pb(6)–S(7) 322.8. Symmetry transformation for generation
of equivalent atoms: –x + 1, –y + 1, –z + 1.
Small, yellow, needle-like plates of [Pb14O6{SC6H3-
(CH3)2}16] (4) were found to be the only product crystalliz-
ing from dilute solutions of the crude orange-red powder in
THF. Again, the use of freshly dried and distilled THF sug-
gests that the oxygen can, in principle, only originate from
compounds with Pb–O units that are already present in the
crude powder. Interestingly, the yield of 4 is considerably
increased upon dissolution of the crude powder in THF
under aerobic conditions, which suggests that 4 can be seen
as a stable oxidation product of the crude orange powder.
This is in agreement with the investigations of Edelmann et
al., who found [Pb5O{S-2,4,6-(CF3)3C6H2}8]·2C7H8 to be
an oxidation product of the lead(ii) thiolate [Pb{S-2,4,6-
(CF3)3C6H2}2].[13] Complex 4 crystallizes in the P1 space
¯
¯
group and exhibits 1 symmetry (Figure 6). The net formed
by the six oxygen [O(1), O(2), O(3), and symmetry-equiva-
lent atoms] and twelve of the lead atoms [Pb(1)–Pb(6) and
symmetry-equivalent atoms] resembles a small piece of a
layer of the solid-state structure of red PbO, every layer of
which is composed of a quadratic packing of oxygen atoms
with the lead atoms occupying the quadratic cavities alter-
nately above and below the oxygen planes. The Pb–O dis-
tances, with an average of 233.5 pm, are slightly longer in 4
than those in the red form of PbO (230 pm).[14] However,
twenty of the contacts lie within a narrow range of 221.5–
232.0(10) pm while four distances, namely Pb(2)–O(1Ј)
[242.1(10) pm], Pb(2)–O(2) [269.6(10) pm], and distances to
symmetry-equivalent atoms, show significantly larger val-
ues. The 16 thiolate ligands additionally bridge the lead
atoms in different coordination modes, including the two
remaining lead atoms Pb(7) and Pb(7Ј). The Pb–S bonds
have been mapped in Figure 6 and range from 262.7(6) to
Figure 7. Measured (top) and calculated (bottom) powder diffrac-
tion pattern of [Pb14O6{S-2,6-(CH3)2C6H3}16] (4).
The UV/Vis spectra of 1, 2, and 4 in the solid state (Fig-
315.0(6) pm. A comparison of the measured X-ray powder ure 8, bottom part) show a decrease in wavelength of the
patterns of a suspension of 4 in the mother liquor with the absorption onsets on going from 1 to 2 to 4. Furthermore,
calculated pattern based on the data from single-crystal X- the spectra display an almost featureless increase in ab-
ray analysis (Figure 7) shows good agreement between the sorbance down to 220 nm hardly indicating any maxima, of
two and thus reveals the crystalline purity of this com- which the small shoulder at 430 nm (2.88 eV) in 4 is the
pound. Small deviations in intensity and reflection position most obvious. The solution spectrum of 4 is similar to that
1686
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Four New Lead(ii) Thiolate Cluster Complexes
FULL PAPER
of the ground crystalline powders. Starting from higher neighboring elements − tin, thallium and bismuth − with
wavelengths one observes the first absorption maximum in related thiols with a special focus on the formation of sim-
solution as a broad shoulder at around 420 nm (2.95 eV; ilar metal thiolate cluster complexes.
the extinction coefficient for 4 in THF at 420 nm is
1.63×105 m–1 cm–1). The following increase in absorbance
in the region from 420 nm to 310 nm indicates one further
Experimental Section
weakly resolved shoulder and shows a last maxima at
General: Standard Schlenk techniques were employed throughout
256 nm (4.84 eV). The onset of the absorption of 4 in the
for the recrystallization of the preliminary reaction product using
solid state is thus slightly shifted to higher wavelength, in
a double manifold vacuum line with high-purity dry nitrogen. All
solvents were dried and distilled under nitrogen prior to use. Tetra-
hydrofuran and diethyl ether were dried with sodium/benzophe-
agreement with findings in other solid-state spectra.[15] In
contrast, for 1 the onset of the solution spectrum is shifted
by roughly 100 nm compared to the solid-state spectrum, a
fact which cannot be simply explained by influences of the
different measurement techniques alone. Rather, we assume
that oligomeric 1 dissociates in solution into smaller units,
probably [Pb{S-2,6-(CH3)2C6H3}2], which displays two ab-
sorption maxima at 333 nm (3.72 eV) and 258 nm (4.8 eV)
with an extinction coefficient of 5.95×105 m–1 cm–1 at
333 nm. Solutions of 2 in THF decompose immediately af-
ter dissolution, as indicated by the formation of a dark pre-
cipitate, while the clear supernatant solution displays the
same UV/Vis spectrum as measured for 1. The powder dif-
fraction pattern of the dark precipitate displays weak and
broad peaks for cubic PbS[16,17] and weak but sharper ones
for cubic elemental lead.[18] This suggests that 2 decomposes
in THF to form PbS/Pb and [Pb{S-2,6-(CH3)2C6H3}2].
none, and pentane with LiAlH4. Pb(OOCCH3)2·3H2O (99+%) and
2,6-(CH3)2C6H3-SH (95%) were purchased from Aldrich. UV/Vis
absorption spectra of cluster molecules in solution were measured
with a Varian Cary 500 spectrophotometer in quartz cuvettes. So-
lid-state reflection spectra were measured for micron-sized crystal-
line powders between quartz plates with a Labsphere integrating
sphere.
Synthesis: A hot solution (60 °C) of 2,6-(CH3)2C6H3SH (0.37 mL,
2.77 mmol) in 10 mL of ethanol was slowly added to a hot solution
(60 °C) of Pb(OOCCH3)2·3H2O (0.5 g, 1.32 mmol) in a mixture of
8 mL of C2H5OH and 2 mL of H2O. A yellow precipitate was
formed immediately which soon turned orange and finally became
red. The reaction solution was heated at 60 °C for a further 30 min
and then cooled to room temperature, filtered, washed with etha-
nol, and dried to give 0.49 g of an orange powder, which contained
less sulfur than the expected product [Pb{S-2,6-(CH3)2C6H3}2].
C16H18PbS2 (481.64): calcd. C 39.9, H 3.8, S 13.31; found C 39.5,
H 3.4, O 0.3, S 12.1.
1, 2, 3: For recrystallization the dried crude powder (0.49 g) was
dissolved in 10 mL of THF and then layered with pentane by slow
diffusion by evaporation from a connected flask to give a mixture
of crystals of 1, 2, and 3.
4: Pure crystals of 4 were obtained by dissolution of the crude
powder (0.49 g) in 50 mL of THF and additional layering of this
solution with pentane by slow diffusion by evaporation from a con-
nected flask. (Yield: 0.063 g, 12.9% calculated for Pb).
C128H144O6Pb14S16 (5192.3): calcd. C 29.6, H 2.8, S 9.9; found C
29.9, H 2.6, S 10.2. Suitable crystals for X-ray analysis were ob-
tained by careful layering of THF solutions of 4 with Et2O in a
Schlenk tube. The yield of 4 was increased by recrystallization of
the crude powder (0.49 g) from 50 mL of THF in air without any
layering with pentane. Yield: 0.29 g (56% calculated for Pb).
2: The solvents of the clear supernatant yellow solution from the
crystallization of 4 were then removed in vacuo and the dry yellow-
orange powder redissolved in 10 mL of THF. Layering of this solu-
tion with pentane by slow diffusion by evaporation from a con-
nected flask yielded initially orange plate-like crystals of 2, which
tend to form solidified droplets of crystalline material during the
layering process. After 2 d (ca. 6 mL of condensed pentane), the
crystals were filtered and washed with pentane to yield 0.135 g
(20.9% calculated for Pb) of 2. C96H122O4Pb6S11 (2935.9)
(2·4C4H8O): calcd. C 39.3, H 4.2, S 12.1; found C 39.6, H 3.9, S
11.5.
Figure 8. UV/Vis spectra of [Pb10{S-2,6-(CH3)2C6H3}20] (1),
[Pb6S{S-2,6-(CH3)2C6H3}10(C4H8O)4] (2), and [Pb14O6{S-2,6-
(CH3)2C6H3}16] (4) in solution (THF) and the solid state (mull in
nujol between two quartz plates).
1: The filtrate of 2 was again connected to the pentane flask and
after 5 d yielded light-orange needles of 1. Yield: 0.192 g (30.2%
calculated for Pb). C160H180Pb10S20 (4816.3): calcd. C 39.9, H 3.8,
S 13.3; found C 40.2, H 3.8, S 13.1. Continuation of the layering
process resulted, at higher concentrations of condensed pentane, in
These observations are currently part of further investi-
gations where the effect of varying the reaction conditions
(temperature, solvent, and stoichiometry) and the arene-
thiol are being studied. An additional focus will be the in-
vestigation of the reaction behavior of metal salts of the the formation of a pale-yellow precipitate of unknown composition
Eur. J. Inorg. Chem. 2005, 1683–1688
www.eurjic.org © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1687

A. Eichhöfer,
FULL PAPER
Crystallographic Data: Data collection was carried out with a
STOE IPDS II diffractometer equipped with a Schneider rotating
anode using graphite-monochromated Mo-Kα (λ = 0.71073 Å) radi-
ation at 190 K. The structure solutions and full-matrix least-
squares refinements based on F2 were performed with the SHELX-
97 program package.[19] Molecular diagrams were prepared with
the program SCHAKAL 97.[20]
tional nanostructures CFN). The author is grateful to Prof. D. Fen-
ske for helpful discussions and for providing excellent working con-
ditions, E. Tröster for her invaluable assistance in the practical
work, and Dr. Dale Cave for careful revision of the manuscript.
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1: Light-orange needle-like plates, 0.5×0.08×0.06 mm, Mr
=
4816.14, orthorhombic, space group Pbcn (no. 60), a = 31.217(6),
b = 21.294(4), c = 30.898(6) Å, V = 20539(7) Å3, Z = 4, Dc
=
1.558 gcm–3, μ(Mo-Kα) = 8.405 mm–1 giving a final R1 value of
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2: Orange hexagonal plates, 0.24×0.18×0.02 mm, Mr = 2935.74,
¯
triclinic, space group P1 (no. 2), a = 13.965(3), b = 14.819(3), c =
15.670(3) Å, α = 94.47(3), β = 114.44(3), γ = 115.45°, V =
2533.5(9) Å3, Z = 1, Dc = 1.924 gcm–3, μ(Mo-Kα) = 10.206 mm–1
giving a final R1 value of 0.0486 for 479 parameters and 8632
unique reflections with I Ն 2σ(I) and wR2 of 0.1424 for all 10 378
reflections (Rint = 0.0598).
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3: Yellow triclinic blocks, 0.2×0.127×0.08 mm, Mr = 3480.27, tri-
¯
clinic, space group P1 (no. 2), a = 14.637(3), b = 15.278(3), c =
15.491(3) Å, α = 97.20(3), β = 108.18(3), γ = 118.38(3)°, V =
2736.0(9) Å3, Z = 1, Dc = 2.112 gcm–3, μ(Mo-Kα) = 12.536 mm–1
giving a final R1 value of 0.0556 for 552 parameters and 8149
unique reflections with I Ն 2σ(I) and wR2 of 0.1584 for all 10 265
reflections (Rint = 0.0602).
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[11]
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4: Yellow plate-like needles, 0.4×0.07×0.04 mm, Mr = 5192.05, tri-
¯
clinic, space group P1 (no. 2), a = 15.948(3), b = 17.919(4), c =
18.273(4) Å, α = 109.42(3), β = 100.93(3), γ = 112.51(3)°, V =
4238.1(15) Å3, Z = 1, Dc = 2.034 gcm–3, μ(Mo-Kα) = 14.083 mm–1
giving a final R1 value of 0.0840 for 428 parameters and 12 414
unique reflections with I Ն 2σ(I) and wR2 of 0.2377 for all 16 723
reflections (Rint = 0.0872).
[15] A. Eichhöfer, O. Hampe, M. Blom, Eur. J. Inorg. Chem. 2003,
CCDC-246835 (1), -246836 (2), -246837 (3) and -246838 (4) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. X-
ray powder diffraction patterns (XRD) were measured with a
STOE STADI P diffractometer (Cu-Kα radiation, Germanium
monochromator, Debye–Scherrer geometry) as a suspension of the
crystals in sealed glass capillaries. Theoretical powder diffraction
patterns were calculated on the basis of the atom coordinates ob-
tained from single-crystal X-ray analysis by using the program
package STOE WinXPOW.[21]
1307–1314.
[16] H. E. Swanson, R. K. Fuyat, National Bureau of Standards Cir-
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[18] H. E. Swanson, E. Tatge, National Bureau of Standards Circu-
lar (U.S. Government Printing Office, Washington, D.C.),
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[19] G. M. Sheldrick, SHELX-97, Program for X-ray crystal struc-
ture determination and refinement, University of Göttingen,
Germany, 1997.
[20] E. Keller, SCHAKAL 97, A Computer Program for the Graphic
Representation of Molecular and Crystallographic Models, Uni-
versität Freiburg, Germany, 1997.
[21] STOE, WinXPOW: STOE & Cie GmbH, Darmstadt, 2000.
Received: August 6, 2004
Acknowledgments
This work was supported by the Deutsch-Israelisches Programm
(DIP) and the Deutsche Forschungsgemeinschaft (center for func-
1688
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1683–1688