Synthesis, structure, and reactivity of kinetically stabilized divalent organolead compounds (plumbylenes)

Article abstract of DOI:10.1021/om990188z

Divalent organolead compounds (plumbylenes; Tip₂Pb (6; Tip = 2,4,6-triisopropylphenyl) and Tbt(R)Pb (7a, R = Tbt; Tb, R = Ttm; 7c, R = Tip; 7d, R = Dis; Tbt = 2,4,6-tris[bis-(trimethylsilyl)methyl]phenyl, Ttm = 2,4,6-tris[(trimethylsilyl)methyl]phenyl, and Dis = bis-(trimethylsilyl)methyl)) were synthesized by taking advantage of kinetic stabilization afforded by bulky substituents and characterized by UV/vis and ²⁰⁷Pb NMR spectroscopy. X-ray structural analysis revealed that plumbylene 7a has a V-shaped, monomeric structure. Reactions of these plumbylenes with methyl iodide, carbon tetrabromide, diphenyl disulfide, diphenyl diselenide, and elemental sulfur are described. New methods for the synthesis of plumbylenes from tetravalent organolead compounds, by reductive debromination of dibromoplumbanes and exhaustive desulfurization of tetrathiaplumbolanes, were developed.

Full text of DOI:10.1021/om990188z

Organometallics 1999, 18, 2999-3007
2999
Syn th esis, Str u ctu r e, a n d Rea ctivity of Kin etica lly
Sta bilized Diva len t Or ga n olea d Com p ou n d s
(P lu m bylen es)
Naokazu Kano, Kazusato Shibata,† Norihiro Tokitoh,*,‡ and Renji Okazaki*,§
Department of Chemistry, Graduate School of Science, The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, J apan
Received March 16, 1999
Divalent organolead compounds (plumbylenes; Tip2Pb (6; Tip ) 2,4,6-triisopropylphenyl)
and Tbt(R)Pb (7a , R ) Tbt; 7b, R ) Ttm; 7c, R ) Tip; 7d , R ) Dis; Tbt ) 2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl, Ttm ) 2,4,6-tris[(trimethylsilyl)methyl]phenyl, and Dis ) bis-
(trimethylsilyl)methyl)) were synthesized by taking advantage of kinetic stabilization afforded
by bulky substituents and characterized by UV/vis and 207Pb NMR spectroscopy. X-ray
structural analysis revealed that plumbylene 7a has a V-shaped, monomeric structure.
Reactions of these plumbylenes with methyl iodide, carbon tetrabromide, diphenyl disulfide,
diphenyl diselenide, and elemental sulfur are described. New methods for the synthesis of
plumbylenes from tetravalent organolead compounds, by reductive debromination of
dibromoplumbanes and exhaustive desulfurization of tetrathiaplumbolanes, were developed.
In tr od u ction
The first stable diaminoplumbylene, [(Me3Si)2N]2Pb
(1), was synthesized by Lappert and co-workers in
1974.4 Other stable plumbylenes with heteroatom sub-
stituents, such as phosphanyl and silyl groups, bonded
to the lead atom have also been reported.5,6 The elec-
tronic or photoelectron spectra of these compounds
indicate that their frontier orbitals were perturbed by
their heteroatom substituents to such an extent that
they are different from those of an intrinsic singlet
carbene analogue.
A few stable heteroleptic plumbylenes are also known.
They form oligomers in most cases,7-9 but we recently
reported a stable aryl(arylthio)plumbylene which exists
in monomeric form.10 Another monomeric and hetero-
leptic plumbylene is known, but this is not a two-
coordinate but rather three-coordinate divalent orga-
nolead compound.11
Remarkable progress has been made in the chemistry
of divalent organic compounds of silicon, germanium,
and tin, R2M (M ) Si, Ge, Sn), the heavier homologues
of carbenes, in recent decades.1 Although these com-
pounds had once been thought to exist only as highly
reactive intermediates, examples of stable R2M com-
pounds have been reported in recent years. However,
divalent organolead compounds (plumbylenes), the heavi-
est carbene analogues, are less well-known. They usu-
ally occur as reactive intermediates in the preparation
of plumbanes R4Pb and polymerize and undergo dis-
proportionation in the absence of suitable stabilizing
groups on the lead atom.2
Dicyclopentadienyllead(II) compounds, formally also
plumbylenes, have been known since 1956.3 Since
dicyclopentadienyllead(II) compounds are stabilized by
η5-coordination of cyclopentadienyl ligands, they are not
the congeners of carbenes.
A few plumbylenes bearing only carbon substituents
have also been reported. Some of them, however, are
stabilized by intramolecular coordination of the lone pair
of a donor group in the organic substituent, thus giving
† Present address: The Institute of Physical and Chemical Research
(RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, J apan.
‡ Present address: Institute for Fundamental Research of Organic
Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka
812-8581, J apan.
(4) (a) Harris, D. H.; Lappert, M. F. J . Chem. Soc., Chem. Commun.
1974, 895. (b) Gynane, M. J . S.; Harris, D. H.; Lappert, M. F.; Power,
P. P.; Rivie`re, P.; Rivie`re-Baudet, M. J . Chem. Soc., Dalton Trans.
1977, 2004. (c) Fjeldberg, T.; Hope, H.; Lappert, M. F.; Power, P. P.;
Thorne, A. J . J . Chem. Soc., Chem. Commun. 1983, 639.
(5) Driess, M.; J anoschek, R.; Pritzkow, H.; Rell, S.; Winkler, U.
Angew. Chem., Int. Ed. Engl. 1995, 34, 1614.
(6) (a) Klinkhammer, K. W.; Schwarz, W. Angew. Chem., Int. Ed.
Engl. 1995, 34, 1334. (b) Gehrhus, B.; Hitchcock, P. B.; Lappert, M. F.
Angew. Chem., Int. Ed. Engl. 1997, 36, 2514.
(7) (a) Eaborn, C.; Izod, K.; Hitchcock, P. B.; So¨zerli, S. E.; Smith,
J . D. J . Chem. Soc., Chem. Commun. 1995, 1829. (b) Eaborn, C.;
Hitchcock, P. B.; Smith, J . D.; So¨zerli, S. E. Organometallics 1997,
16, 5653.
(8) Klinkhammer, K. W.; Fa¨ssler, T. F.; Gru¨tzmacher, H. Angew.
Chem., Int. Ed. Engl. 1998, 37, 124.
§ Present address: Department of Chemical and Biological Sciences,
Faculty of Science, J apan Women’s University, 2-8-1 Mejirodai, Bun-
kyo-ku, Tokyo 112-8681, J apan.
(1) For reviews, see: (a) Raabe, G.; Michl, J . Chem. Rev. 1985, 85,
419. (b) Petz, W. Chem. Rev. 1986, 86, 1019. (c) Lappert, M. F.; Rowe,
R. S. Coord. Chem. Rev. 1990, 100, 267. (d) Barrau, J .; Escudie´, J .;
Satge´, J . Chem. Rev. 1990, 90, 283. (e) Neumann, W. P. Chem. Rev.
1991, 91, 311. (f) Tsumuraya, T.; Batcheller, S. A.; Masamune, S.
Angew. Chem., Int. Ed. Engl. 1991, 30, 902. (g) Driess, M.; Gru¨tzma-
cher, H. Angew. Chem., Int. Ed. Engl. 1996, 35, 828. (h) Weidenbruch,
M. Eur. J . Inorg. Chem. 1999, 373.
(2) For reviews, see: (a) Abel, E. W. Comprehensive Inorganic
Chemistry; Pergamon: Oxford, England, 1973; Vol. 2, p 105. (b) Rivie`re,
P.; Rivie`re-Baudet, M.; Satge´, J . Comprehensive Organometallic
Chemistry; Pergamon: New York, 1982; Vol. 2, p 670. (c) Harrison, P.
G. Comprehensive Organometallic Chemistry II; Pergamon: New York,
1995; Vol. 2, p 305. (d) Harrison, P. G. Comprehensive Coordination
Chemistry; Pergamon: Oxford, England, 1987; Vol. 3, p 185. (e) Parr,
J . Polyhedron 1997, 16, 551.
(9) Stu¨rmann, M.; Weidenbruch, M.; Klinkhammer, K. W.; Lissner,
F.; Marsmann, H. Organometallics 1998, 17, 4425.
(10) (a) Kano, N.; Tokitoh, N.; Okazaki, R. Organometallics 1997,
16, 4237. (b) Kano, N.; Tokitoh, N.; Okazaki, R. Phosphorus, Sulfur
Silicon Relat. Elem. 1997, 124-125, 517.
(3) Fischer, E. O.; Grubert, H. Z. Anorg. Allg. Chem. 1956, 286, 237.
(11) Balch, A. L.; Oram, D. E. Inorg. Chem. 1987, 26, 1906.
10.1021/om990188z CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/07/1999

3000 Organometallics, Vol. 18, No. 16, 1999
Kano et al.
the lead a coordination number greater than 2. For
example, an X-ray diffraction study of the first stable
diarylplumbylene Rf2Pb (2; Rf ) bis[2,4,6-tris(trifluo-
romethyl)phenyl]) showed that four CF3 fluorine atoms
All of the stable plumbylenes reported to date have
been synthesized by nucleophilic substitution of a lead-
(II) compound.4-9,11-18 Other divalent group 14 element
compounds have been prepared by various other meth-
ods from tetravalent precursors.1 It seemed desirable,
therefore, to develop new synthetic methods for plum-
bylenes other than those based on Pb(II) precursors.
Little is known about the reactivity of R2Pb-type
plumbylenes. A few reactions of Dis2Pb (3) have been
reported; it reacts with Mo(CO)6 to give the complex
Dis2PbMo(CO)5, but it gives no adducts in attempted
reactions with methyl iodide, hydrogen chloride, or
DisCl.16 Another example is the reaction of diarylplum-
bylene Rf2Pb (2) with the arenethiol RfSH, affording the
bis(arylthio)plumbylene (RfS)2Pb.12
We previously reported some kinetically stabilized
diarylplumbylenes in preliminary communications.19,20
We describe here the full details of this work: develop-
ment of new synthetic methods, spectroscopic proper-
ties, crystal structure, and reactivities of these diaryl-
and alkylarylplumbylenes. The following bulky substit-
uents were used: Tbt ) 2,4,6-tris[bis(trimethylsilyl)-
methyl]phenyl, Ttm ) 2,4,6-tris[(trimethylsilyl)methyl]-
phenyl, Tip ) 2,4,6-triisopropylphenyl, and Dis )
bis(trimethylsilyl)methyl.
were coordinated to the lead atom.12 Four-coordinate
divalent organolead compounds were also reported
recently,13-15 in which intramolecular coordination of
nitrogen atoms is responsible for their stability. Similar
interactions were also observed in the first alkylarylplum-
bylene.9
Because of such intramolecular coordination by het-
eroatoms these diorganolead compounds may not show
the intrinsic nature of plumbylenes in terms of their
physical properties and reactivities. Kinetically stabi-
lized plumbylenes bearing only organic substituents
that do not contain donor groups are scarce, and their
structures and reactivities are almost unexplored. The
first dialkylplumbylene, Dis2Pb (3; Dis ) bis(trimeth-
ylsilyl)methyl), was obtained in only 3% yield, and its
Resu lts a n d Discu ssion
Syn th esis. (a ) F r om Lea d (II) Am id e. Since our
attempted synthesis of the diarylplumbylene Mes*2Pb
(5; Mes* ) 2,4,6-tri-tert-butylphenyl) resulted in the
formation of an unexpected rearranged product,21,22 we
tried to synthesize the less hindered diarylplumbylene
Tip2Pb (6) by the sequential nucleophilic substitution
of a divalent lead compound with TipLi. Lead(II) amide
1 was selected as a starting material because of its
stability and good solubility in organic solvents together
with the low nucleophilicity of the resulting lithium
hexamethyldisilazide with respect to the plumbylene
produced. The addition of TipLi to a diethyl ether
solution of lead(II) amide 1 at -40 °C afforded the less
hindered plumbylene Tip2Pb (6), the ether solution of
which was intensely purple (Scheme 1).19,20,23
More hindered plumbylenes Tbt(R)Pb (R ) Ttm, Tip,
Dis; 7b-d ) also were prepared by essentially the same
method, addition of 1 molar equiv of TbtLi to 1 at -40
°C, followed by addition of 1 molar equiv of RLi in ether
at -30 °C.20
structure was not determined by X-ray crystallographic
analysis.16 Another dialkylplumbylene with the lead
atom in a seven-membered-ring system was synthesized
and crystallographically characterized recently.17 There
are only two examples of structurally characterized two-
coordinated diarylplumbylenes: [2,6-(mesityl)2C6H3]2-
Pb (4), which bears bulky terphenyl substituents to
provide steric stabilization,18 and R2Pb (R ) 2-tert-butyl-
4,5,6-Me3C6H).9
Plumbylene Tbt2Pb (7a ) was prepared similarly.
However, the second step required a higher reaction
(19) Shibata, K.; Tokitoh, N.; Okazaki, R. Tetrahedron Lett. 1993,
34, 1495.
(20) (a) Tokitoh, N.; Kano, N.; Shibata, K.; Okazaki, R. Phosphorus,
Sulfur, Silicon Relat. Elem. 1994, 93-94, 189. (b) Tokitoh, N.; Kano,
N.; Shibata, K.; Okazaki, R. Organometallics 1995, 14, 3121.
(21) (a) Okazaki, R.; Shibata, K.; Tokitoh, N. Tetrahedron Lett. 1991,
32, 6601. (b) Shibata, K.; Tokitoh, N.; Okazaki, R. Tetrahedron Lett.
1993, 34, 1499.
(22) Weidenbruch and Klinkhammer et al. recently reported the
synthesis and isolation of alkylarylplumbylene Mes*(R)Pb (R ) CH2C-
(CH3)2-3,5-tert-Bu2C6H3) under similar reaction conditions.9
(23) After we had finished writing this paper, Weidenbruch and co-
workers very recently reported that the reaction of TipMgBr with PbCl2
at -110 °C gave the first stable diplumbene, Tip2PbdPbTip2: Stu¨r-
mann, M.; Saak, W.; Marsmann, H.; Weidenbruch, M. Angew. Chem.,
Int. Ed. 1999, 38, 187.
(12) Brooker, S.; Buijink, J .-K.; Edelmann, F. T. Organometallics
1991, 10, 25.
(13) Drost, C.; Hitchcock, P. B.; Lappert, M. F.; Pierssens, L. J .-M.
Chem. Commun. 1997, 1141.
(14) Hitchcock, P. B.; Lappert, M. F.; Wang, Z.-X. Chem. Commun.
1997, 1113.
(15) Leung, W.-P.; Kwok, W.-H.; Weng, L.-H.; Law, L. T. C.; Zhou,
Z. Y.; Mak, T. C. J . Chem. Soc., Dalton Trans. 1997, 4301.
(16) (a) Davidson, P. J .; Lappert, M. F. J . Chem. Soc., Chem.
Commun. 1973, 317. (b) Cotton, J . D.; Davidson, P. J .; Goldberg, D.
E.; Lappert, M. F.; Thomas, K. M. J . Chem. Soc., Chem. Commun.
1974, 893. (c) Davidson, P. J .; Harris, D. H.; Lappert, M. F. J . Chem.
Soc., Dalton Trans. 1977, 2268. (d) Cotton, J . D.; Davidson, P. J .;
Lappert, M. F. J . Chem. Soc., Dalton Trans. 1977, 2275.
(17) Eaborn, C.; Ganicz, T.; Hitchcock, P. B.; Smith, J . D.; So¨zerli,
S. E. Organometallics 1997, 16, 5621.
(24) (a) Tokitoh, N.; Kishikawa, K.; Matsumoto, T.; Okazaki, R.
Chem. Lett. 1995, 827. (b) Saito, M.; Tokitoh, N.; Okazaki, R. Orga-
nometallics 1995, 14, 3620.
(18) Simons, R. S.; Pu, L.; Olmstead, M. M.; Power, P. P. Organo-
metallics 1997, 16, 1920.
(25) Kano, N.; Tokitoh, N.; Okazaki, R. Organometallics 1997, 16,
2748.

Divalent Organolead Compounds
Organometallics, Vol. 18, No. 16, 1999 3001
Sch em e 1
Sch em e 2
Sch em e 3
temperature (-10 °C). It is noteworthy that the intro-
duction of two Tbt groups on the same element was
achieved for the first time in the case of the lead
compound. We were unable to prepare analogous Tbt2M
compounds of silicon, germanium, and tin despite much
effort, very likely because the larger lead atom allows
introduction of two such large substituents. This prepa-
ration of 7a makes clear that in the synthesis of Tbt-
(R)Pb the initial addition of TbtLi should be effected
below -10 °C; otherwise, some 7a might be formed as
a second product.
Sch em e 4
These kinetically stabilized plumbylenes 6 and 7b-d
are sensitive to both air and moisture, but we succeeded
in the isolation of the pure symmetrically substituted
plumbylene 7a . It was synthesized as described above,
and the solvent was changed to hexane after evapora-
tion of ether in vacuo. Removal of insoluble materials
by passing the crude hexane solution through glass
wool, followed by repeated recrystallization from hexane
in an inert-atmosphere box, allowed the isolation of
plumbylene 7a in 40% yield as blue crystals. Plumby-
lene 7a also was synthesized from lead(II) chloride
(39%). Plumbylene 7a is stable at room temperature
under argon both in the crystalline state and in solution;
it is stable in benzene-d6 at 80 °C for 42 h without any
appreciable change but decomposes in benzene-d6 at 100
°C within 48 h, giving quantitatively TbtD and lead
metal.
Sch em e 5
(b) F r om Tetr a va len t Or ga n olea d Com p ou n d s.
Although divalent group 14 element compounds con-
taining Si, Ge, and Sn have been synthesized by various
methods from tetravalent derivatives as mentioned
earlier, no stable plumbylenes have been synthesized
from tetravalent organolead compounds.
Since we previously succeeded in generating stable
overcrowded germylenes and stannylenes by the reduc-
tive debromination of the corresponding dibromoger-
mane and dibromostannane, respectively, with lithium
naphthalenide,24 dibromoplumbanes 8 were expected to
be suitable precursors for the corresponding plumby-
lenes 7. The reaction of dibromoplumbanes 8b-d ,
prepared by the reaction of 7 with carbon tetrabromide
(see Scheme 2), with 2 equiv of lithium naphthalenide
at low temperature followed by treatment with an
excess of elemental sulfur gave tetrathiaplumbolanes
9 in moderate yields as expected. The successful forma-
tion of 9 evidently indicates the generation of the
corresponding plumbylenes 7 as intermediates in these
reactions.
plumbolane 9a , methyl iodide was added after treat-
ment of 8a with lithium naphthalenide in the dark to
verify the generation of plumbylene 7a . As will be
discussed later (Scheme 5), methyl iodide can trap 7a
to give insertion product 10a . Although 10a was ob-
tained in this experiment, the yield was very low,
probably because of the extreme instability of the 8a
intermediate in THF.25
Since the reaction of plumbylene 7a with elemental
sulfur did not provide the expected adduct, tetrathia-

3002 Organometallics, Vol. 18, No. 16, 1999
Kano et al.
Ta ble 1. Sp ectr oscop ic Da ta of P lu m bylen es
Tbt(R)P b (7)
Plumbylene 6 also reacted with diphenyl disulfide and
diphenyl diselenide to give adducts 12 and 13, respec-
tively, very likely by insertion of plumbylene 6 into the
chalcogen-chalcogen bonds. These results show that
plumbylenes have reactivities similar to those of a
carbene.
Tbt(R)Pb
colora
λ
max/nm
δ(207Pb)b
Tbt2Pb
blue
610
560
550
531
9751
8873
8888
8884
Tbt(Ttm)Pb
Tbt(Tip)Pb
Tbt(Dis)Pb
violet
purple
purple
Reactions of more hindered plumbylenes 7a -d with
methyl iodide also gave the corresponding iodoplum-
banes 10a -d .20 On the other hand, we previously
reported that the diaryldibromoplumbane was formed
instead of an insertion product in the reaction of
plumbylene 7a with an excess of carbon tetrabromide.25
When plumbylenes 7b-d were treated with an excess
of carbon tetrabromide, the corresponding diorganodi-
bromoplumbanes 8b-d were produced in low to moder-
ate yield.
a
b
In hexane. In toluene-d8.
Tetrathiaplumbolanes 9 were also expected to be
plumbylene precursors. We previously showed that
overcrowded stannylenes can be formed by exhaustive
desulfurization of the corresponding tetrathiastanno-
lanes with an excess of a tertiary phosphine.26 Thus,
when a toluene solution of tetrathiaplumbolane 9 was
reacted with 4 equiv of triphenylphosphine at 50 °C, the
resulting mixture turned violet or purple, suggesting the
formation of plumbylene 7 (Scheme 3). The formation
of 7 was confirmed by a trapping reaction with methyl
iodide, affording the corresponding iodoplumbanes 10
in low to moderate yields. The formation of 7 was also
confirmed by the extremely low field chemical shifts in
the 207Pb NMR spectra (see Table 1).
Sp ectr oscop ic P r op er ties. The characterization of
plumbylenes 7 was performed by electronic and 207Pb
NMR spectroscopy. Each of the four 7 species has its
own characteristic intense color. The colors and spec-
troscopic data of plumbylenes are summarized in Table
1. The absorption maxima of 7 are most likely attribut-
able to the n-p transition of plumbylenes. In 207Pb NMR
spectra, characteristic broad signals due to the central
lead atoms are observed as a singlet at extremely low
field, which are unambiguously attributable to the
kinetically stabilized monomeric plumbylenes. These
chemical shift values are rather close to those of other
kinetically stabilized monomeric dialkylplumbylenes(δ
10 050 and 9110).17,27 These values are much greater
than those of plumbylenes in which the lead has a
coordination number greater than 2 (δ 1981-4878)7,12-15
and diaminoplumbylene (δ 4916).27 Since diarylplum-
bylene 4 (δ 3870) bearing bulky terphenyl substituents
resonates at much higher field than 7 and other kineti-
cally stabilized plumbylenes,18 there might be some
interaction between the π electrons of the mesityl rings
and the vacant p orbital on the lead atom in 4.
The successful insertion reactions of plumbylene 6
into chalcogen-chalcogen bonds inspired us to examine
the reactivities of the plumbylenes with elemental
sulfur. The reaction of the less hindered plumbylene 6
with an excess of elemental sulfur afforded 1,2,3,4,5-
tetrathiaplumbolane 15 together with two other het-
erocycles bearing two plumbylene units, 1,3,2,4-dithi-
adiplumbetane 16 and 1,2,4,3,5-trithiadiplumbolane 17
(Scheme 4).20 Interestingly, the treatment of 7b-d with
elemental sulfur proceeded in a slightly different way,
leading to the formation of the corresponding tetrathia-
plumbolanes 9b-d as the sole Pb-containing product
in moderate yields. The most hindered plumbylene 7a
behaved in quite a different way under similar reaction
conditions, giving two polysulfides, Tbt-S6-Tbt (18; 25%)
and Tbt-S8-Tbt (19; 25%), together with TbtH (19%)
instead of the expected tetrathiaplumbolane 9a . This
difference most likely results from the steric hindrance
due to the two Tbt groups around the lead atom, which
are too large to provide the space required to form a
Pb-containing polysulfide ring. The formation mecha-
nism of polysulfides 18 and 19 is not clear at present.
It is interesting that the bulkiness of a plumbylene plays
an important role in controlling the reaction pathways.
It should be noted that tetrathiaplumbolanes 15 and
9b-d here described are the first examples of novel Pb-
containing cyclic polysulfides. They are crystalline
compounds stable in the open air and can be separated
by routine silica gel chromatography. The molecular
structures of 15 and 9c were established by X-ray
crystallographic analysis, the results of which have
already been reported.20
Rea ctivities. The successful formation of the kineti-
cally stabilized plumbylenes 6 and 7 prompted us to
examine their reactivities, because very little is known
about the reactivities of plumbylenes to date. Since
Lappert and co-workers have reported that an at-
tempted reaction of dialkylplumbylene 3 with methyl
iodide resulted in the formation of lead(II) iodide instead
of the expected insertion product,16 we first investigated
the reaction of our plumbylenes with methyl iodide.
The reaction of less hindered plumbylene 6 with
methyl iodide resulted in the formation of iodoplumbane
11 (Scheme 4) which can be interpreted in terms of the
insertion of plumbylene 6 into the carbon (CH3)-iodine
bond.19 Formation of lead(II) iodide was not observed.
X-r a y Cr ysta l Str u ctu r e of 7a . Only three examples
have been reported for the crystallographic structures
of kinetically stabilized plumbylenes,9,17,18 despite their
structural importance. The molecular structure of 7a
was established by X-ray crystallographic analysis
(Figure 1). Crystal data for 7a are summarized in Table
2. Plumbylene 7a has a V-shaped geometry with the
nearest Pb‚‚‚Pb intermolecular separation of 11.60 Å,
indicating the monomeric nature of 7a .
The structural features of 7a are fairly different from
those of the usual tetravalent organolead compounds.
The Pb-C bond length (2.327(13) Å) is notably longer
than that (2.19(3) Å) in tetrahedrally coordinated Ph4-
Pb28 as well as the sum of the covalent radii of Pb and
C (2.23 Å).29 Furthermore, the C-Pb-C angle (116.3(7)°)
(26) Saito, M.; Tokitoh, N.; Okazaki, R. Chem. Lett. 1996, 265.
(27) Wrackmeyer, B.; Horchler, K.; Zhou, H. Spectrochim. Acta 1990,
46A, 809.
(28) Busetti, V.; Mammi, M.; Signor, A.; Del Pra, A. Inorg. Chim.
Acta 1967, 1, 424.
(29) Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements;
Pergamon: Oxford, England, 1984; p 431.

Divalent Organolead Compounds
Organometallics, Vol. 18, No. 16, 1999 3003
experimental result (2.327(13) Å) of 7a . Since these
structural features may partly be due to the large steric
repulsion of two bulky Tbt groups on the lead atom, the
structure of 7a is better compared to that of dibro-
moplumbane Tbt2PbBr2 (8a ), bearing two Tbt groups
on the lead atom, as does 7a . The angle of C-Pb-C in
7a (116.3(7)°) is much smaller than that of 8a (135.8-
(3)°) despite bearing the same two Tbt ligands on the
lead atom.25 Meanwhile, the Pb-C bond length (2.327-
(13) Å) in 7a is longer than that of 8a (2.274(6) Å). Such
structural features are also observed for other stable
plumbylenes which have been structurally analyzed; the
Pb-C bond lengths of the previously reported diaryl-
and dialkylplumbylenes (2.334(12)-2.476(14) Å) are
close to that of plumbylene 7a , while the C-Pb-C bond
angle ranges from 88.2(2) to 117.1(2)°.9,12,14,15,17,18 The
degree of its widening may depend on the steric repul-
sion between the substituents on the lead atom, though
it centers around 103°. The C-Pb-C angle in plumby-
lene 7a (116.3(7)°) is one of the widest among the
reported stable plumbylenes, indicating the extremely
large steric repulsion between the two Tbt groups.
J udging from these overall results, the Pb-C bond
lengths are longer and the C-Pb-C bond angle is
smaller in divalent organolead compounds (plumby-
lenes) than in the tetravalent organolead compounds.
These structural features of plumbylenes may be at-
tributable not only to the steric congestion between the
substituents on the lead atom but also to the intrinsic
nature of a plumbylene.
Con clu sion
We have succeeded in the synthesis of several kineti-
cally stabilized plumbylenes by the nucleophilic substi-
tution of lead(II) amide with the corresponding aryl/
alkyllithium reagents. Furthermore, the debromination
of dibromoplumbanes and exhaustive desulfurization of
tetrathiaplumbolanes also gave the corresponding stable
plumbylenes. The last two procedures are new as
methods for the preparation of plumbylenes from the
tetravalent organolead compounds and are useful for
the synthesis of overcrowded plumbylenes. Plumbylene
7a exhibits a monomeric, V-shaped molecular structure,
as predicted by theoretical calculations. The reaction of
plumbylenes thus synthesized with some substrates
gave the corresponding oxidation Pb(IV) products, just
as in the cases of other divalent group 14 element
counterparts. In this study we have shown that stable
plumbylenes are good precursors for various kinds of
organolead compounds which are otherwise difficult to
obtain. These results give new insight into organolead
compounds and the properties of the heavier homo-
logues of carbenes. The next target in the future would
be the application of a plumbylene to the formation of
the novel organolead compounds such as double-bonded
compounds between lead and another element.
F igu r e 1. ORTEP drawing of Tbt2Pb (7a ) with thermal
ellipsoid plot (30% probability). Selected bond length (Å)
and angle (deg); Pb(1)-C(1) 2.327(13), C(1)-Pb(1)-C(1*)
116.3(7).
Ta ble 2. Cr ysta llogr a p h ic Da ta for 7a
empirical formula
C54H118PbSi12
1311.75
0.45 × 0.35 × 0.05
296
fw
cryst size/mm
temp/K
cryst syst
monoclinic
C2/c (No. 15)
29.74(2)
11.601(6)
22.71(1)
97.44(6)
7768(7)
4
space group
a/Å
b/Å
c/Å
â/deg
V/Å3
Z
Dcalcd/g cm-3
1.121
R
Rw
0.059
0.070
goodness of fit
1.50
is much wider than the typical value of a tetravalent
compound (109.5°).
In this connection, the results of ab initio calculation
on the structure of dimethylplumbylene by Kaupp and
Schleyer should be noted.30 The calculation indicates
reduction of C-Pb-C bond angle (97.3°) and elongation
of Pb-C bond length (2.323 Å) compared with those for
tetramethylplumbane (109.5° and 2.238 Å).31 The Pb-C
bond length calculated for Me2Pb fits well with the
Exp er im en ta l Section
All experiments were performed under an argon atmosphere
otherwise noted. 1H (500 MHz), 13C (125 MHz), 77Se (95 MHz),
and 207Pb (105 MHz) NMR spectra were recorded on a J EOL
R-500 MHz spectrometer at 27 °C. Chemical shifts were
measured with tetramethylsilane (δ 0) for 1H and 13C NMR
spectra and tetramethylplumbane (δ 0) for 207Pb NMR spectra
as external standards, respectively, and with diphenyl dis-
elenide (δ 480) for 77Se NMR spectra as internal standard.
(30) Kaupp, M.; Schleyer, P. v. R. J . Am. Chem. Soc. 1993, 115, 1061.
(31) Oyamada, T.; Iijima, T.; Kimura, M. Bull. Chem. Soc. J pn. 1971,
44, 2638.

3004 Organometallics, Vol. 18, No. 16, 1999
Kano et al.
High-resolution mass spectral data were obtained on a J EOL
SX-102 mass spectrometer. Electronic spectra were measured
on a J ASCO Ubest-50 UV/vis spectrometer. Preparative gel
permeation liquid chromatography (GPLC) with a recycling
system was performed on an LC-908 (J apan Analytical In-
dustry Co., Ltd.) equipped with J AI-gel 1H and 2H columns
(eluent CHCl3 or toluene). All melting points were determined
on a Yanaco micro melting point apparatus and are uncor-
rected. Elemental analyses were carried out at the Microana-
lytical Laboratory of the Department of Chemistry, Faculty
of Science, The University of Tokyo.
Ma t er ia ls. 1-Bromo-2,4,6-tris[bis(trimethylsilyl)methyl]-
benzene (TbtBr),32 1-bromo-2,4,6-tris[(trimethylsilyl)methyl]-
benzene (TtmBr),33 1-bromo-2,4,6-triisopropylbenzene (Tip-
Br),34 and bis[bis(trimethylsilyl)amino]lead(II) ([(Me3Si)2N]2Pb,
1)4b were prepared according to procedures reported in the
literature. Bis(trimethylsilyl)chloromethane (DisCl) was pur-
chased from Aldrich Chemical Co., Inc. Solvents and methyl
iodide were dried by standard methods and freshly distilled
prior to use. Carbon tetrabromide was purchased from Wako
Pure Chemical Industries, Ltd., and used as such.
P r ep a r a tion of a n Eth er Solu tion of Ar Li (Ar ) Tbt,
Ttm , Tip ). To an ether solution (5 mL) of ArBr (0.50 mmol)
was added t-BuLi (1.60 M pentane solution, 0.66 mL, 1.05
mmol) at -72 °C. The resulting suspension was stirred for 1
h at -72 °C and for 1 h at -40 °C. The resulting solution was
used as such in the following reactions with lead compounds.
P r ep a r a tion of a n Eth er Solu tion of DisLi. To a
refluxing ether suspension (3 mL) of lithium (31 mg, 4.5 mmol)
was added DisCl (0.33 mL, 1.5 mmol), and the reaction mixture
was refluxed for 23 h. After the reaction mixture had cooled
to room temperature, ether (5 mL) was added, and the excess
P r ep a r a tion of P lu m bylen e 7d . To an ether solution (30
mL) of 1 (797 mg, 1.51 mmol) was added at -40 °C an ether
suspension (15 mL) of TbtLi, prepared from TbtBr (984 mg,
1.56 mmol) as described above. After the resulting red-brown
suspension had been warmed to -25 °C, an ether solution (8
mL) of DisLi, prepared from DisCl (0.33 mL, 1.51 mmol), was
added to give a purple suspension. After the reaction mixture
had been warmed to room temperature, the ether suspension
of Tbt(Dis)Pb (7d ) was used in subsequent reactions.
P r ep a r a tion of Sa m p les of P lu m bylen e 7 for Elec-
tr on ic Sp ectr oscop y. Plumbylene 7, prepared from 1 (264
mg, 0.500 mmol) as described above, was evaporated in vacuo
to remove volatile components. To the residue was added 10
mL of dry, degassed hexane, and the volatile portion was again
removed in vacuo. After repetition of this procedure for solvent
exchange four times followed by exhaustive evaporation of
hexane, 10 mL of hexane was added to the residue to give a
hexane solution of plumbylene 7. A small amount of the
solution (0.25 mL) was transferred to a quartz UV cell (l ) 10
mm), and hexane was introduced into the UV cell until the
total amount of hexane became 3 mL. The electronic spectrum
was measured of this solution. Absorption maxima of plum-
bylenes 7 are summarized in Table 1.
P r ep a r a tion of 207P b NMR Sa m p les of P lu m bylen e 7.
Plumbylene 7, prepared from 1 (264 mg, 0.500 mmol) as
described above, was evaporated in vacuo to remove volatile
components. To the residue was added 5 mL of dry degassed
hexane, and the volatile portion was again removed in vacuo.
After repetition of this procedure for solvent exchange four
times followed by exhaustive evaporation of hexane, 0.7 mL
of toluene-d8 was added to the residue to give a saturated
solution of plumbylene 7. After insoluble materials were
filtered through a sintered-glass filter, the filtrate was trans-
ferred to and sealed in a 5 mm i.d. NMR tube with degassing
to give the 207Pb NMR sample of plumbylene 7. Broad signals
attributable to the plumbylenes 7 in the 207Pb NMR spectrum
are summarized in Table 1.
Syn th esis a n d Isola tion of P lu m bylen e 7a fr om 1. After
removal of the solvent from an ether suspension of plumbylene
7a , prepared from 1 (531 mg, 1.01 mmol) as described above,
hexane (50 mL) was added to the reaction mixture. After the
reaction mixture had been filtered through glass wool in the
glovebox to remove insoluble material, the filtrate was evapo-
rated under reduced pressure to give a blue solid, recrystal-
lization of which from hexane afforded bis{2,4,6-tris[bis-
(trimethylsilyl)methyl]phenyl}plumbylene (7a ; 529 mg, 40%).
7a : blue crystals (hexane); mp 165 °C dec; 1H NMR (C6D6,
500 MHz) δ 0.27 (s, 36H), 0.31 (s, 36H), 0.37 (s, 36H), 1.46 (s,
2H), 1.52 (s, 2H), 1.56 (s, 2H), 7.60 (s, 2H), 7.64 (s, 2H); 13C
NMR (C6D6, 125 MHz) δ 1.3 (q), 2.3 (q), 2.6 (q), 31.2 (d), 33.2
(d), 36.1 (d), 132.3 (d), 137.6 (d), 141.4 (s), 143.2 (s), 151.5 (s),
152.9 (s); 207Pb NMR (toluene-d8, 106 MHz) δ 8971 (br s). Anal.
Calcd for C54H118PbSi12: C, 49.44; H, 9.07. Found: C, 49.14;
H, 8.99.
lithium was filtered through
a sintered-glass filter. The
resulting solution was used as such in the following reactions
with lead compounds.
P r ep a r a tion of P lu m bylen e 6. To an ether solution (50
mL) of bis[bis(trimethylsilyl)amino]lead(II) (1; 1.32 g, 2.50
mmol) was added slowly an ether solution (25 mL) of TipLi
(5.00 mmol) prepared as described above at -40 °C. After it
had been stirred for 2 h at -40 °C, the purple reaction mixture
was warmed gradually to room temperature. The resulting
purple ether suspension of Tip2Pb (6) was used in subsequent
reactions.
P r ep a r a tion of P lu m bylen e 7a . To an ether solution (50
mL) of 1 (1.32 g, 2.50 mmol) was added slowly an ether solution
(25 mL) of TbtLi (2.50 mmol) prepared as described above at
-40 °C. After the resulting red-brown reaction mixture had
been stirred for 2 h at -30 °C, an ether solution (25 mL) of
TbtLi (2.50 mmol), prepared as described above, was added
slowly to the reaction mixture at -10 °C. After further stirring
for 1 h at -10 °C, the blue reaction mixture was warmed
gradually to room temperature. The resulting blue ether
suspension of Tbt2Pb (7a ) was used in subsequent reactions.
P r ep a r a tion of P lu m bylen es 7b a n d 7c. To an ether
solution (10 mL) of 1 (264 mg, 0.500 mmol) was added at -40
°C an ether suspension (5 mL) of TbtLi, prepared from TbtBr
(316 mg, 0.500 mmol) as described above. After the resulting
red-brown suspension had been warmed to -25 °C, an ether
suspension (5 mL) of TtmLi (prepared from TtmBr (208 mg,
0.500 mmol)) or TipLi (prepared from TipBr (128 mL, 0.500
mmol)) was added to give a violet suspension of Tbt(Ttm)Pb
(7b) or Tbt(Tip)Pb (7c), respectively. After the reaction mixture
had been warmed to room temperature, the ether suspension
of Tbt(Ttm)Pb (7b) or Tbt(Tip)Pb (7c) was used in subsequent
reactions.
Syn th esis a n d Isola tion of P lu m bylen e 7a fr om Lea d -
(II) Ch lor id e. To an ether suspension (40 mL) of lead(II)
dichloride (556 mg, 2.00 mmol) was added slowly an ether
solution (40 mL) of TbtLi (4.00 mmol) prepared as described
above, at 0 °C. After the resulting reaction mixture had been
stirred for 1 h at 0 °C, the blue reaction mixture was warmed
to room temperature. After removal of the solvent from the
ether suspension of plumbylene 7a , hexane was added to the
reaction mixture. The reaction mixture was filtered through
glass wool in the glovebox to remove insoluble material, and
the filtrate was evaporated under reduced pressure to give a
blue solid, recrystallization of which from hexane afforded blue
crystals of plumbylene 7a (1.02 g, 39%), having NMR spectra
identical with those previously described.
(32) (a) Auner, A.; Klingebiel, U. In Synthetic Methods of Organo-
metallic and Inorganic Chemistry; Herrmann, W. A., Ed.; Georg
Thieme Verlag: Stuttgart, Germany, 1996; Vol. 2, p 260. (b) Okazaki,
R.; Unno, M.; Inamoto, N. Chem. Lett. 1987, 2293.
(33) Kano, N.; Tokitoh, N.; Okazaki, R. Unpublished results.
(34) Whitesides, G. M.; Eisenhut, M.; Bunting, W. M. J . Am. Chem.
Soc. 1974, 96, 5406.
X-r a y Da ta Collection for P lu m bylen e 7a . A dark blue
platelike crystal of 7a having dimensions 0.45 × 0.35 × 0.05
mm was mounted in a glass capillary. The data set was

Divalent Organolead Compounds
Organometallics, Vol. 18, No. 16, 1999 3005
collected on a Rigaku AFC5R diffractometer with graphite-
monochromated Mo KR radiation (λ ) 0.710 69 Å) at 296 K
and a rotating-anode generator. The structure was solved by
direct methods with SHELXS-86.35 The intensities were cor-
rected for Lorentz and polarization effects. The non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were
included but not refined. The final cycle of full-matrix least-
squares refinement was based on 2384 observed reflections (I
> 3.00σ(I)) and 303 variable parameters and converged (largest
parameter shift was 0.05 times its esd) at R (Rw) ) 0.059
(0.070) with GOF ) 1.50. The crystal data are summarized in
Table 2.
Rea ction of P lu m bylen e 6 w ith Meth yl Iod id e. After
an ether solution (30 mL) of plumbylene 6, prepared from 1
(264 mg, 0.500 mmol) as described above, was treated with
0.12 mL (2.0 mmol) of methyl iodide at -30 °C, the reaction
mixture was warmed to room temperature. After the reaction
mixture had been filtered through Celite, the filtrate was
evaporated to leave an oil. Purification of the crude oil by
preparative GPLC (eluent toluene) afforded iodomethyl{bis-
(2,4,6-triisopropylphenyl)}plumbane (11; 2.7 mg, 9%) as a pale
yellow oil, which could not be completely purified because of
the instability of the plumbane. 11: 1H NMR (CDCl3, 500
GPLC (eluent CHCl3) followed by silica gel chromatography
(hexane/CH2Cl2 5:1) gave three lead-containing cyclic sulfides,
5,5-bis(2,4,6-triisopropylphenyl)-1,2,3,4,5-tetrathiaplum-
bolane (15; 74.4 mg, 20%), 2,2,4,4-tetrakis(2,4,6-triisopropyl-
phenyl)-1,3,2,4-dithiadiplumbetane (16; 42.0 mg, 13%), and
2,2,5,5-tetrakis(2,4,6-triisopropylphenyl)-1,3,4,2,5-trithiad-
iplumbolane (17; 46.3 mg, 14%). 15: orange yellow crystals
1
(CH2Cl2/ethanol); mp 151-153 °C dec; H NMR (CDCl3, 500
3
3
MHz) δ 1.16 (d, J HH ) 6.7 Hz, 24H), 1.20 (d, J HH ) 6.9 Hz,
3
3
12H), 2.83 (sept, J HH ) 6.9 Hz, 2H), 3.13 (sept, J HH ) 6.7
4
Hz, 4H), 7.12 (s, J PbH ) 58.0 Hz, 4H); 13C NMR (CDCl3, 125
3
MHz) δ 23.9 (q), 24.8 (q), 34.2 (d), 38.6 (d, J PbC ) 73.1 Hz),
123.7 (d, 3J PbC ) 89.9 Hz), 150.9 (s), 152.9 (s, 2J PbC ) 92.4 Hz),
164.6 (s, J PbC ) 351.8 Hz); 207Pb NMR (CDCl3, 105 MHz) δ
1
288.6 (s); HRMS (FAB) found m/z 742.2318, calcd for C30H46
-
PbS4 ([M]+) 742.2249. Anal. Calcd for C30H46PbS4: C, 48.55;
H, 6.25; S, 17.28. Found: C, 48.54; H, 6.14; S, 17.63. 16: yellow
crystals (CH2Cl2/ethanol); mp 226-228 °C dec; 1H NMR
(CDCl3, 500 MHz) δ 1.04 (d, 3J HH ) 6.7 Hz, 48H), 1.18 (d, 3J HH
) 6.9 Hz, 24H), 2.80 (sept, 3J HH ) 6.9 Hz, 4H), 3.50 (sept, 3J HH
) 6.7 Hz, 8H), 6.99 (s, 4J PbH ) 57.9 Hz, 8H); 13C NMR (CDCl3,
3
125 MHz) δ 24.0 (q), 24.8 (q), 34.2 (d), 35.9 (d, J PbC ) 83.9
Hz), 123.1 (d, 3J PbC ) 94.6 Hz), 149.8 (s, 4J PbC ) 21.1 Hz), 153.8
2
1
(s, J PbC ) 92.6 Hz), 161.5 (s, J PbC ) 569.2 Hz); 207Pb NMR
(CDCl3, 105 MHz) δ 81.6 (s); HRMS (FAB) found m/z 1089.4369,
calcd for C45H69Pb2S2 [M - Tip]+ 1089.4374. Anal. Calcd for
3
3
MHz) δ 1.10 (d, 12H, J HH ) 6.7 Hz), 1.11 (d, 12H, J HH ) 6.7
3
2
Hz), 1.19 (d, 12H, J HH ) 6.9 Hz), 2.18 (s, 3H, J PbH ) 59.7
3
4
Hz), 2.82 (sept, 4H, J HH ) 6.7 Hz), 7.03 (s, 4H, J PbH ) 48.6
Hz); 13C NMR (CDCl3, 125 MHz) δ 24.0 (q), 24.5 (q), 24.6 (q),
C
60H92Pb2S2: C, 55.78; H, 7.18; S, 4.96. Found: C, 55.49; H,
3
3
7.01; S, 5.34. 17: orange crystals (CH2Cl2/ethanol); mp 193-
24.9 (q), 34.2 (d), 37.4 (d, J PbC ) 75.3 Hz), 122.9 (d, J PbC
)
1
3
80.5 Hz), 150.1 (s, 4J PbC ) 17.7 Hz), 153.3 (s, 2J PbC ) 80.8 Hz),
194 °C(dec); H NMR (CDCl3, 500 MHz) δ 0.99 (d, J HH ) 6.6
Hz, 24H), 1.03 (d, 3J HH ) 6.6 Hz, 24H), 1.16 (d, 3J HH ) 6.9 Hz,
155.5 (s, J PbC ) 487.0 Hz); 207Pb NMR (CDCl3, 105 MHz) δ
1
3
3
24H), 2.78 (sept, J HH ) 6.9 Hz, 4H), 3.30 (sept, J HH ) 6.6
-234 (s); HRMS (FAB) found m/z 629.3617, calcd for C31H49
-
Hz, 8H), 7.01 (s, J PbH ) 54.9 Hz, 8H); 13C NMR (CDCl3, 125
4
Pb ([M - I]+) 629.3601.
3
MHz) δ 23.9 (q), 24.7 (q), 24.9 (q), 34.2 (d), 37.5 (d, J PbC
)
Rea ction of P lu m bylen e 6 w ith Dip h en yl Disu lfid e.
Similarly, the reaction of plumbylene 6, prepared from 1 (264
mg, 0.500 mmol), with diphenyl disulfide (437 mg, 2.00 mmol)
at -40 °C in ether (30 mL) gave bis(phenylthio)bis{(2,4,6-
triisopropylphenyl)}plumbane (12; 138 mg, 33%) as a yellow
71.3 Hz), 123.3 (d, 3J PbC ) 91.6 Hz), 149.8 (s, 4J PbC ) 20.9 Hz),
153.4 (s, J PbC ) 92.8 Hz), 164.9 (s, J PbC ) 449.8 Hz); 207Pb
NMR (CDCl3, 105 MHz) δ 130.0 (s); HRMS (FAB) found m/z
1121.4084, calcd for C45H69Pb2S3 ([M - Tip]+) 1121.4094. Anal.
Calcd for C60H92Pb2S3: C, 54.43; H, 7.00; S, 7.27. Found: C,
54.15; H, 6.83; S, 7.22.
2
1
1
oil. 12: yellow viscous oil; H NMR (CDCl3, 500 MHz) δ 0.97
3
3
(d, 24H, J HH ) 6.7 Hz), 1.19 (d, 12H, J HH ) 7.0 Hz), 2.80
3
3
Rea ction of P lu m bylen e 7a w ith Meth yl Iod id e. Simi-
larly, the reaction of plumbylene 7a , prepared from 1 (152 mg,
0.288 mmol), with methyl iodide (0.18 mL, 2.9 mmol) at room
temperature in THF (4 mL) gave bis{2,4,6-tris[bis(trimethyl-
silyl)methyl]phenyl}iodomethylplumbane (10a; 115.0 mg, 27%).
10a : pale yellow crystals (hexane/ethanol); mp 161.0-165.0
°C dec; 1H NMR (C6D6, 500 MHz) δ 0.24 (s, 27H), 0.26 (s, 36H),
0.38 (s, 18H), 0.44 (s, 18H), 0.50 (s, 9H), 1.28 (s, 2H), 2.46 (s,
3J PbH ) 35.2 Hz, 3H), 4.15 (br s, 4H), 6.63 (s, 1H), 6.74 (s, 1H),
6.83 (s, 1H), 6.92 (s, 1H); 13C NMR (CDCl3, 125 MHz) δ 0.6
(q), 1.1 (q), 1.2 (q), 1.5 (q), 2.7 (q), 3.2 (q), 29.6 (d), 30.0 (d),
(sept, 4H, J HH ) 6.7 Hz), 2.81 (sept, 2H, J HH ) 6.7 Hz), 6.98
(s, 4H, J PbH ) 57.7 Hz), 7.03 (m, 6H), 7.33 (m, 4H); 13C NMR
4
(CDCl3, 125 MHz) δ 24.0 (q), 24.4 (q), 34.1 (d), 37.6 (d, 3J PbC
)
70.3 Hz), 123.2 (d, 3J PbC ) 96.1 Hz), 126.7 (d), 127.9 (d), 135.6
(s, 2J PbC ) 35.8 Hz), 135.9 (d), 150.4 (s, 4J PbC ) 21.4 Hz), 153.4
(s, J PbC ) 91.3 Hz), 161.2 (s, J PbC ) 502.5 Hz); 207Pb NMR
(CDCl3, 105 MHz) δ 69 (s); HRMS (FAB) found m/z 723.3538,
calcd for C36H51PbS ([M - Tip]+) 723.3478.
2
1
Rea ction of P lu m bylen e 6 w ith Dip h en yl Diselen id e.
Similarly, the reaction of plumbylene 6, prepared from 1 (132
mg, 0.250 mmol), with diphenyl diselenide (312 mg, 1.00 mmol)
at -78 °C in ether (30 mL) gave bis(phenylseleno)bis{(2,4,6-
triisopropylphenyl)}plumbane (13; 69 mg, 30%) as an orange
oil. 13: orange oil; 1H NMR (CDCl3, 500 MHz) δ 0.95 (d, 24H,
1
30.2 (d), 32.3 (q, J PbC ) 103.5 Hz), 124.2 (d), 125.3 (d), 129.7
(d), 130.3 (d), 142.0 (s), 142.6 (s), 143.1 (s), 143.6 (s), 148.1 (s),
149.9 (s), 150.4 (s), 151.6 (s); 207Pb NMR (CDCl3, 105 MHz) δ
-191 (s); HRMS (FAB) found: m/z 1325.6420, calcd for
3
3J HH ) 6.8 Hz), 1.19 (d, 12H, J HH ) 6.8 Hz), 2.82 (sept, 6H,
C
55H121208PbSi12 ([M - I]+) 1325.6466. Anal. Calcd for C55H121
-
4
3J HH ) 6.8 Hz), 6.94 (s, 4H, J PbH ) 56.8 Hz), 7.01 (dd, 4H,
4
3
4
3J HH ) 7 Hz, J HH ) 7 Hz), 7.07 (tt, 2H, J HH ) 7 Hz, J HH
)
IPbSi12: C, 45.44; H, 8.39. Found: C, 45.57; H, 8.40.
1 Hz), 7.40 (dd, 4H, J HH ) 7 Hz, J HH ) 1 Hz); 13C NMR
(CDCl3, 125 MHz) δ 24.0 (q), 24.4 (q), 34.4 (d), 37.8 (d, 3J PbC
70.3 Hz), 123.0 (d, 3J PbC ) 86.2 Hz), 127.1 (d), 128.1 (d), 128.7
3
4
Rea ction of P lu m bylen e 7b w ith Meth yl Iod id e. Simi-
larly, the reaction of plumbylene 7b, prepared from 1 (90 mg,
0.17 mmol), with methyl iodide (0.31 mL, 5.0 mmol) at room
temperature in ether gave {2,4,6-tris[bis(trimethylsilyl)meth-
yl]phenyl}iodomethyl[2,4,6-tris(trimethylsilylmethyl)phenyl]-
plumbane (10b ; 28.6 mg, 14%). 10b : yellow crystals (CH2-
Cl2/ethanol); mp 187.0-192.0 °C dec; 1H NMR (CDCl3, 500
MHz) δ -0.02 (br s, 18H), 0.01 (s, 9H), 0.02 (s, 9H), 0.03 (br s,
18H), 0.04 (s, 9H), 0.11 (s, 18H), 1.28 (s, 1H), 1.94 (s, 2H), 2.00
)
4
2
(s), 137.3 (d), 150.1 (s, J PbC ) 19.8 Hz), 153.3 (s, J PbC ) 84.8
Hz), 159.0 (s, 1J PbC ) 430.6 Hz); 77Se NMR (CDCl3, 95 MHz) δ
303 (s, J PbSe ) 1367 Hz);36 207Pb NMR (CDCl3, 105 MHz) δ
1
-261 (s, 1J SePb ) 1367 Hz); HRMS (FAB) found m/z 771.2933,
calcd for C36H51PbSe ([M - Tip]+) 771.2922.
Rea ction of P lu m bylen e 6 w ith Elem en ta l Su lfu r . After
an ether solution (30 mL) of plumbylene 6, prepared from 1
(264 mg, 0.500 mmol), was treated with elemental sulfur (390
mg, 1.52 mmol as S8) at -40 °C, the reaction mixture was
warmed to room temperature. After the reaction mixture had
been filtered through Celite, the filtrate was evaporaed to leave
a brown solid. Purification of the crude solid by preparative
(35) Sheldrick, G. M. SHELXS-86, Program for Crystal Structure
Determination; University of Go¨ttingen, Go¨ttingen, Germany, 1986.
(36) Compound 13 was reported in our previous preliminary com-
munication,19 but its 77Se (δ 931.4) and 207Pb NMR (δ -268.6) chemical
1
shifts were erroneous. The correct values are δ 303 (s, J PbSe ) 1367
1
Hz) and δ -261 (s, J PbSe ) 1367 Hz), respectively.

3006 Organometallics, Vol. 18, No. 16, 1999
Kano et al.
2
(s, 1H), 2.12 (s, J PbH ) 47.7 Hz, 3H), 2.13 (br s, 2H), 2.18 (s,
2H), 6.52 (s, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.7 (q), 0.9
(q), 28.0 (d), 31.0 (d), 122.1 (d), 126.9 (d), 128.2 (s), 146.0 (s),
4
1H), 2.55 (br s, 2H), 6.39 (s, 1H), 6.50 (s, 1H), 6.64 (s, J PbH
)
51.8 Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ -1.4 (q), -0.5 (q),
0.7 (q), 0.8 (q), 1.1 (q), 1.2 (q), 1.4 (q), 26.7 (t), 26.8 (t), 29.4 (q,
1J PbC ) 206.2 Hz), 30.2 (d), 30.7 (d), 31.2 (d), 123.0 (d), 126.5
(d), 127.9 (d), 139.9 (s), 141.2 (s), 144.0 (s), 150.3 (s), 150.8 (s),
154.6 (s), 156.5 (s); 207Pb NMR (CDCl3, 105 MHz) δ -176 (s);
HRMS (FAB) found m/z 1235.4235, calcd for C46H96I208PbSi9
([M - H]+) 1235.4247. Anal. Calcd for C46H97IPbSi9: C, 44.66;
H, 7.90. Found: C, 45.20; H, 8.12.
Rea ction of 7c w ith Meth yl Iod id e. Similarly, the
reaction of plumbylene 7c, prepared from 1 (106 mg, 0.200
mmol), with methyl iodide (0.25 mL, 4.0 mmol) at room
temperature in ether gave {2,4,6-tris[bis(trimethylsilyl)methyl]-
phenyl}iodomethyl(2,4,6-triisopropylphenyl)plumbane (10c;
194.1 mg, 43%). 10c: pale yellow solid (hexane); mp 193.0-
195.0 °C dec; 1H NMR (CDCl3, 500 MHz) δ -0.07 (s, 9H), -0.01
150.4 (s); HRMS (FAB) found m/z 583.2911. Calcd for C27H59
-
SSi6 ([Tbt + S]+) 583.2953. Anal. Calcd for C54H118S8Si12: C,
47.65; H, 8.74; S, 18.84. Found: C, 47.82; H, 8.63; S, 18.71.
Rea ction of 7b w ith Elem en ta l Su lfu r . To an ether
suspension of 7b, prepared from 1 (1.32 g, 2.50 mmol), was
added elemental sulfur (1.92 g, 7.51 mmol as S8) in portions
at room temperature. Immediately the reaction mixture turned
yellow. After it had been stirred for 10 min, the reaction
mixture was filtered through Celite. The filtrate was concen-
trated under reduced pressure to afford a brown solid, which
was purified by preparative GPLC (eluent CHCl3) followed by
silica gel chromatography to give 5-{2,4,6-tris[bis(trimethyl-
silyl)methyl]phenyl}-5-[2,4,6-tris(trimethylsilylmethyl)phenyl]-
1,2,3,4,5-tetrathiaplumbolane (9b; 1.58 g, 52%). 9b: orange
crystals (CH2Cl2/ethanol); mp 180.0-183.0 °C dec; 1H NMR
(CDCl3, 500 MHz) δ -0.02 (s, 18H), 0.00 (br s, 27H), 0.02 (s,
18H), 0.03 (s, 18H), 1.31 (s, 1H), 1.57 (s, 1H), 1.61 (s, 1H), 1.93
(s, 9H), 0.03 (s, 18H), 0.06 (s, 9H), 0.11 (s, 9H), 1.20 (d, 3J HH
)
3
6.7 Hz, 6H), 1.24 (d, J HH ) 6.1 Hz, 6H), 1.29 (s, 1H), 1.34 (d,
2
3J HH ) 6.1 Hz, 6H), 1.97 (s, 1H), 2.21 (s, 1H), 2.26 (s, J PbH
)
4
(s, 2H), 2.47 (br s, 4H), 6.50 (s, J PbH ) 65.0 Hz, 1H), 6.58 (s,
3
3
50.2 Hz, 3H), 2.84 (sept, J HH ) 6.7 Hz, 1H), 3.05 (sept, J HH
4
4J PbH ) 65.0 Hz, 1H), 6.71 (s, J PbH ) 60.0 Hz, 2H); 13C NMR
4
) 6.1 Hz, 2H), 6.36 (s, 1H), 6.52 (s, 1H), 7.09 (s, J PbH ) 49.5
(CDCl3, 125 MHz) δ -1.5 (q), -0.6 (q), 0.7 (q), 1.0 (q), 1.3 (q),
Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.7 (q), 0.9 (q), 1.1 (q),
1.3 (q), 1.4 (q), 1.6 (q), 23.96 (q), 24.01 (q), 26.2 (q), 29.7 (q,
1J PbC ) 234.2 Hz), 30.1 (d), 31.1 (d), 31.6 (d), 34.2 (d), 37.6 (d),
123.2 (d), 123.5 (d), 128.2 (d), 143.8 (s), 149.4 (s), 149.9 (s),
150.3 (s), 153.3 (s), 158.2 (s); 207Pb NMR (CDCl3, 105 MHz) δ
5
5
26.8 (t, J PbC ) 14.3 Hz), 30.5 (d, J PbC ) 12.7 Hz), 31.7 (d,
3J PbC ) 55.0 Hz), 32.2 (t, J PbC ) 62.5 Hz), 123.5 (d, J PbC
)
3
3
90.8 Hz), 126.7 (d, 3J PbC ) 89.0 Hz), 128.6 (d, 3J PbC ) 88.8 Hz),
4
2
141.8 (s, J PbC ) 20.6 Hz), 144.4 (s, J PbC ) 95.0 Hz), 145.2 (s,
4J PbC ) 20.8 Hz), 150.0 (s, J PbC ) 107.2 Hz), 150.2 (s, J PbC
)
2
2
-195 (s); HRMS (FAB) found m/z 1104.4098, calcd for C43H85I208
-
1
1
108.0 Hz), 164.7 (s, J PbC ) 384.9 Hz), 167.7 (s, J PbC ) 371.6
PbSi6 ([M]+) 1104.4078. Anal. Calcd for C43H85IPbSi6: C, 46.75;
H, 7.75. Found: C, 46.86; H, 7.98.
Hz); 207Pb NMR (CDCl3, 105 MHz) δ 312 (s); HRMS (FAB)
found m/z 1222.3862, calcd for
C
45H94208PbS4Si9 ([M]+)
Rea ction of 7d w ith Meth yl Iod id e. Similarly, the
reaction of plumbylene 7d , prepared from 1 (114 mg, 0.216
mmol), with methyl iodide (0.13 mL, 2.1 mmol) at room
temperature in hexane gave {2,4,6-tris[bis(trimethylsilyl)meth-
yl]phenyl}[bis(trimethylsilyl)methyl]iodomethylplumbane (10d;
45.5 mg, 20%). 10d : pale yellow crystals (CH2Cl2/ethanol); mp
1222.3928. Anal. Calcd for C45H94PbS4Si9: C, 44.18; H, 7.85;
S, 10.19. Found: C, 44.43; H, 7.97; S, 10.02.
Rea ction of 7c w ith Elem en ta l Su lfu r . A similar reaction
of 7c, prepared from 1 (1.39 g, 5.0 mmol), with elemental sulfur
(3.85 g, 15.0 mmol as S8) gave 5-{2,4,6-tris[bis(trimethylsilyl)-
methyl]phenyl}-5-(2,4,6-triisopropylphenyl)-1,2,3,4,5-tetrathia-
plumbolane (9c; 3.69 g, 68%). 9c: orange crystals (CH2Cl2/
ethanol); mp 189.0-192.0 °C dec; 1H NMR (CDCl3, 500 MHz)
δ 0.01 (s, 18H), 0.02 (s, 18H), 0.03 (s, 18H), 1.19 (d, 3J HH ) 6.9
1
165.0-170.0 dec; H NMR (CDCl3, 500 MHz) δ 0.04 (s, 9H),
0.05 (s, 9H), 0.11 (s, 9H), 0.13 (s, 27H), 0.17 (s, 9H), 0.33 (s,
9H), 1.31 (s, 1H), 1.46 (s, 1H), 1.78 (s, 1H), 2.01 (s, 1H), 2.02
2
(s, J PbH ) 44.0 Hz, 3H), 6.39 (s, 1H), 6.51 (s, 1H); 13C NMR
3
Hz, 6H), 1.23 (d, J HH ) 6.5 Hz, 12H), 1.32 (s, 1H), 1.66 (s,
(CDCl3, 125 MHz) δ 0.8 (q), 0.9 (q), 1.4 (q), 1.7 (q), 1.8 (q), 3.7
(q), 4.3 (q), 27.0 (q), 28.4 (q), 30.4 (d), 31.2 (d), 31.5 (d), 123.1
(d), 127.9 (d), 144.6 (s), 150.1 (s), 150.5 (s), 153.8 (s); 207Pb NMR
(CDCl3, 105 MHz) δ -10 (s); HRMS (FAB) found m/z 1059.3254,
calcd for C35H80I208PbSi8 ([M - H]+) 1059.3225. Anal. Calcd
for C35H81IPbSi8: C, 39.63; H, 7.70; I, 11.96. Found: C, 39.09;
H, 7.29; I, 11.94.
4J PbH ) 13.1 Hz, 1H), 1.71 (s, 4J PbH ) 14.7 Hz, 1H), 2.83 (sept,
3
3J HH ) 6.9 Hz, 1H), 3.28 (sept, J HH ) 6.5 Hz, 2H), 6.48 (s,
4
4J PbH ) 65.6 Hz, 1H), 6.59 (s, J PbH ) 64.8 Hz, 1H), 7.16 (s,
4J PbH ) 55.6 Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ 0.8 (q),
1.3 (q), 1.6 (q), 24.0 (q), 25.9 (q), 30.5 (d), 32.1 (d), 32.7 (d),
3
3
34.3 (d), 39.5 (d, J PbC ) 70.6 Hz), 124.1 (d, J PbC ) 89.7 Hz),
128.8 (d, 3J PbC ) 87.8 Hz), 145.2 (s, 4J PbC ) 20.7 Hz), 149.6 (s),
149.8 (s), 150.7 (s, 4J PbC ) 19.5 Hz), 152.4 (s, 2J PbC ) 89.7 Hz),
Rea ction of 7a w ith Elem en ta l Su lfu r . To an ether
solution of 7a , prepared from 1 (264 mg, 0.500 mmol), was
added elemental sulfur (640 mg, 2.50 mmol as S8) in portions
at room temperature. Immediately the reaction mixture turned
brown. After it had been stirred for 30 min, the reaction
mixture was filtered through Celite, and the filtrate was
concentrated under reduced pressure to afford a yellow solid,
which was purified by preparative GPLC (eluent CHCl3) to
give TbtH (103.3 mg, 19%) and a 1:1 mixture of bis{2,4,6-tris-
[bis(trimethylsilyl)methyl]phenyl} hexasulfide (18) and bis-
{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl} octasulfide (19)
(115.9 mg, 50%). Further separation by preparative GPLC and
successive repeated recrystallization gave small amounts of
18 and 19, respectively, as pure crystalline compounds. 18:
pale yellow crystals (CHCl3/ethanol); mp 265.0-268.5 °C dec;
1H NMR (CDCl3, 500 MHz) δ 0.05 (s, 36H), 0.07 (s, 72H), 1.37
1
1
165.2 (s, J PbC ) 368.6 Hz), 167.6 (s, J PbC ) 307.6 Hz); 207Pb
NMR (CDCl3, 105 MHz) δ 314 (s); HRMS (FAB) found m/z
1091.3604, calcd for C42H83208PbS4Si6 ([M + H]+) 1091.3760.
Anal. Calcd for C42H82PbS4Si6: C, 46.23; H, 7.57; S, 11.76.
Found: C, 46.25; H, 7.70; S, 12.14.
Rea ction of 7d w ith Elem en ta l Su lfu r . A similar reaction
of 7d , prepared from 1 (2.61 g, 4.94 mmol), with elemental
sulfur (3.79 g, 14.8 mmol as S8) gave 5-{2,4,6-tris[bis(trimeth-
ylsilyl)methyl]phenyl}-5-[bis(trimethylsilyl)methyl]-1,2,3,4,5-
tetrathiaplumbolane (9d ; 869.0 mg, 17%). 9d : yellow-orange
crystals (CH2Cl2/ethanol); mp 176.0-179.0 °C dec; 1H NMR
(CDCl3, 500 MHz) δ 0.02 (s, 18H), 0.11 (s, 36H), 0.22 (s, 18H),
1.34 (s, 1H), 1.65 (s, 1H), 1.73 (s, 1H), 1.87 (s, 2J PbH ) 67.9 Hz,
1H), 6.50 (s, 1H), 6.61 (s, 1H); 13C NMR (CDCl3, 125 MHz) δ
0.8 (q), 1.3 (q), 1.4 (q), 1.6 (q), 4.4 (q), 30.6 (d), 32.1 (d), 32.4
(d), 47.6 (d, 1J PbC ) 170.5 Hz), 123.9 (d, 3J PbC) 88.5 Hz), 129.0
(s, 2H), 2.99 (s, 2H), 3.10 (s, 2H), 6.41 (s, 2H), 6.54 (s, 2H); 13
C
NMR (CDCl3, 125 MHz) δ 0.7 (q), 0.9 (q), 28.0 (d), 31.0 (d),
122.0 (d), 126.8 (d), 129.0 (s), 145.8 (s), 150.2 (s); HRMS (FAB)
found m/z 583.2990, calcd for C27H59SSi6 ([Tbt + S]+) 583.2953.
3
4
(d, J PbC) 85.8 Hz), 145.3 (s, J PbC ) 20.7 Hz), 149.3 (s), 149.8
(s), 165.4 (s, J PbC ) 297.5 Hz); 207Pb NMR (CDCl3, 105 MHz)
1
δ 499 (s); HRMS (FAB) found m/z 1046.2899, calcd for
Anal. Calcd for C54H118S6Si12
: C, 50.01; H, 9.17; S, 14.83.
C
34H78208PbS4Si8 ([M]+) 1046.2907. Anal. Calcd for C34H78PbS4-
Found: C, 49.95; H, 8.65; S, 14.78. 19: yellow crystals (CHCl3/
ethanol); mp 270.0-271.5 °C; 1H NMR (CDCl3, 500 MHz) δ
0.04 (s, 108H), 1.35 (s, 2H), 2.86 (s, 2H), 2.99 (s, 2H), 6.38 (s,
Si8: C, 39.00; H, 7.51; S, 12.25. Found: C, 38.84; H, 7.21; S,
12.00.

Divalent Organolead Compounds
Organometallics, Vol. 18, No. 16, 1999 3007
Syn th esis of Dibr om op lu m ba n e 8b. To an ether suspen-
sion (60 mL) of plumbylene 7b (1.00 mmol), prepared from 1
(528 mg, 1.00 mmol), was added carbon tetrabromide (994 mg,
3.00 mmol) at 0 °C. After the reaction mixture had been stirred
for 5 min, insoluble materials were filtered through Celite.
After removal of the volatile substances under reduced pres-
sure, the residue was subjected to preparative GPLC (eluent
toluene) to yield {2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-
[2,4,6-tris(trimethylsilylmethyl)phenyl]dibromoplumbane (8b;
570.5 mg, 45%). 8b: yellow crystals (hexane); mp 212.0-218.0
°C dec; 1H NMR (CDCl3, 500 MHz) δ 0.02 (s, 27H), 0.04 (s,
18H), 0.07 (s, 18H), 0.12 (s, 18H), 1.33 (s, 1H), 1.97 (s, 2H),
2.13 (s, 1H), 2.35 (s, 1H), 2.56 (br s, 4H), 6.43 (br s, 1H), 6.55
mmol as S8) was added. The reaction mixture was stirred for
10 min at -72 °C and for 10 min at room temperature. After
the reaction mixture had been filtered through Celite, the
filtrate was concentrated under reduced pressure to afford a
pale yellow solid, which was purified by preparative GPLC
(eluent CHCl3) to give tetrathiaplumbolane 9b (47.7 mg, 65%)
and TbtH (3.1 mg, 9%).
Rea ction of Dibr om op lu m ba n e 8c with Lith iu m Na p h -
th a len id e. To a solution of dibromoplumbane 8c (66.4 mg,
0.0590 mmol) in THF (3 mL) was added lithium naphthalenide
(0.65 M in THF, 0.19 mL, 0.12 mmol) at -72 °C. The same
procedure as above, using 46.0 mg (0.180 mmol as S8) of
elemental sulfur, gave a pale yellow solid, which was purified
by preparative GPLC (eluent CHCl3) to give tetrathiaplum-
bolane 9c (41.2 mg, 64%) and TbtH (7.4 mg, 23%).
4
(br s, 1H), 6.66 (s, J PbH ) 84 Hz, 2H); 13C NMR (CDCl3, 125
MHz) δ -1.5 (q), -0.9 (q), 0.7 (q), 0.9 (q), 1.2 (q), 26.9 (t), 29.3
(t), 30.3 (d), 30.66 (d), 30.70 (d), 124.0 (d), 127.7 (d), 128.5 (d),
142.9 (s), 144.9 (s), 146.3 (s), 149.2 (s), 149.9 (s), 163.4 (s), 163.5
(s); 207Pb NMR (CDCl3, 105 MHz) δ -137 (s); HRMS (FAB)
found m/z 1254.3414, calcd for C45H94Br2PbSi9 ([M]+) 1254.3349.
Anal. Calcd for C45H94Br2PbSi9: C, 43.07; H, 7.55. Found: C,
43.18; H, 7.27.
Reaction of Dibr om oplu m ban e 8d with Lith iu m Naph -
th a len id e. To a solution of dibromoplumbane 8d (25.2 mg,
0.0234 mmol) in THF (1 mL) was added lithium naphthalenide
(0.29 M in THF, 0.16 mL, 0.046 mmol) at -72 °C, and the
mixture was stirred at -72 °C for 2 h. To this mixture was
added elemental sulfur (18.2 mg, 0.0709 mmol as S8) at -72
°C, and the reaction mixture was stirred for 4 h, during which
time it was warmed to room temperature. Workup as above
gave tetrathiaplumbolane 9d (9.7 mg, 40%) and TbtH (4.8 mg,
37%).
Syn th esis of Dibr om op lu m ba n e 8c. Similarly, the reac-
tion of plumbylene 7c, prepared from 1 (264 mg, 0.500 mmol),
with carbon tetrabromide (332 mg, 1.00 mmol) at -30 °C in
ether (20 mL) gave {2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}-
(2,4,6-triisopropylphenyl)dibromoplumbane (8c; 78.9 mg, 14%).
8c: yellow crystals (hexane); mp 181.0-186.0 °C dec; 1H NMR
Exh a u stive Desu lfu r iza tion of Tetr a th ia p lu m bola n e
9b w ith Tr ip h en ylp h osp h in e. A toluene solution (2 mL) of
tetrathiaplumbolane 9b (93.1 mg, 0.0761 mmol) and tri-
phenylphosphine (79.9 mg, 0.305 mmol) was sealed in a glass
tube after five freeze-pump-thaw cycles. After the solution
had been heated at 50 °C for 21 h, the sealed tube was opened
in the glovebox filled with argon. The purple reaction solution
was transferred to another flask, and methyl iodide (0.46 mL,
7.4 mmol) was added at room temperature. The reaction
mixture was filtered through Celite, and the filtrate was
concentrated under reduced pressure to afford a pale yellow
solid, which was purified by preparative GPLC (eluent CHCl3)
to give iodoplumbane 10b (36.4 mg, 39%).
3
(CDCl3, 500 MHz) δ 0.06 (s, 36H), 0.16 (s, 18H), 1.22 (d, J HH
3
) 6.6 Hz, 6H), 1.36 (d, J HH ) 6.3 Hz, 12H), 2.21 (s, 1H), 2.42
3
3
(s, 1H), 2.87 (sept, J HH ) 6.6 Hz, 1H), 3.37 (sept, J HH ) 6.3
4
Hz, 2H), 6.42 (s, 1H), 6.57 (s, 1H), 7.17 (s, 2H, J PbH ) 81.5
Hz); 13C NMR (CDCl3, 125 MHz) δ 0.8 (q), 1.0 (q), 1.2 (q), 23.9
(q), 25.8 (q), 30.6 (d), 31.1 (d), 31.3 (d), 34.2 (d), 36.7 (d), 124.3
(d), 124.8 (d), 129.0 (d), 146.1 (s), 148.6 (s), 148.9 (s), 151.7 (s),
152.4 (s), 163.7 (s), 164.9 (s); 207Pb NMR (CDCl3, 105 MHz) δ
-143 (s); HRMS (FAB) found m/z 1041.3942, calcd for C42H82
-
81BrPbSi6 ([M - Br]+) 1041.3940. Anal. Calcd for C42H82Br2-
PbSi6: C, 44.94; H, 7.36. Found: C, 44.72; H, 7.08.
Syn th esis of Dibr om op lu m ba n e 8d . Similarly, the reac-
tion of plumbylene 7d , prepared from 1 (228 mg, 0.432 mmol),
with carbon tetrabromide (425 mg, 1.28 mmol) at room
temperature in hexane (10 mL) gave {2,4,6-tris[bis(trimethyl-
silyl)methyl]phenyl}[bis(trimethylsilyl)methyl]dibromoplum-
bane (8d ; 40.6 mg, 9%). 8d : pale yellow crystals (hexane); mp
176.5-179.0 °C dec; 1H NMR (CDCl3, 500 MHz) δ 0.05 (s, 18H),
0.14 (s, 18H), 0.16 (s, 18H), 0.37 (s, 18H), 1.35 (s, 1H), 2.12 (s,
1H), 2.17 (s, 1H), 2.40 (s, 1H), 6.43 (s, 1H), 6.57 (s, 1H); 13C
NMR (CDCl3, 125 MHz) δ 0.8 (q), 1.2 (q), 1.4 (q), 3.6 (q), 30.62
(d), 30.64 (d), 30.7 (d), 52.7 (d), 124.4 (d), 128.9 (d), 146.5 (s),
148.9 (s), 149.5 (s), 163.7 (s); 207Pb NMR (CDCl3, 105 MHz) δ
Exh a u stive Desu lfu r iza tion of Tetr a th ia p lu m bola n e
9c w ith Tr ip h en ylp h osp h in e. A toluene solution (3.6 mL)
of tetrathiaplumbolane 9c (109 mg, 0.100 mmol) and tri-
phenylphosphine (106 mg, 0.403 mmol) sealed in a glass tube
was heated at 50 °C for 6.5 h. The resulting purple reaction
solution was treated with methyl iodide (0.60 mL, 9.0 mmol)
at room temperature and then was filtered through Celite. The
filtrate was concentrated under reduced pressure to afford a
pale yellow solid, which was purified by preparative GPLC
(eluent CHCl3) to give iodoplumbane 10c (36.9 mg, 33%).
Exh a u stive Desu lfu r iza tion of Tetr a th ia p lu m bola n e
9d w ith Tr ip h en ylp h osp h in e. A similar procedure using
tetrathiaplumbolane 9d (57.5 mg, 0.0549 mmol), triphenylphos-
phine (57.9 mg, 0.221 mmol), and methyl iodide (0.13 mL, 2.1
mmol) gave a pale yellow solid, which was purified by
preparative GPLC (eluent CHCl3) to give iodoplumbane 10d
(5.9 mg, 10%).
82 (s); HRMS (FAB) found m/z 1077.2069, calcd for C34H77
-
79Br81BrPbSi8 ([M]+) 1077.2292. Anal. Calcd for C34H78Br2-
PbSi8: C, 37.86; H, 7.29. Found: C, 38.65; H, 7.42.
Reaction of Dibr om oplu m ban e 8a with Lith iu m Naph -
th a len id e. To a solution of dibromoplumbane 8a (73.8 mg,
0.0501 mmol) in THF (1 mL) was added lithium naphthalenide
(0.098 M in THF, 1.0 mL, 0.098 mmol) at -72 °C in the dark.
The reaction mixture was warmed to 0 °C over 2 h in the dark.
Subsequently, methyl iodide (0.31 mL, 5.0 mmol) was added
at 0 °C and the reaction mixture was stirred for 7 h, during
which time it was warmed to room temperature. Filtration
through Celite was followed by concentration of the filtrate
under reduced pressure to afford a pale yellow solid, which
was purified by preparative GPLC (eluent toluene) to give
iodoplumbane 10a (2.3 mg, 3%) and TbtH (49.7 mg, 90%).
Reaction of Dibr om oplu m ban e 8b with Lith iu m Naph -
th a len id e. To a solution of dibromoplumbane 8b (75.6 mg,
0.0602 mmol) in THF (3 mL) was added lithium naphthalenide
(0.64 M in THF, 0.19 mL, 0.12 mmol) at -72 °C. The mixture
was stirred for 2 h, and then elemental sulfur (46.5 mg, 0.181
Ack n ow led gm en t. This work was partially sup-
ported by a Grant-in Aid for Scientific Research No.
05236102 from the Ministry of Education, Science,
Sports, and Culture of J apan. We are also grateful to
Shin-etsu Chemical Co., Ltd., and Tosoh Akzo Co., Ltd.,
for the generous gift of chlorosilanes and alkyllithiums,
respectively.
Su p p or tin g In for m a tion Ava ila ble: Tables of all bond
lengths and angles, atomic coordinates, and positional and
thermal parameters for 7a . This material is available free of
charge via the Internet at http://pubs.acs.org.
OM990188Z