Tin-chalcogen double-bond compounds, stannanethione and stannaneselone: Synthesis, structure, and reactivities

Article abstract of DOI:10.1021/ja048453h

The first isolation of diarylstannanethione (tin-sulfur double-bond compound) and diarylstannaneselone (tin-selenium double-bond compound), Tbt(Ditp)Sn=X (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]-phenyl; Ditp = 2,2″-diisopropyl-m-terphenyl-2′-yl; X = S

Full text of DOI:10.1021/ja048453h

Published on Web 11/09/2004
Tin-Chalcogen Double-Bond Compounds, Stannanethione
and Stannaneselone: Synthesis, Structure, and Reactivities
Masaichi Saito,† Norihiro Tokitoh,# and Renji Okazaki*,§
Contribution from the Department of Chemistry, Graduate School of Science,
The UniVersity of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
Received March 17, 2004; E-mail: okazaki@fc.jwu.ac.jp
Abstract: The first isolation of diarylstannanethione (tin-sulfur double-bond compound) and diarylstan-
naneselone (tin-selenium double-bond compound), Tbt(Ditp)SndX (Tbt ) 2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl; Ditp ) 2,2′′-diisopropyl-m-terphenyl-2′-yl; X ) S and Se) was accomplished by dechalcogenation
of the corresponding highly hindered tetrachalcogenastannolanes, Tbt(Ditp)SnX4. The 119Sn NMR of
stannanethione, Tbt(Ditp)SndS, and stannaneselone, Tbt(Ditp)SndSe, showed only one low-field broad
signal at 531 and 440 ppm, respectively, characteristic of a tricoordinated tin, and hence, the stannanethione
and stannaneselone display an intrinsic nature of tin-chalcogen double-bond compounds. The X-ray
crystallographic analysis of the isolated stannaneselone, Tbt(Ditp)SndSe 5a, revealed a completely trigonal
geometry around the central tin with a remarkably short Sn-Se bond length, indicative of structural similarity
to a ketone.
Introduction
targets as heavier congeners of a ketone which plays a key role
in organic chemistry, there had been no example of the isolation
For many years, it was commonly accepted that compounds
having double bonds between heavier main group elements
would not be as stable as the corresponding second-row element
compounds because of their weak pπ-pπ bonding, which was
sometimes referred to as the “classical double-bond rule”. Since
the breakthrough of the first stable compound with PdC1 in
1978, those with SidC,2 PdP,3 and SidSi4 in 1981 were
isolated by taking advantage of bulky ligands, which prevent
them from oligomerization (kinetic stabilization); however,
significant and exciting progress has been made in the chemistry
of unsaturated compounds of heavier main group elements,
especially those involving group 14 elements.5,6 Previous studies
on such species, however, have centered on silicon and
germanium compounds, and the chemistry of such compounds
containing tin has been much less explored.
using kinetic stabilization when we undertook a study of such
species several years ago because bulky ligands for steric
protection can be introduced only on the tin atom, and hence,
their oligomerization cannot be efficiently prevented. Recently,
compounds with SndX (X ) S, Se, and Te) bonds, thermo-
dynamically stabilized by intramolecular coordination, have been
synthesized and characterized by Parkin16 and Leung,17 but they
are highly perturbed by electron donation from neighboring
(5) For reviews, see: (a) West, R. Pure Appl. Chem. 1984, 56, 163. (b) Satge´,
J. Pure Appl. Chem. 1984, 56, 137. (c) Raabe, G.; Michl, J. Chem. ReV.
1985, 85, 419. (d) Brook, A. G.; Baines, K. M. AdV. Organomet. Chem.
1986, 25, 1. (e) West, R. Angew. Chem., Int. Ed. Engl. 1987, 26, 1201. (f)
Raabe, G.; Michl, J. In The Chemistry of Organosilicon Compounds; Patai,
S., Rappoport, Z., Eds.; Wiley-Interscience, New York, 1989; p 1015. (g)
Barrau, J.; Escudie´, J.; Satge´, J. Chem. ReV. 1990, 90, 283. (h) Satge´, J. J.
Organomet. Chem. 1990, 400, 121. (i) Tsumuraya, T.; Batcheller, S. A.;
Masamune, S. Angew. Chem., Int. Ed. Engl. 1991, 30, 902. (j) Driess, M.
AdV. Organomet. Chem. 1996, 39, 193. (k) Okazaki, R.; West, R. AdV.
Organomet. Chem. 1996, 39, 232. (l) Baines, K. M.; Stibbs, W. G. AdV.
Organomet. Chem. 1996, 39, 275. (m) Power, P. P. J. Chem. Soc., Dalton
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Weidenbruch, M. In The Chemistry of Organosilicon Compounds; Rap-
poport, Z., Apeloig, Y., Eds.; Wiley-Interscience, New York, 2001; Vol.
3, p 391.
(6) Although the first stable compound having a formal SndSn bond has been
already reported by Lappert in 1976, before the breakthrough,7 it should
be described as bis(stannylene) because of its long Sn-Sn bond and its
large folded angles. Recently, compounds having a remarkably short Snd
Sn bond were reported.8
(7) Goldberg, D. E.; Harris, D. H.; Lappert, M. F.; Thomas, K. M. J. Chem.
Soc., Chem. Commun. 1976, 261.
(8) Wiberg, N.; Lerner, H.-W.; Vasisht, S.-K.; Wagner, S.; Karaghiosoff, K.;
No¨th, H.; Ponikwar, W. Eur. J. Inorg. Chem. 1999, 1211.
As for tin-containing double-bond compounds, some stable
double-bond species with group 14 (SndSn,7-9 SndC,10 Snd
CdN,11 SndSi,12 and SndGe13) and group 15 elements (Snd
N14 and SndP15) have been synthesized. Although tin-
chalcogen double-bond compounds are very fascinating synthetic
† Present address: Department of Chemistry, Faculty of Science, Saitama
University, Shimo-okubo, Sakura-ku, Saitama-city, Saitama 338-8570,
Japan.
# Present address: Institute for Chemical Research, Kyoto University,
Uji, Kyoto 611-0011, Japan.
§ Present address: Department of Chemical and Biological Sciences,
Faculty of Science, Japan Women’s University, Mejirodai, Bunkyo-ku,
Tokyo 112-8681, Japan.
(9) (a) Masamune, S.; Sita, L. R. J. Am. Chem. Soc. 1985, 107, 6390. (b)
Weidenbruch, M.; Kilian, H.; Peters, K.; Schnering, H. G. v.; Marsmann,
H. Chem. Ber. 1995, 128, 983. (c) Klinkhammer, K. W.; Schwarz, W.
Angew. Chem., Int. Ed. Engl. 1995, 34, 1334.
(10) (a) Meyer, H.; Baum, G.; Massa, W.; Berger, S.; Berndt, A. Angew. Chem.,
Int. Ed. Engl. 1987, 26, 546. (b) Anselme, G.; Ranaivonjatovo, H.; Escudie´,
J.; Couret, C.; Satge´, J. Organometallics 1992, 11, 2748. (c) Weidenbruch,
M.; Kilian, H.; Stu¨rmann, M.; Pohl, S.; Saak, W.; Marsmann, H.; Steiner,
D.; Berndt, A. J. Organomet. Chem. 1997, 530, 255.
(1) Klebach, T. C.; Lourens, R.; Bickelhaupt, F. J. Am. Chem. Soc. 1978, 100,
4886.
(2) Brook, A. G.; Abdesaken, F.; Gutekunst, B.; Gutekunst, G.; Kallury, R.
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9
15572
J. AM. CHEM. SOC. 2004, 126, 15572-15582
10.1021/ja048453h CCC: $27.50 © 2004 American Chemical Society

Tin−Chalcogen Double-Bond Compounds
A R T I C L E S
nitrogen atoms to electron-deficient reactive centers, as evi-
denced by their high-field chemical shifts in 119Sn NMR (vide
infra).
of less-stable compounds having several other overcrowded
ligands.
Results and Discussion
We previously reported the synthesis of compounds with Sid
S18 and GedX (X ) S, Se, and Te)19,20 bonds bearing a 2,4,6-
triisopropylphenyl (Tip) group and a very efficient steric
protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt)
group, developed by us.21 Although we also described the
synthesis of tin-chalcogen double-bond compounds, Tbt(Tip)-
SndX (X ) S and Se), which are stable in solution by
dechalcogenation22 of 1,2,3,4,5-tetrachalcogenastannolanes23 and
chalcogenation of the corresponding stannylene,22b,24 they were
found to exist as a dimer in the solid state. These facts clearly
show that for the isolation of tin-chalcogen double-bond
compounds, introduction of a ligand bulkier than a Tip group
onto the tin with a Tbt group is necessary, in contrast to the
cases of the silanethione and the germanium-chalcogen double-
bond compounds isolated by using a Tip group together with a
Tbt group.18-20 This higher tendency of a tin-chalcogen double-
bond compound to dimerize is due to (i) energy gaps between
σ- and π-bonds in tin-chalcogen double-bonds being larger than
those of silicon and germanium18b and (ii) longer bond lengths
involving a tin atom. To stabilize a tin-chalcogen double-bond
compound effectively, it is necessary to introduce a bulkier
ligand than the Tip group. In the course of our studies on
stabilization of tin-chalcogen double-bond compounds by steric
protection, we found recently that the use of the combination
of a Tbt group with a substituted m-terphenyl group25 enabled
the isolation of the first diaryl-substituted tin-selenium double-
bond compound without intramolecular coordination.26 This
paper delineates a detailed account of the successful synthesis,
structure, and reactivities of the first diarylstannanethione and
diarylstannaneselone by using the combination of the m-
terphenyl and Tbt groups on the tin along with the properties
Synthesis of Highly Hindered Tetrachalcogenastannolanes
by Chalcogenation of Stannylene. Highly hindered tetrathia-
stannolanes, Tbt(R)SnS4 1 [1a, R ) 2,2′′-diisopropyl-m-
terphenyl-2′-yl (Ditp), 22%; 1b, R ) 2,2′′-dimethyl-m-terphenyl-
2′-yl (Dmtp), 25%; 1c, R ) 2,4,6-tricyclohexylphenyl (Tcp),
96%; 1d, R ) 2,4,6-tris[(trimethylsilyl)methyl]phenyl (Ttm),
34%; 1e, R ) bis(trimethylsilyl)methyl (Dis), 78%] and
tetraselenastannolanes Tbt(R)SnSe4 2 [2a, 38%; 2b, 29%; 2c,
100%], which are useful precursors for the synthesis of tin-
chalcogen double-bond compounds,22 were easily obtained by
chalcogenation of the corresponding stannylenes Tbt(R)Sn 3,
generated through two routes: successive arylation of stannous
chloride and reduction of dibromostannanes (Scheme 1).27
Isolation of Stable Stannanethione Tbt(Ditp)SndS 4a and
Stannaneselone Tbt(Ditp)SndSe 5a by Introducing a Novel
Ligand, a 2,2′′-Diisopropyl-m-terphenyl-2′-yl (Ditp) Group
Having a m-Terphenyl Skeleton. Unsuccessful attempts at the
isolation of tin-chalcogen double-bond compounds by using
the combination of Tbt-Tip groups prompted us to develop a
ligand bulkier than Tip. One possible strategy might be the
introduction of a ligand that is longer and bulkier than an
isopropyl group, such as a cyclohexyl group. Another possible
approach is the introduction of a m-terphenyl group, which is
expected to be advantageous in terms of not only synthetic
facility but also steric protection.25 Inspection of the CPK model
reveals that both phenyl groups at the 2,6-positions are
perpendicular to the central aromatic ring because of steric
requirement when both m-terphenyl and Tbt groups exist on
tin, and hence, the m-terphenyl group is expected to have a bowl-
shaped conformation, which can effectively protect the reactive
center in cooperation with the Tbt group. At first, introduction
of a 2,2′′-diisopropyl-m-terphenyl-2′-yl (Ditp) group onto tin
was attempted.
(11) Gru¨tzmacher, H.; Freitag, S.; Herbst-Irmer, R.; Sheldrick, G. S. Angew.
Chem., Int. Ed. Engl. 1992, 31, 437.
(12) Sekiguchi, A.; Izumi, R.; Lee, V. Y.; Ichinohe, M. J. Am. Chem. Soc. 2002,
124, 14822.
(13) (a) Sekiguchi, A.; Izumi, R.; Lee, V. Y.; Ichinohe, M. Organometallics
2003, 22, 1483. (b) Scha¨fer, A.; Saak, W.; Weidenbruch, M. Organome-
tallics 2003, 22, 215.
(1) Synthesis, Isolation, and Structure of 4a and 5a
(Scheme 2). When tributylphosphine was added to a toluene-
d8 solution of tetrathiastannolane 1a, the solution turned orange
(λmax ) 491 nm), suggesting the formation of stannanethione
4a.28 The 119Sn NMR at room temperature showed two very
broad signals at about 530 ppm, which suggested the presence
of conformational isomers. At 60 °C, the 119Sn NMR showed
(14) Ossig, G.; Meller, A.; Freitag, S.; Herbst-Irmer, R. J. Chem. Soc., Chem.
Commun. 1993, 497.
(15) (a) Couret, C.; Escudie´, J.; Satge´, J.; Raharinirina, A.; Andriamizaka, J. D.
J. Am. Chem. Soc. 1985, 107, 8280. (b) Ranaivonjatovo, H.; Escudie´, J.;
Couret, C.; Satge´, J. J. Chem. Soc., Chem. Commun. 1992, 1047.
(16) (a) Kuchta, M. C.; Parkin, G. J. Am. Chem. Soc. 1994, 116, 8372. For a
review, see: (b) Kuchta, M. C.; Parkin, G. Coord. Chem. ReV. 1998, 176,
323.
(17) (a) Leung, W.-P.; Kwok, W.-H.; Law, L. T. C.; Zhou, Z.-Y.; Mak, T. C.
W. J. Chem. Soc., Chem. Commun. 1996, 505. (b) Leung, W.-P.; Kwok,
W.-H.; Zhou, Z.-Y.; Mak, T. C. W. Organometallics 2000, 19, 296.
(18) (a) Suzuki, H.; Tokitoh, N.; Nagase, S.; Okazaki, R. J. Am. Chem. Soc.
1994, 116, 11578. (b) Suzuki, H.; Tokitoh, N.; Okazaki, R.; Nagase, S.;
Goto, M. J. Am. Chem. Soc. 1998, 120, 11096.
(19) (a) Tokitoh, N.; Matsumoto, T.; Manmaru, K.; Okazaki, R. J. Am. Chem.
Soc. 1993, 115, 8855. (b) Matsumoto, T.; Tokitoh, N.; Okazaki, R. Angew.
Chem., Int. Ed. Engl. 1994, 33, 2316. (c) Tokitoh, N.; Matsumoto, T.;
Okazaki, R. J. Am. Chem. Soc. 1997, 119, 2337. (d) Matsumoto, T.; Tokitoh,
N.; Okazaki, R. J. Am. Chem. Soc. 1999, 121, 8811.
(20) For an account on the chemistry of germanium-chalcogen double-bond
compounds, see: Tokitoh, N.; Matsumoto, T.; Okazaki, R. Bull. Chem.
Soc. Jpn. 1999, 72, 1665.
(21) (a) Okazaki, R.; Unno, M.; Inamoto, N. Chem. Lett. 1987, 2293. (b)
Okazaki, R.; Unno, M.; Inamoto, N.; Yamamoto, G. Chem. Lett. 1989,
493. (c) Okazaki, R.; Unno, M.; Inamoto, N. Chem. Lett. 1989, 791.
(22) (a) Matsuhashi, Y.; Tokitoh, N.; Okazaki, R. Organometallics 1993, 12,
2573. (b) Saito, M.; Tokitoh, N.; Okazaki, R. J. Organomet. Chem. 1995,
499, 43.
(25) For some recent reports on the synthesis of main group element compounds
with unique structures using m-terphenyl ligands, see: (a) Olmstead, M.
M.; Simons, R. S.; Power, P. P. J. Am. Chem. Soc. 1997, 119, 11705. (b)
Pu, L.; Senge, M. O.; Olmstead, M. M.; Power, P. P. J. Am. Chem. Soc.
1998, 120, 12682. (c) Twamley, B.; Sofield, C. D.; Olmstead, M. M.; Power,
P. P. J. Am. Chem. Soc. 1999, 121, 3357. (d) Pu, L.; Haubrich, S. T.; Power,
P. P. J. Organomet. Chem. 1999, 582, 100. (e) Pu, L.; Twamley, B.;
Haubrich, S. T.; Olmstead, M. M.; Mork, B. V.; Simons, R. S.; Power, P.
P. J. Am. Chem. Soc. 2000, 122, 650. (f) Pu, L.; Twamley, B.; Power, P.
P. J. Am. Chem. Soc. 2000, 122, 3524. (g) Eichler, B. E.; Power, P. P. J.
Am. Chem. Soc. 2000, 122, 8785. (h) Stender, M.; Pu, L.; Power, P. P.
Organometallics 2001, 20, 1820. (i) Stender, M.; Phillips, A. D.; Wright,
R. J.; Power, P. P. Angew. Chem., Int. Ed. 2002, 41, 1785. (j) Phillips, A.
D.; Wright, R. J.; Olmstead, M. M.; Power, P. P. J. Am. Chem. Soc. 2002,
124, 5930. We also developed a new type of bowl-shaped m-terphenyl
ligand: (k) Goto, K.; Holler, M.; Okazaki, R. Tetrahedron Lett. 1996, 37,
3141. (l) Goto, K.; Holler, M.; Okazaki, R. J. Am. Chem. Soc. 1997, 119,
1460. (m) Goto, K.; Holler, M.; Okazaki, R. Chem. Commun. 1998, 1915.
(n) Itoh, M.; Takenaka, K.; Okazaki, R.; Takeda, N.; Tokitoh, N. Chem.
Lett. 2001, 1206.
(23) (a) Tokitoh, N.; Matsuhashi, Y.; Okazaki, R. Tetrahedron Lett. 1991, 32,
6151. (b) Matsuhashi, Y.; Tokitoh, N.; Okazaki, R.; Goto, M.; Nagase, S.
Organometallics 1993, 12, 1351.
(24) (a) Tokitoh, N.; Saito, M.; Okazaki, R. J. Am. Chem. Soc. 1993, 115, 2065.
(b) Saito, M.; Tokitoh, N.; Okazaki, R. Organometallics 1996, 15, 4531.
(26) Saito, M.; Tokitoh, N.; Okazaki, R. J. Am. Chem. Soc. 1997, 119, 11124.
(27) Saito, M.; Tokitoh, N.; Okazaki, R. Organometallics 1995, 14, 3620.
(28) The n-π* transition of the stannanethione, Tbt(Tip)SndS, has already been
observed at 473 nm.24a
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A R T I C L E S
Scheme 1
Saito et al.
Scheme 2
only one broad signal at 531 ppm, which could be assigned to
stannanethione 4a. Contrary to Parkin’s terminal tin-sulfido
complex (-303 ppm),16 this low-field chemical shift is char-
acteristic of a tricoordinated tin, as observed in SndSn (7257
and 427.58 ppm), SndC (83510a and 28810b ppm), SndSi (516.7
ppm),12 SndGe (525.1,13a 373.4,13a 268,13b and 36029 ppm), and
SndP (658.315a and 499.515b ppm), and hence, stannanethione
4a displays an intrinsic nature of tin-sulfur double-bond
compounds. This is the first observation of a diarylstannane-
thione by 119Sn NMR. Even after measurement of 119Sn NMR
at 60 °C, the color of this solution remained orange, indicating
that stannanethione 4a was remarkably stable in solution even
at 60 °C. After slow evaporation of the solvent, followed by
washing with hexane in a glovebox, the first stable stannane-
thione 4a was obtained as orange crystals in 26% yield.
After successful isolation of stannanethione 4a, we examined
the isolation of stannaneselone by using the same combination
of ligands as that of stannanethione 4a. When Tbt(Ditp)SnSe4
2a was allowed to react with 3 equiv of triphenylphosphine in
refluxing hexane for 2 h under argon, the solution turned deep
red (λmax ) 531 nm), indicating the formation of stannaneselone
5a. The absorption maximum due to the n-π* transition at 531
nm is highly red-shifted compared to that of stannanethione,
Tbt(R)SndS (R ) Tip, 473 nm;24 R ) Ditp (4a), 491 nm), as
is observed in germanium analogues.19,20 A red shift was also
found in the transition from germaneselone, Tbt(Tip)GedSe
(519 nm),19,20 to stannaneselone 5a (531 nm), as is observed
also in a series of the sulfur-containing double-bond systems.18-20
In its 119Sn NMR, a signal that could be assigned to 5a was
observed at 440 ppm at 60 °C. Contrary to Parkin’s terminal
tin-selenido complex (-444 ppm),16 this low-field chemical
shift is characteristic of a low-coordinated tin, as in the case of
stannanethione 4a, indicating that stannaneselone 5a, again,
displays an intrinsic nature of tin-selenium double-bond
compounds. Although the coupling constant between 119Sn and
77Se is thought to be diagnostic of the degree of the multiple-
bond character, it was not observed due to a low S/N ratio.
Filtration of triphenylphosphine selenide, insoluble in hexane,
(29) Chaubon, M. A.; Escudie, J.; Ranaivonjatovo, H.; Satge, J. J. Chem. Soc.,
Chem. Commun. 1996, 2621.
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Tin−Chalcogen Double-Bond Compounds
A R T I C L E S
Scheme 3
reactivities of 4a and 5a indicate that there is enough space
around their reactive centers to react with a small reagent by
taking advantage of the intrinsic double-bond nature of their
tin-chalcogen bond because the long arms of the two bulky
ligands enclose each reactive center from a distance.
Synthesis of Tbt(Dmtp)SndX (4b, X ) S; 5b, X ) Se)
with a Novel Ligand, a 2,2′′-Dimethyl-m-terphenyl-2′-yl
(Dmtp) Group with a m-Terphenyl Skeleton (Scheme 3).
Next, introduction of a 2,2′′-dimethyl-m-terphenyl-2′-yl (Dmtp)
group, less bulky than a Ditp group, onto tin was attempted.
Treatment of tetrathiastannolane 1b with tributylphosphine in
Figure 1. ORTEP drawing of stannaneselone, Tbt(Ditp)SndSe 5a, with
thermal ellipsoid plots (30% probability for non-hydrogen atoms). A minor
disordered moiety was omitted for clarity.
followed by removal of hexane, resulted in the isolation of the
stable stannaneselone 5a as red crystals in 84% yield. The
structure of this novel double-bond system was established by
X-ray crystallographic analysis for single crystals obtained by
recrystallization from hexane in a glovebox. The ORTEP
drawing (Figure 1) shows that the stannaselenocarbonyl unit is
effectively protected by one disil group in Tbt and two isopropyl
groups located in a cis fashion in Ditp, which are directed toward
the SndSe bond to avoid the steric repulsion with the Tbt group,
as indicated by inspection of the CPK model. The Sn-Se
distance [2.373(3) Å] is approximately 9% shorter than a Sn-
Se single bond length (2.55-2.60 Å),30 consistent with the
calculated SndSe bond length for H2SndSe (2.346 Å)18b and
slightly shorter than that of Parkin’s terminal selenido complex
(2.39 Å).16 The geometry around the tin atom is trigonal planar,
with the sum of the angles being 359.9°. This is indicative of
structural similarity to a ketone, as in the case of silicon and
germanium analogues.18,19
hexane immediately afforded a yellow-orange solution (λmax )
486 nm), suggesting the formation of stannanethione 4b. The
formation of stannanethione 4b was confirmed by a trapping
reaction with mesitonitrile oxide, leading to the corresponding
[3 + 2] cycloadduct 7b in 85% yield, as well as by 119Sn NMR,
which showed a broad signal at 467 ppm. The color of 4b,
however, gradually disappeared at room temperature, and no
identifiable product was obtained except for recovered 1b. As
in the case of stannanethione 4b, as soon as tributylphosphine
was added to a toluene solution of tetraselenastannolane 2b,
the color of the solution changed from pale orange to deep red,
suggesting the formation of stannaneselone 5b. However, the
color changed to orange so rapidly (after about a minute) that
the UV-vis absorption of the deep-red solution could not be
measured. No identifiable product was obtained from this
reaction mixture. These facts clearly show that the combination
of Tbt-Dmtp groups does not provide enough bulkiness to
isolate tin-chalcogen double-bond compounds.
(2) Reactions of 4a and 5a (Scheme 2). Although X-ray
crystallographic analysis of stannanethione 4a has not been
successful yet, the formation of 4a was also ascertained by
several trapping reactions. Stannanethione 4a reacted with
mesitonitrile oxide to give a [3 + 2] cycloadduct 7a (72%). It
is noted that the reaction of stannanethione 4a with 2,3-dimethyl-
1,3-butadiene gave a [4 + 2] cycloadduct 6 in 39% yield. This
result clearly demonstrates that the stannanethione has a
considerable extent of ene character, like its silicon and
germanium analogues,18,19 as well as like its carbon analogues,
such as thioketones and selenoketones,31 despite severe steric
congestion around the SndS group.
Stannaneselone 5a reacted with mesitonitrile oxide and 2,3-
dimethyl-1,3-butadiene to afford the corresponding cycloadducts
9a and 8 in 90 and 60%, respectively, like stannanethione 4a.
Since the [4 + 2] cycloadduct 8 could not be isolated by flash
column chromatography because of its instability, the yield of
8 was estimated by NMR. These results clearly demonstrate
that stannaneselone 5a also has high ene reactivity. The
Synthesis and Reactions of Tbt(Tcp)SndX (4c, X ) S;
5c, X ) Se): Stable Stannanethione 4c and Stannaneselone
5c, Observable by 119Sn NMR. (1) Synthesis and Reactions
of Tbt(Tcp)SndS 4c (Scheme 4). The combination of Tbt and
2,4,6-tricyclohexylphenyl (denoted as Tcp) groups was next
examined. The Tcp group is potentially another ligand that is
bulkier than the Tip group, where an isopropyl group in Tip is
substituted by a bulkier cyclohexyl group.Treatment of Tbt-
(Tcp)SnS4 1c with 3 equiv of triphenylphosphine in toluene
caused a change in the color of the solution to orange (λmax
)
488 nm), suggesting the formation of stannanethione 4c.32 In
119Sn NMR, a signal that could be assigned to stannanethione
4c was successfully observed at 643 ppm. Furthermore, the
formation of stannanethione 4c was evidenced by trapping
experiments; treatment of the orange solution of stannanethione
4c with phenyl isothiocyanate and mesitonitrile oxide afforded
[2 + 2] and [3 + 2] cycloadducts, 10 (40%) and 7c (35%),
respectively,24 together with an oligomeric mixture containing
mainly dimeric products.34,35 In the absence of the trapping
(30) The average length of a Sn-Se single bond in X-Sn-Se-X systems (428
examples) is 2.579 Å (Cambridge Structural Database).
(31) (a) For thioketones: Duus, F. In ComprehensiVe Organic Chemistry; Barton,
D. H. R., Ollis, W. D., Eds.; Pergamon Press: Oxford, 1979; Vol. 3, p
373. (b) For selenoketones: Guziec, F. S. In The Chemistry of Organic
Selenium and Tellurium Compounds; Patai, S., Ed.; John Wiley & Sons,
New York, 1987; Vol. 2, p 215 and references therein.
(32) The absorption maximum of stannanethione 4c in hexane is 9 nm red-
shifted from that in toluene. This solvent effect observed for 4c is nearly
the same as those for thiobenzophenone.33
(33) (a) Lees, W. A.; Burawoy, A. Tetrahedron 1964, 20, 1527. (b) Lees, W.
A.; Burawoy, A. Tetrahedron 1964, 20, 2229.
(34) Scha¨fer, A.; Weidenbruch, M.; Saak, W.; Pohl, S.; Marsmann, H. Angew.
Chem., Int. Ed. Engl. 1991, 30, 962.
9
J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004 15575

A R T I C L E S
Scheme 4
Saito et al.
Scheme 5
reagents, the orange color of 4c gradually disappeared at room
temperature over 1 day, suggesting the instability of stannaneth-
ione 4c. The absence of the stannanethione in this reaction
indicates that even the combination of Tbt and Tcp groups is
not sufficient for the isolation of a stannanethione.
(2) Synthesis and Reactions of Tbt(Tcp)SndSe 5c (Scheme
4). Treatment of Tbt(Tcp)SnSe4 2c with 3 equiv of triphen-
ylphosphine in toluene gave a deep-red solution, suggesting the
formation of stannaneselone 5c, which is stable in solution at
room temperature. Its 119Sn NMR showed a signal at 556 ppm
that could be assigned to stannaneselone 5c. The 77Se NMR at
-10 °C shows only one singlet at 839 ppm, significantly low-
field-shifted compared to the signal of R-selenium [δ(77Se) 321
ppm] in Tbt(Tcp)SnSe4 2c. The 77Se chemical shift of Tbt(Tip)-
GedSe19b,d,20 was observed at 941 ppm, while those of most
dialkyl selenoketones are in the range between 1600 and 2200
ppm. The formation of stannaneselone 5c was also confirmed
by trapping experiments. Treatment of stannaneselone 5c thus
obtained in solution with mesitonitrile oxide afforded the
corresponding [3 + 2] cycloadduct 9c (58%). Stannaneselone
5c is less stable than stannanethione 4c, and it gradually
decomposed at ambient temperature over a few hours. After
the deep-red color of the solution of 5c completely disappeared,
the 119Sn NMR exhibited six signals at -294, -280, -279,
-276, -119, and -111 ppm.34,35 No identifiable product was
obtained, except triphenylphosphine selenide (91%) from this
solution.
however, there appeared only one signal at 70 ppm that could
be assigned to the starting material, 1d. After 2 h, white
precipitates (Ph3PdS) were suddenly formed together with the
colorless supernatant. The 119Sn NMR of this mixture exhibited
six broad signals at about -50 ppm (δ -62.1, -60.7, -57.7,
-56.5, -55.5, -51.8).34,35 After collection of an oligomeric
fraction by usual workup, its 1H NMR spectrum was too
complicated to assign peaks (Scheme 5).35
Desulfurization of Tbt(Dis)SnS4 1e. The bis(trimethylsilyl)-
methyl (Dis) group is well-known as an effective steric
protection group for low-coordinated compounds of heavier
group 14 elements.7,37 The Dis group is expected to surround
the reactive center at a nearer site than other bulky aryl groups
that were mentioned above.
While a toluene-d8 solution of Tbt(Dis)SnS4 1e and 3 equiv
of triphenylphosphine in an NMR tube were degassed, consider-
able amounts of white precipitates were formed. The 31P NMR
of this mixture exhibited only one signal of Ph3PdS, indicating
that the reaction had completed. The supernatant was colorless,
suggesting the absence of stannanethione 4e in the solution. The
absence of stannanethione 4e in the resulting solution indicated
that the combination of Tbt and Dis groups did not lead to the
isolation of stannanethione 4e, most likely because of longer
bonds involving tin which make its dimerization easier (Scheme
5). In the case of the germanium congeners, Dis groups can
protect the intermolecular attack of the tellurium atom onto the
germanium atom, thus leading to the isolation of stable
germanetellone, Tbt(Dis)GedTe.19,20
Desulfurization of Tbt(Ttm)SnS4 1d. Although it is con-
sidered best to introduce two Tbt groups onto the tin in terms
of steric congestion, this attempt has not been successful yet.36
The combination of Tbt and Ttm, which is a less-encumbered
ligand than a Tbt group, was attempted.
Treatment of Tbt(Ttm)SnS4 1d with 3 equiv of triphen-
ylphosphine in toluene-d8 gave a pale-orange solution, suggest-
ing the formation of stannanethione 4d.28 In 119Sn NMR,
Experimental Section
(35) We tentatively assign the corresponding mixtures to oligomeric products
probably containing mainly dimeric products, judging from the retention
time of gel permeation chromatography. The trimerization of our double-
bond compounds was probably suppressed because of the large 1,3-diaxial
interactions between two bulky ligands, although the possibility that the
fraction contained trimeric products is not completely excluded. The
complexity in the 119Sn NMR suggested the presence of conformational
mixtures or trimeric products.
(36) A diarylplumbylene bearing two Tbt groups on the lead was successfully
synthesized: (a) Kano, N.; Tokitoh, N.; Okazaki, R. Organometallics 1997,
16, 2748. (b) Kano, N.; Shibata, K.; Tokitoh, N.; Okazaki, R. Organome-
tallics 1999, 18, 2999.
General Procedure. All of the reactions were carried out under
argon. 1H (500 MHz) and 13C NMR (125 MHz) spectra were recorded
on Bruker AM-500 and JEOL R-500 spectrometers with chloroform
(37) Isolation of stable dimetallenes using disil groups has been reported. For
SidSi, see: (a) Masamune, S.; Eriyama, Y.; Kawase, T. Angew. Chem.,
Int. Ed. Engl. 1987, 26, 584. For GedGe, see: (b) Hitchcock, P. B.; Lappert,
M. F.; Miles, S. J.; Thorne, A. J. J. Chem. Soc., Chem. Commun. 1984,
480.
9
15576 J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004

Tin−Chalcogen Double-Bond Compounds
A R T I C L E S
[δ(1H) 7.25 ppm; δ(13C) 77.00 ppm] or benzene [δ(1H) 7.15 ppm; δ(13C)
128.00 ppm] as an internal standard. 119Sn NMR (101 MHz) and 77Se
NMR (51 MHz) spectra were recorded on a JEOL EX-270 spectrometer
with tetramethylstannane and dimethylselenide as the external standards,
respectively. High-resolution mass spectral data were obtained on a
JEOL SX-102 mass spectrometer. Electronic spectra were measured
on a JASCO Ubest-50 UV-vis spectrometer. Preparative HPLC was
carried out on an LC-08 or LC-908 with JAIGEL-1H and -2H columns.
Preparative thin-layer chromatography (PTLC), wet-column chroma-
tography (WCC), and dry-column chromatography (DCC) were carried
out with Merck Kieselgel 60 PF254 Art. 7747, Wako gel C-200, and
ICN silica DCC 60A, respectively. All melting points were determined
on a Yanaco micromelting point apparatus and are uncorrected.
Elemental analyses were carried out at the Microanalytical Laboratory
of the Department of Chemistry, Faculty of Science, The University
of Tokyo.
119Sn NMR (CDCl3, 101 MHz) δ 51. Anal. Calcd for C51H84S4Si6Sn:
C, 55.04; H, 7.62; S, 11.53. Found: C, 54.78; H, 7.41; S, 11.69.
Preparation of Tbt(Ditp)SnSe4 2a. A solution of Tbt(Ditp)Sn: 3a,
prepared from TbtBr (844 mg, 1.33 mmol), stannous chloride (274 mg,
1.44 mmol), and DitpI (591 mg, 1.34 mmol), was cooled again to -60
°C and then treated with elemental selenium (446 mg, 5.65 mmol).
After the mixture was warmed to ambient temperature, the solvents
were evaporated, and then the resulting residue was subjected to WCC
(Florisil/methylene chloride) followed by DCC to give crude Tbt(Ditp)-
SnSe4 (875 mg), which was further purified by HPLC to afford pure
5-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-5-[2,6-bis(2-isopropyl-
phenyl)phenyl]-1,2,3,4,5-tetraselenastannolane (2a) (629 mg, 38%).
2a: mp 249-251 °C dec (recrystallized from methylene chloride/
acetonitrile); 1H NMR (CDCl3, 500 MHz, 330 K) δ 0.03 (s, 36H), 0.15
(s, 18H), 1.07 (d, J ) 7 Hz, 6H), 1.14 (d, J ) 7 Hz, 6H), 1.42 (s, 1H),
1.81-2.07 (br s, 2H), 2.52 (sept, J ) 7 Hz, 2H), 6.36-6.64 (br s, 1H),
7.01-7.04 (m, 2H), 7.26 (d, J ) 7 Hz, 2H), 7.30-7.37 (m, 7H); 13C
NMR (CDCl3, 125 MHz, 330 K) δ 1.18 (q), 2.59 (q), 23.75 (q), 25.12
(q), 29.78 (d), 29.78 (d), 30.92 (d), 31.53 (d), 32.30 (d), 124.17 (d),
126.38 (d), 126.84 (d), 127.43 (d), 128.68 (d), 128.72 (d), 129.69 (d),
131.36 (d), 142.60 (s), 143.64 (s), 144.90 (s), 147.29 (s), 148.02 (s),
148.54 (s), 149.86 (s), 152.18 (s); 119Sn NMR (CDCl3, 101 MHz, 330
K) δ 2.0. Anal. Calcd for C51H84Se4Si6Sn: C, 47.10; H, 6.38; Se, 24.29.
Found: C, 46.89; H, 6.38; Se, 24.38.
General Procedures for the Preparation of Tbt(Ar)Sn: 3 (Ar )
Ditp, Dmtp, Ttm). To a THF solution of TbtLi, prepared from TbtBr
and t-BuLi (1.65 M in pentane; 2.2 equiv) at -70 °C, was added an
ether suspension of equimolar stannous chloride. After the mixture was
stirred for 1.5 h at -65 °C, the reaction mixture was treated with a
THF solution of equimolar ArLi, prepared from ArBr or ArI and t-BuLi
(2.2 equiv), to afford an orange solution of stannylene Tbt(Ar)Sn: 3.
Preparation of 2′-Iodo-2,2′′-diisopropyl-1,1′:3′,1′′-terphenyl. To
a solution of (2-isopropylphenyl)magnesium bromide, prepared from
1-bromo-2-isopropylbenzene38 (3.95 g, 19.8 mmol) and magnesium (533
mg, 21.9 mmol) in 20 mL of THF by heating at reflux, was added
dropwise a THF (18 mL) solution of 1,3-dichloro-2-iodobenzene39 (1.82
g, 6.67 mmol). The resulting solution was heated at reflux for 3.5 h,
cooled to 0 °C, and quenched with a THF (5 mL) solution of iodine
(3.62 g, 14.3 mmol). After an aqueous solution of sodium thiosulfate
was added, this mixture was extracted with ether and dried over
anhydrous magnesium sulfate. After removal of the ether, the residue
was separated with DCC to yield 2′-iodo-2,2′′-diisopropyl-1,1′:3′,1′′-
terphenyl (DitpI) (2.34 g, 80%): mp 95-98 °C dec (ethanol). The 1H
NMR suggested the presence of two rotational isomers, two isopropyl
groups of which are located in syn or anti fashion. The ratio probably
depends on the populations of conformers of 2′-lithium-2,2′′-diisopro-
pyl-1,1′:3′,1′′-terphenyl (DitpLi) before the reaction mixture is quenched
by iodine. Inspection of the CPK models indicates that two o-aromatic
rings in DitpI cannot rotate since iodine is much larger than lithium.
For these reasons, the aromatic region of its 1H and 13C NMR spectrum
is too complicated to be assigned. Anal. Calcd for C24H25I: C, 65.45;
H, 5.73; I, 28.82. Found: C, 65.23; H, 5.72; I, 27.86.
Preparation of Tbt(Dmtp)SnS4 1b. A solution of Tbt(Dmtp)Sn:
3b, prepared from TbtBr (669 mg, 1.05 mmol), stannous chloride (224
mg, 1.18 mmol), and DmtpI40 (376 mg, 0.98 mmol), was cooled again
to -65 °C and then treated with elemental sulfur (211 mg, 0.82 mmol).
After the mixture was gradually warmed to ambient temperature, the
solvents were evaporated, and then the resulting residue was subjected
to WCC (Florisil/methylene chloride) followed by HPLC to give
5-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-5-[2,6-bis(2-methylphen-
yl)phenyl]-1,2,3,4,5-tetrathiastannolane (1b) (273 mg, 25%). 1b: mp
277-280 °C dec (recrystallized from methylene chloride/ethanol); 1H
NMR (CDCl3, 500 MHz, 330 K) δ -0.12 (br s, 36H), 0.12 (s, 18H),
1.40 (s, 1H), 1.92 (br s, 2H), 1.95 (s, 6H), 6.35-6.55 (br s, 2H), 7.00
(t, J ) 7 Hz, 2H), 7.14-7.18 (m, 4H), 7.21 (t, J ) 7 Hz, 2H), 7.31 (d,
J ) 7 Hz, 2H), 7.41 (t, J ) 7 Hz, 1H); 13C NMR (CDCl3, 125 MHz,
330 K) δ 1.10 (q), 2.28 (q), 21.29 (q), 30.78 (d), 30.89 (d), 33.00 (d),
123.52 (d), 126.45 (d), 128.32 (d), 128.60 (d), 128.81 (d), 129.08 (d),
130.39 (d), 130.82 (d), 138.21 (s), 140.60 (s), 142.93 (s), 145.51 (s),
145.88 (s), 147.94 (s), 149.64 (s), 152.69(s); 119Sn NMR (CDCl3, 101
MHz, 333 K) δ 53. Anal. Calcd for C47H76S4Si6Sn: C, 53.42; H, 7.26;
S, 12.14. Found: C, 51.79; H, 6.84; S, 11.48.
Preparation of Tbt(Dmtp)SnSe4 2b. A solution of Tbt(Dmtp)Sn:
3b, prepared from TbtBr (766 mg, 1.22 mmol), stannous chloride (240
mg, 1.28 mmol), and DmtpI (466 mg, 1.21 mmol), was cooled again
to -50 °C and then treated with elemental selenium (533 mg, 6.74
mmol). After the mixture was gradually warmed to ambient temperature,
the solvents were evaporated, and then the resulting residue was
subjected to WCC (Florisil/methylene chloride) followed by DCC to
give crude Tbt(Dmtp)SnSe4 (581 mg), which was separated with HPLC
to give 5-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-5-[2,6-bis(2-
methylphenyl)phenyl]-1,2,3,4,5-tetraselenastannolane (2b) (421 mg,
29%). 2b: mp 267-268 °C dec (recrystallized from methylene chloride/
ethanol/acetonitrile); 1H NMR (CDCl3, 500 MHz, 330 K) δ -0.09 (br
s, 18H), 0.09 (br s, 18H), 1.40 (s, 1H), 1.93 (s, 6H), 2.01 (s, 2H), 6.35-
6.55 (br s, 2H), 7.02 (t, J ) 7 Hz, 2H), 7.11-7.15 (m, 4H), 7.21 (t, J
) 7 Hz, 2H), 7.32 (d, J ) 7 Hz, 2H), 7.38 (t, J ) 7 Hz, 1H); 13C NMR
(CDCl3, 125 MHz, 330 K) δ 1.05 (q), 2.28 (q), 21.45 (q), 30.78 (d),
32.42 (d), 123.41 (d), 126.49 (d), 128.56 (d), 128.60 (d), 128.73 (d),
129.77 (d), 130.49 (d), 130.70 (d), 138.18 (s), 142.36 (s), 143.12 (s),
144.96 (s), 147.40 (s), 147.52 (s), 149.49 (s), 152.83 (s); 119Sn NMR
Preparation of Tbt(Ditp)SnS4 1a. To a solution of Tbt(Ditp)Sn: 3a,
prepared from TbtBr (994 mg, 1.57 mmol), stannous chloride (321 mg,
1.69 mmol), and DitpI (700 mg, 1.59 mmol), was added elemental
sulfur (431 mg, 1.68 mmol). The solution was stirred overnight, and
the solvents were removed. The resulting residue was subjected to WCC
(Florisil/methylene chloride) followed by DCC to give crude Tbt(Ditp)-
SnS4 (456 mg), which was further purified by DCC to afford pure 5-
{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-5-[2,6-bis(2-isopropyl-
phenyl)phenyl]-1,2,3,4,5-tetrathiastannolane (1a) (392 mg, 22%). 1a:
mp 280-283 °C dec (recrystallized from methylene chloride/acetoni-
1
trile); H NMR (CDCl3, 500 MHz, 330 K) δ 0.01 (s, 36H), 0.13 (s,
18H), 1.07 (d, J ) 7 Hz, 6H), 1.13 (d, J ) 7 Hz, 6H), 1.41 (s, 1H),
1.49-1.94 (br s, 2H), 2.54 (sept, J ) 7 Hz, 2H), 6.33-6.61 (br s, 2H),
6.97-7.01 (m, 2H), 7.26-7.35 (m, 8H), 7.39 (t, J ) 7 Hz, 1H); 13C
NMR (CDCl3, 125 MHz, 330 K) δ 1.12 (q), 2.35 (q), 23.44 (q), 25.14
(q), 29.78 (d), 30.93 (d), 31.96 (d), 123.75 (d), 126.26 (d), 126.71 (d),
127.76 (d), 128.42 (d), 128.86 (d), 129.04 (d), 131.11 (d), 141.37 (s),
142.29 (s), 145.45 (s), 146.44 (s), 147.55 (s), 148.45 (s), 150.6 (br s);
(38) Kiersznicki, T.; Kulicki, Z.; Troszkiewicz, C. Zesz. Nauk. Politech. Slask.,
Chem. 1967, 40, 113. See also: Chem. Abstr., 69, 51751c.
(39) Bolton, R.; Sandall, J. P. B. J. Chem. Soc., Perkin Trans. 2 1977, 278.
(40) Wehmschulte, R. J.; Khan, M. A.; Hossain, S. I. Inorg. Chem. 2001, 40,
2756.
9
J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004 15577

A R T I C L E S
Saito et al.
(CDCl3, 101 MHz, 333 K) δ 2.31. FAB MS [M + H] calcd for C47H77-
78Se280Se2Si6120Sn 1245.0339. Found 1245.0300. Anal. Calcd for C47H76-
Se4Si6Sn: C, 45.36; H, 6.17; Se, 25.38. Found: C, 44.27; H, 5.93; Se,
23.69.
Preparation of Tbt(Tcp)SnSe4 2c. After lithium naphthalenide (0.53
M in THF, 1.08 mL, 2.2 equiv), prepared from lithium (86 mg, 12.3
mmol) and naphthalene (1.279 g, 9.98 mmol) in THF (15 mL), was
added to a THF solution (10 mL) of Tbt(Tcp)SnBr2 (305 mg, 0.26
mmol) at -65 °C, the reaction mixture was stirred for 1.5 h at this
temperature. After treatment of this solution with elemental selenium
(209 mg, 2.64 mmol) at -70 °C, the resulting mixture was stirred
overnight during which time it was warmed to room temperature. After
removal of the solvent, the residue was subjected to column chroma-
tography (Florisil/methylene chloride) followed by HPLC to afford
5-(2,4,6-tricyclohexylphenyl)-5-{2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl}-1,2,3,4,5-tetraselenastannolane (2c) (351 mg, 100%). 2c: mp
224-226.5 °C dec (recrystallized from methylene chloride/acetonitrile);
1H NMR (CDCl3, 500 MHz) δ 0.00 (s, 18H), 0.04 (s, 18H), 0.05 (s,
18H), 1.02-1.99 (m, 32H), 1.31 (s, 1H), 2.36-2.45 (m, 1H), 3.18-
3.29 (m, 2H), 6.30 (s, 1H), 6.47 (s, 1H), 7.03 (s, 2H); 13C NMR (CDCl3,
125 MHz) δ 0.98 (q), 2.11 (q), 2.40 (q), 25.46 (t), 25.62 (t), 25.86 (t),
26.15 (t), 26.89 (t), 30.58 (d), 30.89 (t), 31.24 (d), 34.02 (t), 34.33 (t),
38.64 (t), 44.69 (d), 48.96 (d), 123.28 (d), 124.82 (d), 128.93 (d), 138.93
(s), 144.86 (s), 145.30 (s), 149.09 (s), 152 (br s), 152.21 (s); 119Sn NMR
(CDCl3, 101 MHz) δ 5.7 (1JSn-Se ) 1337 Hz); 77Se NMR (CDCl3, 51
MHz) δ 321, 734. Anal. Calcd for C51H94Se4Si6Sn: C, 46.74; H, 7.24;
Se, 24.10. Found: C, 46.53; H, 7.33; Se, 23.90.
Preparation of Dibromo{2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl}(2,4,6-tricyclohexylphenyl)stannane. To a solution of TbtBr
(2.04 g, 3.22 mmol) in THF (20 mL) was added t-BuLi (4.3 mL, 1.65
M in pentane, 2.2 equiv) at -65 °C. After the reaction mixture was
stirred at the same temperature for 30 min, SnCl4 (0.50 mL, 4.29 mmol)
was added at -65 °C. The solution was gradually warmed to room
temperature. After removal of the solvent, hexane was added to the
residue to precipitate inorganic salts. The residue obtained from its
filtrate was dissolved in THF (30 mL). To this solution was added, at
room temperature, a solution of TcpMgBr, prepared from TcpBr41 (978
mg, 2.42 mmol) and Mg (85 mg, 3.48 mmol) in THF (4 mL) with a
small amount of iodine under reflux for several hours, and the mixture
was heated under reflux for 16 h. After the reaction mixture was cooled
to room temperature and the solvent was evaporated, hexane was added
to this residue to precipitate inorganic salts, and the resulting mixture
was subjected to WCC (hexane) followed by HPLC to afford the
corresponding crude dichlorostannane (1.27 g, 37%) as a white solid.
The crude dichlorostannane (1.27 g, 1.19 mmol) was added to a THF
(30 mL) suspension of LiAlH4 (110 mg, 2.90 mmol). After the mixture
was stirred for 2 h, the reaction mixture was treated with some portions
of ethyl acetate and water. Volatile substances were evaporated, and
then the residue was subjected to DCC to afford the corresponding
dihydrostannane (872 mg, 74%). Bromine (0.1 mL, 1.94 mmol) was
added to an ether (40 mL) solution of the dihydrostannane (872 mg,
0.87 mmol). After removal of the solvent, crude dibromostannane was
obtained. It was recrystallized from ethanol to afford pure dibromo-
stannane (800 mg, 80%) as white crystals: mp 253-255.5 °C
(recrystallized from ethanol); 1H NMR (CDCl3, 500 MHz) δ -0.01 (s,
18H), 0.06 (s, 18H), 0.11 (s, 18H), 1.22-1.55 (m, 11H), 1.33 (s, 1H),
1.55-1.88 (m, 19H), 2.05 (br s, 2H), 2.46 (br s, 1H), 3.04-3.12 (m,
2H), 6.25 (s, 1H), 6.46 (s, 1H), 7.09 (s, 2H); 13C NMR (CDCl3, 125
MHz) δ 0.95 (q), 1.51 (q), 1.69 (q), 25.65 (br t), 25.88 (t), 26.11 (t),
26.84 (t), 30.64 (d), 30.76 (d), 30.76 (d), 33.26 (br t), 34.28 (t), 38.56
(br t), 44.73 (d), 46.56 (d), 123.34 (d), 125.00 (d), 128.18 (d), 138.13
(s), 140.95 (s), 146.33 (s), 150.61 (s), 151.86 (s), 152.10 (s), 153.11
(s). Anal. Calcd for C51H94Br2Si6Sn: C, 53.05; H, 8.22; Br, 13.84.
Found: C, 53.30; H, 8.12; Br, 13.98.
Preparation of Tbt(Ttm)SnS4 1d. After addition of t-BuLi (1.66
M in pentane, 1.70 mL, 2.2 equiv) to an ether solution (14 mL) of
TbtBr (812 mg, 1.79 mmol) at -60 °C, the solution of TbtLi thus
obtained was kept at -60 °C for 45 min. It was treated with an ether
(12 mL) suspension of stannous chloride (256 mg, 1.35 mmol). After
the mixture was stirred for 1 h at about -60 °C, an ether (6 mL) solution
of TtmLi, prepared from TtmBr42 (541 mg, 1.30 mmol) and t-BuLi
(1.66 M in pentane, 1.72 mL, 2.2 equiv), was added to this reaction
mixture. The resulting blue-purple solution of stannylene Tbt(Ttm)Sn:
3d was stirred for 30 min at -60 °C, and then elemental sulfur (344
mg, 1.34 mmol) was added to this solution at the same temperature. It
was stirred for 1.5 h while being warmed to room temperature. After
removal of the solvent, the residue was chromatographed (Florisil/
methylene chloride) to give a crude mixture, from which sulfur was
removed by HPLC. The crude mixture was purified again by HPLC to
provide a monomeric fraction (554 mg), which was separated with DCC
to give 5-{2,4,6-tris[(trimethylsilyl)methyl]phenyl}-5-{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-1,2,3,4,5-tetrathiastannolane (1d) (492
mg, 34%). 1d: mp 176-180 °C (recrystallized from methylene
Preparation of Tbt(Tcp)SnS4 1c. After lithium naphthalenide (0.57
M in THF, 1.84 mL, 2.5 equiv), prepared from lithium (79 mg, 11.3
mmol) and naphthalene (1.22 g, 9.50 mmol) in THF (15 mL), was
added to a THF solution (10 mL) of Tbt(Tcp)SnBr2 (486 mg, 0.42
mmol) at -70 °C, the reaction mixture was stirred for 30 min at this
temperature. After treatment of this solution with elemental sulfur (111
mg, 0.43 mmol) at -70 °C, the resulting mixture was stirred for 3 h
during which time it was warmed to room temperature. After removal
of the solvent, the residue was submitted to chromatography (Florisil/
methylene chloride) followed by HPLC to afford 5-(2,4,6-tricyclo-
hexylphenyl)-5-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-1,2,3,4,5-
tetrathiastannolane (1c) (455 mg, 96%). 1c: mp 262-265 °C dec
(recrystallized from methylene chloride/acetonitrile); 1H NMR (CDCl3,
500 MHz) δ -0.08 (s, 18H), 0.04 (s, 36H), 1.12-1.39 (m, 12H), 1.32
(s, 1H), 1.56-1.95 (m, 20H), 2.42 (br s, 1H), 2.97 (br s, 2H), 6.31 (s,
1H), 6.48 (s, 1H), 7.04 (s, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.95
(q), 1.73 (q), 2.01 (q), 25.50 (t), 25.71 (t), 25.85 (t), 26.14 (t), 26.88
(t), 30.66 (d), 31.18 (d), 31.36 (d), 33.70 (t), 34.34 (t), 38.62 (t), 44.75
(d), 49.44 (d), 123.17 (d), 124.71 (d), 128.60 (d), 137.26 (s), 143.53
(s), 145.84 (s), 149.67 (s), 151.79 (s), 152.23 (s), 152.64 (s); 119Sn NMR
(toluene-d8, 101 MHz) δ 75. Anal. Calcd for C51H94S4Si6Sn: C, 54.54;
H, 8.45; S, 11.42. Found: C, 55.41; H, 8.73; S, 11.67.
1
chloride/ethanol/acetonitrile); H NMR (CDCl3, 500 MHz) δ -0.02
(s, 18H), 0.00 (s, 18H), 0.01 (s, 9H), 0.03 (s, 18H), 0.04 (s, 18H), 1.31
(s, 1H), 1.67 (s, 1H), 1.71 (s, 1H), 1.94 (s, 2H), 2.35-2.60 (m, 4H),
6.38 (s, 1H), 6.48 (s, 1H), 6.61 (s, 2H); 13C NMR (CDCl3, 125 MHz)
δ -1.40 (q), -0.40 (q), 0.81 (q), 1.20 (q), 1.49 (q), 26.91 (t), 30.67
(d), 31.08 (d), 31.68 (d), 32.10 (t), 122.69 (d), 125.73 (d), 127.81 (d),
137.63 (s), 142.28 (s), 142.70 (s), 145.72 (s), 145.75 (s), 151.99 (s),
152.16 (s); 119Sn NMR (toluene-d8, 101 MHz) δ 70. Anal. Calcd for
C45H94S4Si9Sn: C, 47.61; H, 8.36; S, 11.30. Found: C, 47.45; H, 8.65;
S, 11.33.
Preparation of Dibromo[bis(trimethylsilyl)methyl]{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}stannane. To a solution of TbtBr (3.25
g, 5.13 mmol) in THF (50 mL) was added t-BuLi (6.64 mL, 1.70 M in
pentane, 2.2 equiv) at -65 °C. After the reaction mixture was stirred
at the same temperature for 30 min, SnCl4 (0.90 mL, 7.69 mmol) was
added at -65 °C. The mixture was stirred overnight during which time
it was warmed to room temperature. After removal of the solvent,
hexane was added to the residue to precipitate inorganic salts. The
residue obtained from its filtrate was dissolved in THF (50 mL). To
this solution was added, at room temperature, a solution of DisMgCl,
prepared from DisCl (1 mL, 4.58 mmol) and Mg (121 mg, 4.96 mmol)
in THF (10 mL), and the mixture was heated under reflux for 26 h.
(41) Koudelka, J.; Saman, D.; Exner, O. Collect. Czech. Chem. Commun. 1985,
50, 208.
(42) Kano, N.; Tokitoh, N.; Okazaki, R. Chem. Lett. 1997, 277.
9
15578 J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004

Tin−Chalcogen Double-Bond Compounds
A R T I C L E S
After removal of volatile substances, hexane was added to the resulting
residue to precipitate inorganic salts, and this filtrate was subjected to
WCC (silica gel, hexane) to provide the corresponding crude dichlo-
rostannane (1.27 g, 37%) as a white solid. The crude dichlorostannane
(623 mg, 0.67 mmol) was added to a THF (15 mL) suspension of
LiAlH4 (53 mg, 1.40 mmol). After the mixture was stirred for 13 h,
the reaction mixture was treated with an additional amount of LiAlH4
(19 mg, 0.49 mmol), and then the resulting mixture was heated under
reflux for 1 h. After the mixture cooled to room temperature, the
reaction was quenched by addition of some portions of ethyl acetate
and water. Volatile substances were evaporated, and then the residue
was purified by DCC to give the corresponding dihydrostannane (336
mg, 59%). Bromine (0.05 mL, 0.97 mmol) was added to an ether (20
mL) solution of the dihydrostannane (336 mg, 0.40 mmol). The reaction
solution was kept at room temperature for 4 days. After removal of
the solvent, crude dibromostannane was obtained. It was recrystallized
from ethanol to afford pure dibromostannane (263 mg, 57%) as white
caused by restricted rotation around the C (aromatic)-CH (SiMe3)2
bond. Although two m-aromatic carbons in a Tbt group usually
resonated at about 123 and 127 ppm, their signals could not be identified
due to broadening and overlapping with the signals of benzene solvent.
Since one of the m-aromatic carbons in the Ditp group was also
overlapped with carbons of the solvent, as evidenced by CH-COSY,
it could not be identified. Four quaternary carbons could not be found,
probably due to their broadening. The elemental analysis and measure-
ment of the melting point of 4e could not be carried out because of its
extremely high reactivity toward water.
Isolation of Stannaneselone Tbt(Ditp)SndSe 5a. An orange
solution of 2a (182 mg, 0.14 mmol) and triphenylphosphine (112 mg,
0.43 mmol) in hexane (5 mL) was refluxed for 2 h in a glovebox filled
with argon. The solution turned deep red, and triphenylphosphine
selenide was precipitated nearly quantitatively upon the mixture being
cooled to room temperature. After filtration of the selenide in a
glovebox, the residual deep-red solution was concentrated in a glovebox
to give pure stannaneselone 5a (111 mg, 84% yield) as red crystals:
1H NMR (C6D6, 500 MHz) δ 0.13 (s, 36H), 0.18 (s, 18H), 0.99 (d, J
) 7 Hz, 6H), 1.48 (s, 1H), 1.49 (d, J ) 7 Hz, 6H), 3.16 (br sept, J )
7 Hz, 2H), 6.47 (s, 1H), 6.63 (s, 1H), 6.96-7.08 (m, 3H), 7.10-7.13
(m, 2H), 7.18-7.21 (m, 2H), 7.30-7.32 (m, 2H), 7.47 (d, J ) 7 Hz,
2H); 13C NMR (C6D6, 500 MHz) δ 0.94 (q), 1.57 (q), 23.00 (q), 24.64
(q), 29.96 (d), 31.23 (d), 124.21 (d), 126.13 (d), 127.08 (d), 127.78
(d), 128.50 (d), 129.77 (d), 131.03 (d), 141.18 (s), 142.91 (s), 145.40
(s), 146.14 (s), 148.06 (s), 148.93 (s), 152.34 (s), 158.65 (s). The signals
that could be assigned to o-benzylic protons and carbons in the Tbt
group could not be found even when CH-COSY spectra were measured
at higher temperatures, which is probably due to line broadening caused
by restricted rotation around the C (aromatic)-CH (SiMe3)2 bond, as
in the case of stannanethione 4a. Although one of the m-aromatic
carbons in the Tbt group usually resonates at about 127 ppm, its signal
could not be identified due to overlapping with the signals of aromatic
carbons in the Ditp group. The elemental analysis and measurement
of the melting point of 5a could not be carried out because of its
extremely high reactivity toward water.
1
crystals: mp 219-221.5 °C (recrystallized from ethanol); H NMR
(CDCl3, 500 MHz) δ 0.05 (s, 18H), 0.12 (s, 18H), 0.14 (s, 1H), 0.32
(s, 18H), 0.96 (s, 1H), 2.10 (s, 1H), 2.45 (s, 1H), 6.32 (s, 1H), 6.45 (s,
1H); 13C NMR (CDCl3, 125 MHz) δ 0.84 (q), 1.42 (q), 1.56 (q), 3.75
(q), 21.23 (d), 30.63 (br d), 30.76 (d), 123.21 (d), 127.78 (d), 135.88
(s), 146.51 (s), 146.57 (s), 150.77 (s), 151.36 (s). Anal. Calcd for C34H78-
Br2Si8Sn: C, 41.23; H, 7.95; Br, 16.14. Found: C, 41.31; H, 7.69; Br,
16.26.
Preparation of Tbt(Dis)SnS4 1e. After lithium naphthalenide (0.58
M in THF, 0.65 mL, 2.7 equiv), prepared from lithium (59 mg, 8.46
mmol) and naphthalene (884 mg, 6.70 mmol) in THF (10 mL), was
added to a THF solution (6 mL) of the dibromostannane (141 mg, 0.14
mmol), prepared as described above at -70 °C, the reaction mixture
was stirred for 1 h at this temperature. The mixture was gradually
warmed to room temperature to give a THF solution of stannylene Tbt-
(Dis)Sn: 3e. After the mixture was stirred for 30 min, a THF solution
of the stannylene was treated with elemental sulfur (58 mg, 0.23 mmol).
After removal of the solvent, the residue was submitted to chroma-
tography (Florisil/methylene chloride) followed by HPLC to provide
5-[bis(trimethylsilyl)methyl]-5-{2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl}-1,2,3,4,5-tetrathiastannolane (1e) (107 mg, 78%). 1e: mp 219-
X-ray Data Collections of 5a. Crystals suitable for X-ray structural
analysis were obtained by slow evaporation of a hexane solution of 5a
in an argon atmosphere. Crystallographic data for 5a: C51H84SeSi6Sn,
M ) 1063.39, triclinic, a ) 11.939(8) Å, b ) 23.478(5) Å, c ) 11.471-
(4) Å, R ) 91.86(2)°, â ) 112.61(3)°, γ ) 97.45(4)°, V ) 2931(2)
Å3, Z ) 2, space group P1h. The crystal was mounted in a glass capillary.
Data were collected on a Rigaku AFC5R diffractometer with Mo KR
radiation (λ ) 0.71069 Å) at 296 K. The structure was solved by direct
methods using SHELXS-9743 and refined with full-matrix least-squares
(SHELXL-97)43 using all independent reflections (10 257 reflections)
for 606 parameters. The non-hydrogen atoms were refined anisotro-
pically and all of the hydrogen atoms were placed at calculated positions
[d(C-H) ) 0.96 Å]. Two trimethylsilyl groups at one of the o-positions
of the Tbt group were disordered. The occupancies of the disordered
trimethylsilyl groups were refined to be 0.62:0.38. Uij values of
disordered trimethylsilyl groups were restrained using SIMU and ISOR
instructions. R1 ) 0.104 (I > 2σ(I), 3427 reflections), wR2 ) 0.318
(for all reflections), GOF ) 1.007.
1
221.5 °C (recrystallized from methylene chloride/ethanol); H NMR
(CDCl3, 500 MHz) δ 0.04 (s, 18H), 0.10 (s, 36H), 0.22 (s, 18H), 0.86
(s, 1H), 1.33 (s, 1H), 1.74 (s, 1H), 1.83 (s, 1H), 6.36 (s, 1H), 6.49 (s,
1H); 13C NMR (CDCl3, 125 MHz) δ 0.88 (q), 1.47 (q), 1.77 (q), 4.34
(q), 19.60 (d), 30.69 (d), 32.00 (d), 32.07 (d), 122.93 (d), 128.07 (d),
137.98 (s), 145.73 (s), 151.09 (s), 151.62 (s); 119Sn NMR (CDCl3, 101
MHz) δ 145. Anal. Calcd for C34H78S4Si8Sn: C, 42.59; H, 8.22; S,
13.38. Found: C, 42.52; H, 8.48; S, 13.31.
Isolation of Stannanethione Tbt(Ditp)SndS 4a. Tributylphosphine
(0.12 mL, 0.46 mmol) was added to a hexane (1 mL) solution of Tbt-
(Ditp)SnS4 1a (147 mg, 0.13 mmol) at room temperature in an 8φ tube.
After the solution was degassed and sealed, it was kept at room
temperature for 12 h. The sealed tube was opened in a glovebox. After
slow evaporation of the solvent over 1 day, an orange solid containing
stannanethione 4a was obtained. Removing tributylphosphine sulfide,
by washing with a small portion of hexane, afforded stannanethione
4a (35 mg, 26%) as orange crystals with a small amount of tribu-
tylphosphine sulfide as an impurity. 4a: 1H NMR (C6D6, 500 MHz) δ
0.13 (s, 36H), 0.18 (s, 18H), 1.00 (d, J ) 7 Hz, 6H), 1.48 (s, 1H), 1.51
(d, J ) 6 Hz, 6H), 3.13-3.21 (m, 2H), 6.48 (s, 1H), 6.63 (s, 1H),
7.03-7.08 (m, 3H), 7.11-7.14 (m, 2H), 7.19-7.22 (m, 2H), 7.31-
7.33 (m, 2H), 7.47-7.48 (m, 2H); 13C NMR (C6D6, 125 MHz) δ 1.21
(q), 1.84 (q), 23.26 (q), 24.91 (q), 30.23 (d), 31.51 (d), 126.40 (d),
127.34 (d), 128.30 (d), 130.02 (d), 131.27 (d), 141.79 (s), 146.09 (s),
146.70 (s), 149.32 (s); 119Sn NMR (C6D6, 60 °C) δ 531. The signals
that could be assigned to o-benzylic protons and carbons in the Tbt
group could not be found even when CH-COSY spectra were measured
at higher temperatures, which was probably due to line broadening
Reaction of Tbt(Ditp)SndS 4a with Mesitonitrile Oxide. Tribu-
tylphosphine (45 µL, 0.18 mmol) was added to a hexane (2 mL) solution
of Tbt(Ditp)SnS4 1a (65 mg, 0.059 mmol) at room temperature. After
10 min, this solution was treated with mesitonitrile oxide (18 mg, 0.11
mmol) to give 2-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-2-[2,6-
bis(2-isopropylphenyl)phenyl]-4-mesityl-1,3,5,2-oxathiazastannole (7a)
(50 mg, 72%). 7a: mp 250-253 °C dec (recrystallized from chloro-
1
form); H NMR (CDCl3, 500 MHz) δ -0.01 (s, 36H), 0.15 (s, 9H),
0.16 (s, 9H), 0.92 (d, J ) 7 Hz, 3H), 1.17 (d, J ) 7 Hz, 3H), 1.27 (d,
(43) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refinement;
Go¨ttingen University: Go¨ttingen, Germany, 1997.
9
J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004 15579

A R T I C L E S
Saito et al.
J ) 7 Hz, 3H), 1.30 (d, J ) 7 Hz, 3H), 1.46 (s, 1H), 1.94 (s, 6H), 2.13
(s, 2H), 2.18 (s, 3H), 2.81-2.84 (m, 2H), 6.41 (s, 1H), 6.53 (s, 1H),
6.66 (s, 2H), 6.81-6.84 (m, 1H), 7.04-7.07 (m, 1H), 7.17-7.23 (m,
2H), 7.27-7.30 (m, 2H), 7.34-7.43 (m, 5H); 13C NMR (CDCl3, 125
MHz) δ 1.16 (q), 1.26 (q), 1.80 (q), 1.95 (q), 20.92 (q), 20.98 (q),
24.47 (q), 24.53 (q), 25.84 (q), 26.35 (q), 29.66 (d), 29.69 (d), 30.89
(d), 31.18 (d), 123.97 (d), 126.24 (d), 126.75 (d), 127.17 (d), 127.55
(d), 127.72 (d), 127.79 (d), 127.88 (d), 128.07 (d), 128.53 (d), 128.82
(d), 129.67 (d), 130.43 (d), 130.96 (d), 131.84 (s), 136.89 (s), 137.38
(s), 139.93 (s), 141.72 (s), 142.38 (s), 145.77 (s), 146.56 (s), 146.90
(s), 147.56 (s), 147.80 (s), 148.07 (s), 148.24 (s), 151.2 (s), 152.5 (s).
FAB MS [M + H] calcd for C61H96NO32SSi6120Sn 1178.4851. Found
1178.4799.
room temperature in an 8φ tube, the solution was degassed and sealed.
After this tube was kept at ambient temperature for 10 h, it was opened
in a glovebox. To the solution was added 2,3-dimethyl-1,3-butadiene
(0.15 mL, 1.33 mmol), and the resulting mixture was kept at room
temperature overnight. Volatile substances were removed, and then the
residue was subjected to HPLC to give a monomeric product (58 mg).
1
The H NMR of the crude products showed an AB quartet that could
be assigned to methylene protons next to the selenium at about 3.0
ppm. The absence of olefinic protons in the 1H NMR excludes a
possibility that the product was derived from an ene reaction. Mass
spectrum of the crude products showed the parent peak of a [4 + 2]
cycloadduct 8. FAB MS [M - H] calcd for C57H9380SeSi6120Sn
1145.4080. Found 1145.3989. Although this crude product contained
a [4 + 2] cycloadduct, 2-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-
2-[2,6-bis(2,6-diisopropylphenyl)phenyl]-4,5-dimethyl-1-selena-2-stan-
nacyclohex-4-ene (8), this cycloadduct decomposed during purification
by flash column chromatography.
Reaction of Tbt(Ditp)SndS 4a with 2,3-Dimethyl-1,3-butadiene.
Tributylphosphine (90 µL, 0.36 mmol) was added to a hexane (1 mL)
solution of Tbt(Ditp)SnS4 1a (105 mg, 0.095 mmol) in an 8φ tube at
room temperature. After the solution was degassed and sealed, it was
transferred into another 10φ Pyrex tube in a glovebox. To this solution
was added 2,3-dimethyl-1,3-butadiene (0.3 mL, 2.65 mmol) at ambient
temperature, and the solution was allowed to stand at room temperature
for 6 h. The reaction mixture was purified by HPLC and PTLC to give
a [4 + 2] cycloadduct, 2-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-
2-[2,6-bis(2,6-diisopropylphenyl)phenyl]-4,5-dimethyl-1-thia-2-stanna-
cyclohex-4-ene (6) (63 mg, 61%). 6: mp 204.5-206.5 °C dec
(recrystallized from methylene chloride/ethanol); 1H NMR (CDCl3, 500
MHz) δ -0.10 (s, 18H), 0.03 (br s, 18H), 0.10 (s, 9H), 0.12 (s, 9H),
0.97 (d, J ) 14 Hz, 1H), 1.05 (d, J ) 7 Hz, 3H), 1.11-1.14 (m, 9H),
1.29 (d, J ) 14 Hz, 1H), 1.35 (s, 1H), 1.39 (s, 3H), 1.65 (s, 3H), 1.83
(br s, 2H), 2.50 (sept, J ) 7 Hz, 1H), 2.65 (d, J ) 14 Hz, 1H), 2.75
(sept, J ) 7 Hz, 1H), 2.80 (d, J ) 14 Hz, 1H), 6.34 (s, 1H), 6.47 (s,
1H), 6.68 (br s, 1H), 6.80 (d, J ) 8 Hz, 1H), 7.06-7.13 (m, 3H), 7.18-
7.21 (m, 1H), 7.24-7.29 (m, 2H), 7.34-7.38 (m, 2H), 7.49 (d, J ) 7
Hz, 1H); 13C NMR (CDCl3, 125 MHz) δ 0.98 (q), 1.05 (q), 1.25 (q),
2.14 (q), 2.18 (q), 2.31 (q), 20.31 (q), 22.70 (q), 22.96 (q), 23.31 (q),
23.56 (t), 25.07 (q), 25.14 (q), 29.66 (d), 29.75 (d), 30.28 (d), 30.83
(t), 31.61 (d), 31.92 (d), 123.30 (d), 125.55 (d), 125.68 (d), 126.19 (d),
126.61 (d), 127.19 (d), 127.27 (d), 128.06 (d), 128.13 (d), 128.44 (d),
128.81 (d), 130.69 (d), 140.52 (s), 143.27 (s), 143.29 (s), 143.72 (s),
143.96 (s), 147.14 (s), 147.66 (s), 147.80 (s), 149.51 (s), 151.54 (s).
FAB MS [M] calcd for C57H9432SSi6120Sn 1098.4714. Found 1098.4725.
Reaction of Tbt(Dmtp)SndS 4b with Mesitonitrile Oxide. To a
hexane (5 mL) solution of Tbt(Dmtp)SnS4 1b (94 mg, 0.088 mmol),
was added tributylphosphine (66 µL, 0.26 mmol) at -68 °C. After the
mixture was warmed to ambient temperature over 10 min, the yellow-
orange solution was stirred for 10 min at room temperature. Treatment
of this solution with mesitonitrile oxide (18 mg, 0.11 mmol) followed
by usual workup afforded 2-{2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl}-2-[2,6-bis(2-methylphenyl)phenyl]-4-mesityl-1,3,5,2-oxathi-
azastannole (7b) (86 mg, 85%). 7b: mp 258-261 °C dec (recrystallized
1
from chloroform/acetonitrile); H NMR (CDCl3, 500 MHz, 330 K) δ
0.00 (br s, 36H), 0.15 (s, 18H), 1.43 (s, 1H), 2.07 (br s, 12H), 2.09 (br
s, 2H), 2.22 (s, 3H), 6.49 (br s, 2H), 6.73 (s, 2H), 6.96 (br s, 1H), 7.06
(br s, 1H), 7.18 (br s, 4H), 7.24-7.27 (m, 3H), 7.36 (br s, 1H), 7.40-
7.45 (m, 1H); 13C NMR (CDCl3, 125 MHz) δ 1.26 (q), 1.30 (q), 1.81
(q), 1.98 (q), 20.73 (q), 20.91 (q), 21.06 (q), 21.34 (q), 31.13 (d), 31.38
(d), 123.93 (d), 126.44 (d), 127.55 (d), 128.20 (d), 128.46 (d), 128.60
(d), 128.74 (d), 129.46 (s), 130.76 (d), 130.88 (d), 131.66 (d), 137.01
(s), 137.62 (s), 137.94 (s), 138.21 (s), 139.06 (s), 142.21 (s), 142.81
(s), 145.85 (s), 145.90 (s), 147.00 (s), 147.44 (s), 148.30 (s), 151.98
(s). Anal. Calcd for C57H87NOSSi6Sn: C, 61.03; H, 7.83; N, 1.25; S,
2.86. Found: C, 61.00; H, 7.84; N, 1.29; S, 2.88.
Spectral Detection of Tbt(Tcp)SndS 4c. Toluene-d8 (0.5 mL) was
added to a mixture of 1c (86 mg, 0.077 mmol) and triphenylphosphine
(61 mg, 0.23 mmol) in a 5φ NMR tube. After the solution was degassed
and sealed, its 119Sn NMR spectrum was measured. It showed a broad
singlet at 643 ppm that could be assigned to stannanethione Tbt(Tcp)-
SndS 4c, together with peaks at 75 (a signal due to the starting material
1c), -63.5, -61, -59, and -56 ppm, which were assigned to an
oligomeric fraction.34,35 This reaction solution was kept at room
temperature overnight. After removal of the solvent, the residue was
purified by HPLC to give mainly oligomeric (50 mg)35 and monomeric
fractions (9 mg), which contained mainly the starting material together
with triphenylphosphine sulfide (77%) and triphenylphosphine (18%).
Reaction of Tbt(Ditp)SndSe 5a with Mesitonitrile Oxide. Toluene
(0.8 mL) was added to a mixture of Tbt(Ditp)SnSe4 2a (80 mg, 0.061
mmol), and triphenylphosphine (48 mg, 0.19 mmol) at room temper-
ature in an 8φ tube. After the solution was degassed and sealed, it was
poured into mesitonitrile oxide (21 mg, 0.13 mmol) in a glovebox.
The reaction mixture was subjected to HPLC to give 2-{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-2-[2,6-bis(2,6-diisopropylphenyl)phenyl]-
4-mesityl-1,3,5,2-oxaselenazastannole (9a) (68 mg, 90%). 9a: mp 267-
1
269 °C dec (recrystallized from chloroform); H NMR (CDCl3, 500
MHz) δ -0.01 (s, 36H), 0.14 (s, 9H), 0.16 (s, 9H), 0.94 (d, J ) 7 Hz,
3H), 1.18 (d, J ) 7 Hz, 3H), 1.26 (d, J ) 7 Hz, 3H), 1.30 (d, J ) 7
Hz, 3H), 1.45 (s, 1H), 1.94 (s, 6H), 2.18-2.25 (br s, 2H), 2.18 (s, 3H),
2.78-2.84 (m, 2H), 6.39 (s, 1H), 6.51 (s, 1H), 6.67 (s, 2H), 6.75-
6.77 (m, 1H), 7.08-7.11 (m, 1H), 7.14-7.19 (m, 2H), 7.26-7.32 (m,
2H), 7.36-7.42 (m, 5H); 13C NMR (CDCl3, 125 MHz, 330 K) δ 1.23
(q), 1.34 (q), 2.00 (q), 2.15 (q), 20.92 (q), 21.21 (q), 24.51 (q), 24.52
(q), 25.69 (q), 26.18 (q), 29.71 (d), 29.82 (d), 31.09 (d), 31.35 (d),
125.85 (d), 126.65 (d), 126.98 (d), 127.43 (d), 127.71 (d), 128.31 (d),
128.36 (d), 128.50 (d), 128.86 (d), 130.91 (d), 131.35 (d), 132.61 (s),
136.91 (s), 137.52 (s), 140.98 (s), 141.75 (s), 142.31 (s), 142.52 (s),
145.55 (s), 146.88 (s), 147.76 (s), 147.90 (s), 148.09 (s), 148.40 (s),
152.01 (s). Anal. Calcd for C61H95NOSeSi6Sn: C, 59.82; H, 7.83; N,
1.14; Se, 6.45. Found: C, 59.74; H, 7.62; N, 1.40; Se, 5.58.
Reaction of Tbt(Tcp)SndS 4c with Phenyl Isothiocyanate.
Hexane (3 mL) was added to a mixture of Tbt(Tcp)SnS4 1c (52 mg,
0.046 mmol), and triphenylphosphine (42 mg, 0.16 mmol). After the
mixture was refluxed for 70 min, the solution was cooled and treated
with phenyl isothiocyanate (0.050 mL, 0.42 mmol) at ambient tem-
perature. Hexane was evaporated, and then the residue was subjected
to HPLC to give an oligomeric fraction35 (12 mg), 1c (11 mg, 23%),
2-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-2-(2,4,6-tricyclohexyl-
phenyl)-4-phenylimino-1,3,2-dithiastannetane (10) (16 mg, 31%; the
conversion yield was 40%), and triphenylphosphine sulfide (10 mg,
70%), along with triphenylphosphine (11 mg, 28%). The 1H NMR
spectrum of the oligomeric fraction was very complicated. The 119Sn
NMR of this oligomeric fraction showed four signals at -70, -67,
-66, and -63 ppm.35 10: mp 128-131 °C dec (recrystallized from
methylene chloride/acetonitrile/ethanol); 1H NMR (CDCl3, 500 MHz)
δ -0.07 (s, 9H), 0.00 (s, 9H), 0.04 (s, 9H), 0.05 (s, 18H), 0.11 (s, 9H),
Reaction of Tbt(Ditp)SndSe 5a with 2,3-Dimethyl-1,3-butadiene.
After toluene (0.8 mL) was added to a mixture of Tbt(Ditp)SnSe4 2a
(102 mg, 0.078 mmol), and triphenylphosphine (62 mg, 0.24 mmol) at
9
15580 J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004

Tin−Chalcogen Double-Bond Compounds
A R T I C L E S
1
1.15-1.20 (m, 6H), 1.35 (s, 1H), 1.38-1.46 (m, 6H), 1.62-1.97 (m,
16H), 2.17-2.32 (m, 4H), 2.45-2.58 (m, 3H), 6.34 (s, 1H), 6.51 (s,
1H), 6.91 (d, J ) 7 Hz, 2H), 7.03 (t, J ) 7 Hz, 1H), 7.08 (s, 1H), 7.10
(s, 1H), 7.24-7.27 (m, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.87 (q),
0.89 (q), 1.17 (q), 1.24 (q), 1.40 (q), 1.57 (q), 25.51 (t), 25.71 (t), 25.77
(t), 25.89 (t), 26.12 (t), 26.86 (t), 30.79 (d), 31.05 (br d), 32.55 (t),
33.00 (t), 34.38 (t), 38.55 (t), 39.02 (t), 44.86 (d), 49.31 (d), 50.19 (d),
121.44 (d), 123.32 (d), 123.71 (d), 124.54 (d), 128.40 (d), 128.57 (d),
134.41 (s), 142.00 (s), 146.52 (s), 149.59 (s), 150.47 (s), 152.48 (s),
152.80 (s), 152.98 (s), 157.36 (s). Anal. Calcd for C58H99NS2Si6Sn:
C, 59.95; H, 8.61; N, 1.21; S, 5.52. Found: C, 59.67; H, 8.62; N, 1.47;
S, 5.47.
acetonitrile); H NMR (CDCl3, 500 MHz) δ -0.03 (s, 18H), 0.06 (s,
9H), 0.07 (s, 9H), 0.11 (s, 18H), 1.00-1.43 (m, 12H), 1.36 (s, 1H),
1.57-2.15 (m, 20H), 2.13 (br s, 6H), 2.24 (s, 3H), 2.42-2.48 (m, 2H),
2.63-2.70 (m, 1H), 6.39 (s, 1H), 6.54 (s, 1H), 6.79 (s, 2H), 7.01 (s,
2H); 13C NMR (CDCl3, 125 MHz) δ 0.98 (q), 1.11 (q), 1.32 (q), 1.49
(q), 1.51 (q), 1.51 (q), 20.46 (q), 21.06 (q), 25.41 (t), 25.51 (t), 25.76
(t), 25.97 (t), 26.16 (t), 26.24 (t), 26.88 (t), 30.83 (d), 30.91 (d), 31.37
(t), 32.49 (t), 32.91 (t), 34.27 (t), 34.42 (t), 37.98 (t), 39.45 (t), 44.74
(d), 48.06 (d), 48.82 (d), 123.71 (d), 124.20 (d), 124.54 (d), 128.21
(d), 129.00 (d), 132.31 (s), 136.89 (s), 136.97 (s), 138.04 (s), 142.46
(s), 143.68 (s), 145.96 (s), 149.76 (s), 152.08 (s), 152.13 (s), 152.83
(s), 158.82 (s). FAB MS [M + H] calcd for C61H106NO80SeSi6120Sn
1236.5077. Found 1236.5149. Anal. Calcd for C61H105NOSeSi6Sn: C,
59.33; H, 8.59; N, 1.13; Se, 6.39. Found: C, 59.08; H, 8.31; N, 1.30;
Se, 5.38.
Reaction of Tbt(Tcp)SndS 4c with Mesitonitrile Oxide. After
hexane (1 mL) was added to a mixture of Tbt(Tcp)SnS4, 1c (82 mg,
0.073 mmol), and triphenylphosphine (59 mg, 0.22 mmol) in an 8φ
Pyrex tube, it was degassed and sealed. The reaction mixture was kept
at ambient temperature overnight. This tube was opened in a glovebox,
and the resulting solution was poured into mesitonitrile oxide (14 mg,
0.089 mmol). After the reaction tube was opened in the air, the solvent
was removed. The residue was purified by HPLC to yield an oligomeric
fraction35 (20 mg) and 2-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-
2-(2,4,6-tricyclohexylphenyl)-4-mesityl-1,3,5,2-oxathiazastannole (7c)
(31 mg, 35%). The 1H NMR spectrum of this oligomeric fraction was
complicated, similarly to that of the above-mentioned oligomer. 7c:
mp 224-235 °C dec (recrystallized from methylene chloride/acetoni-
trile); 1H NMR (CDCl3, 500 MHz) δ 0.00 (s, 18H), 0.05 (s, 9H), 0.06
(s, 9H), 0.07 (s, 18H), 1.00-1.40 (m, 12H), 1.36 (s, 1H), 1.55-2.05
(m, 18H), 2.13 (br s, 6H), 2.24 (s, 3H), 2.38-2.50 (m, 3H), 6.40 (s,
1H), 6.54 (s, 1H), 6.79 (s, 2H), 7.01 (s, 1H), 7.02 (s, 1H); 13C NMR
(CDCl3, 125 MHz) δ 1.00 (q), 1.08 (q), 1.28 (q), 1.36 (q), 1.39 (q),
1.45 (q), 20.37 (q), 21.05 (q), 25.59 (t), 25.66 (t), 25.73 (t), 25.97 (t),
26.06 (t), 26.10 (t), 26.16 (t), 26.88 (t), 30.87 (d), 31.24 (d), 31.69 (d),
32.39 (d), 32.82 (d), 34.29 (t), 34.40 (t), 38.27 (t), 39.56 (t), 44.76 (d),
48.34 (d), 49.52 (d), 123.65 (d), 124.17 (d), 124.38 (d), 128.13 (d),
128.96 (d), 131.69 (s), 136.37 (s), 136.99 (s), 137.91 (s), 142.49 (s),
146.19 (s), 148.00 (s), 149.93 (s), 152.11 (s), 152.16 (s), 152.64 (s),
152.77 (s). Anal. Calcd for C61H105NOSSi6Sn: C, 61.67; H, 8.93; N,
1.18; S, 2.70. Found: C, 60.75; H, 9.01; N, 0.99; S, 2.81.
Desulfurization of Tbt(Ttm)SnS4 1d by Triphenylphosphine.
Toluene-d8 (0.7 mL) was added to Tbt(Ttm)SnS4 1d (88 mg, 0.078
mmol) and triphenylphosphine (62 mg, 0.23 mmol) and placed in a 5φ
NMR tube at room temperature. After it was degassed and sealed, the
solution gradually turned pale orange. When the solution was kept at
room temperature for 2 h, this solution suddenly turned colorless, and
white precipitates were formed. After removal of the solvent, the residue
was separated with HPLC to yield an oligomeric fraction35 (59 mg)
together with triphenylphosphine sulfide (61 mg, 88%).
Desulfurization of Tbt(Dis)SnS4 1e by Triphenylphosphine.
Toluene-d8 (0.5 mL) was added to Tbt(Dis)SnS4 1e (73 mg, 0.076
mmol) and triphenylphosphine (60 mg, 0.23 mmol) in a 5φ NMR tube
at room temperature. After it was degassed and sealed, the solvent was
removed, and then the resulting residue was subjected to HPLC to afford
an oligomeric fraction35 (61 mg) and triphenylphosphine sulfide (61
mg, 91%).
Conclusion
Introduction of appropriately bulky ligands onto the tin led
to the isolation of the first stable diaryl-substituted tin-
chalcogen double-bond compounds, stannanethione Tbt(Ditp)-
SndS and stannaneselone Tbt(Ditp)SndSe, without resorting
to intramolecular coordination. In the 119Sn NMR and 77Se
NMR, their tin and selenium atoms resonate at very low fields,
characteristic of the doubly bonded species. X-ray structural
analysis of Tbt(Ditp)SndSe revealed that the Sn-Se distance
[2.373(3) Å] was approximately 9% shorter than a Sn-Se single
bond length (2.55-2.60 Å), with trigonal planar geometry
around the tin atom (sum of the angles ) 359.9°), indicative of
structural similarity to carbon, silicon, and germanium ana-
logues. Their considerable double-bond character was also
verified by their reactivity in the cycloaddition with 2,3-
dimethyl-1,3-butadiene to afford Diels-Alder adducts, such as
other group 14 element-chalcogen double-bond compounds.
Despite severe steric congestion around the reactive center, they
showed reactivities as double-bond compounds because long
branched arms enclose the SndX moieties from the remote site.
These facts clearly show that the chemistry of tin-chalcogen
double-bond compounds is essentially similar to the chemistry
of a ketone and its silicon and germanium analogues. However,
they are much less stable and much more difficult to isolate
even compared to silicon and germanium congeners because
of longer bonds involving tin and because of energy gaps
between σ- and π-bonds that are longer than those of silicon
and germanium.
Spectral Detection of Tbt(Tcp)SndSe 5c. Toluene-d8 (0.5 mL) was
added to a mixture of Tbt(Tcp)SnSe4 2c (88 mg, 0.067 mmol), and
triphenylphosphine (54 mg, 0.21 mmol) in a 5φ NMR tube. After it
was degassed and sealed, the 119Sn NMR of this solution was measured
at room temperature. The 119Sn NMR of this solution showed a broad
singlet at 556 ppm that could be assigned to stannaneselone Tbt(Tcp)-
SndSe 5c. After 119Sn NMR spectra were measured overnight, the color
of the solution changed from deep red to colorless. Its 119Sn NMR
showed two signals around -100 ppm (-111.4 and -118.8 ppm) and
four signals around -300 ppm (-275.9, -278.7, -279.0, and -294.2
ppm). After removal of the solvent, the residue was subjected to HPLC
to give only an oligomeric product31 (58 mg) together with triphen-
ylphosphine selenide (64 mg, 91%). In this case, stannaneselone 5c
dimerized slowly at room temperature before the 77Se NMR spectrum
was measured. The 77Se NMR spectrum of Tbt(Tcp)SndSe 5c, prepared
in a manner similar to that described above, showed a broad signal at
839 ppm.
Reaction of Tbt(Tcp)SndSe 5c with Mesitonitrile Oxide. After
toluene (1.5 mL) was added to a mixture of Tbt(Tcp)SnSe4 2c (77 mg,
0.059 mmol), and triphenylphosphine (48 mg, 0.18 mmol) and placed
in an 8φ Pyrex tube, the solution was degassed and sealed. The tube
was kept at ambient temperature for 2 h and then opened in a glovebox.
After this red solution was poured into mesitonitrile oxide (28 mg,
0.17 mmol), the resulting solution was exposed to the air. Chromato-
graphic separation by DCC and HPLC afforded an oligomeric fraction35
(24 mg) and 2-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-2-(2,4,6-
tricyclohexylphenyl)-4-mesityl-1,3,5,2-oxaselenazastannole (9c) (43 mg,
58%). 9c: mp 225-227 °C dec (recrystallized from methylene chloride/
Acknowledgment. This work was partially supported by a
Grant-in-Aid for Scientific Research 05236102 from the Min-
9
J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004 15581

A R T I C L E S
Saito et al.
istry of Education, Science, and Culture, Japan. M.S. thanks
Research Fellowships of the Japan Society for the Promotion
of Science for Young Scientists. We are also grateful to Shin-
etsu Chemical Company, Ltd. and Tosoh Akzo Company, Ltd.
for the generous gift of chlorosilanes and alkyllithiums,
respectively.
Supporting Information Available: Refinement, atomic
coordinates, bond lengths and angles, anisotropic displacement
parameters, torsion angles, for 5a. This material is available
free of charge via the Internet at http://pubs.acs.org.
JA048453H
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15582 J. AM. CHEM. SOC. VOL. 126, NO. 47, 2004