Synthesis and reactions of a stannanethione derived from a kinetically stabilized diarylstannylene

Article abstract of DOI:10.1021/om960449u

Stannanethione Tbt(Tip)Sn=S (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Tip = 2,4,6-triisopropylphenyl), containing a novel tin-sulfur double bond, was synthesized by the reactions of the corresponding kinetically stabilized diarylstannylene Tbt(Tip)Sn: with styrene episulfide or elemental sulfur. An absorption maximum due to the n-π* transition of the tin-sulfur double bond appeared at 473 nm in hexane. It reacted with thiocumulenes such as carbon disulfide and phenyl isothiocyanate and with styrene oxide and mesitonitrile oxide to give the corresponding cycloadducts. The structure of the [2 + 2] cycloadduct of a stannanethione with carbon disulfide was determined by X-ray structural analysis. In contrast to Tbt(Tip)Sn=S, the less hindered stannanethione Tbt(Mes)Sn=S (Mes = mesityl) dimerized at room temperature to afford the corresponding 1,3,2,4-dithiadistannetane.

Full text of DOI:10.1021/om960449u

Organometallics 1996, 15, 4531-4536
4531
Syn th esis a n d Rea ction s of a Sta n n a n eth ion e Der ived
fr om a Kin etica lly Sta bilized Dia r ylsta n n ylen e
Masaichi Saito, Norihiro Tokitoh, and Renji Okazaki*
Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo,
Bunkyo-ku, Tokyo 113, J apan
Received J une 4, 1996X
Stannanethione Tbt(Tip)SndS (Tbt ) 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Tip )
2,4,6-triisopropylphenyl), containing a novel tin-sulfur double bond, was synthesized by
the reactions of the corresponding kinetically stabilized diarylstannylene Tbt(Tip)Sn: with
styrene episulfide or elemental sulfur. An absorption maximum due to the n-π* transition
of the tin-sulfur double bond appeared at 473 nm in hexane. It reacted with thiocumulenes
such as carbon disulfide and phenyl isothiocyanate and with styrene oxide and mesitonitrile
oxide to give the corresponding cycloadducts. The structure of the [2 + 2] cycloadduct of a
stannanethione with carbon disulfide was determined by X-ray structural analysis. In
contrast to Tbt(Tip)SndS, the less hindered stannanethione Tbt(Mes)SndS (Mes ) mesityl)
dimerized at room temperature to afford the corresponding 1,3,2,4-dithiadistannetane.
In tr od u ction
dynamically stabilized by intramolecular coordination.
More recently, compounds containing GedX (X ) S,
Te)8c and SndX (X ) S, Se, Te)9 bonds of similar kinds
were also isolated. Since they are strongly perturbed
by electron donation from neighboring nitrogen atoms
to electron-deficient group 14 metals, they do not show
the intrinsic nature of such double bond species in terms
of their physical properties and reactivities. The dif-
ficulty in the synthesis of kinetically stabilized “heavy
ketones” consists in the fact that bulky substituents for
steric protection can be introduced only on the group
14 elements and, hence, their oligomerization cannot
be effectively hindered.
For many years it was considered that compounds
having double bonds between heavier main group ele-
ments would be unstable because of their weak pπ-pπ
bonding (the so-called “double-bond rule”). Since the
isolation of the first stable compounds with SndSn,1
PdC,2 SidC,3 PdP,4 and SidSi5 by taking advantage
of bulky ligands which prevent them from oligomeriza-
tion (kinetic stabilization), however, significant and
exciting progress has been made in the chemistry of
unsaturated compounds of heavier main group ele-
ments, especially of group 14 elements.6 As for stable
compounds having double bonds between group 14 and
group 16 elements, the chemistry of thioketones and
selenoketones has been well explored for a few decades.
On the other hand, when we undertook a study of such
species several years ago, there were no examples of
“genuine” double-bonded compounds involving the
heavier group 14 and 16 elements, heavier congeners
of ketones (RR′MdX; M ) Si, Ge, Sn, and Pb; X ) S,
Se, and Te) which we refer to as “heavy ketones”,
although Corriu7 and Veith8ab had reported compounds
having SidX (X ) S and Se) and GedS bonds thermo-
Recently we succeeded in the isolation and X-ray
structural characterization of a kinetically stabilized
silanethione,10 germanethione,11 and germaneselone12
bearing a new steric protection group, 2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl (Tbt) group, developed in
our laboratory13 by dechalcogenation of the correspond-
14
ing tetrachalcogenametallolanes, Tbt(Tip)MX4 (M )
Si and Ge; X ) S and Se) (Tip ) 2,4,6-triisopropylphen-
yl), with phosphine reagents. We also reported the
synthesis of tin-chalcogen double-bonded compounds15
by dechalcogenation of 1,2,3,4,5-tetrachalcogenastan-
X Abstract published in Advance ACS Abstracts, September 15, 1996.
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T.; Matsuhashi, Y.; Okazaki, R.; Goto, M. J . Am. Chem. Soc. 1991,
113, 7047. For Tbt(Tip)GeX4, see: (b) Matsumoto, T.; Tokitoh, N.;
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S0276-7333(96)00449-9 CCC: $12.00 © 1996 American Chemical Society

4532 Organometallics, Vol. 15, No. 21, 1996
Saito et al.
Sch em e 1
nolanes16 and chalcogenation of the corresponding stan-
nylene.17 In this paper we report full details of the
synthesis and reactions of stannanethione Tbt(Tip)-
SndS (1a ) derived from the corresponding stannylene
Tbt(Tip)Sn (2a ).18 The X-ray structural analysis of the
newly obtained cycloadduct of stannanethione 1a with
carbon disulfide is also described.
[2,4,6-tris(trifluoromethyl)phenyl]stannylene24a and bis-
(2,4,6-tri-tert-butylphenyl)stannylene24b were reported.
Rea ction s of Dia r ylsta n n ylen e Tbt(Tip )Sn : (2a ).
The formation of 2a was also confirmed by chemical
trapping reactions with 2,3-dimethyl-1,3-butadiene and
benzil which gave the expected [4 + 1] cycloadducts 3
and 4, respectively (37 and 22%), as shown in Scheme
1. Stannylene 2a also reacted with an excess of
elemental chalcogens to furnish the corresponding tet-
rachalcogenastannolanes 5 and 6.16,17,25 The yield of the
trapping products was not satisfactory probably due to
low efficiency in the attack of a bulky aryllithium, TipLi,
to sterically congested TbtSnCl3 in the second step. The
remarkable stability of stannylene 2a prompted us to
examine its sulfurization, because the reaction was
expected to lead to the formation of stable stannane-
thione 1a .
Resu lts a n d Discu ssion
Syn th esis a n d P r op er ties of Kin etica lly Sta bi-
lized Dia r ylsta n n ylen e Tbt(Tip )Sn : (2a ). Stan-
nylene 2a was readily obtained by the treatment of a
THF solution of TbtLi with an ether suspension of
stannous chloride at -70 °C followed by the addition of
an equimolar amount of TipLi at the same temperature.
Under an inert atmosphere, stannylene 2a was quite
stable in solution even at 60 °C, and it showed a deep
purple color (λmax ) 561 nm) after solvent exchange into
hexane. On the other hand, in a mixed solvent (THF:
hexane ) 1:6) there appeared a new absorption at 394
nm at -40 °C assignable to a stannylene-THF complex,
which was substantially blue-shifted from the absorp-
tion of the stannylene in hexane. The reasonable
interpretation is that destabilization of an empty p-
orbital of the stannylene upon complexation results in
an increased energy gap between n- and p-orbitals, thus
causing a blue shift as observed in complexations of
silylenes19 and germylenes20 with Lewis bases such as
ethers, sulfides, amines, phosphines, and alcohols. The
119Sn NMR spectra of 2a in toluene-d8 showed only one
signal at 2208 ppm, attributable to the characteristic
chemical shift of a divalent organotin compound. The
bandwidth and chemical shift of 2a were almost un-
changed between -30 and 60 °C, indicating the absence
of a monomer-dimer equilibrium in this temperature
range.21 Recently, the X-ray structural analyses of bis-
Syn th esis a n d Rea ction s of Sta n n a n eth ion e Tbt-
(Tip )Sn dS (1a ). When the deep purple solution of 1a
in hexane was treated with styrene episulfide at room
temperature, the solution turned yellow, suggesting the
formation of stannanethione 1a . Monitoring of this
reaction by UV/vis spectroscopy showed an appearance
of a new absorption at 473 nm at the expense of the
absorption of stannylene 2a at 561 nm. The absorption
at 473 nm is assignable to the n-π* transition of the
tin-sulfur double bond of stannanethione 1a , being red-
shifted compared to silanethione (396 nm)10 and ger-
manethione (450 nm).11 The red shift on going from
silanethione to stannanethione is theoretically sup-
ported by calculated spectra of H2MdS (M ) Si, Ge, and
Sn) at the CIS/DZ+d level using the Gaussian 92/DFT
program.10
(21) The first monomeric dialkylstannylene, 2,2,5,5-tetrakis(tri-
methylsilyl)-1-stannacyclopentane-1,1-diyl, showed a sharp singlet at
2323 ppm in 119Sn NMR without any temperature dependence,22 while
bis[bis(trimethylsilyl)methyl]stannylene which exists as a monomer-
dimer equilibrium mixture has been reported to show δSn at 2315 ppm
(toluene-d8, 375 K).23
(22) Kira, M.; Yauchibara, R.; Hirano, R.; Kabuto, C.; Sakurai, H.
J . Am. Chem. Soc. 1991, 113, 7785.
(23) Zilm, K. W.; Lawless, G. A.; Merrill, R. M.; Millar, J . M.; Webb,
G. G. J . Am. Chem. Soc. 1987, 109, 7236. For the synthesis, see ref 1
and: Cotton, J . D.; Davidson, P. J .; Lappert, M. F. J . Chem. Soc.,
Dalton. Trans. 1976, 2275.
(24) (a) Gru¨tzmacher, H.; Pritzkow, H.; Edelmann, F. T. Organo-
metallics 1991, 10, 23. (b) Weidenbruch, M.; Schlaefke, J .; Scha¨fer,
A.; Peters, K.; Schnering, H. G. v.; Marsmann, H. Angew. Chem., Int.
Ed. Engl. 1994, 33, 1846.
(25) For experimental details of the reaction of stannylene 2a with
elemental selenium, see ref 16b.
(16) (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.
(17) (a) Tokitoh, N.; Saito, M.; Okazaki, R. J . Am. Chem. Soc. 1993,
115, 2065. (b) Saito, M.; Tokitoh, N.; Okazaki, R. J . Organomet. Chem.
1995, 499, 43.
(18) For preliminary results, see ref 17a.
(19) (a) Gillette, G. R.; Noren, G. H.; West, R. Organometallics 1987,
6, 2617. (b) Ando, W.; Hagiwara, K.; Sekiguchi, A.; Sakakibara, A.;
Yoshida, H. Organometallics 1988, 7, 558. (c) Gillette, G. R.; Noren,
G. H.; West, R. Organometallics 1989, 8, 487.
(20) (a) Ando, W.; Itoh, H.; Tsumuraya, T.; Yoshida, H. Organome-
tallics 1988, 7, 1880. (b) Ando, W.; Itoh, H.; Tsumuraya, T. Organo-
metallics 1989, 8, 2759.

Tbt(Tip)SndS
Organometallics, Vol. 15, No. 21, 1996 4533
Sch em e 2
Sch em e 3
oxide gave 1,3,5,2-oxathiazastannole 10, which is of
interest not only as the first example of a 1,3-dipolar
cycloaddition reaction of a stannanethione but also as
a novel tin-containing heterocycle. The trapping of
stannanethione 1a with styrene oxide was also carried
out, since we found previously that stannanethione 1a
generated by desulfurization of 5 with triphenylphos-
phine reacted with styrene oxide to afford 1,3,2-oxathia-
stannolane.15 Contrary to the sole formation of 11 in
the reported reaction,15 the products in the present
reaction were 11 and 1227 as had been observed in the
reaction of stannaneselone Tbt(Tip)SndSe generated by
the reaction of 2a with elemental selenium.17b The
difference between these two reactions probably results
The formation of stannanethione 1a was chemically
evidenced by trapping experiments with an excess of a
thiocumulene such as carbon disulfide and phenyl
isothiocyanate at room temperature which afforded
1,3,2-dithiastannetane derivatives 7 and 8 in 19 and
38% yields, respectively. The formation of adducts, 7
and 8, is worthy of note. They are the first examples of
[2 + 2] cycloaddition of a tin-sulfur double-bond
compound except for self-dimerization.26 The possibility
that a chemical species involved in these cycloadditions
is a dimer can be reasonably eliminated by the fact that
dithiadistannetane 9,15 the dimer of 1a , is inert to the
thiocumulenes under the reaction conditions. The above
reactions show that a stannylene is a useful, potential
precursor to novel tin-containing double-bond species.
The head-to-tail coupling mode in the formation of 7
was unambiguously determined by its X-ray structural
analysis (Figure 1). Selected bond lengths and angles
are listed in Table 1. The angles of C(2)-Sn-C(3) and
S(1)-Sn-S(2) are 123.0 and 73.6°, respectively. The
SnS2C four-membered ring is folded with an interplanar
angle of 5.4° between Sn-S(1)-C(1) and S(1)-C(1)-
S(2) planes.
F igu r e 1. ORTEP drawing of Tbt(Tip)SnS2CdS (7).
Ta ble 1. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg)
Sn-S(1)
2.448
1.758
1.626
1.727
S(2)-Sn
Sn-C(2)
Sn-C(3)
2.444
2.160
2.159
S(1)-C(1)
C(1)-S(3)
C(1)-S(2)
Stannanethione 1a was also trapped by a 1,3-dipolar
cycloaddition. The reaction of 1a with mesitonitrile
S(2)-Sn-S(1)
Sn-S(1)-C(1)
S(1)-C(1)-S(3)
S(3)-C(1)-S(2)
73.6
C(1)-S(2)-Sn
C(2)-Sn-C(3)
C(2)-Sn-S(2)
C(3)-Sn-S(1)
85.4
86.2
122.3
123.3
123.0
120.7
115.8
(26) (a) Puff, H.; Gattermayer, R.; Hundt, R.; Zimmer, R. Angew.
Chem., Int. Ed. Engl. 1977, 16, 547. (b) Schumann, H. Z. Anorg. Allg.
Chem. 1967, 354, 192.

4534 Organometallics, Vol. 15, No. 21, 1996
Saito et al.
uncorrected. Elemental analyses were carried out at the
Microanalytical Laboratory of Department of Chemistry,
Faculty of Science, The University of Tokyo.
Ma ter ia ls. 1-Bromo-2,4,6-tris[bis(trimethylsilyl)methyl]-
benzene (TbtBr)13 and 1-bromo-2,4,6-triisopropylbenzene (Tip-
Br)28 were prepared according to procedures reported in the
literature. Stannous chloride was purchased from Wako Pure
Chemical Ind., Ltd. THF, ether, and hexane used in the
synthesis were all distilled from benzophenone ketyl under
argon atmosphere before use.
Gen er a l P r oced u r es for th e P r ep a r a tion of Tbt(Tip )-
Sn : (2a ). (a ) P r ep a r a tion of a THF -Eth er Solu tion of
Tbt(Tip )Sn : (2a ). To a THF solution (5 mL) of TbtLi,
prepared from TbtBr (572 mg, 0.90 mmol) and t-BuLi (1.65 M
in pentane; 1.20 mL, 2.2 equiv) at -70 °C was added an ether
suspension (9 mL) of stannous chloride (184 mg, 0.97 mmol).
After being stirred for 1.5 h at -65 °C, the reaction mixture
was treated with a THF solution (5 mL) of equimolar TipLi,
prepared from TipBr (253 mg, 0.89 mmol) and t-BuLi (2.2
equiv), to afford an orange solution of stannylene Tbt(Tip)Sn:
(2a ).
(b) P r ep a r a tion of a Hexa n e Solu tion of Tbt(Tip )Sn :
(2a ). After a THF-ether solution of 2a , synthesized by the
above procedure a from TbtBr (572 mg, 0.90 mmol) and
stannous chloride (184 mg, 0.97 mmol), was warmed to about
-30 °C, the volatile substances were removed in vacuo. After
drying of the dark-orange residue at room temperature, to the
residue was added 7 mL of degassed dry hexane and the
volatile portion was again removed at room temperature in
vacuo. Several repetitions of this procedure for solvent
exchange gave a deep purple hexane solution of 2a .
Rea ction s of Dia r ylsta n n ylen e Tbt(Tip )Sn : (2a ). (a )
Rea ction of Tbt(Tip )Sn : (2a ) w ith 2,3-Dim eth yl-1,3-
bu ta d ien e. To a deep purple hexane solution (2 mL) of 2a
synthesized from TbtBr (446 mg, 0.70 mmol) and stannous
chloride (142 mg, 0.75 mmol) was added 2,3-dimethyl-1,3-
butadiene (1 mL, 8.84 mmol) at room temperature. After
removal of volatile substances, the residue was subjected to
column chromatography (Florisil/dichloromethane) followed by
HPLC to yield 1-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-
1-(2,4,6-triisopropylphenyl)-3,4-dimethyl-2,4-dihydrostan-
nole (3) (235 mg, 37%). 3: Mp 189-190 °C; 1H NMR (CDCl3,
500 MHz) δ -0.08 (s, 18H), -0.04 (s, 18H), 0.02 (s, 18H), 1.16
(br s, 12H), 1.20 (d, J ) 7 Hz, 6H), 1.26 (s, 1H), 1.66 (s, 1H),
1.74 (s, 6H), 1.77 (s, 1H), 2.05 (d, J ) 16 Hz, 2H), 2.12 (d, J )
16 Hz, 2H), 2.83 (sept, J ) 7 Hz, 1H), 2.99 (sept, J ) 7 Hz,
2H), 6.25 (s, 1H), 6.40 (s, 1H), 6.97 (s, 2H); 13C NMR (CDCl3,
125 MHz) δ 0.89 (q), 1.21 (q), 1.40 (q), 21.49 (q), 24.07 (q), 25.74
(q), 30.03 (d), 30.86 (d), 31.34 (d), 32.26 (t), 34.33 (d), 37.92
(d), 121.31 (d), 121.99 (d), 127.22 (d), 131.69 (s), 137.70 (s),
142.50 (s), 142.77 (s), 149.18 (s), 151.11 (s), 151.29 (s), 154.20
(s). Anal. Calcd for C48H92Si6Sn.H2O: C, 59.15; H, 9.74.
Found: C, 59.20; H, 9.46.
Although elemental analyses were carried out twice after
drying 3 at 80 °C in vacuo for 3 days, both results were
consistent with a formula of monohydrate 3‚H2O. It still
contains 0.75 H2O even after drying at 110 °C for 14 h in vacuo,
as evidenced by 1H NMR. Compounds having a Tbt group tend
to crystallize as a hydrate probably because of the unique
features of the very bulky Tbt group which leaves some space
among molecules in the crystalline state. Indeed we have
observed several hydrates of such type for other tin compounds
bearing the Tbt group (for example, see: Matsuhashi, Y.;
Tokitoh, N.; Okazaki, R.; Goto, M.; Nagase, S. Organometallics
1993, 12, 1351).
from the presence of triphenylphosphine sulfide, a
nucleophilic catalyst, in the former reaction.17b
Since the reaction of a less encumbered diarylstan-
nylene Tbt(Mes)Sn: (2b) with styrene episulfide in
THF-ether at -78 °C did not give monomeric products
but a mixture of cis and trans isomers of 1,3,2,4-
dithiadistannetanes 13 (13a (cis, 5%); 13b (trans, 6%),15
which are the dimerization products of the intermediate
stannanethione Tbt(Mes)SndS (1b), the prominent
stability of the stannanethione 1a obviously is due to
the steric congestion of the combination of Tbt and Tip
groups. Although 1a is stable at room temperature, it
undergoes dimerization, giving 915 at 90 °C. The 119Sn
NMR signal of stannanethione 1a has not been detected
yet, probably due to low generation efficiency of 1a or
complexation of 1a with THF even after solvent ex-
change into toluene-d8.
Alt er n a t ive Met h od for t h e Gen er a t ion of a
Sta n n a n eth ion e: Rea ction of a Sta n n ylen e w ith
Elem en ta l Su lfu r . Since Parkin’s terminal sulfido
complex was successfully synthesized by the reaction
of a thermodynamically stabilized stannylene with
elemental sulfur,9a we also examined the the reaction
of stannylene 2a with elemental sulfur. When sulfur
(1/8 equimolar to TbtBr as S8) was added to 2a , the
reaction solution turned yellow, suggesting the forma-
tion of stannanethione 1a . Treatment of this reaction
mixture with styrene oxide followed by column chro-
matography gave 1,3,2-oxathiastannolanes 11 (2%) and
12 (28%). Similar treatment of that mixture with
mesitonitrile oxide afforded 1,3,5,2-oxathiazastannole
10 (39%). The formation of 10-12 clearly indicates the
initial generation of stannanethione 1a by the reaction
of stannylene 2a with elemental sulfur, as in the case
of the reaction of 2a with styrene episulfide. In this
reaction, however, tetrathiastannolane 5 (5% based on
TbtBr) was also obtained as a result of the reaction of
stannanethione 1a with an excess of elemental sulfur;
the amount of sulfur used is probably still excess
because of low efficiency in the generation of stannylene
2a .
In order to isolate a stable stannanethione, further
investigation on the introduction of a ligand bulkier
than a Tip group on the tin is now under way.
Exp er im en ta l Section
Gen er a l P r oced u r e. All reactions were carried out under
argon. 1H (500 MHz) and 13C NMR (125 MHz) spectra were
recorded on a Bruker AM-500 spectrometer with tetrameth-
ylsilane as an external standard. 119Sn NMR (34 MHz) spectra
were recorded on a J EOL FX-90Q spectrometer with tetra-
methylstannane as an external standard. High-resolution
mass spectral data were obtained on a J EOL SX-102 mass
spectrometer. Electronic spectra were measured on a J ASCO
U
best-50 UV/vis spectrometer. Preparative HPLC was carried
out on an LC-08 or LC-908 (J apan Analytical Ind. Co., Ltd.)
with J AIGEL-1H and -2H columns. Preparative thin-layer
chromatography (PTLC), wet column chromatography (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 deter-
mined on a Yanaco micro melting point apparatus and are
(b) Rea ction of Tbt(Tip )Sn : (2a ) w ith Ben zil. To a deep
purple hexane solution (10 mL) of 2a synthesized from TbtBr
(541 mg, 0.86 mmol) and stannous chloride (174 mg, 0.92
mmol) was added benzil (301 mg, 1.43 mmol) at room tem-
(27) Both 11 and 12 were found to be cis and trans isomers. Although
the stereochemistry of two ligands on the tin and a phenyl group in
them was not confirmed, a less polar compound on silica gel is
designated as a in each case.
(28) Whitesides, G. M.; Eisenhut, M.; Bunting, W. M. J . Am. Chem.
Soc. 1974, 96, 5406.

Tbt(Tip)SndS
Organometallics, Vol. 15, No. 21, 1996 4535
perature. After removal of the solvent, the residue was
subjected to DCC to afford 2-{2,4,6-tris[bis(trimethylsilyl)-
methyl]phenyl}-2-(2,4,6-triisopropylphenyl)-1,3-dioxa-4,5-di-
phenyl-2-stannole (4) (210 mg, 23%). 4: Mp 219-221 °C (dec);
1H NMR (CDCl3, 500 MHz) δ -0.04 (s, 18H), -0.02 (s, 18H),
0.06 (s, 18H), 1.23 (d, J ) 7 Hz, 6H), 1.31 (d, J ) 6 Hz, 12H),
1.37 (s, 1H), 1.87 (s, 1H), 2.11 (s, 1H), 2.88 (sept, J ) 7 Hz,
1H), 3.03 (sept, J ) 6 Hz, 2H), 6.37 (s, 1H), 6.51 (s, 1H), 7.05-
7.06 (m, 2H), 7.07 (s, 2H), 7.09-7.12 (m, 4H), 7.35-7.37 (m,
4H); 13C NMR (CDCl3, 125 MHz) δ 0.53 (q), 0.78 (q), 0.79 (q),
23.95 (q), 25.74 (q), 30.79 (d), 32.42 (d), 34.47 (d), 38.81 (d),
122.01 (d), 122.54 (d), 125.49 (d), 127.21 (d), 127.38 (d), 128.34
(d), 137.40 (s), 138.48 (s), 139.27 (s), 141.39 (s), 146.33 (s),
151.01 (s), 151.38 (s), 151.90 (s), 154.34 (s). Anal. Calcd for
Calcd for C49H87NS2Si6Sn: C, 56.49; H, 8.43; N, 1.21; S, 6.16.
Found: C, 56.21; H, 8.51; N, 0.99; S, 5.80.
R ea ct ion of St a n n a n et h ion e 1a w it h Mesit on it r ile
Oxid e. Styrene episulfide (72 mg, 0.54 mmol) was added to
a hexane solution of stannylene 2a synthesized from TbtBr
(552 mg, 0.87 mmol) and stannous chloride (180 mg, 0.95
mmol) at room temperature. After the solution was stirred
for 5 min, treatment with mesitonitrile oxide (224 mg, 1.39
mmol) followed by usual workup gave 2-{2,4,6-tris[bis(tri-
methylsilyl)methyl]phenyl}-2-(2,4,6-triisopropylphenyl)-4-mes-
ityl-1,3,5,2-oxathiazastannole (10) (373 mg, 40%). 10: Mp
202.5-204 °C; 1H NMR (CDCl3, 500 MHz) δ 0.00 (s, 9H), 0.03
(s, 9H), 0.06 (s, 18H), 0.06 (s, 18H), 1.21 (d, J ) 7 Hz, 6H),
1.28 (d, J ) 3 Hz, 6H), 1.30 (d, J ) 3 Hz, 6H), 1.36 (s, 1H),
1.90 (s, 1H), 2.10 (s, 1H), 2.13 (br s, 6H), 2.24 (s, 3H), 2.86
(sept, J ) 7 Hz, 1H), 2.95 (br s, 2H), 6.41 (s, 1H), 6.54 (s, 1H),
6.80 (s, 2H), 7.03 (s, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.87
(q), 0.89 (q), 0.92 (q), 1.06 (q), 1.10 (q), 1.35 (q), 20.34 (q), 21.02
(q), 23.84 (q), 23.91 (q), 25.73 (br q), 30.75 (d), 32.75 (d), 32.91
(d), 34.29 (d), 38.70 (d), 122.60 (d), 123.01 (d), 128.10 (d), 128.33
(d), 131.29 (s), 137.16 (s), 137.96 (s), 138.70 (s), 143.22 (s),
145.94 (s), 147.65 (s), 150.98 (s), 151.23 (s), 151.33 (s), 153.83
(s). Anal. Calcd for C52H93NOSSi6Sn: C, 58.49; H, 8.80; N,
1.31; S, 3.00. Found: C, 58.35; H, 8.59; N, 1.57; S, 2.96.
Rea ction of Sta n n a n eth ion e 1a w ith Styr en e Oxid e.
After addition of styrene episulfide (74 mg, 0.54 mmol) to
stannylene 2a prepared from TbtBr (363 mg, 0.57 mmol) and
stannous chloride (112 mg, 0.59 mmol) in THF-ether at -70
°C, the reaction solution was stirred for 1.5 h at this temper-
ature. Styrene oxide (263 mg, 2.19 mmol) was added to the
reaction solution at the same temperature. After the solution
was warmed to ambient temperature, the usual workup by
DCC afforded a cis and trans mixture of 2-{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-2-(2,4,6-triisopropylphenyl)-5-
phenyl-1,3,2-oxathiastannolane (12a ) (109 mg, 18%) and 12b
(99 mg, 15%) which contained a small amount of 2-{2,4,6-tris-
[bis(trimethylsilyl)methyl]phenyl}-2-(2,4,6-triisopropylphenyl)-
4-phenyl-1,3,2-oxathiastannolane (11a )15 (2%), as evidenced by
1H NMR. 12a : Mp 210-212.5 °C (dec); 1H NMR (CDCl3, 500
MHz) δ -0.05 (s, 9H), -0.01 (s, 9H), 0.05 (s, 36H), 1.18 (br s,
6H), 1.23 (d, J ) 7 Hz, 6H), 1.49 (s, 1H), 1.52 (br s, 6H), 1.85
(s, 1H), 1.96 (s, 1H), 2.71 (dd, J ) 12, 12 Hz, 1H), 2.90 (sept,
J ) 7 Hz, 1H), 3.3 (br s, 2H), 3.39 (dd, J ) 3, 12 Hz, 1H), 4.78
(dd, J ) 3, 12 Hz, 1H), 6.36 (s, 1H), 6.50 (s, 1H), 7.07 (s, 2H),
7.17 (t, J ) 8 Hz, 1H), 7.23 (dd, J ) 7, 8 Hz, 2H), 7.36 (d, J )
7 Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.82 (q), 0.93 (q),
1.08 (q), 1.29 (q), 1.37 (q), 1.60 (q), 23.98 (q), 28 (q), 30.42 (d),
30.59 (d), 30.69 (d), 34.35 (d), 38.39 (d), 43.31 (t), 78.75 (d),
122.37 (d), 122.89 (d), 126.25 (d), 126.71 (d), 127.87 (d), 127.98
(d), 138.71 (s), 141.70 (s), 145.18 (s), 145.59 (s), 150.77 (s),
150.96 (s), 151.26 (s). Anal. Calcd for C50H90OSSi6Sn: C,
58.49; H, 8.85; S, 3.12. Found: C, 57.85; H, 8.64; S, 3.17.
12b: Mp 231-234 °C (dec); 1H NMR (CDCl3, 500 MHz) δ
-0.02 (s, 9H), 0.02 (s, 9H), 0.05 (s, 18H), 0.06 (s, 18H), 1.21
(d, J ) 7 Hz, 6H), 1.28 (br s, 12H), 1.34 (s, 1H), 2.15 (s, 1H),
2.40 (s, 1H), 2.73 (dd, J ) 11, 11 Hz, 1H), 2.85 (sept, J ) 7 Hz,
1H), 2.96 (br s, 1H), 3.34 (dd, J ) 3, 11 Hz, 1H), 3.38 (br s,
1H), 4.77 (dd, J ) 3, 11 Hz, 1H), 6.38 (s, 1H), 6.50 (s, 1H),
7.04 (s, 2H), 7.21 (t, J ) 7 Hz, 1H), 7.28 (dd, J ) 7, 8 Hz, 2H),
7.49 (d, J ) 8 Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.83 (q),
0.91 (q), 1.18 (q), 1.22 (q), 1.45 (q), 1.48 (q), 23.95 (q), 28.73
(q), 28.95 (q), 30.59 (d), 31.17 (d), 31.34 (d), 34.34 (d), 36.91
(d), 38.38 (d), 40.61 (t), 80.03 (d), 122.18 (d), 122.56 (d), 122.82
(d), 126.18 (d), 126.26 (d), 126.71 (d), 137.76 (s), 142.10 (s),
144.89 (s), 145.28 (s), 150.93 (s), 151.16 (s), 151.61 (s). Anal.
Calcd for C50H90OSSi6Sn: C, 58.49; H, 8.85. Found: C, 57.75;
H, 8.49.
C
56H92O2Si6Sn: C, 62.00; H, 8.57. Found: C, 61.82; H, 8.47.
(c) Rea ction of Tbt(Tip )Sn : (2a ) w ith Elem en ta l Su l-
fu r . To a THF-ether solution of stannylene 2a prepared from
TbtBr (1801 mg, 2.85 mmol) and stannous chloride (586 mg,
3.09 mmol) was added elemental sulfur (1045 mg, 4.07 mmol)
at -50 °C. After gradual warming to room temperature, the
usual workup by DCC and HPLC afforded 5-{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-5-(2,4,6-triisopropylphenyl)-
1,2,3,4,5-tetrathiastannolane (5) (1427 mg, 50%).16
Gen er a l P r oced u r e for th e Tr a n sfor m a tion of Sta n -
n ylen e 2a in to Sta n n a n eth ion e 1a . To a THF-ether or
hexane solution of stannylene 2a prepared according to the
procedure described above was added styrene episulfide,
during which time the solution turned yellow, suggesting the
formation of stannanethione 1a .
Rea ction of Sta n n a n eth ion e 1a w ith Ca r bon Disu lfid e.
Styrene episulfide (53 mg, 0.39 mmol) was added at -70 °C
to a THF-ether solution of stannylene synthesized from TbtBr
(231 mg, 0.36 mmol) and stannous chloride (78 mg, 0.41 mmol).
After being warmed to 0 °C, the reaction solution was treated
with carbon disulfide (0.20 mL, 3.32 mmol). After removal of
the solvent, separation of the residue by DCC gave 2-{2,4,6-
tris[bis(trimethylsilyl)methyl]phenyl}-2-(2,4,6-triisopropylphe-
nyl)-1,3,2,4-dithiastannetanethione (7) (68 mg, 19%). 7: Mp
207-208 °C (dec); 1H NMR (CDCl3, 500 MHz) δ -0.02 (s, 18H),
0.05 (s, 36H), 1.23 (d, J ) 7 Hz, 6H), 1.33 (d, J ) 7 Hz, 12H),
1.35 (s, 1H), 2.04 (s, 1H), 2.34 (s, 1H), 2.78 (sept, J ) 7 Hz,
2H), 2.89 (sept, J ) 7 Hz, 1H), 6.36 (s, 1H), 6.53 (s, 1H), 7.09
(s, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.80 (q), 0.83 (q), 1.08
(q), 23.92 (q), 28.58 (q), 30.93 (d), 32.75 (d), 32.99 (d), 34.41
(d), 40.49 (d), 122.88 (d), 123.08 (d), 128.00 (d), 135.25 (s),
140.43 (s), 146.91 (s), 151.58 (s), 151.99 (s), 152.39 (s), 153.61
(s), 228.99 (s). Anal. Calcd for C43H82S3Si6Sn: C, 52.55; H,
8.43; S, 9.76. Found: C, 52.31; H, 8.24; S, 10.04.
Rea ction of Sta n n a n eth ion e 1a w ith P h en yl Isoth io-
cya n a te. Styrene episulfide (46 mg, 0.33 mmol) was added
at -45 °C to a THF-ether solution of stannylene 2a prepared
from TbtBr (438 mg, 0.69 mmol) and stannous chloride (141
mg, 0.75 mmol). After it had been stirred for 1 h at this
temperature, the reaction mixture was warmed to room
temperature and then treated with phenyl isothiocyanate (1
mL, 8.36 mmol). After removal of the solvent, separation of
the residue by WCC and DCC afforded 2-{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-2-(2,4,6-triisopropylphenyl)-4-
(phenylimino)-1,3,2-dithiastannetane (8) (273 mg, 38%). The
reaction of stannanethione 1a synthesized from stannylene 2a
and styrene episulfide with phenyl isothiocyanate in hexane
at room temperature also gave 8 (38%). 8: Mp 145-147.5 °C;
1H NMR (CDCl3, 500 MHz) δ -0.03 (s, 9H), -0.01 (s, 9H), 0.03
(s, 9H), 0.04 (s, 9H), 0.05 (s, 18H), 1.23 (d, J ) 7 Hz, 6H), 1.30
(d, J ) 6 Hz, 6H), 1.33 (br s, 6H), 1.62 (s, 1H), 2.19 (s, 1H),
2.49 (s, 1H), 2.9 (m, 3H), 6.37 (s, 1H), 6.52 (s, 1H), 6.90 (d, J
) 7 Hz, 2H), 7.02 (t, J ) 7 Hz, 1H), 7.07 (s, 2H), 7.27 (dd, J )
7 Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.85 (q), 1.01 (q),
1.22 (q), 1.26 (q), 23.98 (q), 30.65 (q), 30.82 (d), 31.92 (d), 32.17
(d), 34.40 (d), 39.73 (d), 121.22 (d), 122.69 (d), 123.03 (d), 123.80
(d), 127.97 (d), 128.68 (d), 136.14 (s), 141.63 (s), 146.35 (s),
149.88 (s), 151.42 (s), 151.86 (s), 153.44 (s), 157.39 (s). Anal.
Cr ysta l a n d Exp er im en ta l Da ta for 7: C43H82S3Si6Sn, M
) 982.50, monoclinic, space group C2/ c, a ) 46.25(1) Å, b )
13.470(5) Å, c ) 18.645(5) Å, â ) 105.48(3)°, V ) 11195(6) Å3,
Z ) 8, Dc ) 1.166 g cm-1, R ) 0.046 (Rw ) 0.047). The
intensity data (2θ e 60°) were collected on a Rigaku AFC5R

4536 Organometallics, Vol. 15, No. 21, 1996
Saito et al.
diffractometer with graphite-monochromated Mo KR radiation
(λ ) 0.710 69 Å), and the structure was solved by direct
methods. The non-hydrogen atoms were refined anisotropi-
cally, and all the hydrogen atoms were located by calculation.
The final cycle of full-matrix least-squares refinement was
based on 6659 observed reflections [I > 3.00(σ)] and 478
variable parameters.
Rea ction of Sta n n ylen e Tbt(Mes)Sn : (2b) w ith Sty-
r en e Ep isu lfid e. Styrene episulfide (126 mg, 0.93 mmol) was
added at -70 °C to stannylene Tbt(Mes)Sn: (2b) prepared
from TbtBr (576 mg, 0.91 mmol) and stannous chloride (175
mg, 0.92 mmol). After the mixture was warmed to ambient
temperature, the usual workup of the crude reaction mixture
by HPLC, DCC, and PTLC gave cis-2,4-bis{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-2,4-dimesityl-1,3,2,4-dithia-
stannetane (13a ) (30 mg, 5%) and trans-2,4-bis{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-2,4-dimesityl-1,3,2,4-dithia-
stannetane (13b) (32 mg, 6%).15
Rea ction of Sta n n a n eth ion e 1a , Gen er a ted by th e
Rea ction of Sta n n ylen e 2a w ith Elem en ta l Su lfu r , w ith
Styr en e Oxid e. Elemental sulfur (33 mg, 1.02 mmol as S)
was added to a THF-ether solution of stannylene 2a synthe-
sized from TbtBr (552 mg, 0.87 mmol), stannous chloride (177
mg, 0.94 mmol), and TipBr (260 mg, 0.92 mmol) at -70 °C.
After being stirred for 2 h at this temperature, the reaction
mixture was treated with styrene oxide (0.16 mL, 1.40 mmol).
After removal of the solvent at room temperature, separation
of the residue by DCC gave a fraction containing oxathiast-
annolanes (333 mg), a part (102 mg) of which was further
purified by PTLC (hexane:methylene chloride ) 10:1) to afford
12a (40 mg, 15%) and 12b (35 mg, 13%), and 2-{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}-2-(2,4,6-triisopropylphenyl)-4-
phenyl-1,3,2-oxathiastannolane (11b)15 (7 mg, 2%).
Rea ction of Sta n n a n eth ion e 1a , Gen er a ted by th e
Rea ction of Sta n n ylen e 2a w ith Elem en ta l Su lfu r , w ith
Mesiton itr ile Oxid e. Elemental sulfur (29 mg, 0.90 mmol
as S) was added to a THF-ether solution of stannylene 2a
synthesized from TbtBr (534 mg, 0.84 mmol), stannous
chloride (173 mg, 0.91 mmol), and TipBr (218 mg, 0.77 mmol)
at -70 °C. After being stirred for 1 h at this temperature,
the reaction mixture was treated with mesitonitrile oxide (147
mg, 0.91 mmol). After removal of the solvent at room tem-
perature, separation of the residue by DCC followed by HPLC
gave 10 (353 mg, 39%).
Ack n ow led gm en t. This work was partially sup-
ported by Grant-in Aid for Scientific Research No.
05236102 from the Ministry of Education, Science, and
Culture of J apan. M.S. thanks the Research Fellow-
ships of the J apan Society for the Promotion of Science
for Young Scientists. We are also grateful to Shin-etsu
Chemical Co., Ltd., and Tosoh Akzo Co., Ltd., for the
generous gift of chlorosilanes and alkyllithiums, respec-
tively.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal-
lographic data, bond lengths, bond angles, and thermal and
positional parameters and ORTEP diagrams for 7 (36 pages).
Ordering information is given on any current masthead page.
OM960449U