Intramolecularly coordinated organotin tellurides: Stable or unstable?

Article abstract of DOI:10.1002/anie.201107666

The step-wise oxidation of an organotin(I) compound with elemental tellurium gave a variety of unprecedented organotin tellurides containing tin atoms in the oxidation states +II and +IV (see examples). Copyright

Full text of DOI:10.1002/anie.201107666

.
Angewandte
Communications
DOI: 10.1002/anie.201107666
Organotin Compounds
Intramolecularly Coordinated Organotin Tellurides: Stable or
Unstable?**
ˇ
ˇ
ˇ
ˇ
Marek Bouska, Libor Dostꢀl, Zdenka Padelkovꢀ, Antonꢁn Lycka, Sonja Herres-Pawlis,*
Klaus Jurkschat,* and Roman Jambor*
Increasing interest in the chemistry of organotin chalcoge-
nides arises in part from their intriguing chemical and physical
properties, providing possible technological applications such
as semiconductivity, photoconductivity, or nonlinear optics.[1]
Examples of tri- and diorganotin chalcogenides are known to
form dimers or trimers with chalcogen atoms in the bridging
R2M2E3 (R = organic group, E = S, Se, Te) have a [1.1.1]pro-
pellane structure, as was either suggested theoretically[5] or
shown
experimentally
(Supporting
Information,
Scheme S1).[6] Recently, compounds with the composition of
R2Sn2Te5 were isolated (R = bulky aryl substituent).[7] All of
these structures, however, contain chalcogen atoms in the
ꢀ
positions. There are also rare examples of organotin chalco-
bridging positions with an M E single bond, and most
[2]
=
genides containing terminal Sn E (E = S, Se, Te) bonds.
investigations are limited to sulfides or selenides (Supporting
Information, Scheme S1). The corresponding tellurium com-
pounds have not been investigated in detail, which is probably
due to their thermal instability and sensitivity towards light.
Recently, we have reported the organotin(I) compound
[2,6-(Me2NCH2)2C6H3Sn]2 (1) and shown that the employ-
ment of intramolecularly coordinating pincer-type ligand is an
alternative concept to the use of sterically demanding
substituents for the stabilization of reactive distannyne
derivatives.[8] The oxidation of compound 1 with elemental
sulfur or selenium provided the unprecedented monoorgano-
In recent years, monoorganotin chalcogenides have
received increasing attention, and among these tin sesqui-
chalcogenide cages of the general formula [(RSn)4E6] con-
taining both non-reactive organic groups R = alkyl, aryl, CF3,
C6F5 and functionalized organic substituents R =
CH2CH2COOH, CH(CH2COOH)2 are the most popular.[3]
These compounds usually have adamantane or double-decker
structures (Supporting Information, Scheme S1). Dehnen and
co-workers have shown that anionic tin chalcogenide poly-
2ꢀ
mers [(RSn)2E3
]
containing functionalized organic sub-
1
stituents may be prepared in this way as well.[4] Monomeric
chalcogenides of Group 14 elements of the general formula
tin
chalcogenides
[2,6-(Me2NCH2)2C6H3Sn]2E,
[2,6-
(Me2NCH2)2C6H3Sn(Se)]2Se,
and
[{2,6-
(Me2NCH2)2C6H3}2Sn2(S)7].[9]
In the course of systematic studies on the reactivity of
distannyne 1, we present here its reaction with elemental
tellurium as a step-wise oxidation of the tin(I) atom
(Scheme 1).
The addition of elemental tellurium to the dark red
solution of compound 1 in n-hexane caused an immediate
color change of the solution to pale yellow. From this solution,
the bis(organotin(II)) telluride [2,6-(Me2NCH2)2C6H3Sn]2Te
ˇ
ˇ
[*] M. Bouska, Dr. L. Dostꢀl, Z. Padelkovꢀ, Dr. R. Jambor
Department of General and Inorganic Chemistry
Faculty of Chemical Technology, University of Pardubice
Cs. legiꢁ 565, 53210 Pardubice (Czech Republic)
E-mail: roman.jambor@upce.cz
ˇ
Prof. Dr. S. Herres-Pawlis, Prof. Dr. K. Jurkschat
Lehrstuhl fꢂr Anorganische Chemie II
Fakultꢃt Chemie der TU Dortmund, 44221 Dortmund (Germany)
E-mail: klaus.jurkschat@tu-dortmund.de
ˇ
Prof. Dr. A. Lycka
Research Institute for Organic Chemistry
VUOS a.s. 53210 Pardubice (Czech Republic)
Prof. Dr. S. Herres-Pawlis
Department Chemie, Ludwig-Maximilians-Universitꢃt Mꢂnchen
Butenandtstrasse 5, 81377 Mꢂnchen (Germany)
E-mail: sonja.herres-pawlis@cup.uni-muenchen.de
[**] We are grateful to the Ministry of Education of the Czech Republic
(project no. VZ0021627501) and the Grant Agency of the Czech
Republic (grant no. GA207/10/0130) for supporting this work.
DAAD financial support (R.J.) is also acknowledged. S.H.-P. thanks
the Fonds der Chemischen Industrie for granting a Liebig fellowship
and the Bundesministerium fꢂr Bildung und Forschung (MoSGrid,
01IG09006) for financial support.
Supporting information for this article (Scheme S1 for different
structural motives, Scheme S2 for exchange of the terminal
tellurium atom of 3, and Scheme S3 for decomposition process of
4; Figure S1 for the transition state (3TS) and Figure S2 for thermal
decomposition of 4 and 6; computational details of 2–6; additional
data on the NBO analysis and crystallographic details) is available
on the WWW under http://dx.doi.org/10.1002/anie.201107666.
Scheme 1. Synthesis of compounds 2–6. a) Te, 4 h, hexane; b) Te, 24 h
hexane; c) Te, 24 h, toluene; d)+moisture from toluene; e) hn, C6D6.
3478
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 3478 –3482

Angewandte
Chemie
Figure 1. Molecular structure of 2. Ellipsoids set at 50% probability,
hydrogen atoms omitted for clarity. Selected bond lengths [ꢄ] and
bond angles [8]: Sn1–Te1 2.8218(7), Sn2–Te1 2.8334(8); Sn1-Te1-Sn2
95.32(2), Te1-Sn1-C1 95.1(2), Te1-Sn2-C13 95.0(2).
Figure 2. Molecular structure of 3. Ellipsoids set at 50% probability,
hydrogen atoms omitted for clarity. Selected bond distances [ꢄ] and
bond angles [8]: Sn1–Te1 2.8974(3), Sn2–Te2 2.6110(4), Sn2–Te1
2.7270(3); Sn1-Te1-Sn2 95.95(1), Te1-Sn1-C1 93.79(9), Te1-Sn2-C13
105.2(1).
(2) was obtained as yellow crystalline material in 78% yield.
The molecular structure of 2 is shown in Figure 1.
well (see the Supporting Information). In accordance with the
structure, the different charges were found on the Sn atoms
(+ 1.102(Sn2)/ + 0.770 (Sn1)) as well as on the Te atoms
Compound 2 is the first example of a structurally charac-
ꢀ
ꢀ
terized telluride of low-valent Group 14 elements. The Sn1
(ꢀ0.640(Te2), ꢀ0.554 (Te1)). The Wiberg Sn2 Te2 bond
ꢀ
Te1 (2.8218(7) ꢀ) and Sn2 Te1 (2.8334(8) ꢀ) bond lengths
index amounts to 1.345, which clarifies the donation of the
terminal tellurium atom to the tin atom. Furthermore, there is
ꢀ
are similar and fall in the range expected for a Sn Te single
bond (sum of covalent radii Scov(Sn,Te) = 2.77 ꢀ).[10] The C1-
Sn1-Te1 (95.1(2)8) and C13-Sn2-Te1 (95.0(2)8) angles are very
similar to the C-Sn-E angles (range of 95.0(3)8) in the
organotin(II) chalcogenides[9] and indicate that the s char-
acter of the lone pair is rather similar in these compounds.
The 119Sn NMR spectrum of 2 in C6D6 revealed a reso-
nance at d = 67.8 ppm and the 1H NMR spectrum showed
a singlet resonance at d = 3.56 ppm for the methylene groups
CH2N and a singlet resonance at d = 2.42 ppm for the methyl
NCH3 groups. Prolongation of the reaction time to 24 h gave
a red solution from which the unprecedented compound [2,6-
(Me2NCH2)2C6H3(Te)Sn(m-Te)Sn-2,6-(Me2NCH2)2C6H3] (3)
containing tin atoms in the oxidation states + II and + IV
was isolated in 69% yield. The molecular structure of 3 is
shown in Figure 2.
a Te Te interaction with a Wiberg bond index of 0.172,
ꢀ
suggesting that the exchange of the tellurium atoms, as
observed in solution, can be performed through the sym-
metrical transition state with a Sn2Te2 four-membered ring.
DFT calculations gave a symmetrical transition state for 3TS
(Supporting Information, Figure S1).
ꢀ
The Sn Te bond distances amount to 2.766 and 3.307 ꢀ.
The transition state is estimated to be 20 kcalmolꢀ1 higher in
energy than the minimum structure for 3. This value can be
regarded rather as the upper limit. The presence of the N
donor atoms stabilizes compound 3 significantly: the donation
to the formal tin(II) atom amounts to 23 kcalmolꢀ1, whereas
the formal tin(IV) atom is stabilized by 28 kcalmolꢀ1 per
donor atom.
The complete oxidation of bis(organotin(II)) telluride 2
by Te to give the organotin(IV) telluride [2,6-
(Me2NCH2)2C6H3Sn(Te)]2Te (4) in 71% yield was achieved
after a reaction time of 24 h in toluene solution. The identity
of 4 in solution was confirmed by 119Sn and 125Te NMR
spectroscopy. The 119Sn NMR spectrum of 4 in C6D6 revealed
a resonance at d = ꢀ84.6 ppm flanked by 1J(119Sn,125Te)
satellites of 7418 Hz. This large coupling constant is consistent
with the presence of a tellurium atom that is terminally bound
to a tin atom.[11] The 125Te NMR spectrum showed two signals
at d = ꢀ764.1 ppm and d = ꢀ1349.5 ppm (1J(125Te,119Sn) =
7418 Hz). While the former signal corresponds to a bridging
tellurium atom, the latter was assigned to the terminal atom.
DFT calculations on compound 4 were performed (see the
Supporting Information). The charge on the Sn atoms is
+ 1.106 and on the terminal Te atoms ꢀ0.632. Both terminal
tellurium atoms donate additionally to the tin atom and
ꢀ
ꢀ
The Sn1 Te1 (2.8974(3) ꢀ) and Sn2 Te1 (2.7270(3) ꢀ)
bond lengths are similar and fall in the range expected for
a Sn Te single bond (Scov(Sn,Te) = 2.77 ꢀ).[10] The Te2 Sn2
ꢀ
ꢀ
ꢀ
(2.6110(4) ꢀ) bond distance is comparable to terminal Sn Te
bonds found in the diarylstannanetellurones (range of
2.5705(6)–2.618(1) ꢀ).[11] The C1-Sn1-Te1 (93.79(9)8) angle
resembles those found in 2, and the C13-Sn2-Te1 (105.2(1)8)
angle suggests the absence of the lone pair at the Sn2 atom.
In contrast to the unsymmetrical structure of compound 3
found in the solid state, the 1H, 13C, and 119Sn NMR spectra at
ambient temperature of 3 each showed one set of signals in
C6D6. The 1H NMR spectrum showed a singlet at d =
3.14 ppm for the methylene protons CH2N and a singlet
resonance at d = 2.17 ppm for methyl NCH3 protons. The
119Sn spectrum revealed a resonance at d = ꢀ131.0 ppm and
the 125Te NMR spectrum showed a single resonance at d =
ꢀ743.6 ppm. This observation suggests the fast exchange of
the terminal tellurium atom (Supporting Information,
Scheme S2).
ꢀ
strengthen the Sn Te bonds to a bond order of 1.380/1.379.
The stabilization provided by one N donor atom has been
calculated to be approximately 26 kcalmolꢀ1. For a model
compound that lacks the intramolecularly coordinating
dimethylaminomethyl substituents, calculations reveal
DFT calculations on compound 3 were performed and the
geometry obtained reproduced the experimental values very
Angew. Chem. Int. Ed. 2012, 51, 3478 –3482
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3479

.
Angewandte
Communications
ꢀ
a decrease of the Sn Te bond lengths (see the Supporting
Information).
In solution, compound 4 is very sensitive and reacts with
traces of moisture to give compound 5 as the partial
hydrolysis product. The molecular structure of compound 5
is shown in Figure 3. The {Sn4O6} unit of compound 5 is
composed of the chemically different entities [2,6-
(Me2NCH2)2C6H3]Sn(OH)O
and
[2,6-
(Me2NCH2)2C6H3]Sn(OH)Te that are linked by oxido/
hydroxido bridges. While both molecules of stannonic acid
[2,6-(Me2NCH2)2C6H3]Sn(OH)O form the inner part of the
{Sn4O6} moiety, the remaining two molecules of telluro-
(hydroxo)stannonic acid [2,6-(Me2NCH2)2C6H3]Sn(OH)Te
are located in the outer part.
The 119Sn NMR spectrum of compound 5 in C6D6 revealed
two resonances at d = ꢀ424.0 and ꢀ444.4 ppm. The 1H NMR
spectrum showed two AX spin systems for the methylene
protons CH2N at dA = 2.88 ppm and dx = 5.55 ppm, and at
dA = 3.02 ppm and dx = 4.17 that are consistent with the
molecular structure.
Further studies also showed that compound 4 is redox-
unstable. When a sealed NMR tube containing the deep red
solution of 4 in C6D6 was exposed to visible light for two
weeks or heated at 408C for two days, the solution turned
deep violet. From this solution, single crystals were obtained
and identified as the unprecedented compound [2,6-
(Me2NCH2)2C6H3Sn(m-Te)2]2Sn (6) containing both organotin
and inorganic tin sites. The molecular structure of 6 is given in
Figure 4a.
Figure 4. a) Molecular structure of 6. Selected bond distances [ꢄ] and
bond angles [8]: Sn1–Te1 2.6926(5), Sn2–Te1 2.8979(5), Sn2–Te2
3.2162(4), Sn1–Te2 2.6633(5); Te1-Sn1-Te2 107.23(2), Sn1-Te2-Sn2
78.39(2). Ellipsoids set at 50% probability, hydrogen atoms omitted
for clarity. b) The electron lone pair of the central SnII atom (red).
axial and the carbon and tellurium atoms occupy the
ꢀ
equatorial positions. The Sn1/Sn1a Te (2.6926(5)/
ꢀ
2.6633(5) ꢀ) bond lengths are shorter than those of Sn2 Te
[11]
ꢀ
and are comparable with terminal Sn Te bonds.
The
ꢀ
presence of different Sn Te bonds in 6 is in direct contrast
to structurally similar spiro[bis(ditelluradistannetane)],
ꢀ
The central Sn2 atom is coordinated by four tellurium
where all Sn Te bond lengths are nearly equal (2.7445(13)–
ꢀ
ꢀ
atoms. Interestingly, the Sn2 Te1 (2.8979(5) ꢀ) and Sn2 Te2
(3.2162(4) ꢀ) bond lengths are rather different. While the
2.7661(13) ꢀ) and define two Sn2Te2 four-membered rings
[10f]
ꢀ
with Sn Te covalent bonds.
ꢀ
ꢀ
Sn2 Te1 bonds fall in the range expected for a Sn Te single
The identity of compound 6 was confirmed by NMR
spectroscopy. The 119Sn NMR spectrum in C6D6 revealed
equally intense resonances at d = ꢀ294.4 ppm and d =
ꢀ295.0 ppm that were assigned to terminal Sn atoms Sn1/
Sn1a and at d = ꢀ379.3 ppm assigned to the Sn2 atom that
suggests a distortion of the molecular structure of 6 in
solution, which is most probably due to the weakening of the
Te !Sn intramolecular interaction in C6D6 solution. As result,
all the Te atoms are equivalent in solution, as shown by the
125Te NMR spectrum: one signal at d = ꢀ394.9 ppm with
1J(125Te,119Sn) = 4142 Hz was observed. This dynamic behav-
ior of 6 is in contrast to spiro[bis(ditelluradistannetane)],
where the structural rigidity resulted in the presence of three
signals in the 119Sn NMR spectrum at d = ꢀ149, ꢀ384, and
ꢀ387 ppm, together with four signals in the 125Te NMR
spectrum at d = 762.9, 765.0, 766.0, and 771.3 ppm.[10f]
ꢀ
bond, the Sn2 Te2 bond is substantially longer than the sum
of the covalent radii of Sn (1.40 ꢀ) and Te (1.37 ꢀ) and can be
interpreted in terms of the Te!Sn intramolecular interaction
in 6. The Sn1/Sn1a atoms coordinate to five atoms Te1,Te2/
Te1a,Te2a, C1/C1a, N1,N2/N1a,N2a to give a distorted trigo-
nal bipyramidal configuration. The nitrogen atoms occupy the
The overall composition of 6 may be best described as an
insertion product of in situ generated tin(II) telluride, SnTe,
ꢀ
into one of the two Sn Te bonds of [2,6-
(Me2NCH2)2C6H3Sn(Te)]2Te (4). The tin(II) telluride origi-
nates from reduction of a part of 4, and consequently there
must also be an oxidation product. To identify the oxidation
product, the crude reaction mixture was monitored by 125Te
NMR spectroscopy. The spectrum revealed two signals at d =
300 ppm and d = 350 ppm that fall in the range that is typical
for intramolecularly coordinated organotellurium(II) com-
pounds.[12] The signals were tentatively assigned to [2,6-
Figure 3. Molecular structure of 5. Ellipsoids set at 50% probability,
hydrogen atoms omitted for clarity.
3480 www.angewandte.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 3478 –3482

Angewandte
Chemie
Compound 1[8a] and 2,6-(Me2NCH2)2C6H3SnClI2
according to the literature procedures.
were prepared
[13]
(Me2NCH2)2C6H3]2Te
and
[2,6-(Me2NCH2)2C6H3]2Te2,
respectively. These observations show that compound 4 is
indeed redox-unstable and decomposes to organotelluri-
um(II) and organotellurium(I) compounds and SnTe, which
in turn interacts with 4 to produce complex 6 (Supporting
Information, Scheme S3). Interestingly, an alternative syn-
thesis of compound 4 by reaction of the monoorganotin(IV)
compound 2,6-(Me2NCH2)2C6H3SnClI2 with Li2Te produced
a mixture of similar composition. The heating of 4 at 3508C
for 2 h under vacuum resulted in the complete decomposition
providing SnTe and Te as the final products (for powder X-ray
diffraction, see the Supporting Information, Figure S2).
DFT calculation of compound 6 was performed to give
insight into the bonding situation. Starting from the crystal
structure, the geometry of 6 was fully optimized and it
reproduced the experimental values very well. Natural bond
orbital analysis reveals a lone pair on the central Sn atom with
2: Te powder (0.20 g, 1.6 mmol) was added at room temperature
with stirring to a solution of 1 (0.20 g, 0.3 mmol) in hexane (20 mL).
The reaction mixture was stirred for an additional 4 h and the color
changed from deep red to colorless. The solution was filtered and the
filtrate was concentrated to a volume of approximately 5 mL. Storage
overnight at 58C gave yellow crystals of 2 (0.188 g, 78% yield). M.p.
1
146–1488C. H NMR (500.18 MHz, [D6]benzene, 258C): d = 2.42 (br
s, 12H, NCH3), 3.56 (s, 4H, CH2), 7.05 (d, 2H, ArH), 7.17 ppm (t, 1H,
ArH). 13C NMR (125.77 MHz, [D6]benzene, 258C): d = 46.9 (NCH3),
67.1 (CH2N), 124.7 (C3,5), 127.4, (C4), 146.4 (C2,6), 168.7 ppm (C1).
119Sn NMR (186.49 MHz, [D6]benzene, 258C): d = 67.8 ppm.
125Te NMR (157.84 MHz, [D6]benzene) not found.
3: Te powder (0.20 g, 1.6 mmol) was added at room temperature
with stirring to a solution of 1 (0.20 g, 0.3 mmol) in n-hexane (20 mL).
The reaction mixture was stirred for an additional 24 h and the color
changed from deep red to orange. The solution was filtered and the
filtrate was concentrated to a volume of approximately 8 mL. Storage
overnight at 58C gave orange crystals of 3 (0.195 g, 69% yield). M.p.
ꢀ
95% s character (Figure 4b). Wiberg Te Sn1/Sn1a bond
1
1608C decomp. H NMR (500.18 MHz, [D8]toluene, 258C): d = 2.17
orders are in the range 1.000–1.1552, which exceeds the
normal single-bond character and hints that the tin atoms Sn1/
Sn1a strongly bind to tellurium atoms. In contrast, Wiberg
(s, 12H, NCH3), 3.14 (s, 4H, CH2), 6.61 (d, 2H, ArH), 6.82 (t, 1H,
ArH) ppm. 13C NMR (125.77 MHz, [D8]toluene, 258C): d = 46.6
(NCH3), 65.5 (CH2N), 124.8 (C3,5), 127.9, (C4), 137.4 (C2,6),
145.1 ppm (C1). 119Sn NMR (186.49 MHz, [D8]toluene, 258C): d =
ꢀ131 ppm. 125Te NMR (157.84 MHz, [D8]toluene, 258C) d =
ꢀ743.6 ppm.
ꢀ
Te1/Te1a Sn2 bond orders amount to 0.715, which agrees
ꢀ
with a single bond. Finally, the Wiberg Te2/Te2a Sn2 bond
orders amount to 0.387 only, which proves the absence of
a single bond and supports that the bond can be interpreted as
a Te!Sn donor–acceptor interaction. As in compound 4, the
N-donor stabilization in 6 is again 26 kcalmolꢀ1 per donor
atom.
4: Te powder (0.25 g, 1.9 mmol) was added at room temperature
with stirring to a solution of 1 (0.25 g, 0.4 mmol) in toluene (3 ꢁ
freeze–pump–thaw, 20 mL). The reaction mixture was stirred for 24 h.
The resulting suspension was filtered and the dark red filtrate was
concentrated to approximately 5 mL. Storage overnight at ꢀ208C
gave dark red crystals of 4 (0.29 g, 71% yield). M.p. 2058C decomp.
1H NMR (500.18 MHz, [D6]benzene, 258C): d = 2.45 (s, 12H, NCH3),
3.38 (s, 4H, CH2), 6.95 (d, 2H, ArH), 7.33 ppm (t, 1H, ArH).
13C NMR (125.77 MHz, [D6]benzene, 258C): d = 46.4 (NCH3), 64.4
(CH2N), 124.7 (C3,5), 128.2 (C4), 138.9 (C1), 144.3 ppm (C2,6).
119Sn NMR (186.49 MHz, [D6]benzene, 258C): d = ꢀ84.6 ppm
(1J(119Sn,125Te) = 7418 Hz). 125Te NMR (157.84 MHz, [D6]benzene,
258C): d = ꢀ764.1 and ꢀ1349.5 ppm (1J(125Te,119Sn) = 7418 Hz).
5: Compound 4 (0.1 g, 0.11 mmol) was dissolved in 5 mL of wet
toluene. After the filtration of black precipitate, the resulting orange
solution was stored three days at room temperature to give colorless
crystals of 5 (10.5 mg, 12% yield). M.p. 758C decomp. 1H NMR
(500.18 MHz, [D6]benzene, 258C): d = 1.15 (6H, d, NCH3), 2.22 (6H,
s, NCH3), 2.38 (6H, s, NCH3), 2.63 (6H, s, NCH3), 2.88 (2H, AX
system, CH2N), 5.55 (2H, AX system, CH2N), 3.02 (2H, AX system,
CH2N), 4.17 (2H, AX system, CH2N), 6.78–7.26 (6H, m, ArH), 11.82
(2H, s, SnOH), 11.84 ppm (2H, s, SnOH). 119Sn NMR (186.49 MHz,
[D6]benzene, 258C): d = ꢀ424, ꢀ444 ppm. 125Te NMR (C6D6,
157.84 MHz) not found.
In conclusion, we have shown a stepwise oxidation of
ꢀ
distannyne 1 by tellurium, which easily inserts into the Sn Sn
bond to give the bis(organotin(II))telluride [2,6-
(Me2NCH2)2C6H3Sn]2Te (2). The further oxidation process
is slow and can be tuned easily. Slow oxidation of compound 2
produced
the
unprecedented
compound
[2,6-
(Me2NCH2)2C6H3(Te)Sn(m-Te)Sn-2,6-(Me2NCH2)2C6H3] (3),
containing tin atoms in the oxidation states + II and + IV,
and led to the final oxidation product [2,6-
(Me2NCH2)2C6H3Sn(Te)]2Te (4). Compound 4 is the first
example of an intramolecularly coordinated tritellurostan-
ꢀ
nonic acid anhydride with two terminal Sn Te bonds. In
solution, compound 4 is thermodynamically unstable and
decomposes to give compound 6, which can formally be
regarded as a complex of 4 with tin(II) telluride, SnTe. DFT
calculations of compounds 3, 4, and 6 revealed highly positive
charges at the Sn atoms and negative charges at the terminal
6: A Young valve NMR tube containing the C6D6 solution of 4
(50 mg, 0.05 mmol) was exposed to visible light for two weeks. During
this period the solution became dark violet and the crystals suitable
for X-ray diffraction analysis were grown. This material was identified
as compound 6. Alternatively, compound 6 was prepared by following
procedure. 2,6-(Me2NCH2)2C6H3SnClI2 (0.34 g, 0.57 mmol) was
added with stirring at room temperature to a solution of Li2Te
(0.11 g Te, 0.93 mmol, 1.73 mL 1m lithium triethylborohydride) in
THF (3 ꢁ freeze–pump–thaw, 20 mL) at room temperature. The
reaction mixture was stirred for 24 h. The resulting suspension was
filtered and the dark violet filtrate was concentrated to approximately
5 mL. Storage overnight at ꢀ208C gave dark violet crystals of 6
(0.15 g, 43% yield). M.p. 223.3–226.08C. 1H NMR (500.18 MHz,
[D8]THF, 258C): d = 2.48 (s, 12H, NCH3), 4.38 (bs, 4H, CH2), 6.96 (d,
2H, ArH), 7.09 ppm (t, 1H, ArH). 13C NMR (125.77 MHz, [D8]THF,
258C): d = 45.8 (NCH3), 62.4 (CH2N), 124.8 (C3,5), 127.4 (C4),
ꢀ
Te atoms. Consequently, the terminal Sn Te bond can be
interpreted as a formal “single” bond, where the bond order is
increased owing to the strong electrostatic interaction
between Sn+ and Teꢀ. The presence of the N,C,N-chelating
ligand {2,6-(Me2NCH2)2C6H3}ꢀ is thus crucial for the stabili-
zation of the positive charge at the tin atom by strong N!Sn
donation.
Experimental Section
Unless otherwise stated, all manipulations were carried out under
anaerobic and anhydrous conditions. The 1H, 13C, 119Sn, and
125Te NMR spectra were recorded on a Bruker Avance 500 spec-
trometer and referenced to known standards (SiMe4, SnMe4, TeMe2).
Angew. Chem. Int. Ed. 2012, 51, 3478 –3482
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3481

.
Angewandte
Communications
143.1 ppm (C2,6); signal for C1 not found; 119Sn NMR (186.49 MHz,
[D8]THF, 258C): d = ꢀ294.4, ꢀ295.0, and ꢀ379.3 ppm. 125Te NMR
(157.84 MHz, [D8]THF, 258C): d = ꢀ394.9 ppm (1J(125Te,119Sn):
4142 Hz).
M. Krahn, M. Parvez, G. Schatte, Eur. J. Inorg. Chem. 2003, 1857;
n) M. Saito, N. Tokitoh, R. Okazaki, J. Am. Chem. Soc. 1997, 119,
11124; o) M. Saito, N. Tokitoh, R. Okazaki, J. Am. Chem. Soc.
2004, 126, 15572; p) P. B. Hitchcock, J. Hu, M. F. Lappert, J. R.
Severn, Dalton Trans. 2004, 4193.
Crystallography: Analysis of a yellow crystal of 2·(0.56ꢁ0.21 ꢁ
0.18 mm3), an orange crystal of 3·(0.30ꢁ0.14ꢁ 0.13 mm3), a colorless
crystal of 5 (0.14 ꢁ 0.10 ꢁ 0.10 mm3), and a red crystal of 6 (0.22 ꢁ
0.16 ꢁ 0.08 mm3) was performed on a Nonius KappaCCD diffractom-
eter at 150(1) K. Crystal data for 2: C24H38N4TeSn2, M =
747.56 gmolꢀ1, monoclinic, space group P21/c, a = 6.7710(5), b =
45.553(3), c = 9.5530(5) ꢀ; b = 108.255(5)8; V= 2798.2(3) ꢀ3, Z = 4,
[3] For example see a) M. Unno, Y. Kawai, H. Shioyama, H.
Matsumoto, Organometallics 1997, 16, 4428; b) Z. Hassanzadeh
Fard, L. Xiong, Ch. Mꢃller, M. Holynska, S. Dehnen, Chem. Eur.
J. 2009, 15, 6595; c) W. Ando, T. Kadowaki, Y. Kabe, M. Ishii,
Angew. Chem. 1992, 104, 84; Angew. Chem. Int. Ed. Engl. 1992,
31, 59; d) K. Wraage, T. Pape, R. Herbst-Irmer, M. Noltemeyer,
H. G. Schmidt, H. W. Roesky, Eur. J. Inorg. Chem. 1999, 869;
e) Z. Hassanzadeh Fard, M. R. Halvagar, S. Dehnen, J. Am.
Chem. Soc. 2010, 132, 2848; f) Z. Hassanzadeh Fard, C. Mꢃller,
T. Harmening, R. Pçttgen, S. Dehnen, Angew. Chem. 2009, 121,
4507; Angew. Chem. Int. Ed. 2009, 48, 4441.
m = 2.824 mmꢀ1, 23782 independent reflections (qmin = 2.14, qmax
27.50), 5846 with I ꢁ 2s(I), R1 = 0.042, wR2 (all data) = 0.0692.
Crystal data for 3: C24H38N4Te2Sn2·0.13C4H8O, M = 884.18 gmolꢀ1
=
,
orthorombic, space group Pbca, a = 12.1250(8), b = 18.2339(15), c =
27.8581(15) ꢀ; V= 6159.0(7) ꢀ3, Z = 8, m = 3.498 mmꢀ1, 67649 inde-
pendent reflections (qmin = 1.75, qmax = 27.49), 7042 with I ꢁ 2s(I),
R1 = 0.0394, wR2 (all data) = 0.0551. Crystal data for 5:
[4] Z. Hassanzadeh Fard, M. Holynska, S. Dehnen, Inorg. Chem.
2010, 49, 5748.
C48H80N8O6Te2Sn4·2C7H8, M = 1779.43 gmolꢀ1
,
monoclinic, space
[5] a) S. Nagase, T. Kudo, T. Kurakake, J. Chem. Soc. Chem.
Commun. 1988, 1063; b) S. Nagase, Polyhedron 1991, 10, 1299;
c) M. S. Gordon, K. A. Nguyen, M. T. Carroll, Polyhedron 1991,
10, 1247; d) K. A. Nguyen, M. T. Carroll, M. S. Gordon, J. Am.
Chem. Soc. 1991, 113, 7924; e) N. Sandstrçm, H. Ottosson,
Chem. Eur. J. 2005, 11, 5067.
[6] a) H. Yoshida, Y. Takahara, T. Erata, W. Ando, J. Am. Chem.
Soc. 1992, 114, 1098; b) W. Ando, S. Watanabe, N. Choi, J. Chem.
Soc. Chem. Commun. 1995, 1683; c) N. Choi, K. Asano, W.
Ando, Organometallics 1995, 14, 3146.
group P21/c, a = 14.6871(12), b = 13.3910(12), c = 21.0689(14) ꢀ; b =
120.95(3); V= 3554.1(9) ꢀ3, Z = 2, m = 2.245 mmꢀ1, 34982 independ-
ent reflections (qmin = 2.14, qmax = 27.50), 8097 with I ꢁ 2s(I), R1 =
0.0408, wR2 (all data) = 0.0785. Crystal data for 6: C24H38N4Te4Sn3,
M = 1249.05 gmolꢀ1, monoclinic, space group P2/c, a = 24.8331(6),
b = 9.2740(2), c = 14.9088(12) ꢀ; b = 93.093(7); V= 3428.5(3) ꢀ3, Z =
4, m = 5.524 mmꢀ1, 14391 independent reflections (qmin = 2.14, qmax
=
27.50), 3922 with I ꢁ 2s(I), R1 = 0.0330, wR2 (all data) = 0.0785.
CCDC847113 (6), 847114 (2), 847115 (3), and 847116 (5) contain the
supplementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
[7] M. Saito, H. Hashimoto, T. Tajima, Acta Crystalogr. Sect. E 2010,
66, m885.
ˇ
[8] a) R. Jambor, B. Kasnꢄ, K. N. Kirschner, M. Schꢃrmann, K.
Jurkschat, Angew. Chem. 2008, 120, 1674; Angew. Chem. Int. Ed.
2008, 47, 1650; b) S. Khan, R. Michel, J. M. Dieterich, R. A. F.
Mata, H. W. Roesky, J. P. Demers, A. Lange, D. Stalke, J. Am.
Chem. Soc. 2011, 133, 17889.
Received: October 31, 2011
Revised: December 28, 2011
Published online: February 29, 2012
ˇ
˚ ˇ ˇ
ˇ
[9] a) M. Bouska, L. Dostꢄl, A. Ruzicka, L. Benes, R. Jambor,
ˇ
Chem. Eur. J. 2011, 17, 450; b) M. Bouska, L. Dostꢄl, F. De Proft,
Keywords: density functional calculations ·
intramolecular coordination · organotin compounds ·
119Sn NMR spectroscopy · X-ray diffraction analysis
.
˚
ˇ ˇ
ˇ
A. Ruzicka, A. Lycka, R. Jambor, Chem. Eur. J. 2011, 17, 455; for
recent reactivity studies of SnI compound see c) Y. Peng, B. D.
Ellis, X. Wang, J. C. Fettinger, P. P. Power, Science 2009, 325,
1668; d) O. T. Summerscales, X. Wang, P. P. Power, Angew.
Chem. 2010, 122, 4898; Angew. Chem. Int. Ed. 2010, 49, 4788.
[10] a) P. B. Hitchcock, M. F. Lappert, L. J.-M. Pierssens, A. V.
Protchenko, P. G. H. Uiterweerd, Dalton Trans. 2009, 4578;
b) H. Bera, H. Braunschweig, R. Dçrfler, K. Hammond, A.
Oechsner, K. Radacki, K. Uttinger, Chem. Eur. J. 2009, 15,
12092; c) M. C. Janzen, H. A. Jenkins, L. M. Rendina, J. J. Vittal,
R. J. Puddephatt, Inorg. Chem. 1999, 38, 2123; d) H. Lange, U.
Herzog, U. Bçhme, G. Rheinwald, J. Organomet. Chem. 2002,
660, 43; e) H. Braunschweig, R. Dçrfler, K. Gruss, J. Kçhler, K.
Radacki, Organometallics 2011, 30, 305; f) T. Tajima, N. Takeda,
T. Sasamori, N. Tokitoh, Eur. J. Inorg. Chem. 2005, 4291; g) P.
Pyykkç, M. Atsumi, Chem. Eur. J. 2009, 15, 186.
[11] a) T. Tajima, N. Takeda, T. Sasamori, N. Tokitoh, Organo-
metallics 2006, 25, 3552; b) W.-P. Leung, W.-H. Kwok, L. T. C.
Law, Z.-Y. Zhou, T. C. W. Mak, Chem. Commun. 1996, 505; c) T.
Chivers, D. J. Eisler, Angew. Chem. 2004, 116, 6854; Angew.
Chem. Int. Ed. 2004, 43, 6686; d) T. Chivers, G. Schatte, Chem.
Commun. 2001, 2264.
[12] a) J. Beckmann, J. Bolsinger, A. Duthie, Organometallics 2009,
28, 4610; b) H. Fujihara, H. Mima, N. Furukawa, J. Am. Chem.
Soc. 1995, 117, 10153; c) B. K. Sarma, D. Manna, M. Minoura, G.
Mugesh, J. Am. Chem. Soc. 2010, 132, 5364.
[1] a) J. Llanos, C. Mujica, V. Sanchez, O. Pena, J. Solid State Chem.
2003, 173, 78; b) U. Simon, F. Schueth, S. Schunk, X. Wang, F.
Liebau, Angew. Chem. 1997, 109, 1138; Angew. Chem. Int. Ed.
Engl. 1997, 36, 1121; c) C. L. Bowes, G. A. Ozin, Adv. Mater.
1996, 8, 13; d) R. L. Gitzendanner, F. L. Di Salvo, Inorg. Chem.
1996, 35, 2623; e) J. B. Parise, Y. Ko, J. Rijssenbeek, D. M. Nellis,
K. Tan, S. Koch, J. Chem. Soc. Chem. Commun. 1994, 527;
f) R. R. Chianelli, T. A. Pecoraro, T. R. Halber, W. H. Pan, E. I.
Stiefel, J. Catal. 1984, 86, 226.
[2] For reviews, see: a) R. C. Fischer, P. P. Power, Chem. Rev. 2010,
110, 3877; b) N. Tokitoh, R. Okazaki, Adv. Organomet. Chem.
2001, 47, 121; c) R. Okazaki, N. Tokitoh, Acc. Chem. Res. 2000,
33, 625; d) N. Tokitoh, T. Matsumoto, R. Okazaki, Bull. Chem.
Soc. Jpn. 1999, 72, 1665; e) J. Escudiꢂ, H. Ranaivonjatovo, Adv.
Organomet. Chem. 1999, 44, 113; f) M. C. Kuchta, G. Parkin,
Coord. Chem Rev. 1998, 176, 323; for other examples, see: g) N.
Tokitoh, T. Sadahiro, K. Hatano, T. Sasaki, N. Takeda, R.
Okazaki, Chem. Lett. 2002, 34; h) N. Tokitoh, T. Matsumoto, R.
Okazaki, J. Am. Chem. Soc. 1997, 119, 2337; i) Y. Ding, H. W.
Roesky, M. Noltemeyer, H.-G. Schmidt, J. Am. Chem. Soc. 2002,
124, 8542; j) L. W. Pineda, V. Jancik, H. W. Roesky, R. Herbst-
Irmer, Angew. Chem. 2004, 116, 5650; Angew. Chem. Int. Ed.
2004, 43, 5534; k) W.-P. Leung, W.-H. Kwok, Z.-Y. Zhou,
T. C. W. Mak, Organometallics 2000, 19, 296; l) T. Chivers, G.
Schatte, Chem. Commun. 2004, 2264; m) T. Chivers, T. J. Clark,
ˇ
˚ ˇ ˇ
[13] M. Bouska, L. Dostꢄl, R. Jirꢄsko, A. Ruzicka, R. Jambor,
Organometallics 2009, 28, 4258.
3482
www.angewandte.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 3478 –3482