Palladium-catalyzed arylation of bis(4-bromo-2-methylinden-1-yl) dimethylsilane and related compounds

Article abstract of DOI:10.1007/s11172-008-0325-z

A new procedure was developed for the synthesis of a broad range of ansa-zirconocenes containing bis(2-methyl-4-arylindenyl)dimethylsilane ligands. The method is based on the palladium-catalyzed reaction of halogen-substituted bis(indenyl)dimethylsilanes with various organozinc compounds. The aryl-substituted bridging ligands thus prepared serve as the starting compounds for the synthesis of ansa-zirconocenes, which can be used as components of promising catalysts for propylene polymerization.

Full text of DOI:10.1007/s11172-008-0325-z

Russian Chemical Bulletin, International Edition, Vol. 57, No. 11, pp. 2298—2306, November, 2008
2298
Palladiumꢀcatalyzed arylation
of bis(4ꢀbromoꢀ2ꢀmethylindenꢀ1ꢀyl)dimethylsilane and related compounds
M. V. Nikulin, A. A. Tsarev, A. V. Lygin, A. N. Ryabov, I. P. Beletskaya, and A. Z. Voskoboinikov
Department of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (495) 939 4764. Eꢀmail: voskoboy@org.chem.msu.ru
A new procedure was developed for the synthesis of a broad range of ansaꢀzirconocenes
containing bis(2ꢀmethylꢀ4ꢀarylindenyl)dimethylsilane ligands. The method is based on the
palladiumꢀcatalyzed reaction of halogenꢀsubstituted bis(indenyl)dimethylsilanes with various
organozinc compounds. The arylꢀsubstituted bridging ligands thus prepared serve as the
starting compounds for the synthesis of ansaꢀzirconocenes, which can be used as components
of promising catalysts for propylene polymerization.
Key words: ansaꢀzirconocenes, crossꢀcoupling, Negishi reaction, organozinc compounds,
organosilicon compounds, bis(4ꢀbromoꢀ2ꢀmethylindenꢀ1ꢀyl)dimethylsilane.
Since the indenyl moiety in the intermediate of this reacꢀ
tion, i.e., in indenyldimethylchlorosilane, is more acidic
than the starting indene,6 the synthesis of the bridging
ligand is accompanied by transmetallation of this interꢀ
mediate with the starting lithium salt of indene as the side
reaction. This results in a decrease in the yield of the
target product and the formation of large amounts of polyꢀ
meric and oligomeric byꢀproducts. If it is necessary to
prepare a series of different zirconium ansaꢀcomplexes
of the A (or B) type according to the aboveꢀmentioned
procedure, the corresponding arylꢀsubstituted indenes
(or cyclopenta[b]thiophenes) must first be synthesized.
Earlier, we have shown that in this case, the approach
based on the palladiumꢀcatalyzed arylation of halogenꢀ
substituted indenes and related substrates is the method
of choice.7 In the next step, it is necessary to synthesize
the corresponding bridging ligands by the reaction of the
salt of indene with dimethylchlorosilane. Hence, the
synthesis of a number of ansaꢀcomplexes A (or B) inꢀ
volves a series of similar reactions, in particular, the
introduction of the dimethylsilylene bridge giving rise to
the target products in rather low yields. In this connecꢀ
tion, a more convenient approach can be suggested
based on the synthesis of a single halogenꢀsubstituted
bis(indenyl)dimethylsilane as the precursor. In the next
step, this compound can be used as the template for the
catalytic crossꢀcoupling involving various arylꢀsubstituted
organometallic derivatives. This allows the simultaneous
synthesis of a number of bridging ligands and then of the
corresponding ansaꢀmetallocenes. Therefore, the aims
of the present study were to synthesize bis(4ꢀbromoꢀ
2ꢀmethylindenꢀ1ꢀyl)dimethylsilane and related comꢀ
Recent extensive research into the relationship beꢀ
tween the structures of ansaꢀmetallocenes and the activity
and stereoselectivity of the corresponding catalysts for
propylene polymerization showed that the best results were
achieved for catalysts based on the soꢀcalled improved
ansaꢀzirconocenes A containing bis(2ꢀmethylꢀ4ꢀarylꢀ
indenyl)dimethylsilane ligands, as well as on related comꢀ
plexes B containing 3ꢀarylꢀ2,5ꢀdimethylcyclopenta[b]ꢀ
thienyl moieties.1—4
The main method for the synthesis of ansaꢀzirconoꢀ
cenes is based on the reaction of the dilithium salt of the
bisꢀindenyl ligand with zirconium tetrachloride.5 In turn,
bis(indenyl)dimethylsilanes are prepared by the reaction
of 2 equiv. of the lithium salt of the corresponding indene
with dichlorodimethylsilane. This synthesis has drawbacks.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2253—2261, November, 2008.
1066ꢀ5285/08/5711ꢀ2298 © 2008 Springer Science+Business Media, Inc.

Bis(4ꢀarylꢀ1Hꢀindenꢀ1ꢀyl)dimethylsilanes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008 2299
Scheme 1
pounds and to develop a procedure for the palladiumꢀ
catalyzed arylation of these substrates. It should be noted
that, when designing this study, the success was not
evident. This is associated with two facts. First, silyl
derivatives of indenes are not completely inert in the presꢀ
ence of palladium catalysts. These compounds containing
olefin and allylsilyl moieties are potential substrates
for the Heck6,7 and Hiyama reactions,10,11 respectively.
Second, the silicon—cyclopentadienyl bond in bis(indenyl)ꢀ
dimethylsilanes is known to be sensitive to alkalis and
particularly to acids.6 Hence, rather strict limitations were
initially placed on the conditions of catalytic arylation. In
particular, the reactions in the presence of bases in protic
solvents (for example, in water) were completely excluded.
The use of strongly basic reagents (for example, of
ArMgX), which are substrates in the Kumada reaction,
was also impractical, because these reactions can be
accompanied by metallation of the indenyl moieties and
a decrease in the yields of the target compounds.
Compound
Hal
X
1
Br
H
2
Cl
H
3
Br
Me
taining the 3ꢀbromoꢀ5ꢀmethylcyclopenta[b]thienꢀ4ꢀyl
moiety (Scheme 2). These three compounds have similar
solubilities, which makes difficult the isolation of analytiꢀ
cally pure isomer 4 by crystallization. A mixture of three
compounds was isolated in 42% yield by silica gel flash
chromatography. The content of 6,6´ꢀisomer 4 in this
mixture was 60%.
The observed difference in the regioselectivity of the
reactions involving indenyl and cyclopenta[b]thienyl deꢀ
rivatives is apparently attributed to the fact that the broꢀ
mine atom in 3ꢀbromoꢀ5ꢀmethylcyclopenta[b]thiophene
is spatially remote from the cyclopentadienyl moiety and,
consequently, this bromine atom cannot provide suffiꢀ
cient steric shielding of the nearest carbon atom in the
cyclopentadienyl ring. A radically different situation
is observed for analogous indene derivatives. In these
compounds, the halogen atom is substantially closer to
one of the carbon atoms of the cyclopentadienyl ring. It is
known that organosilyl substituents in cyclopentadiene
and its derivatives can be involved in the 1,3ꢀsigmatropic
Results and Discussion
In the first step, we synthesized halogenꢀsubstituted
bridging ligands. For this purpose, 4(7)ꢀbromoꢀ2ꢀmethylꢀ
1(3)Hꢀindene, 4(7)ꢀbromoꢀ2,5(6)ꢀdimethylꢀ1(3)Hꢀ
indene, or 4(7)ꢀchloroꢀ2ꢀmethylꢀ1(3)Hꢀindene were
metallated with nꢀbutyllithium in diethyl ether, and
then 0.5 equiv. of dimethyldichlorosilane was added
(Scheme 1). Analytically pure samples of compounds 1
and 3 were obtained in 47 and 61% yields, respectively,
by washing the organic reaction products with hexane.
Ligand 2 was isolated in 69% yield by recrystallization
from hexane.
It appeared that the analogous reaction with the lithium
salt of 3ꢀbromoꢀ5ꢀmethylꢀ4(5)Hꢀcyclopenta[b]thiophene
is not regioselective. This reaction affords the target
6,6´ꢀsubstituted bis(3ꢀbromoꢀ5ꢀmethylcyclopenta[b]ꢀ
thienꢀ6ꢀyl)dimethylsilane (4) along with isomeric
4,6´ꢀ and 4,4´ꢀsubstituted compounds 4´ and 4″ conꢀ
Scheme 2

2300
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008
Nikulin et al.
rearrangement even at room temperature.6 Therefore, the
bridging bisꢀindenyl ligands, in which the halogen atom is
adjacent to the organosilicon moiety, even if are produced,
should undergo the rearrangement to form sterically less
hindered bis(4ꢀbromoindenꢀ1ꢀyl)dimethylsilanes, and
that is the case. This conclusion is not true for comꢀ
pounds containing the 3ꢀbromoꢀ5ꢀmethylcyclopenta[b]ꢀ
thienyl moiety. In the latter case, the thermodynamic
stabilities of isomeric silylꢀsubstituted products are rather
similar, due to which the complete stereocontrol in the
synthesis of the corresponding bridging ligands cannot be
performed.
It should be noted that, according to NMR spectroꢀ
scopic data, the double bonds in the cyclopentadienyl
rings in all the ligands synthesized in the present study are
in allylic positions with respect to the bridging dimethylꢀ
silylene moiety.
Table 1. Yields of ligands 5—7 synthesized by the Negishi reaction
Run
Starting
Product
Yield (%)
compound
1
2
3
4
5
6
7
8
1
1
1
1
1
1
1
1
1
3
3
2
5a
5b
5c
5d
5e
5f
5g
5h
5i
6a
6b
5b
7a
7b
7c
97
96
94
97
98
92
95
97
98
95
95
82
97
93
88
9
10
11
12
13
14
15
4 + 4´ + 4´´
4 + 4´ + 4´´
4 + 4´ + 4´´
Bridging ligands 1—4 (ligand 4 was obtained in a mixꢀ
ture with isomers 4´ and 4´´ as impurities) were used as
the starting substrates in the crossꢀcoupling reactions cataꢀ
lyzed by palladium complexes. In our studies, the main
attention was paid to bridging ligand 1 containing the
4ꢀbromoꢀ2ꢀmethylindenꢀ1ꢀyl moieties. The investigation
of the transformations of ligand 2 is important from the
viewpoint of the development of a procedure employing
cheaper and more readily available but less reactive
chlorineꢀcontaining substrates. Ligand 3 is the sterically
hindered substrate. The choice of ligand 4 was deterꢀ
mined by the fact that ansaꢀzirconocenes B are apparꢀ
ently promising compounds, as well as by the necessity of
evaluating the applicability of the methods developed for
the crossꢀcoupling to sulfurꢀcontaining substrates, which
are by themselves or their transformation products can, in
some cases, serve as catalytic poisons for systems based
on transition metals.7,12
containing alkyl (example 5) or hetaryl (example 7) groups
and can also be used for the crossꢀcoupling with sterically
crowded substrates, for example, with bromineꢀsubstiꢀ
tuted ligand 3 (see Scheme 3, X = Me; see Table 1,
examples 10 and 11).
In the next step, we studied the reactivity of chlorineꢀ
substituted compound 2. Initially, we used the Pd(PBut3)2
complex as the catalyst for the crossꢀcoupling reactions
with the involvement of this substrate. The reaction with
phenylzinc chloride was carried out in THF at 70 °C for
5 h. The analysis of the reaction mixture showed that the
desired product was absent when the ~40% conversion of
the starting compound was achieved. This indicates that,
Scheme 3
We used the Negishi reaction with organozinc
compounds as the main method for the synthesis of
arylꢀsubstituted bridging ligands.12 The starting arylzinc
chlorides were synthesized in situ by the reaction of zinc
chloride with the corresponding Grignard reagent in THF.
The crossꢀcoupling reaction was carried out at 70 °C for
several hours. The Pd(PBut3)2 complex, whose high
activity was demonstrated in the study13 and was conꢀ
firmed in our studies performed with halogenꢀsubstituted
indenes,7 was used as the catalyst. The experimental reꢀ
sults are presented in Table 1. In the case of bromineꢀ
substituted substrate 1, the crossꢀcoupling products were
obtained in nearly quantitative yields (Scheme 3, X = H),
which is indicative of the applicability of this method to
the synthesis of a broad range of arylꢀsubstituted bridging
ligands, including ligands containing sterically crowded
(see Table 1, example 3), electronꢀwithdrawing (examples
4 and 8), or electronꢀdonating (examples 6 and 9) aryl
groups at position 4 of the indenyl moiety. In addition, this
method allows the synthesis of the corresponding products
X = H (1, 5), Me (3, 6); R = Ph (5a, 6a), 4ꢀMeC6H4 (5b),
2,4,6ꢀMe3C6H2 (5c), 3ꢀF3CC6H4 (5d), Me (5e), 4ꢀMe2NC6H4 (5f),
1ꢀbenzothienꢀ2ꢀyl (5g), 2ꢀF3CC6H4 (5h), 4ꢀButC6H4 (5i),
3,5ꢀ(F3C)2C6H3 (6b).
Reagents and conditions: RZnCl, Pd(PBut3)2, THF, 70 °C.

Bis(4ꢀarylꢀ1Hꢀindenꢀ1ꢀyl)dimethylsilanes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008 2301
Scheme 6
under the conditions used, either the slow decomposition
of the starting substrate occurs or the crossꢀcoupling proꢀ
ceeds only at one of the chlorine atoms of the starting
substrate. Hence, we developed an alternative procedure14
for the Negishi reaction with the involvement of aryl chloꢀ
rides. Thus, we used the Pd(dba)2—2ꢀ(diꢀtertꢀbutylphosꢀ
phino)biphenyl system as the catalyst. It appeared that
the reaction of substrate 2 with pꢀtolylzinc chloride in the
presence of this catalyst in THF at 70 °C for 15 h afforded
double crossꢀcoupling product 5b in 82% yield (Scheme 4,
see Table 1, run 12). Therefore, the reactions in the presꢀ
ence of this catalyst for crossꢀcoupling can be performed
with cheaper chlorineꢀcontaining substrates, due to which
the target ansaꢀmetallocenes also become more readily
available.
Compound
Ar
X
5e, 8a
CF3C6H4
H
5f, 8b
4ꢀMe2NC6H4
H
6a, 9
Ph
Me
Reagents and conditions: 1) BunLi; 2) ZrCl4•2 THF.
Scheme 4
mers 4 + 4´ + 4″ afforded individual compounds 7a—c
rather than mixtures of the corresponding isomeric arylꢀ
substituted products. This is attributed to the fact that
organosilicon derivatives of cyclopentadienes and related
compounds readily undergo the 1,3ꢀsigmatropic rearꢀ
rangement,6 as well as to the lower thermodynamic stabilꢀ
ity of isomers, in which the bulky aryl moiety is in the
immediate vicinity of the SiMe2 bridge. As a result, the
arylation products of the isomeric bridging ligands conꢀ
taining the 3ꢀarylꢀ5ꢀmethylcyclopenta[b]thienyl moieties
with the silyl substituent at position 4 are rearranged into
sterically less hindered products containing the silyl subꢀ
stituent at position 6. Due to the observed isomerization
of the products in the course of crossꢀcoupling, the laborꢀ
consuming isolation of isomers with similar properties is
not required and a series of interesting compounds for the
subsequent synthesis of ansaꢀmetallocenes can be rather
easily prepared.
Reagents and conditions: PhZnCl, Pd(dba)2, 2ꢀPhC6H4PBut2
THF, 70 °C.
,
Runs 13—15 (see Table 1) show that the approach
under consideration can be used to synthesize related
cyclopenta[b]thiophene derivatives (Scheme 5).
When studying this reaction, we obtained unexpected
results. Thus, the reaction starting from a mixture of isoꢀ
Arylꢀsubstituted bridging ligands 5e, 5f, 6a, 7a, and 7c
were used to synthesize ansaꢀzirconocenes 8a, 8b, 9, 10a,
and 10b, respectively (Schemes 6 and 7).
Scheme 5
Ar = Ph (7a), 4ꢀButC6H4 (7b), 1ꢀnaphthyl (7c).
Reagents and conditions: RZnCl, Pd(PBut3)2, THF, 70 °C.

2302
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008
Nikulin et al.
Scheme 7
Pd(PBut
)
(Aldrich), and other reagents were used without
2
3
addition purification, unless otherwise mentioned. 4(7)ꢀBromoꢀ
2ꢀmethylꢀ1(3)Hꢀindene, 4(7)ꢀbromoꢀ2,5(6)ꢀdimethylꢀ1(3)Hꢀ
indene, and 4(7)ꢀchloroꢀ2ꢀmethylꢀ1(3)Hꢀindene were syntheꢀ
sized according to known procedures.7 5ꢀMethylꢀ4,5ꢀdihydroꢀ
6Hꢀcyclopenta[b]thiophenꢀ6ꢀone was prepared from thiophene
and methacrylic acid according to a known procedure.15 3ꢀBromoꢀ
5ꢀmethylꢀ4(5)Hꢀcyclopenta[b]thiophene was synthesized by broꢀ
mination of 5ꢀmethylꢀ4,5ꢀdihydroꢀ6Hꢀcyclopenta[b]thiophenꢀ
6ꢀone followed by reduction and dehydration according to a
known procedure.5 The 1H and 13C NMR spectra were recorded
on a Bruker Avance 400 DPX spectrometer operating at 400
and 100 MHz, respectively; the chemical shifts are given with
respect to SiMe4. The elemental analysis was carried out on a
CHNꢀOꢀRapid analyzer (Heraeus).
Ar = Ph (7a, 10a), 1ꢀnaphthyl (7c, 10b).
Bis(4ꢀbromoꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl)(dimethyl)silane (1).
A 1.6 M solution of MeLi (29.9 mL, 47.8 mmol) in diethyl ether
was added to a solution of 4(7)ꢀbromoꢀ2ꢀmethylindene (10.0 g,
47.8 mmol) in diethyl ether (250 mL) at 10 °C. The reaction
mixture was stirred at room temperature for 1 h and cooled to
0 °C. Then Me2SiCl2 (2.89 mL, 3.08 g, 23.9 mmol) was added.
The reaction mixture was stirred at room temperature for 2 h.
Then water (100 mL) was added, the organic layer was separated
and dried over K2CO3, and the solvent was distilled off on a
rotary evaporator. After evaporation, the residue was washed
with hexane (3Ѕ30 mL) and dried in vacuo. The white solid
compound was obtained as an equimolar mixture of the rac
and meso isomers in a yield of 5.37 g (47%). Calculated (%):
C, 55.71; H, 4.68. C22H22Br2Si. Found (%): C, 56.02; H, 4.77.
1H NMR (CDCl3), δ: 7.36 and 7.34 (both d, 2 H each, 5,5´ꢀH in
meso and rac isomers, J = 8.5 Hz); 7.32 and 7.23 (both d, 2 H
each, 7,7´ꢀH in meso and rac isomers, J = 7.6 Hz); 6.95 and 6.93
(both t, 2 H each, 6,6´ꢀH in meso and rac isomers, J = 8.1 Hz);
6.70 (br.s, 4 H, 3,3´ꢀH in racꢀ and meso isomers); 3.74 and 3.73
(both s, 2 H each, CHSiCH in meso and rac isomers); 2.23
and 2.17 (both d, 6 H each, 2,2´ꢀMe in meso and rac isomers,
J = 1.2 Hz); –0.19 (s, 3 H, SiMe in meso isomer); –0.24 (s, 6 H,
SiMe2 in rac isomer); –0.27 (s, 3 H, SiMe´ in meso isomer).
13C{1H} NMR (CDCl3), δ: 148.4, 148.3, 145.9, 145.1, 145.0, 128.4,
126.5, 124.2, 124.1, 121.8, 114.1, 48.6, 48.5, 17.9, –5.4, –5.6.
Bis(4ꢀchloroꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl)(dimethyl)silane (2).
A 1.6 M solution of MeLi (23.4 mL, 37.4 mmol) in diethyl ether
was added to a solution of 4(7)ꢀchloroꢀ2ꢀmethylindene (6.15 g,
37.4 mmol) in diethyl ether (200 mL) at 0 °C. The reaction
mixture was stirred at room temperature for 2 h and cooled to
0 °C. Then Me2SiCl2 (2.26 mL, 2.41 g, 18.7 mmol) was added.
The reaction mixture was stirred at room temperature for 2 h.
Then water (100 mL) was added, the organic layer was separated
and dried over K2CO3, and the solvent was distilled off on a
rotary evaporator. After evaporation, the residue was recrystalꢀ
lized from hexane (30 mL). The precipitate was filtered off,
washed with hexane (2×10 mL), and dried in vacuo. The white
solid compound was obtained as an equimolar mixture of the
rac and meso isomers in a yield of 4.97 g (69%). Calculated (%):
C, 68.56; H, 5.75. C22H22Cl2Si. Found (%): C, 68.70; H, 5.88.
1H NMR (CDCl3), δ: 7.18 and 7.15 (both m, 2 H each, 5,5´ꢀH
in meso and rac isomers); 7.09 and 7.07 (both d, 2 H each, 7,7´ꢀH
in meso and rac isomers, J = 7.9 Hz); 6.90 and 6.88 (both m, 2 H
each, 6,6´ꢀH in meso and rac isomers); 6.63 (m, 4 H, 3,3´ꢀH in
racꢀ and meso isomers); 3.59 and 3.58 (both m, 2 H each,
CHSiCH in meso and rac isomers); 2.11 and 2.06 (both d, 6 H
Reagents and conditions: 1) BunLi; 2) ZrCl4•2 THF.
The complexes were synthesized according to the conꢀ
ventional procedure,7 which involves the metallation of
the starting ligand with nꢀbutyllithium in diethyl ether
followed by the reaction of the dilithium salt of the ligand
with zirconium tetrachloride tetrahydrofuranate. Analytiꢀ
cally pure racemic complexes 8a, 8b, 9, and 10a were
isolated in 22, 23, 29, and 25% yields, respectively, by
crystallization of the reaction products, i.e., mixtures of
the rac and meso complexes, from dichloromethane. The
rac isomer of complex 10b was obtained by recrystallizaꢀ
tion of the reaction product from toluene.
To summarize, we developed a new approach to the
synthesis of arylꢀsubstituted bis(indenyl)dimethylsilanes
and related compounds based on the palladiumꢀcatalyzed
Negishi arylation of the corresponding halogenꢀsubstiꢀ
tuted substrates. In spite of the fact that the starting haloꢀ
genꢀsubstituted bridging ligands containing cyclopenta[b]ꢀ
thienyl moieties are mixtures of regioisomers as to the
position of the bridging fragments with respect to
the halogen atoms, the products of the Negishi reaction
are rearranged to give the only isomer required for the
synthesis of ansaꢀmetallocenes. The new approach allows
the preparation of a library of arylꢀsubstituted ligands startꢀ
ing from a single parent compound. The arylꢀsubstiꢀ
tuted ligands can be used for the synthesis of arylꢀsubꢀ
stituted ansaꢀmetallocenes serving as components of
promising catalysts for propylene polymerization.
Experimental
All experiments with the use of atmospheric oxygenꢀ and
moistureꢀsensitive compounds were carried out under argon
using the standard Schlenk techniques or in a glove box under
a nitrogenꢀcontrolled atmosphere. The solvents were purified
according to standard procedures. Tetrahydrofuran and diethyl
ether were stored over potassium hydroxide and then distilled
over sodium metal in the presence of benzophenone. Toluene
and nꢀhexane were stored and then distilled over sodium metal.
Dichloromethane was distilled over P4O10. nꢀButyllithium
(Aldrich), ZnCl2 (Acros), 2ꢀbromotoluene (Acros), ZrCl4•2 THF,

Bis(4ꢀarylꢀ1Hꢀindenꢀ1ꢀyl)dimethylsilanes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008 2303
each, 2,2´ꢀMe in meso and rac isomers, J = 1.0 Hz); –0.33 (s,
3 H, SiMe in meso isomer); –0.38 (s, 6 H, SiMe2 in rac isomer);
–0.40 (s, 3 H, SiMe´ in meso isomer). 13C{1H} NMR (CDCl3),
δ: 148.31, 148.24, 146.1, 143.15, 143.05, 128.0, 126.3, 125.3, 124.6,
123.88, 123.82, 121.3, 48.3, 48.2, 17.9, –5.52, –5.59, –5.8.
Bis(4ꢀbromoꢀ2,5ꢀdimethylꢀ1Hꢀindenꢀ1ꢀyl)(dimethyl)silane
(3). A 2.5 M solution of nꢀBuLi (17.9 mL, 44.8 mmol) in hexane
was added to a solution of 4(7)ꢀbromoꢀ2,5(6)ꢀdimethylindene
(10.0 g, 44.8 mmol) in diethyl ether (400 mL) at 10 °C. The
reaction mixture was stirred at room temperature for 12 h and
cooled to 0 °C. Then Me2SiCl2 (2.72 mL, 2.89 g, 22.4 mmol)
was added. The reaction mixture was stirred at room temperaꢀ
ture for 24 h. Then water (50 mL) was added, the organic layer
was separated and dried over Na2CO4, and the solvent was disꢀ
tilled off on a rotary evaporator. After evaporation, the residue
was washed with hexane (3×30 mL) and dried in vacuo. The
white solid compound was obtained as an equimolar mixture of
the rac and meso isomers in a yield of 7.02 g (61%). Calculated
(%): C, 57.38; H, 5.22. C24H26Br2Si. Found (%): C, 57.55; H,
isolated by silica gel flash chromatography (40—63 μm, d 30 mm,
l 100 mm, hexane as the eluent).
Bis(2ꢀmethylꢀ4ꢀphenylꢀ1Hꢀindenꢀ1ꢀyl)(dimethyl)silane (5a).
Compound 5a was synthesized according to the general proceꢀ
dure by the Negishi reaction starting from aryl bromide 1 and
phenylmagnesium bromide. The white solid compound was
obtained as an equimolar mixture of the rac and meso isomers in
a yield of 4.54 g (97%). Calculated (%): C, 87.13; H, 6.88.
C34H32Si. Found (%): C, 87.30; H, 6.93. 1H NMR (CDCl3), δ:
7.60—7.16 (m, 18 H, 5,5´,6,6´,7,7´ꢀH in indenyl and Ph in rac
and meso isomers); 6.84 (m, 2 H, 3,3´ꢀH in indenyl of rac or
meso isomer); 6.82 (m, 2 H, 3,3´ꢀH in indenyl of meso or rac
isomer); 3.83 (s, 4 H, 1,1´ꢀH in indenyl of rac and meso isoꢀ
mers); 2.27 (d, 6 H, 2,2´ꢀMe in rac or meso isomer, J = 0.9 Hz);
2.19 (d, 6 H, 2,2´ꢀMe in meso or rac isomer, J = 0.9 Hz); –0.150
(s, 3 H, SiMe in meso isomer); –0.152 (s, 6 H, SiMe2 in rac
isomer); –0.17 (s, 3 H, SiMe´ in meso isomer). 13C{1H} NMR
(CDCl3), δ: 147.7, 147.6, 145.52, 145.48, 143.0, 142.9, 141.40,
141.36, 134.2, 128.9, 128.4, 126.7, 126.05, 126.00, 125.60,
125.58, 123.11, 123.05, 122.19, 122.14, 47.7, 47.6, 18.0, 17.9,
–5.57, –5.60.
Bis[4ꢀ(4ꢀmethylphenyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5b). A. Compound 5b was synthesized accordꢀ
ing to the general procedure by the Negishi reaction starting
from aryl bromide 1 and pꢀtolylmagnesium bromide. The white
solid compound was obtained as an equimolar mixture of the
rac and meso isomers in a yield of 4.76 g (96%). Calculated (%):
C, 87.04; H, 7.30. C36H36Si. Found (%): C, 87.22; H, 7.39.
1H NMR (CDCl3), δ: 7.45—7.51 (m, 6 H, 7,7´ꢀH in indenyl
rac isomer and 3,3´,5,5´ꢀH in pꢀtolyl of rac and meso isomers);
7.38 (m, 2 H, 7,7´ꢀH in indenyl of meso isomer); 7.27—7.32 (m,
12 H, 5,5´ꢀH in indenyl and 2,2´,6,6´ꢀH in pꢀtolyl of rac and
meso isomers); 7.16—7.22 (m, 4 H, 6,6´ꢀH in indenyl of rac and
meso isomers); 6.84 (m, 2 H, 3,3´ꢀH in indenyl of meso isomer);
6.82 (m, 2 H, 3,3´ꢀH in indenyl of rac isomer); 3.82 (s, 4 H,
1,1´ꢀH in indenyl of rac and meso isomers); 2.46 (s, 6 H, 4,4´ꢀMe
in pꢀtolyl of rac isomer); 2.45 (s, 6 H, 4,4´ꢀMe in pꢀtolyl of meso
isomer); 2.27 (d, 6 H, 2,2´ꢀMe in indenyl of meso isomer, J = 0.9 Hz);
2.19 (d, 6 H, 2,2´ꢀMe in indenyl of rac isomer, J = 0.9 Hz);
–0.15 (s, 9 H, SiMe2 in rac isomer and SiMe in meso isomer);
–0.17 (s, 3 H, SiMe´ in meso isomer). 13C{1H} NMR (CDCl3),
δ: 147.6, 147.4, 145.47, 145.42, 143.0, 142.9, 136.46, 136.41,
136.39, 136.35, 134.1, 129.1, 128.8, 126.1, 126.0, 125.49, 125.46,
123.1, 123.0, 122.0, 121.9, 47.6, 47.5, 21.2, 18.0, 17.9, –5.7.
B. A 1.0 M solution of pꢀtolylmagnesium bromide (10.1 mL,
10.1 mmol) in THF was added to a 0.50 M solution of ZnCl2
(22.7 mL, 11.3 mmol) in THF at room temperature. The reacꢀ
tion mixture was stirred for 1 h. Then aryl chloride 2 (1.85 g,
3.91 mmol), Pd(dba)2 (86.3 mg, 0.15 mmol), and 2ꢀdiꢀ
(tertꢀbutyl)phosphinobiphenyl (89.5 mg, 0.30 mmol) were added.
The reaction mixture was stirred at 70 °C for 15 h, cooled, and
passed through a layer of silica gel (d 30 mm, l 50 mm, THF as
the eluent). The solvent was distilled off on a rotary evaporator.
The product was isolated by silica gel flash chromatography
(40—63 μm, d 30 mm, l 100 mm, hexane as the eluent). The
white solid compound as an equimolar mixture of the rac and
meso isomers, which is identical to that prepared according to the
method A, was obtained in a yield of 1.59 g (82%). Calculated
(%): C, 87.04; H, 7.30. C36H36Si. Found (%): C, 87.14; H, 7.25.
Bis[4ꢀ(2,4,6ꢀtrimethylphenyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5c). Compound 5c was synthesized according
1
5.34. H NMR (CDCl3), δ: 7.53 (d, 2 H, 7,7´ꢀH in rac isomer,
J = 7.5 Hz); 7.41 (d, 2 H, 7,7´ꢀH in meso isomer, J = 7.5 Hz);
7.25 (d, 2 H, 6,6´ꢀH in rac isomer, J = 7.5 Hz); 7.22 (d, 2 H,
6,6´ꢀH in meso isomer, J = 7.5 Hz); 7.02 (m, 4 H, 3,3´ꢀH in
racꢀ and meso isomers); 4.02 (s, 2 H, 1,1´ꢀH in rac isomer); 3.99
(s, 2 H, 1,1´ꢀH in meso isomer); 2.74 (s, 6 H, 5,5´ꢀMe in rac
isomer); 2.72 (s, 6 H, 5,5´ꢀMe in meso isomer); 2.51 (m, 6 H,
2,2´ꢀMe in meso isomer); 2.46 (m, 6 H, 2,2´ꢀMe in rac isomer);
0.08 (s, 3 H, SiMe in meso isomer); 0.015 (s, 3 H, SiMe´ in meso
isomer); 0.006 (s, 6 H, SiMe2 in rac isomer).
Bis(3ꢀbromoꢀ5ꢀmethylꢀ6Hꢀcyclopenta[b]thienꢀ6ꢀyl)ꢀ
(dimethyl)silanes (4, 4´, and 4″). A 1.6 M solution of MeLi
(16.0 mL, 25.6 mmol) in diethyl ether was added to a solution of
3ꢀbromoꢀ5ꢀmethylcyclopenta[b]thiophene (5.50 g, 25.6 mmol)
in diethyl ether (250 mL) at –60 °C. The reaction mixture was
stirred at room temperature for 1 h and cooled. Then Me2SiCl2
(1.55 mL, 1.65 g, 12.8 mmol) was added. The reaction mixture
was stirred at room temperature for 12 h. Then water (50 mL)
was added, the organic layer was separated and dried over
K2CO3, and the solvent was distilled off on a rotary evaporator.
The product was isolated by silica gel flash chromatography
(40—63 μm, d 40 mm, l 500 mm, hexane as the eluent), which
afforded a mixture of the 6,6´ isomer (~60%) along with the
4,4´ꢀ and 4,6´ꢀisomeric compounds (~40%) in a total yield of
2.61 g (42%). The analytically pure product was isolated by
recrystallization of the reaction mixture from a hexane—diethyl
ether mixture (3 : 1, v/v). Calculated (%): C, 44.45; H, 3.73.
C18H18Br2C2Si. Found (%): C, 44.90; H, 3.87. 1H NMR
(CDCl3), δ, rac isomer: 7.11 (s, 2 H, 2,2´ꢀH); 6.52 (m, 2 H,
4,4´ꢀH); 3.84 (s, 2 H, 6,6´ꢀH); 2.25 (s, 6 H, 5,5´ꢀMe); –0.25
(s, 6 H, SiMe2); meso isomer, 7.09 (s, 2 H, 2,2´ꢀH); 6.52 (m,
2 H, 4,4´ꢀH); 3.76 (s, 2 H, 6,6´ꢀH); 2.26 (s, 6 H, 5,5´ꢀMe);
–0.21 (s, 3 H, SiMe); –0.26 (s, 3 H, SiMe´).
Negishi reaction (general procedure). A 1.0 M solution of the
Grignard reagent (26.0 mL, 26.0 mmol) in THF was added to a
0.50 M solution of ZnCl2 (58.0 mL, 29.0 mmol) in THF at room
temperature. The reaction mixture was stirred for 1 h. Then
aryl bromide (10.0 mmol) and a 0.02 M solution of Pd(PBut3)2
(20.0 mL, 0.40 mmol) in THF were added. The reaction mixꢀ
ture was stirred at 70 °C for 5 h, cooled, and passed through a
layer of silica gel (d 30 mm, l 50 mm, THF as the eluent). The
solvent was distilled off on a rotary evaporator. The product was

2304
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008
Nikulin et al.
to the general procedure by the Negishi reaction starting from
aryl bromide 1 and mesitylmagnesium bromide. The white
solid compound was obtained as an equimolar mixture of the
rac and meso isomers in a yield of 5.20 g (94%). Calculated (%):
C, 86.90; H, 8.02. C40H44Si. Found (%): C, 87.17; H, 8.10.
1H NMR (CDCl3), δ: 7.72 and 7.49 (both d, 2 H each, 7,7´ꢀH in
indenyl of meso and rac isomers, J = 7.5 Hz); 7.29 and 7.24
(both t, 2 H each, 6,6´ꢀH in indenyl of meso and rac isomers,
J = 7.5 Hz); 7.05—7.13 (m, 12 H, 6,6´ꢀH in indenyl and
3,3´,5,5´ꢀH in mesityl of rac and meso isomers); 6.31 (s, 4 H,
3,3´ꢀH in indenyl of rac and meso isomers); 4.03 (s, 2 H, 1,1´ꢀH
in indenyl of rac and meso isomers); 4.00 (s, 2 H, 1,1´ꢀH in
indenyl of meso and rac isomers); 2.45 (s, 12 H, 2,6ꢀMe
in mesityl of rac and meso isomers); 2.34 (d, 6 H, 2,2´ꢀMe in
indenyl of rac and meso isomers, J = 0.9 Hz); 2.23 (d, 6 H, 2,2´ꢀMe
in indenyl of meso and rac isomers, J = 0.9 Hz); 2.11 and 2.10
(both s, 6 H each, 4,4´ꢀH in mesityl of meso and rac isomers);
2.07 (s, 12 H, 2,6ꢀMe in mesityl of meso and rac isomers); –0.22
(s, 3 H, SiMe of meso isomer); –0.246 (s, 3 H, SiMe´ of meso
isomer), –0.252 (s, 6 H, SiMe2 of rac isomer). 13C{1H} NMR
(CDCl3), δ: 147.01, 146.97, 144.75, 144.70, 144.0, 143.9, 137.5,
136.28, 136.23, 132.9, 132.8, 127.93, 127.89, 126.0, 123.0, 122.9,
121.6, 47.63, 47.61, 21.1, 20.5, 18.0, 17.8, –6.3, –6.8.
isomer). 13C{1H} NMR (CD2Cl2), δ: 146.6, 146.5, 144.61,
144.55, 144.26, 144.20, 129.04, 129.01, 126.0 , 124.98, 124.95,
122.81, 122.74, 120.71, 120.67, 47.49, 47.42, 18.8 , 18.0 , –5.7,
–5.9, –6.1.
Bis[4ꢀ(4ꢀdimethylaminophenyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5f). Compound 5f was synthesized according
to the general procedure by the Negishi reaction starting from
aryl bromide 1 and 4ꢀdimethylaminophenylmagnesium bromide.
The white solid compound was obtained as an equimolar
mixture of the rac and meso isomers in a yield of 5.10 g (92%).
Calculated (%): C, 82.26; H, 7.63. C38H42N2Si. Found (%):
C, 82.41; H, 7.58. 1H NMR (CDCl3), δ: 7.45—7.51 (m, 6 H,
7,7´ꢀH in indenyl of rac isomer and 3,3´,5,5´ꢀH in C6H4 of
rac and meso isomers); 7.34 (d, 2 H, 7,7´ꢀH in indenyl of
meso isomer, J = 7.5 Hz); 7.29 (m, 2 H, 6,6´ꢀH in indenyl
of rac isomer); 7.26 (m, 2 H, 6,6´ꢀH in indenyl of meso isomer);
7.18 (dd, 2 H, 6,6´ꢀH in indenyl of meso isomer, J = 7.5 Hz,
J = 5.9 Hz); 7.16 (dd, 2 H, 6,6´ꢀH in indenyl of rac isomer,
J = 7.5 Hz, J = 5.9 Hz); 6.85—6.90 (m, 12 H, 3,3´ꢀH in indenyl
and 2,2´,6,6´ꢀH in C6H4 of rac and meso isomers); 3.82 (s,
4 H, 1,1´ꢀH in indenyl of rac and meso isomers); 3.04 (s, 12 H,
4,4´ꢀNMe2 of rac isomer); 3.03 (s, 12 H, 4,4´ꢀNMe2 of meso
isomer); 2.27 (d, 6 H, 2,2´ꢀMe in indenyl of meso isomer,
J = 0.9 Hz); 2.18 (d, 6 H, 2,2´ꢀMe in indenyl of rac isomer,
J = 0.9 Hz); –0.16 (s, 6 H, SiMe2 in rac isomer); –0.17 (s, 3 H,
SiMe in meso isomer); –0.19 (SiMe´ in meso isomer). 13C{1H}
NMR (CDCl3), δ: 149.5, 147.1, 146.9, 145.51, 145.46, 142.84,
142.76, 134.3, 129.8, 129.6, 126.35, 126.30, 125.18, 125.14,
123.02, 122.97, 121.38, 121.32, 112.6, 47.6, 47.5, 40.7, 17.94,
17.85, –5.67.
Bis[4ꢀ(3ꢀtrifluoromethylphenyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5d). Compound 5d was synthesized according
to the general procedure by the Negishi reaction starting from
aryl bromide 1 and 3ꢀtrifluoromethylphenylmagnesium bromide.
The white solid compound was obtained as an equimolar
mixture of the rac and meso isomers in a yield of 5.92 g (98%).
Calculated (%): C, 71.50; H, 5.00. C36H30F6Si. Found (%):
1
C, 71.69; H, 5.13. H NMR (CDCl3), δ: 7.39—7.84 (m, 24 H,
Bis[4ꢀ(1ꢀbenzothienꢀ2ꢀyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5g). A 2.5 M solution of nꢀBuLi (5.24 mL,
13.0 mmol) in hexane was added to a solution of benzothiophene
(1.74 g, 13.0 mmol) in THF (30 mL) at room temperature. The
reaction mixture was stirred for 2 h. Then a 0.50 M solution of
ZnCl2 (29.0 mL, 14.5 mmol) in THF was added. The reaction
mixture was stirred for 1 h. Then compound 1 (2.37 g, 5.0 mmol)
and a 0.02 M solution of Pd(PBut3)2 (10.0 mL, 0.20 mmol) in
THF were added. The reaction mixture was stirred at 70 °C for
5 h, cooled, and passed through a layer of silica gel (d = 30 mm,
l = 50 mm, THF as the eluent). The solvent was distilled off on a
rotary evaporator. The product was isolated by silica gel flash
chromatography (40—63 μm, d 30 mm, l 100 mm, hexane as the
eluent). The white solid compound was obtained as an equimoꢀ
lar mixture of the rac and meso isomers in a yield of 2.76 g
(95%). Calculated (%): C, 78.57; H, 5.55. C38H32C2Si. Found
(%): C, 78.70; H, 5.46. 1H NMR (CDCl3), δ: 6.96—7.82 (m,
36 H, 3,3´,5,5´,6,6´,7,7´ꢀH in indenyls and benzothienyls of
rac and meso isomers); 3.70 and 3.66 (both s, 2 H each, 1,1´ꢀH
in indenyls of meso or rac isomer); 2.22 and 2.07 (both m, 6 H
each, 2,2´ꢀMe in indenyls of meso or rac isomer); –0.11 (s, 3 H,
SiMe2 of rac isomer), –0.14 (s, 3 H, SiMe of meso isomer);
–0.18 (s, 6 H, SiMe´ of meso isomer). 13C{1H} NMR (CDCl3),
δ: 148.7, 148.5, 145.8, 143.83, 143.81, 143.0, 142.8, 140.5,
139.77, 149.76, 126.57, 126.55, 126.2, 126.1, 126.0, 125.9, 124.3,
123.9, 123.39, 123.35, 123.07, 123.04, 122.9, 122.05, 122.03,
121.5, 47.8, 47.7, 18.0, 17.8, –4.9, –5.1, –5.2.
5,5´,7,7´ꢀH in indenyl and CF3C6H4 of rac and meso isomers);
7.29 (m, 2 H, 6,6´ꢀH in indenyl of rac isomer); 7.23 (t, 2 H,
6,6´ꢀH in indenyl of meso isomer, J = 7.5 Hz); 6.76 (s, 4 H,
3,3´ꢀH in indenyl of rac and meso isomers); 3.85 (s, 2 H, 1,1´ꢀH
in indenyl of rac isomer); 3.82 (s, 2 H, 1,1´ꢀH in indenyl of meso
isomer); 2.28 (s, 12 H, 2,6ꢀMe in mesityl of meso isomer); 2.23
(d, 6 H, 2,2´ꢀMe in indenyl of rac isomer, J = 0.9 Hz); –0.11
(s, 3 H, SiMe of meso isomer); –0.15 (s, 3 H, SiMe´ of meso
isomer); –0.16 (s, 6 H, SiMe2 of rac isomer). 13C{1H} NMR
(CDCl3), δ: 148.60, 148.55, 145.7, 142.95, 142.88, 142.12,
142.10, 132.63, 132.57, 132.2, 130.9 (q, 1J(13C—19F) = 32.2 Hz),
128.8, 125.65, 125.62, 125.57, 125.53, 125.37, 125.34, 123.50,
123.47, 123.43, 122.9, 122.78, 122.75, 47.80, 47.74, 18.0, –5.33,
–5.39, –5.6.
Bis(2,4ꢀdimethylꢀ1Hꢀindenꢀ1ꢀyl)(dimethyl)silane (5e). Comꢀ
pound 5e was synthesized according to the general procedure by
the Negishi reaction starting from aryl bromide 1 and methylꢀ
magnesium chloride. The white solid compound was obtained
as an equimolar mixture of the rac and meso isomers in a yield of
3.34 g (97%). Calculated (%): C, 83.66; H, 8.19. C24H28Si.
Found (%): C, 83.70; H, 8.26. 1H NMR (CDCl3), δ: 7.32—7.38
(m, 4 H, 7,7´ꢀH in rac and meso isomers); 7.19—7.25 (m, 4 H,
5,5´ꢀH in rac and meso isomers); 6.96—7.06 (m, 4 H, 6,6´ꢀH in
rac and meso isomers); 6.71 (m, 4 H, 3,3´ꢀH in rac and meso
isomers); 3.75 (s, 2 H, 1,1´ꢀH in rac isomer); 3.72 (s, 2 H,
1,1´ꢀH in meso isomer); 2.45 (s, 6 H, 4,4´ꢀMe in rac isomer);
2.44 (s, 6 H, 4,4´ꢀMe in meso isomer); 2.26 (d, 6 H, 2,2´ꢀMe
in rac isomer, J = 1.0 Hz); 2.21 (d, 6 H, 2,2´ꢀMe in meso isomer,
J = 1.0 Hz); –0.28 (s, 3 H, SiMe in meso isomer); –0.325 (s,
6 H, SiMe2 in rac isomer); –0.334 (s, 3 H, SiMe´ in meso
Bis[4ꢀ(2ꢀtrifluoromethylphenyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5h). Compound 5h was synthesized according
to the general procedure by the Negishi reaction starting from
aryl bromide
1 and 2ꢀtrifluoromethylphenylmagnesium

Bis(4ꢀarylꢀ1Hꢀindenꢀ1ꢀyl)dimethylsilanes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008 2305
bromide. The white solid compound was obtained as an equiꢀ
molar mixture of the rac and meso isomers in a yield of 5.86 g
(97%). Calculated (%): C, 71.50; H, 5.00. C36H30F6Si. Found
(%): C, 71.66; H, 5.12. 1H NMR (CDCl3), δ: 7.21—7.94 (m,
28 H, 5,5´,6,6´,7,7´ꢀH in indenyl and 3,3´,4,4´,5,5´,6,6´ꢀH in
C6H4 of rac and meso isomers); 6.40 (m, 4 H, 3,3´ꢀH in indenyl
of rac and meso isomers); 3.92—4.07 (m, 4 H, 1,1´ꢀH in indenyl of
rac and meso isomers); 2.21—2.39 (m, 12 H, 2,2´ꢀMe in indenyl
of rac and meso isomers); –0.04—0.24 (m, 12 H, Me2Si in
indenyl of rac and meso isomers).
Bis[4ꢀ(4ꢀtertꢀbutylphenyl)ꢀ2ꢀmethylꢀ1Hꢀindenꢀ1ꢀyl]ꢀ
(dimethyl)silane (5i). Compound 5i was synthesized according
to the general procedure by the Negishi reaction starting from
aryl bromide 1 and 4ꢀtertꢀbutylphenylmagnesium bromide. The
white solid compound was obtained as a 1 : 1 mixture of the rac
and meso isomers in a yield of 5.70 g (98%). Calculated (%):
C, 86.84; H, 8.33. C42H48Si. Found (%): C, 86.90; H, 8.39.
1H NMR (CDCl3), δ: 7.52—7.57 (m, 18 H, 7,7´ꢀH in indenyl
of racꢀ and meso isomers and 2,2´,3,3´,5,5´,6,6´ꢀH in C6H4 of
racꢀ and meso isomers); 7.39—7.43 (m, 2 H, 7,7´ꢀH in indenyl
of meso and rac isomers); 7.31—7.36 (m, 4 H, 5,5´ꢀH in indenyl of
rac and meso isomers); 7.19—7.26 (m, 4 H, 6,6´ꢀH in indenyl
of rac and meso isomers); 6.92 (m, 4 H, 3,3´ꢀH in indenyl of
rac and meso isomers); 3.88 and 3.85 (both m, 2 H each, 1,1´ꢀH
in indenyl of meso and rac isomers); 2.30 and 2.24 (both m, 6 H
each, 2,2´ꢀMe in indenyl of meso and rac isomers); 1.46 and
1.45 (both s, 18 H each, But of meso and rac isomers); –0.13 (s,
3 H, MeMe´Si of meso isomer); –0.15 (s, 3 H, MeMe´Si of meso
isomer), –0.16 (s, 6 H, Me2Si of rac isomer). 13C{1H} NMR
(CDCl3), δ: 149.6, 147.5, 147.4, 145.52, 145.50, 143.00, 142.95,
138.49, 138.45, 134.09, 134.04, 128.6, 126.3, 126.2, 125.63,
125.58, 125.3, 123.14, 123.06, 122.05, 122.00, 47.7, 47.6, 34.6,
31.5, 18.03, 18.01, –5.58, –5.59, –5.8.
δ: 8.02 (m, 4 H, 4,4´ꢀH in aryl of rac and meso isomers); 7.93
and 7.89 (both m, 4 H each, 2,2´,6,6´ꢀH in aryl of meso and
rac isomers); 7.57 and 7.46 (both m, 2 H each, 7,7´ꢀH in indenyl
of meso and rac isomers); 7.20 and 7.17 (both m, 2 H each,
6,6´ꢀH in indenyl of meso and rac isomers); 6.36 (m, 4 H,
3,3´ꢀH in indenyl of racꢀ and meso isomers); 3.92 and 3.91
(both m, 2 H each, 1,1´ꢀH in indenyl of meso and rac isomers);
2.34 (m, 6 H, 2,2´ꢀMe of racꢀ and meso isomers); 2.33 and 2.32
(both s, 6 H each, 5,5´ꢀMe of meso and rac isomers); 2.28 (m,
6 H, 2,2´ꢀMe of meso and rac isomers); –0.05 (s, 3 H, SiMeMe´
of meso isomer); –0.08 (s, 3 H, SiMeMe´ of meso isomer); –0.09
(s, 6 H, SiMe2 of rac isomer).
Bis(5ꢀmethylꢀ3ꢀphenylꢀ6Hꢀcyclopenta[b]thienꢀ6ꢀyl)ꢀ
(dimethyl)silane (7a). Compound 7a was synthesized according
to the general procedure by the Negishi reaction starting from
aryl bromide 4 and phenylmagnesium bromide. The white solid
compound was obtained as an equimolar mixture of the rac and
meso isomers in a yield of 4.61 g (96%). Calculated (%): C,
74.95; H, 5.87. C30H28S2Si. Found (%): C, 75.20; H, 5.99. 1H
NMR (CDCl3), δ, racꢀ7a: 7.63—7.67 (m, 4 H, 2,2´,6,6´ꢀH in
C6H4); 7.39—7.46 (m, 4 H, 3,3´,5,5´ꢀH in C6H4), 7.30—7.34
(m, 2 H, 4,4´ꢀH in C6H4); 7.29 (d, 2 H, 5ꢀH in cycloꢀ
penta[b]thienyl, J = 0.6); 6.80 (m, 2 H, 3,3´ꢀH in cyclopenta[b]ꢀ
thienyl); 3.94 (m, 2 H, 1,1´ꢀH in cyclopenta[b]thienyl); 2.19 (d,
6 H, 2,2´ꢀMe in cyclopenta[b]thienyl, J = 1.4 Hz); –0.23 (s,
6 H, SiMe2); mesoꢀ7a: 7.62—7.66 (m, 4 H, 2,2´,6,6´ꢀH in C6H4);
7.39—7.46 (m, 4 H, 3,3´,5,5´ꢀH in C6H4); 7.30—7.34 (m, 2 H,
4,4´ꢀH in C6H4); 7.26 (d, 2 H, 5ꢀH in cyclopenta[b]thienyl,
J = 0.6); 6.81 (m, 2 H, 3,3´ꢀH in cyclopenta[b]thienyl); 3.83
(m, 2 H, 1,1´ꢀH in cyclopenta[b]thienyl); 2.32 (d, 6 H, 2,2´ꢀMe
in cyclopenta[b]thienyl, J = 1.4 Hz); –0.20 (s, 3 H, SiMe),
–0.21 (s, 3 H, SiMe´).
Bis[3ꢀ(4ꢀtertꢀbutylphenyl)ꢀ5ꢀmethylꢀ6Hꢀcyclopenta[b]thienꢀ
6ꢀyl](dimethyl)silane (7b). Compound 7b was synthesized
according to the general procedure by the Negishi reaction startꢀ
ing from aryl bromide 4 and 4ꢀtertꢀbutylphenylmagnesium bromide.
The white solid compound was obtained as a mixture of the rac
and meso isomers in a ratio of ~1 : 3. in a yield of 5.52 g (93%).
Calculated (%): C, 76.97; H, 7.48. C38H44S2Si. Found (%):
C, 77.21; H, 7.56. 1H NMR (CDCl3), δ, racꢀ7b: 7.57—7.61 (m,
4 H, 3,3´,5,5´ꢀH in C6H4); 7.42—7.46 (m, 4 H, 2,2´,6,6´ꢀH
in C6H4); 7.26 (m, 2 H, 5ꢀH in cyclopenta[b]thienyl); 6.81 (m,
2 H, 3,3´ꢀH in cyclopenta[b]thienyl); 3.93 (m, 2 H, 1,1´ꢀH in
cyclopenta[b]thienyl); 2.19 (d, 6 H, 2,2´ꢀMe in cyclopenta[b]ꢀ
thienyl, J = 1.3 Hz); 1.367 (s, 18 H, But), –0.26 (s, 6 H, SiMe2);
mesoꢀ7b: 7.55—7.59 (m, 4 H, 3,3´,5,5´ꢀH in C6H4); 7.43—7.47
(m, 4 H, 2,2´,6,6´ꢀH in C6H4); 7.23 (m, 2 H, 5ꢀH in cycloꢀ
penta[b]thienyl); 6.81 (m, 2 H, 3,3´ꢀH in cyclopenta[b]thienyl);
3.82 (m, 2 H, 1,1´ꢀH in cyclopenta[b]thienyl); 2.31 (d, 6 H,
2,2´ꢀMe in cyclopenta[b]thienyl, J = 1.3 Hz); 1.363 (s, 18 H,
But), –0.23 (s, 3 H, SiMe); –0.24 (s, 3 H, SiMe´).
Bis[5ꢀmethylꢀ3ꢀ(1ꢀnaphthyl)ꢀ6Hꢀcyclopenta[b]thienꢀ6ꢀyl]ꢀ
(dimethyl)silane (7c). Compound 7c was synthesized according
to the general procedure by the Negishi reaction starting from
aryl bromide 4 and 1ꢀnaphthylmagnesium bromide. The white
solid compound was obtained as a mixture of the rac and meso
isomers in a ratio of ~1 : 2 in a yield of 5.12 g (88%). Calculated
(%): C, 78.57; H, 5.55. C38H32S2Si. Found (%): C, 78.79;
H, 5.66. 1H NMR (CDCl3), δ, racꢀ7c: 7.25—7.96 (m, 14 H,
naphthyl); 7.20 (s, 2 H, 5,5´ꢀH in cyclopenta[b]thienyl); 6.26
(s, 2 H, 3,3´ꢀH in cyclopenta[b]thienyl); 3.96 (s, 2 H, 1,1´ꢀH in
Bis(2,5ꢀdimethylꢀ4ꢀphenylꢀ1Hꢀindenꢀ1ꢀyl)(dimethyl)silane
(6a). Compound 6a was synthesized according to the general
procedure by the Negishi reaction starting from aryl bromide 3
and phenylmagnesium bromide. The white solid compound was
obtained as an equimolar mixture of the rac and meso isomers in
a yield of 4.72 g (95%). Calculated (%): C, 87.04; H, 7.30.
C36H36Si. Found (%): C, 87.91; H, 7.38. 1H NMR (CDCl3),
δ: 7.28—7.50 (m, 24 H, 7,7´ꢀH and 4,4´ꢀPh in indenyl of rac
and meso isomers); 7.07 and 7.04 (both d, 2 H each, 6,6´ꢀH in
indenyl of meso and rac isomers, J = 7.5 Hz); 6.34 (m, 4 H, 3,3´ꢀH
in racꢀ and meso isomers); 3.80 and 3.79 (both s, 2 H each,
1,1´ꢀH in indenyl of meso and rac isomers); 2.254 and 2.246
(both s, 6 H each, 5,5´ꢀMe in indenyl of meso and rac isomers);
2.21 and 2.14 (both d, 6 H each, 2,2´ꢀMe in indenyl of meso
and rac isomers, J = 0.9 Hz); –0.21 (s, 3 H, SiMe meso isomer);
–0.22 (s, 9 H, SiMe´ meso isomer and SiMe2 rac isomer).
13C{1H} NMR (CDCl3), δ: 147.17, 147.05, 144.58, 144.53,
142.27, 142.23, 140.4 , 133.89, 133.84, 132.05, 132.01, 129.9,
129.7, 128.0 , 126.6 , 126.38, 126.33, 124.88, 124.81, 122.04,
122.01, 47.32, 47.26, 20.1 , 17.89, 17.85, –5.9, –6.0, –6.1.
Bis[4ꢀ(3,5ꢀbis(trifluoromethyl)phenyl)ꢀ2,5ꢀdimethylꢀ1Hꢀ
indenꢀ1ꢀyl](dimethyl)silane (6b). Compound 6b was synthesized
according to the general procedure by the Negishi reaction startꢀ
ing from aryl bromide 3 and 3,5ꢀbis(trifluoromethyl)phenylꢀ
magnesium bromide. The white solid compound was obtained
as a mixture of the rac and meso isomers in a ratio of ~1 : 2 in a
yield of 7.30 g (95%). Calculated (%): C, 62.49; H, 4.20.
C40H32F12Si. Found (%): C, 62.55; H, 4.28. 1H NMR (CDCl3),

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Russ.Chem.Bull., Int.Ed., Vol. 57, No. 11, November, 2008
Nikulin et al.
cyclopenta[b]thienyl); 2.06 (s, 6 H, 2ꢀMe in cyclopenta[b]ꢀ
thienyl); –0.22 (s, 6 H, SiMe2); mesoꢀ7c: 7.25—7.96 (m, 14 H,
naphthyl); 7.17 (s, 2 H, 5,5´ꢀH in cyclopenta[b]thienyl); 6.26
(s, 2 H, 3,3´ꢀH in cyclopenta[b]thienyl); 3.84 (s, 2 H, 1,1´ꢀH in
cyclopenta[b]thienyl); 2.19 (s, 6 H, 2ꢀMe in cyclopenta[b]ꢀ
thienyl); –0.18 (s, 3 H, SiMe); –0.22 (s, 3 H, SiMe´).
2 H, 4,4´ꢀH Ph); 6.86 (s, 2 H, 3,3´ꢀH cyclopenta[b]thienyl);
2.32 (s, 6 H, 2,2´ꢀMe cyclopenta[b]thienyl); 1.09 (s, 6 H, SiMe2).
13C{1H} NMR (CD2Cl2), δ: 144.7, 137.7, 136.2, 135.7, 130.8,
130.4, 129.4, 128.6, 121.4, 120.4, 72.5, 20.7, 0.7.
5
racꢀ6,6´ꢀDimethylsilylenebis[η ꢀ3ꢀ(1ꢀnaphthyl)ꢀ5ꢀmethylꢀ
cyclopenta[b]thiophenꢀ6ꢀyl]zirconium dichloride (10b). Comꢀ
pound 10b was synthesized according to the general procedure
starting from ligand 7c. The red solid compound was obtained in
22% yield. Calculated (%): C, 61.59; H, 4.08. C38H30Cl2C2SiZr.
Found (%): C, 61.68; H, 4.15. 1H NMR (CD2Cl2), δ: 8.06
(d, 2 H, 4,4´ꢀH in naphthyl, J = 8.4 Hz); 7.87 (m, 2 H, 8,8´ꢀH
in naphthyl); 7.83 (d, 2 H, 2,2´ꢀH in naphthyl, J = 8.4 Hz);
7.72 (dd, 2 H, 5,5´ꢀH in naphthyl, J = 7.2 Hz, J = 0.9 Hz);
7.53 (s, 2 H, 5,5´ꢀH in cyclopenta[b]thienyl); 7.37—7.52 (m, 6
H, 3,3´,6,6´,7,7´ꢀH in naphthyl); 6.58 (s, 2 H, 3,3´ꢀH in cycloꢀ
penta[b]thienyl); 2.34 (s, 6 H, 2,2´ꢀMe in cyclopenta[b]thienyl);
1.14 (s, 6 H, SiMe2).
Synthesis of ansaꢀzirconocenes (general procedure). A 2.5 M
solution of nꢀBuLi (7.92 mL, 20.0 mmol) in hexane was added
to a solution of the ligand (10.0 mmol) in diethyl ether (220 mL)
at room temperature. The reaction mixture was stirred for 24 h
and cooled to –78 °C. Then ZrCl4(THF)2 (10.0 mmol) was
added. The reaction mixture was stirred at room temperature
for 24 h, and the solvent was distilled off to dryness. Toluene
(220 mL) was added to the residue, the reaction mixture was
stirred at 90 °C for 8 h, and the hot solution was filtered through
a G4 filter. The residue was additionally washed with hot
toluene (3Ѕ100 mL). The combined extracts were dried to
dryness. The product was isolated by crystallization of the
residue from dichloromethane (for all zirconocenes, except for
10b) or toluene (for 10b).
References
5
racꢀ1,1´ꢀDimethylsilylenebis[η ꢀ2ꢀmethylꢀ4ꢀ(3ꢀtrifluoroꢀ
1. L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev.,
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2. W. Spaleck, F. Küber, A. Winter, J. Rohrmann, B. Bachmann,
M. Antberg, M. Dolle, E. F. Paulus, Organometallics, 1994,
13, 954.
3. J. A. Ewen, R. L. Jones, M. J. Elder, A. L. Rheingold, L. M.
LiableꢀSands, J. Am. Chem. Soc., 1998, 120, 10786.
4. J. A. Ewen, M. J. Elder, R. L. Jones, A. L. Rheingold, L. M.
LiableꢀSands, R. D. Sommer, J. Am. Chem. Soc., 2001, 123,
4763.
5. E. A. Togni, R. L. Halterman, in Metallocenes: Synthesis,
Reactivity, Applications, Eds E. A. Togni, R. L. Halterman,
WileyꢀVCH, 1998, p. 600.
6. The Chemistry of Organic Silicon Compounds, Eds. S. Patai,
Z. Rappoport, V. 1, Wiley, 1989.
7. V. V. Izmer, A. Y. Lebedev, M. V. Nikulin, A. N. Ryabov, A.
F. Asachenko, A. V. Lygin, D. A. Sorokin, A. Z. Voskoboynikov,
Organometallics, 2006, 25, 1217.
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Laishevtsev, Y. N. Luzikov, Tetrahedron Lett., 2002, 43, 3213.
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35, 6511.
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113, 7075.
12. E. Negishi, X. Zeng, Z. Tan, M. Qian, Q. Hu, Z. Huang,
MetalꢀCatalyzed CrossꢀCoupling Reactions (2nd ed.), 2004, 2,
815.
13. C. Dai, G. C. Fu, J. Am. Chem. Soc., 2001, 123, 2719.
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13028.
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Organometallics, 2002, 21, 2842.
methylphenyl)indenꢀ1ꢀide]zirconium dichloride (8b). Compound
8b was synthesized according to the general procedure starting
from ligand 5f. The orange solid compound was obtained in 22%
yield. Calculated (%): C, 56.53; H, 3.69. C36H28Cl2F6SiZr.
Found (%): C, 56.70; H, 3.75. 1H NMR (CD2Cl2), δ: 7.81—7.90
(m, 4 H, 2,2´,6,6´ꢀH C6H4); 7.69—7.74 (m, 2 H, 7,7´ꢀH of
indenyl); 7.51—7.63 (m, 4 H, 5,5´,4,4´ꢀH C6H4); 7.37 (dd, 2 H,
5,5´ꢀH of indenyl, J = 7.0 Hz, J = 0.6 Hz); 7.12 (dd, 2 H, 6,6´ꢀH
of indenyl, J = 8.7 Hz, J = 7.0 Hz); 6.84 (s, 2 H, 3,3´ꢀH of
indenyl); 2.22 (s, 6 H, 2,2´ꢀMe of indenyl); 1.33 (s, 6 H, SiMe2).
5
racꢀ1,1´ꢀDimethylsilylenebis[η ꢀ2ꢀmethylꢀ4ꢀ(4ꢀdimethylꢀ
aminophenyl)indenꢀ1ꢀide]zirconium dichloride (8a). Compound
8a was synthesized according to the general procedure starting
from ligand 5e. The orange solid compound was obtained in
23% yield. Calculated (%): C, 63.84; H, 5.64. C38H40Cl2N2SiZr.
Found (%): C, 64.05; H, 5.77. 1H NMR (CD2Cl2), δ: 7.54—7.70
(m, 6 H, 7,7´ꢀH in indenyl and 2,2´,6,6´ꢀH in C6H4); 7.27—7.40
(m, 6 H, 5,5´ꢀH in indenyl and 3,3´,5,5´ꢀH in C6H4); 7.09 (dd,
2 H, 6,6´ꢀH in indenyl, J = 8.7 Hz, J = 7.2 Hz); 6.87 (s, 2 H,
3,3´ꢀH in indenyl); 3.15 (s, 12 H, 4,4´ꢀNMe2 in C6H4); 2.20 (s,
6 H, 2,2´ꢀMe in indenyl); 1.32 (s, 6 H, SiMe2).
5
racꢀ1,1´ꢀDimethylsilylenebis[η ꢀ2,5ꢀdimethylꢀ4ꢀphenylindenꢀ
1ꢀide]zirconium dichloride (9). Compound 9 was synthesized
according to the general procedure starting from ligand 3a. The
orange solid compound was obtained in 29% yield. Calculated
(%): C, 65.83; H, 5.22. C36H34Cl2SiZr. Found (%): C, 65.95;
H, 5.31. 1H NMR (CD2Cl2), δ: 7.51 (d, 2 H, 7,7´ꢀH in indenyl,
J = 8.9 Hz); 7.40 (m, 4 H, 2,2´,6,6´ꢀH in Ph); 7.35 (m, 4 H,
3,3´,5,5´ꢀH in Ph); 7.20 (m, 2 H, 4,4´ꢀH in Ph); 6.95 (d, 2 H,
6,6´ꢀH in indenyl, J = 8.9 Hz); 6.35 (m, 2 H, 3,3´ꢀH in indenyl); 2.23
(s, 6 H, 5,5´ꢀMe); 2.14 (s, 6 H, 2,2´ꢀMe); 1.26 (s, 6 H, SiMe2).
5
racꢀ6,6´ꢀDimethylsilylenebis(η ꢀ5ꢀmethylꢀ3ꢀphenylcycloꢀ
penta[b]thiophenꢀ6ꢀide)zirconium dichloride (10a). Compound
10a was synthesized according to the general procedure starting
from ligand 7a. The orange solid compound was obtained in
25% yield. Calculated (%): C, 56.22; H, 4.09. C30H26Cl2C2SiZr.
Found (%): C, 56.41; H, 4.15. 1H NMR (CDCl3), δ: 7.54—7.62
(m, 4 H, 2,2´,6,6´ꢀH Ph); 7.49 (s, 2 H, 3,3´ꢀH cyclopenta[b]ꢀ
thienyl); 7.34—7.43 (m, 4 H, 3,3´,5,5´ꢀH Ph); 7.25—7.34 (m,
Received April 28, 2008