Zirconium complexes with cyclopentadienyl ligands involving fused a thiophene fragment

Article abstract of DOI:10.1021/om010810z

The following cyclopentadienes (Cp′H) with fused thiophene and benzothiophene fragments were synthesized: 4,5-dimethyl-6H-cyclopenta[b]thiophene (2), 5,6-dimethyl-4H-cyclopenta[b]thiophene (4), 1,3,5-trimethyl-4H-cyclopenta[c]thiophene (6), 2-methyl-1(and 3)H-cyclopenta[b][1]thiophenes (9), 2,3-dimethyl-1H-cyclopenta[b][1]benzothiophene (11), 1,2-dimethyl-3H-cyclopenta[b][1]benzothiophene (14). After a deprotonation of 2, 4, 11, and 14 with n-BuLi, followed by treatment of the resulting lithium salts with (η⁵-C₅Me₅)ZrCl₃, complexes (η⁵-Cp′)(η⁵-C₅Me₅)ZrCl ₂ were obtained. The ligand 6 gave a mixture of undesirable products instead of the respective metallocene. Two of them were isolated and turned out to be the polynuclear hydride complex {(Cp*Zr)(μ-H)(μ-Cl)₂(Cp*ZrCl)}₂(μ-Cl) ₆Li₂ and a binuclear complex containing an unusual bridged bis[1,5-dimetnyl-3-methylene-1,3-dihydro-η⁵-cyclopenta[c]thien-1- yl] ligand. Starting from the cyclopentadienes 2, 4, 11, and 14, several bis(cyclopentadienyl)dimethylsilanes were obtained and further used for the synthesis of the respective ansa-zirconocenes, which were isolated and unambiguously characterized either as pure diastereomeres or as rac/meso mixtures. Unbridged complex Cp′₂ZrCl₂ was prepared in a similar manner from the ligand 9.

Full text of DOI:10.1021/om010810z

2842
Organometallics 2002, 21, 2842-2855
Articles
Zir con iu m Com p lexes w ith Cyclop en ta d ien yl Liga n d s
In volvin g F u sed a Th iop h en e F r a gm en t
Alexey N. Ryabov, Denis V. Gribkov, Vyatcheslav V. Izmer, and
Alexander Z. Voskoboynikov*
Department of Chemistry, Moscow State University, V-234,
Moscow, GSP, 119899, Russian Federation
Received September 10, 2001
The following cyclopentadienes (Cp′H) with fused thiophene and benzothiophene fragments
were synthesized: 4,5-dimethyl-6H-cyclopenta[b]thiophene (2), 5,6-dimethyl-4H-cyclopenta-
[b]thiophene (4), 1,3,5-trimethyl-4H-cyclopenta[c]thiophene (6), 2-methyl-1(and 3)H-cyclopenta-
[b][1]thiophenes (9), 2,3-dimethyl-1H-cyclopenta[b][1]benzothiophene (11), 1,2-dimethyl-3H-
cyclopenta[b][1]benzothiophene (14). After a deprotonation of 2, 4, 11, and 14 with n-BuLi,
followed by treatment of the resulting lithium salts with (η5-C5Me5)ZrCl3, complexes (η5-
Cp′)(η5-C5Me5)ZrCl2 were obtained. The ligand 6 gave a mixture of undesirable products
instead of the respective metallocene. Two of them were isolated and turned out to be the
polynuclear hydride complex {(Cp*Zr)(µ-H)(µ-Cl)2(Cp*ZrCl)}2(µ-Cl)6Li2 and a binuclear
complex containing an unusual bridged bis[1,5-dimethyl-3-methylene-1,3-dihydro-η5-cyclo-
penta[c]thien-1-yl] ligand. Starting from the cyclopentadienes 2, 4, 11, and 14, several bis-
(cyclopentadienyl)dimethylsilanes were obtained and further used for the synthesis of the
respective ansa-zirconocenes, which were isolated and unambiguously characterized either
as pure diastereomeres or as rac/meso mixtures. Unbridged complex Cp′2ZrCl2 was prepared
in a similar manner from the ligand 9.
In tr od u ction
The group 4 metallocenes including η5-cyclopentadi-
enyl ligands with fused heterocyclic fragments are
regarded as new promising olefin polymerization cata-
lysts.1,2 Quite recently we described zirconium com-
plexes including a η5-cyclopenta[b]pyridinyl ligand with
a cyclopentadienyl fused to the pyridine ring:3
In the present paper we extended this thiophene-
based ligand family to new zirconocenes. We have
developed selective synthetic methods for ansa-metal-
locenes containing sulfur in different positions (with
respect to bridge B) of the fused thiophene fragment,
e.g., as in the following ligands:
The other important metallocene family is based on
Cp fused to a five-membered thiophene ring. Ewen et
al.1,2 described several zirconium complexes of this type
involving the following ligands:
Some of these complexes have unprecedented catalytic
activity in propene polymerization. For instance, rac-
dimethylsilylbis(2,5-dimethyl-3-phenyl-6H-cyclopenta-
[b]thiophenyl)zirconium dichloride in the presence of
MAO and H2 produces 5004 kg isotactic PP/(mmol Zr
h).
The second problem under investigation is the syn-
thesis of various zirconocenes with a fused benzo[b]-
thiophene fragment, such as
(1) Ewen, J . A.; J ones, R. L.; Elder, M. J .; Rheingold, A. L.; Liable-
Sands, L. M. J . Am. Chem. Soc. 1998, 120, 10786.
(2) Ewen, J . A.; Elder, M. J .; J ones, R. L.; Rheingold, A. L.; Liable-
Sands, L. M.; Sommer, R. D. J . Am. Chem. Soc. 2001, 123, 4763.
(3) (a) Voskoboynikov, A. Z.; Ryabov, A. N.; Izmer, V. V. In
Proceedings of the 222nd American Chemical Society Meeting, Chicago,
IL, 2001. (b) Ryabov, A. N.; Izmer, V. V.; Borisenko, A. A.; Kuz′mina,
L. G.; Howard, J . A. K.; Canich, J . A. M.; Voskoboynikov, A. Z. J . Chem.
Soc., Dalton Trans., in press.
10.1021/om010810z CCC: $22.00 © 2002 American Chemical Society
Publication on Web 06/08/2002

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2843
Sch em e 1
Sch em e 5
Sch em e 2
3-(chloromethyl)-2,5-dimethylthiophene as starting ma-
terial, by a procedure described by Merle and co-
workers7 and involving intermolecular acylation of the
respective 3-(thienyl)propionic acid. Reduction of 5 with
sodium borohydride and successive H2O elimination
gave 1,3,5-trimethyl-4H-cyclopenta[c]thiophene (6).
Whereas the one-pot acylation-Nazarov-like cycliza-
tion reaction for thiophene (Scheme 2) is selective, an
analogous reaction between benzo[b]thiophene and
methacrylic acid was found to give a ca. 5:1 mixture of
2-methyl-2,3-dihydro-1H-cyclopenta[b][1]benzothiophen-
1-one (7) and 2-methyl-1,2-dihydro-3H-cyclopenta[b][1]-
benzothiophen-3-one (8) (Scheme 4), which is due to a
different regioselectivity of acylation of thiophene8 and
benzo[b]thiophene.9 Then, a mixture of 2-methyl-1H-
and 2-methyl-3H-cyclopenta[b][1]thiophenes (9) was
prepared as shown in Scheme 4.
Sch em e 3
Pure cyclic ketone 8 was synthesized in a different
manner (Scheme 5). Cuprate derived from benzo[b]-
thiophene10 reacts with methacryloyl chloride to give
vinyl ketone 10. The desired cyclic ketone was obtained
in almost quantitative yield via the Nazarov-like
cyclization.11-13 This ketone was used for the synthesis
of 2,3-dimethyl-1H-cyclopenta[b][1]benzothiophene (11),
as shown in Scheme 5.
Analogously, vinyl ketone 12 and cyclic ketone 13, as
well as a mixture of 1,2-dimethyl-1H- and 1,2-dimethyl-
3H-cyclopenta[b][1]benzothiophenes (14), were prepared
as outlined in Scheme 6.
Syn t h esis a n d Molecu la r St r u ct u r es of Un -
br id ged Zir con ocen es. Ligand 9 was deprotonated
with 1 equiv of n-BuLi, then treated with 0.5 equiv of
ZrCl4 in toluene, to give the respective metallocene 15
as a mixture of rac and meso versions (Scheme 7).
Starting from Cp*ZrCl3 and the ligands (Cp′) 2, 4, 11,
and 14, several unsymmetrical unbridged metallocenes
Cp′Cp*ZrCl2 were prepared in moderate yield as out-
lined in Scheme 8. These complexes were unambigu-
ously characterized by NMR spectroscopy (see Experi-
mental Section).
The knowledge of accurate structure is an important
key to the understanding of catalytic properties.4 We
have therefore performed a detailed crystallographic
study for several zirconocenes synthesized.
Resu lts a n d Discu ssion
Syn th esis of Cyclop en ta d ien es w ith F u sed Th io-
p h en e a n d Ben zo[b]th iop h en e F r a gm en ts. 5-Meth-
yl-5,6-dihydro-4H-cyclopenta[b]thiophen-1-one (1) was
prepared as shown in Scheme 1, with 2-(chloromethyl)-
thiophene as starting material, by a procedure described
by Sam and Thompson.5 Under treatment of this ketone
with MeLi, followed by HCl, 4,5-dimethyl-6H-cyclopenta-
[b]thiophene (2) was obtained.
The isomeric ketone 5-methyl-4,5-dihydro-6H-cyclo-
penta[b]thiophen-6-one (3) was prepared using the one-
pot reaction (Scheme 2) developed by Gronowitz and
Meth-Cohn.6 Then, 5,6-dimethyl-4H-cyclopenta[b]thio-
phene (4) was isolated using the above-mentioned
approach for the synthesis of 2.
1,3,5-Trimethyl-5,6-dihydro-4H-cyclopenta[c]thiophen-
4-one (5) was prepared as shown in Scheme 3, with
Sch em e 4

2844 Organometallics, Vol. 21, No. 14, 2002
Ryabov et al.
Sch em e 6
Sch em e 7
Å in 16 and 2.227 and 2.225 Å in 17 (average 2.220 Å).
The distance Cl‚‚‚S is in 17 rather short (3.314 and
3.323 Å). In both molecules of the unit cell of 17 one Cl
atom is located in the space between two Me groups of
the Cp′ ligand, whereas the position of the second Cl
atom is constrained by the Cl1-Zr-Cl2 angle (95.6-
97.1°). Thus, in 17 this chlorine atom is located near
the S atom to give the close Cl‚‚‚S contact observed.
An attempt to obtain Cp′Cp*ZrCl2 starting from 1,3,5-
trimethyl-4H-cyclopenta[c]thiophene (6) failed. The re-
action mixture (Scheme 9) turned dark brown, and a
specific mercaptane-like smell appeared.
Sch em e 8
On the evidence of NMR spectroscopy, the resulting
mixture included several new zirconium compounds.
One of them, complex 20, is crystallized slowly from
toluene solution to give yellowish blocks. The molecular
structure of this unusual compound was established by
X-ray crystal structure analysis shown in Figure 3.
The centrosymmetric complex consists of two bi-
nuclear zirconium units (Cp*Zr)2(µ-H)(µ-Cl)2Cl4 bridged
by two lithium atoms. To the best of our knowledge, this
Molecular structures of 16 and 17 determined by
X-ray crystal structure analysis are shown in Figures
1 and 2, respectively.
Both compounds crystallize with two molecules in the
asymmetric unit. Whereas the unit cell of 16 contains
two molecules of the same enantiomers, the unit cell of
17 contains both enantiomers. Each isomeric molecule
has the same bent sandwich geometry, with two Cl
ligands in the bisecting plane. The angle between the
σ-bonds is equal to 97°; the angle centroid-Cp′-Zr-
centroid-Cp* is equal to 132°. The dihedral angle
between the planar η5-Cp fragments is equal to 53.5°.
The Zr-Cpcent(1) distances are the following: 2.240 and
2.247 Å in 16 and 2.238 and 2.241 Å in 17 (average
2.242 Å), whereas for the second molecule in the unit
the Zr-Cpcent(2) distances are equal to 2.219 and 2.210
(4) (a) Rappe, A. K.; Skiff, W. M.; Casewit, C. J . Chem. Rev. 2000,
100, 1435, and references therein. (b) Angermund, K.; Fink, G.; J ensen,
V. R.; Kleinschmidt, R. Chem. Rev. 2000, 100, 1457, and references
therein.
(5) Sam, J .; Thompson, A. C. J . Pharm. Sci. 1963, 52, 898.
(6) Meth-Cohn, O.; Gronowitz, S. Acta Chim. Scand. 1966, 20, 1577.
(7) Cagniant, P.; Merle, G.; Cagniant, D. Bull. Soc. Chim. Fr. 1970,
316 and 322.
(8) Gronowitz, S. Adv. Heterocycl. Chem. 1963, 1, 1.
(9) Iddon, B.; Scrowston, R. M. Adv. Heterocycl. Chem. 1970, 11,
177.
(10) Casarini, A.; Dembech, P.; Lazzari, D.; Marini, E.; Reginato,
G.; Ricci, A.; Seconi, G. J . Org. Chem. 1993, 58, 5620.
(11) Burckhalter, J . H.; Sam, J . J . Am. Chem. Soc. 1951, 73, 4460.
(12) Meth-Cohn, O.; Gronowitz, S. Acta Chim. Scand. 1966, 20, 1577.
(13) Blanchard, P.; Brisset, H.; Illien, B.; Riou, A.; Roncali, J . J . Org.
Chem. 1997, 62, 2401.
F igu r e 1. Structure of 16, showing the 50% thermal
ellipsoids and atom-labeling scheme for one of the inde-
pendent molecules. Selected bond lengths (Å): Zr(1)-Cl-
(1) 2.4391(13), Zr(1)-Cl(2) 2.4467(12), Zr(1)-C(1) 2.457(4),
Zr(1)-C(2) 2.509(4), Zr(1)-C(5) 2.617(4), Zr(1)-C(6) 2.620-
(4), Zr(1)-C(7) 2.524(4), S(1)-C(2) 1.738(5), S(1)-C(3)
1.746(5), C(1)-C(7) 1.415(6), C(1)-C(2) 1.428(6), C(2)-C(5)
1.420(6), C(3)-C(4) 1.340(7), C(4)-C(5) 1.424(6), C(5)-C(6)
1.429(6), C(6)-C(7) 1.418(6).

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2845
(1) and Zr(2) centers are not structurally similar. Zr(1)
bears four bridging chlorine ligands, while Zr(2) is
linked to one terminal Cl(5) and three bridging Cl
atoms. Four structurally different chlorine atoms were
found in the structure of 20: (a) Cl(1) and Cl(2)
represent Zr-Cl-Zr bridges; (b) Cl(3) and Cl(6) repre-
sent Zr-Cl-Li bridges; (c) Cl(4) coordinates Zr(1) and
two lithium atoms; (d) Cl(5) is terminally connected to
Zr(2). The Zr-Cla bond lengths show noticeable asym-
metry. Thus, the Zr(1)-Cl(1) and Zr(1)-Cl(2) distances
(2.5651(7) and 2.5696(6) Å) are shorter than the Zr(2)-
Cl(1) and Zr(2)-Cl(2) distances (2.6124(6) and 2.6249-
(6) Å, respectively). It should be noticed that the Zr(2)-
H(1M) distance is also slightly longer than Zr(1)-H(1M)
(2.01(2) and 1.92(2) Å, respectively). The Zr-Clb dis-
tances (Zr(1)-Cl(3), 2.4804(6), Zr(2)-Cl(6), 2.5082(7) Å)
are comparable with the values for Zr-Cl(-Li) found
in the related structure of Zr2(Cp))2Cl4(µ-Cl3)Li(dme),
2.474(6) and 2.478(6) Å.14 However, the Clb-Li bond
lengths in 20 (2.304(4) and 2.432(5) Å) are significantly
shorter than in Zr2(Cp))2Cl4(µ-Cl3)Li(dme) (2.74(8) and
2.79(8) Å) due to a different type of coordination
environment of the Li atoms. The hydride-zirconium
bond lengths (2.01(2) and 1.92(2) Å) are comparable with
the values observed for Zr-Hap in Zr2(Cp*)2(µ-H3)Cl3-
(PMe3) (2.00(3) and 2.04(4) Å).17 In the structure of
complex 20 the Zr(1)-Zr(2) distance is 3.4148(5) Å. This
value is regularly shorter than in Zr2(Cp))2Cl4(µ-Cl3)-
Li(dme) (3.880(1) Å) due to the shorter Zr-H-Zr
bridge.14 In the structure of 20 the coordination poly-
hedron of the Li atom represents a highly distorted
tetrahedron with Cl-Li-Cl angles ranging from 90.21-
(14)° to 127.02(19)°. The Li(1)-Li(1A) distance is 3.101-
(9) Å. To the best of our knowledge, compound 20 is the
first example of a structure containing two transition
metal centers bridged by a tetrahedral LiCl4 moiety. On
the other hand, octahedral LiCl4(OR)2 bridges are well
known.14,19 In addition, the asymmetric unit in the
structure of 20 contains two solvent toluene molecules.
F igu r e 2. Structure of 17, showing the 50% thermal
ellipsoids and atom-labeling scheme for one of the inde-
pendent molecules. Selected bond lengths (Å): Zr(1)-Cl-
(1) 2.4442(16), Zr(1)-Cl(2) 2.4359(15), Zr(1)-C(1) 2.604(6),
Zr(1)-C(2) 2.610(6), Zr(1)-C(5) 2.513(6), Zr(1)-C(6) 2.455-
(6), Zr(1)-C(7) 2.528(6), S(1)-C(2) 1.727(6), S(1)-C(3)
1.750(7), C(1)-C(2) 1.419(9), C(1)-C(7) 1.406(9), C(2)-C(5)
1.425(9), C(3)-C(4) 1.330(10), C(4)-C(5) 1.449(9), C(5)-
C(6) 1.439(9), C(6)-C(7) 1.411(9).
Sch em e 9
In the 1H{13C} NMR spectrum of compound 20 in
C6D6 appears two resonances at 2.16 and 0.76 ppm (in
a ratio of integral intensivities equal to 30:1) attributed
to Cp* and a bridging hydride ligand,20 respectively.
Additionally, in the IR spectrum of 20 (in Nujol emul-
sion) a broad absorption band appears at 1390 cm-1
,
structure is the first example of two monocyclopenta-
dienyl zirconium centers linked by two chlorine and one
hydrogen atom. However, the systems (CpZrIV)2(µ-X)3
(where X ) Cl,14-16 H17) were previously reported. Both
independent Zr(1) and Zr(2) atoms possess a distorted
octahedral coordination assuming that the Cp* ligands
occupy one site. The pentahapto cyclopentadienyl rings
and bridging hydrogen atoms lie in apical positions,
while the Cl atoms occupy equatorial ones. The devia-
tions of both Zr atoms from the equatorial planes toward
the Cp* ligands are 0.70 Å. In the structure of 20 the
Zr-Cpcent distances (2.20 and 2.22 Å) are somewhat
longer than the respective distances in the parent
double-bridged structure (Cp*ZrCl2)2(µ-Cl)2, 2.18 Å.18 Zr-
which is characteristic for many zirconium complexes
involving bridging hydrides.20,21 Additional evidence for
this hydride was obtained from a protonolysis experi-
ment. A sample of 20 in argon was decomposed by
i-PrOH, and GC analysis of the resulting gas phase was
performed. This analysis gave 0.10(2) wt % of hydride
hydrogen in 20 (calculated for 20‚(C7H8)4: 0.117%).22
While complex 20 was isolated in an analytically pure
form, only several colorless crystals of the other product,
complex 21, were obtained (Scheme 9). This compound
turned out to be binuclear complex 21 involving bridged
(18) Mart´ın, A.; Mena, M.; Palacios, F. J . Organomet. Chem. 1994,
480, C10.
(19) Secaur, C. A.; Day, V. W.; Ernst, R. D.; Kennelly, W. J .; Marks,
T. J . J . Am. Chem. Soc. 1976, 98, 3713.
(20) Cardin, D. J ., Lappert, M. F. Chemistry of Organo-Zirconium
and Hafnium Compounds; Wiley: New York, 1986, and references
therein.
(14) Butakoff, K. A.; Lemenovskii, D. A.; Mountford, P.; Kuzmina,
L. G.; Churakov, A. V. Polyhedron 1996, 15, 489.
(15) Krut’ko, D. P.; Borzov, M. V.; Veksler, E. N.; Churakov, A. V.;
Howard, J . A. K. Polyhedron 1998, 17, 3889.
(16) Dias, H. V. R.; Wang, Z. J . Am. Chem. Soc. 1997, 119, 4650.
(17) van den Hende, J . R.; Hessen, B.; Meetsma, A.; Teuben, J . H.
Organometallics 1990, 9, 537.
(21) Wailes, P. C.; Weigold, H. J . Organomet. Chem. 1970, 24, 405.
(22) Anal. Calcd for 20‚(C7H8)4, C68H94Cl2Li2Zr4: C, 47.60; H, 5.52;
Cl, 24.80; Li, 0.81. Found: C, 47.35; H, 5.40; Cl, 24.93; Li, 0.84.

2846 Organometallics, Vol. 21, No. 14, 2002
Ryabov et al.
F igu r e 3. Structure of 20, showing the 50% thermal ellipsoids and atom-labeling scheme. Selected bond lengths (Å):
Zr(1)-C(1) 2.495(2), Zr(1)-C(2) 2.490(2), Zr(1)-C(3) 2.506(2), Zr(1)-C(4) 2.546(2), Zr(1)-C(5) 2.538(2), Zr(2)-C(11) 2.504-
(2), Zr(2)-C(12) 2.504(2), Zr(2)-C(13) 2.511(2), Zr(2)-C(14) 2.546(2), Zr(2)-C(15) 2.551(2), Zr(1)-H(1M) 1.92(2), Zr(2)-
H(1M) 2.01(2), Zr(1)-Cl(1) 2.5651(7), Zr(1)-Cl(2) 2.5696(6), Zr(1)-Cl(3) 2.4804(6), Zr(1)-Cl(4) 2.5145(6), Zr(2)-Cl(1)
2.6124(6), Zr(2)-Cl(2) 2.6249(6), Zr(2)-Cl(5) 2.4208(7), Zr(2)-Cl(6) 2.5082(7).
F igu r e 4. Structure of 21, showing the 50% thermal ellipsoids and atom-labeling scheme. Selected bond lengths (Å):
Zr(1)-Cl(2) 2.416(3), Zr(1)-Cl(1) 2.427(2), Zr(1)-C(3) 2.498(4), Zr(1)-C(4) 2.507(4), Zr(1)-C(5) 2.562(4), Zr(1)-C(2) 2.563-
(4), Zr(1)-C(6) 2.611(4), S(1)-C(7) 1.783(5), S(1)-C(1) 1.859(5), C(1)-C(2) 1.509(5), C(1)-C(8) 1.521(5), C(1)-C(1)#1 1.576-
(8), C(2)-C(6) 1.402(6), C(2)-C(3) 1.419(6), C(3)-C(4) 1.415(6), C(4)-C(5) 1.412(7), C(5)-C(6) 1.386(6), C(6)-C(7) 1.464(6),
C(7)-C(9) 1.341(8).
a bis[1,5-dimethyl-3-methylene-1,3-dihydro-η5-cyclopen-
ta[c]thien-1-yl] ligand. The molecular structure of this
compound (Figure 4) was determined by X-ray crystal
structure analysis.
Sch em e 10
The symmetrical dimer 21 consists of two equivalent
Cp*-Zr(Cl2)-Cp′ fragments bonded via a C-C′ bridge
(1.575 Å). The dihedral angle between the planar η5-
Cp fragments is equal to 50.4°; the angle centroid-Cp′-
Zr-centroid-Cp*, 132°. The 1,5-dimethyl-3-methylene-
1,3-dihydro-η5-cyclopenta[c]thien-1-yl fragment includes
a nonplanar C4S cycle. The displacements of sulfur and
C(9) are 0.282 and 0.413 Å, respectively. The dihedral
to 10.9°. This geometry corresponds to a loss of aromac-
angle between C1-C2-C6-C7 and Cp′ planes is equal
ity of the thiophene system in 21.

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2847
F igu r e 5. Structure of 24, showing the 50% thermal ellipsoids and atom-labeling scheme. Selected bond lengths (Å):
Si(1)-C(1) 1.9241(15), S(1)-C(7) 1.7356(18), S(1)-C(6) 1.7418(16), C(1)-C(2) 1.506(2), C(1)-C(5) 1.530(2), C(2)-C(6) 1.365-
(2), C(2)-C(3) 1.432(2), C(3)-C(7) 1.363(2), C(3)-C(4) 1.463(2), C(4)-C(5) 1.340(2).
Sch em e 11
To understand the mechanism of formation of 20 and
21, the deprotonation of 6 can be supposed to proceed
by two different pathways. Pathway I (Scheme 10) gives
the traditional cyclopentadienyl-like anion. Pathway II
should include deprotonation of the Me substituent in
the thiophene ring to form the CH2d fragment. The
formation of the symmetrical dimer of 6 can result from
the dimerization of the respective radicals rather than
from any heterolytic transformations. These radicals can
be formed by homolytic cleavage of an alkyl zirconium
complex involving sulfur in the R-position to the zirco-
nium atom. On the other hand, the only pathway for
hydride-zirconium bond formation (in 20) seems to be
â-H elimination in this alkyl zirconium complex formed.
Syn th esis of Me2Si-Br id ged Liga n d s. To synthe-
size the respective bis(cyclopentadienyl)dimethylsilanes,
the above-mentioned cyclopentadienes with fused het-
erocyclic fragments were deprotonated with n-BuLi and,
then, treated with 0.5 equiv of Me2SiCl2 as shown in
Scheme 11.
is likely to result from a possible formation of (2-methyl-
1H-cyclopenta[b][1]benzothien-1-yl)silanes.
Side reactions involving a loss of aromacity of the
thiophene ring were observed during the synthesis of
24 (see above). Evidence for this is a specific strong
mercaptane-like smell of the reaction mixture. The
molecular structure of rac-dimethyl[bis(1,3,5-trimethyl-
4H-cyclopenta[c]thien-4-yl)]silane (rac-24) as deter-
mined by X-ray crystal structure analysis is shown in
Figure 5.
Syn th esis a n d Molecu la r Str u ctu r es of a n sa -
Zir con ocen es. The bridged ligands listed above, 22, 23,
25-27, were deprotonated with 2 equiv of n-BuLi, and
the resulting dilithium bis(cyclopentadienyl)s were
treated with ZrCl4 in toluene to give the respective
zirconium dichlorides 28, 29, and 30-32 (Scheme 11).
Complexes 28 and 29 were isolated from toluene solu-
tion as pure racemates, but compound 30 was obtained
as a pure meso isomer. Complexes 31 and 32 were
prepared and isolated as mixtures of rac and meso
diastereoisomers. We were not able to separate the
diastereoisomers of 31 and 32 because of the very low
solubility of these compounds in all common solvents.
An attempt to prepare the ansa-zirconium complex
starting from 24 failed. This can be a result of metala-
tion of Me groups of 24 by n-BuLi (see above).
Ligands 22-25 and 27 were isolated as 1:1 mixtures
of rac and meso diastereomers; ligand 26 was obtained
as a 1:4 rac/meso mixture. The low yield of 22 was due
to problems in chromatographic separation, rather than
low chemical yield. Pure ligand 27 was obtained by a
low-temperature crystallization, which explains its low
isolated yield. The low yield of rac-/meso-dimethyl[bis-
(2-methyl-3H-cyclopenta[b][1]benzothien-3-yl)]silanes (25)
We obtained single crystals of rac-28, rac-29, meso-
31, and meso-32 and carried out their X-ray crystal-

2848 Organometallics, Vol. 21, No. 14, 2002
Ryabov et al.
chlorine atoms in the bisecting plane. All structures are
centrosymmetric. Structure 28 includes the respective
racemate, whereas structures 31 and 32 contain meso
isomers only. Alternatively, structure 29 consists of both
isomeric molecules in rac to meso ratio equal to 4:1.
Similar cocrystallization of rac/meso isomers was ob-
served recently for a Me2Si-bridged ansa-zirconocene
including methylcyclopentadienyl fused to a thiophene
fragment.1 Although, in the latter case, a ca. 3:1 rac/
meso ratio was found, actually, the detailed analysis of
the crystallographic data show that this crystal includes
isomeric 5-methyl-6H-cyclopenta[b]thien-6-yl and 5-meth-
yl-4H-cyclopenta[b]thien-4-yl fragments; that is, the
Me2Si substituent cannot be localized during the syn-
thesis of the respective bridging ligand. So, the only
reason we used double methylated Cp′ ligands is to
localize the position of the Me2Si bridge in the metal-
locenes synthesized.
The angles centroid-Cp′1-Zr-centroid-Cp′2 in com-
plexes 28, 29, 31, and 32 are equal to 128.8°, 120.2°,
130.1°, and 128.8°, respectively. The corresponding
dihedral angles between the planar η5-Cp fragments are
67.1°, 65.5°, 61.6°, and 61.1°. The Zr-Cpcent distances
are equal to 2.254 and 2.242 Å for 28, 2.219 and 2.232
Å for 29, 2.247 and 2.258 Å for 31, and 2.234 and 2.236
Å for 32. Close contacts S‚‚‚Cl were found in the case of
29 (3.379-3.390 Å) and 31 (3.378-3.436 Å). These two
molecules have similar structures with sulfur and
silicon atoms in trans positions with respect to the C-C
bond connecting cyclopentadienyl and thiophene rings.
In conclusion we elaborated selective synthetic pro-
cedures for zirconocenes involving cyclopentadienyl
ligands with fused thiophene and benzo[b]thiophene
fragments. Several complexes were characterized by
X-ray crystal structure analysis. These metallocenes
should be promising catalyst precursors for Ziegler-
Natta olefin polymerization. Variable structure of the
complexes obtained is expected to allow for the elucida-
tion of trends in the structure-catalytic efficiency
relationship in olefin polymerization. In the near future,
we plan to study olefin polymerization catalyzed by the
zirconium complexes synthesized.
F igu r e 6. Structure of rac-28, showing the 50% thermal
ellipsoids and atom-labeling scheme. Selected bond lengths
(Å): Zr(1)-Cl(1) 2.414(7), Zr(1)-Cl(1′) 2.422(6), Zr(1)-C(1)
2.483(10), Zr(1)-C(2) 2.455(10), Zr(1)-C(3) 2.521(10), Zr-
(1)-C(4) 2.652(9), Zr(1)-C(5) 2.655(9), Si(1)-C(2) 1.900-
(10), S(1)-C(7) 1.736(10), S(1)-C(1) 1.752(8), C(1)-C(5)
1.377(13), C(1)-C(2) 1.419(13), C(2)-C(3) 1.416(12), C(3)-
C(4) 1.432(14), C(4)-C(5) 1.424(11), C(5)-C(6) 1.440(12),
C(6)-C(7) 1.347(13).
Exp er im en ta l Section
Gen er a l P r oced u r e. All manipulations with compounds,
which are sensitive to both moisture and air, were performed
either on a high-vacuum line in all-glass apparata equipped
with PTFE stopcocks or in an atmosphere of thoroughly
purified argon using a standard Schlenk technique. Tetrahy-
drofuran was purified by distillation over LiAlH4 and kept over
sodium benzophenone ketyl. Hydrocarbon solvents were dis-
tilled and stored over CaH2 or Na/K alloy. Methylene chloride
(and CD2Cl2) was distilled and stored over CaH2. Chloroform-d
was distilled over P4O10 and stored over molecular sieves (3
Å). Thiophene (Aldrich), 2,5-dimethylthiophene (Aldrich),
1-benzothiophene (Aldrich), diethylmethylmalonate (Acros),
and methacrylic acid were distilled before use. Anhydrous
ZrCl4 (Aldrich), CuCN (Merck), NaBH4 (Aldrich), methane-
sulfonic acid (Aldrich), n-BuLi in hexanes (Chemetall), and
MeLi in ether (Merck) were used as obtained. 2-Chlorometh-
ylthiophene,23 methacryloyl chloride (analogously, (2E)-2-
methyl-2-butenoyl chloride from tiglic acid),24 and ZrCl4-
F igu r e 7. Structure of rac-29, showing the 50% thermal
ellipsoids and atom-labeling scheme. The unit includes both
rac and meso isomeric molecules in a ratio of ca. 4:1.
Selected bond lengths (Å): Zr(1)-Cl(1) 2.419(2), Zr(1)-Cl-
(2) 2.412(2), Zr(1)-C(3) 2.500(5), Zr(1)-C(4) 2.446(5), Zr-
(1)-C(5) 2.492(5), Zr(1)-C(6) 2.609(5), Zr(1)-C(7) 2.639(5),
S(1)-C(7) 1.681(6), S(1)-C(1) 1.758(8), Si(1)-C(4) 1.867-
(6), C(1)-C(2) 1.312(10), C(2)-C(3) 1.449(8), C(3)-C(7)
1.443(8), C(3)-C(4) 1.443(8), C(4)-C(5) 1.425(8), C(5)-C(6)
1.392(8), C(6)-C(7) 1.425(8).
lographic study. Molecular structures of these complexes
are shown in Figures 6-9, respectively.
All molecules display a normal coordination environ-
ment for Me2Si-bridged ansa-metallocenes with two
(23) Wiberg, K. B.; McShane, H. F. Org. Synth. 1955, 3, 197.
(24) Stempel, G. H.; Cross, R. P.; Mariella, R. P. J . Am. Chem. Soc.
1950, 72, 2299.

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2849
F igu r e 8. Structure of meso-31, showing the 50% thermal ellipsoids and atom-labeling scheme for one of the independent
molecules. Selected bond lengths (Å): Zr(1)-Cl(1) 2.4131(10), Zr(1)-Cl(2) 2.4334(10), Zr(1)-C(4) 2.467(3), Zr(1)-C(3) 2.498-
(4), Zr(1)-C(5) 2.534(3), Zr(1)-C(2) 2.632(4), Zr(1)-C(1) 2.634(3), Zr(2)-Cl(3) 2.3991(10), Zr(2)-Cl(4) 2.4404(10), S(1)-
C(1) 1.743(4), S(1)-C(11) 1.758(4), Si(1)-C(4) 1.888(4), C(1)-C(2) 1.392(5), C(1)-C(5) 1.420(5), C(2)-C(3) 1.427(5), C(3)-
C(4) 1.451(5), C(5)-C(6) 1.469(5), C(6)-C(7) 1.397(5), C(6)-C(11) 1.423(5), C(7)-C(8) 1.393(5), C(8)-C(9) 1.394(5), C(9)-
C(10) 1.386(5), C(10)-C(11) 1.377(5),
chromatographic separation. Analytical and semipreparative
liquid chromatography was performed using a Waters Delta
600 HPLC system including a 996 photodiode array detector
and Nova-Pack C18 or HR silica columns (60 Å, 6 µm, 3.9 and
19 × 300 mm). IR spectra were recorded using an UR-20
instrument. The content of H2 in argon was measured using
GLC analysis on a Tsvet 101 (Russia) chromatograph (3 m ×
1
3 mm column packed with charcoal). H and 13C spectra were
recorded with Brucker AM 360 and Varian VXR 400 instru-
ments for 1-10% solutions in deuterated solvents. Chemical
shifts for 1H and 13C were measured relative to TMS. C, H
microanalyses were done using a CHN-O-Rapid analyzer
(Heracus).
(C5Me5)Zr Cl3. Toluene (150 mL) was added to a mixture
of 21.5 g (92.0 mmol) of freshly sublimed ZrCl4 and 11.9 g (84.0
mmol) of C5Me5Li. The slurry was refluxed and stirred for 2
days. Then, the pale yellow precipitate was filtered off (G4)
and washed with toluene (50 mL). The crude product was
treated with hot decane (3 × 100 mL) using a special thick
wall filtering (G4 frit) funnel equipped with a thermostated
(165-170 °C) oil jacket. A yellowish precipitate was formed
as soon as the filtrate was cooled to room temperature. This
precipitate was filtered off (G4), washed with pentane (3 × 50
mL), and dried in vacuo for 3 h. Yield: 20.5 g (73%). Anal.
Calcd for C10H15Cl3Zr: C, 36.09; H, 4.54. Found: C, 36.13; H,
F igu r e 9. Structure of meso-32, showing the 50% thermal
ellipsoids and atom-labeling scheme. Selected bond lengths
1
4.50. H NMR (C6D5CD3): δ 2.17 (s, ∆ν1/2 ) 12.0 Hz, C5Me5).
13C{1H} NMR (C6D5CD3): δ 130.45 (C5Me5), 13.31 (C5Me5).
(Å): Zr(1)-Cl(1) 2.4159(13), Zr(1)-Cl(2) 2.4216(12), Zr(1)-
2-Meth yl-3-(2-th ien yl)p r op a n oic Acid . Sodium metal
C(1) 2.511(4), Zr(1)-C(2) 2.625(4), Zr(1)-C(3) 2.622(4), Zr-
(30.0 g, 1.30 mol) was dissolved in 600 mL of dry ethanol. To
(1)-C(4) 2.506(4), Zr(1)-C(5) 2.475(4), S(1)-C(1) 1.743(4),
the resulting solution was added dropwise 240 mL (217 g, 1.27
mol) of diethylmethylmalonate for 10 min; then, a solution of
167.5 g (1.26 mol) of 2-chloromethylthiophene in 250 mL of
dry ethanol was added dropwise. This mixture was refluxed
for 3.5 h and cooled to room temperature. A solution of 253 g
(4.5 mol) of KOH in 600 mL of water was added. This mixture
was refluxed for 4 h to saponificate the ester formed. Ethanol
S(1)-C(6) 1.767(4), Si(1)-C(5) 1.875(4), C(1)-C(2) 1.416-
(5), C(1)-C(5) 1.429(5), C(2)-C(3) 1.382(5), C(2)-C(7)
1.454(5), C(3)-C(4) 1.431(5), C(4)-C(5) 1.454(5), C(6)-
C(11) 1.383(5), C(6)-C(7) 1.413(5), C(7)-C(8) 1.382(6),
C(8)-C(9) 1.378(6), C(9)-C(10) 1.388(6), C(10)-C(11) 1.373-
(6).
25
(THF)2 were prepared according to the published methods.
Silica gel 60 (230-400 mesh, Fluka) was used for flash
(25) Manzer, L. E. Inorg. Synth. 1982, 22, 135.

2850 Organometallics, Vol. 21, No. 14, 2002
Ryabov et al.
was distilled off. To this mixture was added 2 L of water and,
then, 1 M HCl was added to pH 1. The substituted methyl-
malonic acid precipitated at 5 °C was separated, washed with
3 × 200 mL of cold water, and dried. Crude product was
obtained after decarboxylation at 150 °C. Fractional distillation
gave 2-methyl-3-(2-thienyl)propanoic acid as a white solid, bp
112-120 °C/1 mmHg. Yield: 76 g (36%). Anal. Calcd for
C8H10O2S: C, 56.44; H, 5.92. Found: C, 56.58; H, 6.02. 1H
NMR (CDCl3): δ 11.88 (br s, 1H, COOH), 7.13 (m, 1H, 5-H in
C4H3S), 6.92 (m, 1H, 4-H in C4H3S), 6.82 (m, 1H, 3-H in C4H3S),
3.25 (dd, J ) 14.7 Hz, J ) 6.7 Hz, 1H, CHH′), 2.93 (dd, J )
7.4 Hz, J ) 14.7 Hz, 1H, CHH′), 2.93 (m, 1H, CH), 1.25 (d, J
) 7.0 Hz, 3H, Me). 13C NMR (CDCl3): δ 182.3, 141.2, 126.8,
125.7, 123.8, 41.6, 33.1, 16.5.
5-Me t h yl-5,6-d ih yd r o-4H -cyclop e n t a [b]t h iop h e n -4-
on e (1). To polyphosphoric acid (prepared from 750 g of P4O10
and 540 g of 85% H3PO4) was added a solution of 76 g (0.45
mol) of 2-methyl-3-(2-thienyl)propanoic acid in 300 mL of
chlorobenzene for 15 min by vigorous stirring. This mixture
was left for 10 min and, then, immersed in 2 kg of ice. The
product was extracted with 5 × 200 mL of ether. The extract
was washed with a saturated aqueous solution of Na2CO3,
dried over K2CO3, and evaporated to dryness. Fractional
distillation gave pinkish crystalline 1, bp 100-120 °C/1 mmHg.
Yield: 36 g (53%). Anal. Calcd for C8H8OS: C, 63.13; H, 5.30.
Found: C, 63.22; H, 5.38. 1H NMR (CDCl3): δ 7.34 (d, J ) 5.6
Hz, 1H, 2-H), 7.14 (d, J ) 5.6 Hz, 1H, 3-H), 3.43 (dd, J ) 17.6
Hz, J ) 6.8 Hz, 1H, 6-H), 3.05 (m, 1H, 5-H), 2.78 (dd, J ) 17.6
Hz, J ) 3.2 Hz, 1H, 6′-H), 1.35 (d, J ) 7.2 Hz, 3H, Me). 13C
NMR (CDCl3): δ 200.7, 168.6, 144.8, 130.7, 119.5, 47.8, 32.9,
16.5.
temperature. Cold water (100 mL) was added dropwise. The
organic layer was separated, dried over K2CO3, and evaporated
to dryness. The bridged ligand was isolated using flash
chromatography over silica gel with hexanes as eluents.
Yield: 4.07 g (18%) of a yellow oil of a rac/meso mixture of 22.
Anal. Calcd for C20H24S2Si: C, 67.36; H, 6.78. Found: C, 67.50;
1
H, 6.84. H NMR (CDCl3): rac δ 7.24 (d, J ) 5.0 Hz, 2H, 3,3′-
H), 6.98 (d, J ) 5.0 Hz, 2H, 2,2′-H), 3.75 (m, 2H, CHSi), 2.11
(s, 6H, 4,4′-Me), 2.09 (s, 6H, 5,5′-Me), -0.35 (s, 6H, Me2Si);
meso δ 6.97 (d, J ) 5.0 Hz, 2H, 3,3′-H), 6.96 (d, J ) 5.0 Hz,
2H, 2,2′-H), 3.63 (m, 2H, CHSi), 2.14 (s, 6H, 4,4′-Me), 2.00 (s,
6H, 5,5′-Me), -0.31 (s, 3H, MeSi), -0.38 (s, 3H, Me′Si). 13C
NMR (CDCl3): rac and meso δ 151.9, 139.7, 139.2, 129.7, 128.2,
125.7, 125.4, 123.6, 120.8, 117.6, 117.3, 117.2, 45.2, 44.9, 15.2,
15.0, 11.7, 11.6, -6.8, -7.4, -8.5.
Com p lex r a c-28. To a solution of 4.07 g (11.4 mmol) of 22
in 100 mL of hexane was added 14.3 mL (22.8 mmol) of 1.6 M
n-BuLi in hexanes at -40 °C. This mixture was stirred for 24
h at room temperature. The formed precipitate was filtered,
washed with 3 × 40 mL of hexane, and dried in vacuo. To the
suspension of this dilithium salt in 120 mL of toluene was
added 2.66 g (11.4 mmol) of ZrCl4 at -40 °C. This mixture
was stirred for 48 h at room temperature, 5 h at 60 °C, and
then, this hot mixture was filtered (G4). The filtrate was
evaporated to ca. 40 mL. The yellow crystals that precipitated
from the filtrate at -30 °C were separated and dried in vacuo.
Yield: 0.92 g (16%) of pure rac-28. Anal. Calcd for C20H22Cl2S2-
SiZr: C, 46.49; H, 4.29. Found: C, 46.32; H, 4.35. 1H NMR
(CD2Cl2): δ 7.37 (d, J ) 5.6 Hz, 2H, 3,3′-H), 6.89 (d, J ) 5.6
Hz, 2H, 2,2′-H), 2.17 (s, 6H, 4,4′-Me), 1.98 (s, 6H, 5,5′-Me),
1.02 (s, 6H, Me2Si).
4,5-Dim eth yl-6H-cyclop en ta [b]th iop h en e (2). To 123
mL (0.20 mol) of a 1.62 M solution of MeLi in ether was added
dropwise a solution of 25.0 g of 1 in 175 mL of ether at -80
°C. This mixture was stirred at room temperature for 1.5 h
and, then, 25 mL of 40% HCl was added dropwise at -10 °C.
The resulting mixture was stirred for 40 min at room tem-
perature. The organic layer was separated; the aqueous layer
was extracted by 2 × 100 mL of methyl-tert-butyl ether. The
combined organic extract was washed with a saturated aque-
ous solution of Na2CO3, dried over K2CO3, and evaporated to
dryness. Fractional distillation gave a white solid of 2, bp 62
°C/2 mmHg. Yield: 19,1 g (77,6%). Anal. Calcd for C9H10S: C,
5-Me t h yl-4,5-d ih yd r o-6H -cyclop e n t a [b]t h iop h e n -6-
on e (3). To polyphosphoric acid (prepared from 660 g of P4O10
and 460 g of 85% H3PO4) was added a mixture of 62.5 mL (65.7
g, 0.78 mol) of thiophene and 65.6 mL (66.6 g, 0.77 mol) of
methacrylic acid in 100 mL of CH2Cl2 at 50 °C. This mixture
was stirred at this temperature for 2 h and, then, immersed
in 1 kg of ice. The product was extracted by 4 × 150 mL of
methyl-tert-butyl ether. The combined extract was washed
with a saturated aqueous solution of Na2CO3, dried over K2-
CO3, and evaporated to dryness. Fractional distillation gave
white solid 3, bp 110 °C/5 mmHg. Yield: 47.8 g (40%). Anal.
Calcd for C8H8OS: C, 63.13; H, 5.30. Found: C, 63.20; H, 5.36.
1H NMR (CDCl3): δ 7.91 (d, J ) 4.7 Hz, 1H, 2-H), 7.03 (d, J
) 4.7 Hz, 1H, 3-H), 3.28 (dd, J ) 17.1 Hz, J ) 6.9 Hz, 1H,
4-H), 3.03 (m, 1H, 5-H), 2.61 (dd, J ) 17.1 Hz, J ) 3.0 Hz, 1H,
4′-H), 1.34 (d, J ) 7.7 Hz, 3H, Me). 13C NMR (CDCl3): δ 200.3,
167.2, 140.7, 140.2, 124.1, 47.5, 32.9, 17.0.
1
71.95; H, 6.71. Found: C, 72.13; H, 6.80. H NMR (CDCl3): δ
7.20 (d, J ) 4.8 Hz, 1H, 2-H), 6.87 (d, J ) 4.8 Hz, 1H, 3-H),
3.19 (br s, 2H, 6-H), 2.00 (br s, 6H, 4,5-Me). 13C NMR
(CDCl3): δ 152.8, 138.1, 137.8, 129.7, 126.3, 117.4, 39.4, 13.7,
11.2.
Com p lex 16. To a solution of 1.12 g (7.4 mmol) of 2 in 70
mL of toluene was added 2.96 mL (7.4 mmol) of 2.5 M n-BuLi
in hexanes at room temperature. The reaction mixture was
stirred for 10 h. Then, 2.47 g (7.4 mmol) of Cp*ZrCl3 was added
at -70 °C. The resulting mixture was stirred for 24 h at room
temperature and refluxed for 5 h. The hot solution was
filtrated (G4). The crystals that precipitated from the filtrate
at -30 °C were separated, washed with 3 × 20 mL of cold
toluene, and dried in vacuo. Yield: 1.48 g (45%) of yellow
crystals of 16. Anal. Calcd for C19H24Cl2SZr: C, 51.10; H, 5.42.
Found: C, 50.98; H, 5.33. 1H NMR (CD2Cl2): δ 7.16 (d, J )
5.4 Hz, 1H, 2-H in C9H9S), 6.94 (d, J ) 5.4 Hz, 1H, 3-H in
C9H9S), 5.77 (s, 1H, 6-H in C9H9S), 2.22 (s, 3H, 4-Me in C9H9S),
1.94 (s, 15H, C5Me5), 1.93 (s, 3H, 5-Me in C9H9S). 13C NMR
(CD2Cl2): δ 133.6, 131.5, 125.6, 121.9, 121.2, 118.9, 107.3, 99.0,
16.1, 13.6, 13.3.
Bis(4,5-d im eth yl-6H-cyclop en ta [b]th ien -6-yl)(d im eth -
yl)sila n e (22). To a solution of 19.1 g (0.127 mol) of 2 in 250
mL of toluene/THF (10:1) mixture was added dropwise 105
mL (0.127 mol) of 1.21 M n-BuLi in hexanes at -80 °C. This
mixture was stirred for 10 h at room temperature. Then, 7.72
mL (8.22 g, 63.7 mmol) of Me2SiCl2 was added at -40 °C, and
the resulting reaction mixture was stirred for 48 h at room
5,6-Dim eth yl-4H-cyclop en ta [b]th iop h en e (4). To 243
mL (0.40 mol) of 1.62 M MeLi in ether was added a solution
of 47.8 g (0.31 mol) of 3 in 350 mL of ether for 30 min at -80
°C. This reaction mixture was stirred for 1.5 h at room
temperature. Then, 50 mL of 40% HCl was added dropwise at
-10 °C. The resulting mixture was stirred for 40 min at room
temperature. The organic layer was separated, and the aque-
ous one was extracted by 2 × 100 mL of methyl-tert-butyl
ether. The combined extract was washed with a saturated
aqueous solution of Na2CO3, dried over K2CO3, and evaporated
to dryness. Fractional distillation gave 4 as a colorless liquid,
bp 100 °C/13 mmHg. Yield: 40.4 g (86%). Anal. Calcd for
1
C9H10S: C, 71.95; H, 6.71. Found: C, 72.09; H, 6.66. H NMR
(CDCl3): δ 7.05 (d, J ) 4.7 Hz, 1H, 2-H), 6.97 (d, J ) 4.7 Hz,
1H, 3-H), 3.09 (s, 2H, 4-H), 2.02 (br s, 6H, 5,6-Me). 13C NMR
(CDCl3): δ 149.0, 143.3, 138.3, 129.5, 122.5, 122.0, 39.4, 14.1,
11.7.
Com p lex 17. To a solution of 1.12 g (7.45 mmol) of 4 in 70
mL of toluene was added 3.0 mL of 2.5 M n-BuLi in hexanes.
This mixture was stirred 10 h at room temperature and 1 h
at 100 °C. Then, 2.49 g (7.48 mmol) of Cp*ZrCl3 was added at
-70 °C. The reaction mixture was stirred for 24 h at room
temperature and refluxed for 5 h. The hot mixture was filtered

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2851
(G4). The crystals that precipitated from the filtrate at -30
°C were separated, washed with 3 × 20 mL of cold toluene,
and dried in vacuo. Yield: 1.83 g (54%) of yellow crystals of
17. Anal. Calcd for C19H24Cl2SZr: C, 51.10; H, 5.42. Found:
C, 51.00; H, 5.47. 1H NMR (CD2Cl2): δ 7.09 (d, J ) 5.4 Hz,
1H, 2-H in C9H9S), 6.81 (d, J ) 5.4 Hz, 1H, 3-H in C9H9S),
5.80 (s, 1H, 4-H in C9H9S), 2.16 (s, 3H, 5-Me in C9H9S), 1.95
(s, 3H, 6-Me in C9H9S), 1.93 (s, 15H, C5Me5). 13C NMR (CD2-
Cl2): δ 133.7, 131.8, 128.7, 125.4, 119.0, 118.4, 107.3, 98.6,
16.4, 13.8, 13.7.
solution of 72 g (1.28 mol) of KOH in 200 mL of water was
added. This mixture was refluxed for 4 h to saponificate the
ester formed. Ethanol was distilled off. To this mixture was
added 800 mL of water and, then, 1 M HCl was added to pH
1. The substituted methylmalonic acid precipitated at 5 °C was
separated, washed with 3 × 200 mL of cold water, and dried.
Crude product was obtained after decarboxylation at 180 °C.
Fractional distillation gave 3-(2,5-dimethyl-3-thienyl)-2-me-
thylpropanoic acid as a white solid, bp 158 °C/5 mmHg. Yield:
50.5 g (71%). Anal. Calcd for C10H14O2S: C, 60.57; H, 7.12.
1
Bis(5,6-d im eth yl-4H-cyclop en ta [b]th ien -4-yl)(d im eth -
yl)sila n e (23). To a solution of 20.0 g (133 mmol) of 4 in 300
mL of a toluene/THF (5:1) mixture was added 53.2 mL (133
mmol) of 2.5 M n-BuLi in hexanes at -80 °C. This mixture
was stirred for 10 h at room temperature, then cooled to -40
°C, and 8.07 mL (8.58 g, 66.5 mmol) of Me2SiCl2 was added.
The resulting mixture was stirred for 36 h at room tempera-
ture and 4 h at 60 °C. Cold water (50 mL) was added dropwise.
The organic layer was separated, dried over K2CO3, and
evaporated to dryness. The bridged ligand was isolated using
flash chromatography over silica gel. First, 4 was separated
with hexanes as eluent. The product 23 as a mixture of rac
and meso isomers was obtained with a hexanes/methyl-tert-
butyl ether (10:1) mixture as eluent. Yield: 16.7 g (71%) of a
yellow solid. Anal. Calcd for C20H24S2Si: C, 67.36; H, 6.78.
Found: C, 67.51; H, 6.85. 1H NMR (CDCl3): rac δ 7.13 (m,
4H, 2,2′,3,3′-H), 3.46 (m, 2H, CHSi), 2.09 (s, 6H, 5,5′-Me), 2.01
(s, 6H, 6,6′-Me), -0.33 (s, 6H, Me2Si); meso δ 7.09 (d, J ) 4.7
Hz, 2H, 2,2′-H), 6.96 (d, J ) 4.7 Hz, 2H, 3,3′-H), 3.50 (m, 2H,
CHSi), 2.16 (s, 6H, 6,6′-Me), 2.12 (s, 6H, 5,5′-Me), -0.33 (s,
3H, MeSi), -0.40 (s, 3H, Me′Si). 13C NMR (CDCl3): rac and
meso δ 147.5, 147.4, 144.2, 144.1, 139.4, 139.3, 129.3, 129.1,
122.4, 122.3, 121.8, 121.7, 45.7, 45.4, 15.2, 15.0, 11.8, 11.7,
-6.3, -6.5, -6.7.
Com p lex r a c-29. To a solution of 16.7 g (46.9 mmol) of 23
in 470 mL of toluene was added 37.5 mL of 2.5 M n-BuLi in
hexanes at -40 °C. This mixture was stirred for 10 h at room
temperature, then 10.9 g (46.9 mmol) of ZrCl4 was added at
-40 °C. The resulting mixture was stirred for 48 h at room
temperature and refluxed for 5 h. The hot mixture was filtered
(G4); the precipitate was washed with 5 × 150 mL of hot
toluene. The crystals that precipitated from the combined
filtrate at -30 °C were separated, washed with 5 × 40 mL of
cold CH2Cl2, and dried in vacuo. Yield: 2.43 g (10%) of yellow
crystals of pure rac-29. Anal. Calcd for C20H22Cl2S2SiZr: C,
46.49; H, 4.29. Found: C, 46.55; H, 4.37. 1H NMR (CD2Cl2): δ
7.17 (d, J ) 5.38 Hz, 2H, 3,3′-H), 6.83 (d, J ) 5.38 Hz, 2H,
2,2′-H), 2.16 (s, 6H, 6,6′-Me), 1.88 (s, 6H, 5,5′-Me), 1.06 (s, 6H,
Me2Si).
3-(Ch lor om eth yl)-2,5-d im eth ylth iop h en e. A mixture of
84.3 g (0.75 mol) of 2,5-dimethylthiophene and 46 mL of 40%
HCl was prepared in a small vessel. While dry HCl gas was
bubbled through this mixture at 0 °C, 22.6 g (0.75 mol) of
paraform was slowly added during 2 h. Then, this mixture was
purged in 400 mL of cold water. The organic layer was
separated, and the aqueous one was extracted by 4 × 200 mL
of methyl-tert-butyl ether. The combined organic extracts were
washed with a saturated aqueous solution of Na2CO3, dried
over K2CO3, and evaporated to dryness. Fractional distillation
gave the title product as a colorless liquid, bp 77-90 °C/6
mmHg. Yield: 57.7 g (48%). Anal. Calcd for C7H9ClS: C, 52.33;
H, 5.65. Found: C, 52.49; H, 5.60. 1H NMR (CDCl3): δ 6.59
(m, 1H, 4-H), 4.43 (s, 2H, CH2), 2.35 (m, 3H, 5-Me), 2.34 (s,
3H, 2-Me).
3-(2,5-Dim eth yl-3-th ien yl)-2-m eth ylp r op a n oic Acid . To
a solution of sodium ethylate (prepared from 8.42 g (0.366 mol)
of sodium metal and 200 mL of dry ethanol) was added 61.7
mL (62.5 g, 0.359 mol) of diethylmethylmalonate at room
temperature. This mixture was stirred for 15 min, then 57.7
g (0.359 mmol) of 2-chloromethylthiophene in 65 mL of dry
ethanol was added. This mixture was stirred for 3.5 h, then a
Found: C, 60.64; H, 7.03. H NMR (CDCl3): δ 11.3 (s br, 1H,
COOH), 6.44 (s, 1H, 4-H), 2.87 (dd, J ) 13.8 Hz, J ) 6.4 Hz,
1H, CHH′), 2.67 (m, 1H, CH), 2.53 (dd, J ) 13.8 Hz, J ) 8.1
Hz, 1H, CHH′), 2.37 (s, 3H, 2-Me), 2.29 (s, 3H, 5-Me), 1.17 (d,
J ) 7.0 Hz, 3H, CHMe). 13C NMR (CDCl3): 183.2, 135.6, 134.4,
132.1, 127.1, 40.9, 31.9, 16.8, 15.4, 13.2.
1,3,5-Tr im eth yl-5,6-dih ydr o-4H-cyclopen ta[c]th ioph en -
4-on e (5). To polyphosphoric acid (prepared from 220 g of
P4O10 and 160 g of 85% H3PO4) was added a solution of 24.6 g
(0.124 mol) of 3-(2,5-dimethyl-3-thienyl)-2-methylpropanoic
acid in 90 mL of chlorobenzene for 15 min by vigorous stirring.
This mixture was left for 10 min and, then, immersed in 600
cm3 of ice. The product was extracted with 5 × 200 mL of ether.
The extract was washed with a saturated aqueous solution of
Na2CO3, dried over K2CO3, and evaporated to dryness. The
ketone was isolated using flash chromatography over silica gel
with a hexanes/methyl-tert-butyl ether (2:1) mixture as eluent.
Yield: 16.0 g (68%) of sandy solid. Anal. Calcd for C10H12OS:
1
C, 66.63; H, 6.71. Found: C, 66.49; H, 6.70. H NMR (CDCl3):
δ 2.98 (m, 2H, 6-H), 2.60 (s, 3H, 1-Me), 2.32 (m, 1H, 5-H), 2.29
(s, 3H, 3-Me), 1.28 (d, J ) 7.2 Hz, 3H, 5-Me). 13C NMR
(CDCl3): δ 201.3, 146.8, 140.1, 138.6, 126.3, 49.1, 29.0, 16.5,
12.9, 12.0.
1,3,5-Tr im eth yl-4H-cyclop en ta [c]th iop h en e (6). To a
solution of 16.0 g (89 mmol) of 5 in 130 mL of a THF/methanol
(2:1) mixture was slowly added 5.37 g (143 mmol) of NaBH4
for 1 h at 0 °C. This mixture was stirred for 10 h at room
temperature. To the resulting mixture was added 170 mL of
water, and then, 10% HCl was added to pH 1. 1,3,5-Trimethyl-
5,6-dihydro-4H-cyclopenta[c]thiophen-4-ol was extracted by 4
× 100 mL of CH2Cl2. The combined extract was washed with
a saturated aqueous solution of Na2CO3, dried over K2CO3, and
evaporated to dryness. A mixture of this product and a
catalytic quantity of p-toluenesulfonic acid in 700 mL of
toluene was refluxed for 10 min, passed through a short
column with silica gel, and evaporated to dryness. Yield: 11.3
g (78%) of a beige solid. Anal. Calcd for C10H12S: C, 73.12; H,
1
7.36. Found: C, 73.30; H, 7.44. H NMR (CDCl3): δ 6.15 (m,
1H, 6-H), 2.91 (m, 2H, 4-H), 2.32 (s, 3H, 1-Me), 2.27 (m, 3H,
3-Me), 2.01 (m, 3H, 5-Me). 13C NMR (CDCl3): δ 148.9, 146.9,
142.0, 124.8, 121.7, 118.5, 36.0, 17.7, 13.2, 13.0.
Dim eth yl[bis(1,3,5-tr im eth yl-4H-cyclop en ta [c]th ien -4-
yl)]sila n e (24). To a solution of 12.6 g (77 mmol) of 6 in 170
mL of toluene/THF (10:1) was added 62 mL (77 mmol) of 1.24
M of n-BuLi in hexanes at -80 °C. This mixture was stirred
for 1 h at room temperature, then 4.65 mL (4.95 g, 38 mmol)
of Me2SiCl2 was added at -40 °C. The mixture was stirred for
48 h at 20 °C and filtered (G4); toluene from the filtrate was
evaporated. The crude product was isolated using flash chro-
matography over silica gel with hexanes as eluent. Yield: 4.41
g (30%) of a white solid. Anal. Calcd for C22H28S2Si: C, 68.69;
H, 7.34. Found: C, 68.81; H, 7.39. 1H NMR (CDCl3): rac δ
6.13 (m, 2H, 6,6′-H, rac), 2.94 (m, 2H, 4,4′-H), 2.35 (s, 6H, 1,1′-
Me), 2.32 (s, 6H, 3,3′-Me), 2.05 (s, 6H, 5,5′-Me), -0.05 (s, 6H,
Me2Si); meso δ 6.18 (m, 2H, 6,6′-H), 2.94 (m, 4H, 4,4′-H), 2.34
(s, 6H, 1,1′-Me), 2.30 (s, 6H, 3,3′-Me), 2.03 (s, 6H, 5,5′-Me),
0.02 (s, 3H, MeSi), -0.02 (s, 3H, Me′Si). 13C NMR (CDCl3):
rac δ 150.2, 147.1, 144.1, 123.0, 120.5, 118.1, 41.4, 19.1, 15.0,
13.2, 3.5; meso δ 151.3, 147.6, 145.1, 122.6, 119.9, 117.8, 42.2,
18.9, 15.2, 13.5, 2.4, 2.7.

2852 Organometallics, Vol. 21, No. 14, 2002
Ryabov et al.
Mixtu r e of 2-Meth yl-2,3-d ih yd r o-1H-cyclop en ta [b][1]-
ben zoth iop h en -1-on e (7) a n d 2-Meth yl-1,2-d ih yd r o-3H-
cyclop en ta [b][1]ben zoth iop h en -3-on e (8). To a solution of
19.6 g (138 mmol) of P4O10 in 130 mL of methanesulfonic acid
was added 19.1 mL (112 mmol) of methacrylic acid at room
temperature, then 15.0 g (143 mmol) of melted 1-ben-
zothiophene was added dropwise for 15 min under vigorous
stirring at room temperature. This mixture was stirred ad-
ditionally for 30 min at this temperature, then for 30 min at
40 °C. The resulting mixture was poured in a cold solution of
261 g (1.89 mol) of K2CO3 in 1100 mL of water. The products
were extracted by 4 × 200 mL of CH2Cl2. The combined extract
was washed with a saturated aqueous solution of Na2CO3,
dried over K2CO3, and evaporated to dryness. Fractional
distillation gave a white solid, bp 132°C/0.3 mmHg. Yield: 14.8
g (66%) of 5:1 mixture of 7 and 8. Anal. Calcd for C12H10OS:
chromatography over silica gel with a hexanes/CH2Cl2 (20:1)
mixture as eluent. Yield: 5.33 g (15%) of a yellow solid of 25
as a mixture of rac/meso versions. Anal. Calcd for C26H24S2Si:
C, 72.85; H, 5.64. Found: C, 72.80; H, 5.55.
Com p lex m eso-30. To a solution of 5.33 g (12.4 mmol) of
25 in 100 mL of toluene was added 17.7 mL (24.9 mmol) of
1.40 M n-BuLi in hexanes at -40 °C. This mixture was stirred
for 10 h at room temperature, then 2.90 g (12.4 mmol) of ZrCl4
was added at -30 °C. The resulting mixture was stirred for
12 h at room temperature and 2 h at 70 °C. The crystals that
precipitated from the combined filtrate at -30 °C were
separated, washed with 2 × 10 mL of cold hexane, and dried
in vacuo. Yield: 2.14 g (29%) of orange crystals. Anal. Calcd
for C26H22Cl2S2SiZr: C, 53.04; H, 3.77. Found: C, 53.20; H,
1
3.71. H NMR (CD2Cl2): δ 7.70 (m, 2H, 5,5′-H), 7.55 (m, 2H,
8,8′-H), 7.31-7.21 (m, 4H, 6,6′,7,7′-H), 6.85 (s, 2H, 1,1′-H), 2.43
(s, 6H, 2,2′-Me), 1.19 (s, 3H, MeSi), 1.13 (s, 3H, Me′Si).
1-(1-Ben zoth ien -2-yl)-2-m eth yl-2-p r op en -1-on e (10). To
a solution of 30.0 g (0.223 mol) of 1-benzothiophene in 300 mL
of THF was added 160 mL (0.223 mol) of 1.40 M n-BuLi in
hexanes for 30 min at -80 °C. This mixture was stirred for
30 min at room temperature, and then, 10.0 g (0.112 mol) of
CuCN was added at -80 °C. The resulting mixture was stirred
for an additional 30 min at room temperature, then 26.0 g
(0.224 mol) of methacryloyl chloride was added for 10 min at
-80 °C. The mixture was stirred for 10 h at room temperature,
then 170 mL of 10% HCl was added. The organic layer was
separated, and the aqueous one was extracted by 4 × 150 mL
of CH2Cl2. The combined extract was washed with a saturated
aqueous solution of Na2CO3, dried over K2CO3, and evaporated
to dryness. The product was isolated using flash chromatog-
raphy over silica gel with a hexanes/CH2Cl2 (4:1) mixture as
eluent. Yield: 20.2 g (45%) of pink crystals of 10. Anal. Calcd
1
C, 71.25; H, 4.98. Found: C, 71.27; H, 5.09. H NMR (CDCl3):
δ 8.23 (m), 7.86 (m), 7.78 (m), 7.47 (m), 7.43 (m), 7.36 (m), 3.51
(dd, J ) 17.9 Hz, J ) 7.0 Hz), 3.45 (dd, J ) 17.4 Hz, J ) 6.7
Hz), 3.08 (m), 2.86 (dd, J ) 17.9 Hz, J ) 2.6 Hz), 2.77 (dd, J
) 17.4 Hz, J ) 2.6 Hz), 1.41 (s), 1.39 (s), 1.37(s).
Mixt u r e of 2-Met h yl-1H -cyclop en t a [b][1]b en zot h io-
p h en e a n d 2-Meth yl-3H-cyclop en ta [b][1]ben zoth iop h en e
(9). To a solution of 14.8 g (73 mmol) of the above-mentioned
mixture of 7 and 8 in 100 mL of a THF/methanol (2:1) mixture
was slowly added 4.15 g (110 mmol) of NaBH4 at 0 °C. This
mixture was stirred for 10 h at room temperature, then 800
mL of water and 10% HCl (to pH 1) were added. A mixture of
the cyclopentanols was extracted by 3 × 50 mL of CH2Cl2. The
combined extract was washed with a saturated aqueous
solution of Na2CO3, dried over K2CO3, and evaporated to
dryness. A mixture of the resulting yellow oil, 500 mL of
toluene, and a catalytic quantity of p-toluenesulfonic acid was
refluxed for 20 min. The product was isolated using flash
chromatography over silica gel with a hexanes/methyl-tert-
butyl ether (10:1) mixture as eluent. Yield: 12.6 g (92%) of
white crystals of 9. Anal. Calcd for C10H12S: C, 77.37; H, 5.41.
1
for C12H10OS: C, 71.25; H, 4.98. Found: C, 71.09; H, 5.04. H
NMR (CDCl3): 7.88 (m, 1H, 3-H), 7.87 (m, 1H, 4-/7-H), 7.85
(m, 1H, 7-/4-H), 7.45 (m, 1H, 5-/6-H), 7.39 (m, 1H, 6-/5-H), 5.89
(m, 1H, HH′CdC), 5.86 (m, 1H, HH′CdC), 2.10 (m, 3H, Me).
2-Met h yl-1,2-d ih yd r o-3H -cyclop en t a [b][1]b en zot h io-
p h en -3-on e (8). To 144 mL of 96% H2SO4 was added 20.2 g
(99.8 mmol) of 10 in 20 mL of chlorobenzene. This mixture
was stirred for 1 h at room temperature and then immersed
in 800 cm3 of ice. The product was extracted by 4 × 200 mL of
ether. The extract was washed with a saturated aqueous
solution of Na2CO3, dried over K2CO3, and evaporated to
dryness. Yield: 18.9 g (94%) of a white solid. Anal. Calcd for
1
Found: C, 77.14; H, 5.50. H NMR (CDCl3): δ 7.79 (m), 7.77
(m), 7.73 (m), 7.59 (m), 7.33 (m), 7.29 (m), 7.23 (m), 7.15 (m),
6.64 (m), 3.33 (d, J ) 1.25 Hz), 3.26 (d, J ) 1.24 Hz), 2.19 (d,
J ) 1.74 Hz), 2.17 (d, J ) 1.74 Hz). 13C NMR (CDCl3): δ 148.3,
146.3, 144.4, 144.3, 139.9, 132.2, 128.0, 126.5, 124.0, 123.9,
123.7, 123.4, 123.1, 123.0, 122.7, 122.3, 121.7, 121.5, 121.0,
119.8, 40.7, 38.8, 16.9, 16.8.
Com p lex 15. To a solution of 5.00 g (26.8 mmol) of 9 in
260 mL of toluene was added 16.3 mL (26.8 mmol) of 1.64 M
n-BuLi in hexanes. This mixture was stirred for 1 h at room
temperature and 3 h at 60 °C. Then, 3.13 g (13.4 mmol) of
ZrCl4 was added at -40 °C. The resulting mixture was stirred
for 24 h at 20 °C, refluxed for 2 h, and filtered (G4). The
precipitate was washed with 5 × 100 mL of hot toluene. The
crystals that precipitated from the combined filtrate at -30
°C were separated and dried in vacuo. Yield: 1.60 g (23%) of
yellow crystals of 15 as a mixture of rac and meso versions.
Anal. Calcd for C24H18Cl2S2Zr: C, 54.12; H, 3.41. Found: C,
54.01; H, 3.36. 1H NMR (CD2Cl2): δ 7.83 (m), 7.79 (m), 7.71
(m), 7.70 (m), 7.44-7.35 (m), 6.47 (m), 6.27 (m), 5.82 (m), 5.44
(m), 2.01 (s), 1.98 (s). 13C NMR (CD2Cl2): δ 138.1, 137.0, 135.0,
134.4, 133.6, 133.5, 133.4, 133.1, 132.9, 131.6, 131.2, 128.2,
128.1, 126.8, 126.6, 125.1, 125.0, 124.8, 124.6, 109.1, 107.3,
106.3, 18.5, 18.3.
Dim eth yl[bis(2-m eth yl-3H-cyclopen ta[b][1]ben zoth ien -
3-yl)]sila n e (25). To a solution of 15.0 g (80.6 mmol) of 9 in
230 mL of a toluene/THF (10:1) mixture was added dropwise
39.0 mL (80.6 mmol) of 2.05 M n-BuLi in hexanes at 0 °C.
This mixture was stirred for 1 h at room temperature and 1 h
at 70 °C. Then, 4.89 mL (40.3 mmol) of Me2SiCl2 was added
at -30 °C. The resulting mixture was stirred for 10 h at room
temperature and 1 h at 60 °C. Then, 100 mL of water was
added. The organic layer was separated, dried over K2CO3, and
evaporated to dryness. The product was isolated using flash
C
12H10OS: C, 71.25; H, 4.98. Found: C, 71.22; H, 5.92. 1H
NMR (CDCl3): δ 7.84-7.90 (m, 2H, 6,7-H), 7.52-7.42 (m, 2H,
5,8-H), 3.46 (dd, J ) 17.3 Hz, J ) 6.7 Hz, 1H, 1-H), 3.10 (m,
1H, 2-H), 2.78 (dd, J ) 17.3 Hz, J ) 2.7 Hz, 1H, 1′-H), 1.41 (d,
J ) 7.4 Hz, 3H, 2-Me).
2,3-Dim eth yl-1H-cyclop en ta [b][1]ben zoth iop h en e (11).
To 37.5 mL (60,8 mmol) of 1.62 M MeLi in ether was added
dropwise a solution of 9.78 g (48.6 mmol) of 8 in 50 mL of THF
for 30 min at -80 °C. The reaction mixture was stirred 1.5 h
at room temperature, then cooled to -10 °C, and 6.08 mL of
40% HCl was added dropwise. This mixture was stirred for
40 min at 20 °C. The organic layer was separated, and the
aqueous one was extracted by 2 × 40 mL of methyl-tert-butyl
ether. The combined extract was washed with a saturated
aqueous solution of Na2CO3, dried over K2CO3, and evaporated
to dryness. Yield: 9.20 g (95%) of pink crystals of 11. Anal.
Calcd for C13H12S: C, 77.95; H, 6.04. Found: C, 78.06; H, 6.10.
1H NMR (CDCl3): δ 7.80 (m, 1H, 5-H), 7.62 (m, 1H, 8-H), 7.30
(m, 1H, 6-H), 7.15 (m, 1H, 7-H), 3.28 (m, 2H, 1-H), 2.09 (s,
3H, 3-Me), 2.06 (m, 3H, 2-Me). 13C NMR (CDCl3): δ 149.1,
142.4, 139.9, 137.4, 135.3, 130.1, 124.3, 123.8, 121.8, 120.1,
39.1, 14.4, 11.7.
Com p lex 18. To a solution of 0.88 g (4.4 mmol) of 11 in 70
mL of toluene was added 1.76 mL (4.4 mmol) of 2.5 M n-BuLi
in hexanes. This mixture was stirred for 10 h at room
temperature and 1 h at 100 °C, then 1.46 g (4.4 mmol) of

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2853
Cp*ZrCl3 was added. The resulting mixture was stirred for
24 h at room temperature and refluxed for 5 h. This hot
mixture was filtered (G4); the filtrate was evaporated to ca.
2/3 of its starting volume. Hexane (100 mL) was added. The
formed precipitate was filtered off (G3) and dried in vacuo.
Yield: 0.79 g (36%) of yellow crystals of 18. Anal. Calcd for
1,2-Dim et h yl-1,2-d ih yd r o-3H -cyclop en t a [b][1]b en zo-
th iop h en -3-on e (13). To 17 mL of 96% H2SO4 was added a
solution of 2.47 g (11.4 mmol) of 12 in 2.5 mL of chlorobenzene
with vigorous stirring. This mixture was stirred for 1 h at room
temperature, then immersed in 90 cm3 of ice. The product was
extracted by 3 × 100 mL of ether. The extract was washed
with a saturated aqueous solution of Na2CO3, dried over K2-
CO3, and evaporated to dryness. Yield: 2.39 g (97%) of beige
solid as a 1:1 mixture of cis/trans isomers. Anal. Calcd for
C
23H26Cl2SZr: C, 55.62; H, 5.28. Found: C, 55.68; H, 5.31. 1H
NMR (CD2Cl2): δ 7.75 (m, 1H, 5-H in C13H11S), 7.66 (m, 1H,
8-H in C13H11S), 7.31-7.23 (m, 2H, 6,7-H in C13H11S), 6.12 (s,
1H, 1-H in C13H11S), 2.19 (s, 3H, 3-Me in C13H11S), 2.00 (s,
3H, 2-Me in C13H11S), 1.90 (s, 15H, C5Me5). 13C NMR (CD2-
Cl2): δ 133.0, 129.9, 129.6, 127.2, 126.2, 125.6, 125.5, 125.3,
123.4, 122.8, 107.3, 100.1, 15.9, 14.3, 13.8.
C
13H12OS: C, 72.19; H, 5.59. Found: C, 72.05; H, 5.54. 1H
NMR (CDCl3): δ 7.91 (m, 1H, 8-H), 7.46 (m, 1H, 5-H), 7.35-
7.20 (m, 2H, 6,7-H), 3.73 (m, 0.5H, 1-H), 3.19 (m, 1H, 1,2-H),
2.61 (m, 0.5H, 2-H), 1.57 (d, J ) 7.2 Hz, 1.5H, 1-/2-Me), 1.39
(d, J ) 7.5 Hz, 1.5H, 2-/1-Me), 1.36 (d, J ) 7.2 Hz, 1.5H, 1-/
2-Me), 1.30 (d, J ) 7.5 Hz, 1H, 1.5H, 2-/1-Me). 13C NMR
(CDCl3): δ 201.1, 200.7, 168.3, 166.8, 147.0, 146.7, 139.5, 133.9,
133.8, 130.7, 129.7, 128.5, 127.8, 126.4, 124.9, 124.6, 124.2,
124.0, 55.7, 50.2, 40.6, 35.1, 19.0, 16.3, 15.4, 11.2.
Mixtu r e of 1,2-Dim eth yl-1H- a n d 1,2-Dim eth yl-3H-
cyclop en ta [b][1]ben zoth iop h en es (14). To a solution of
2.39 g (11.1 mmol) of 13 in 15 mL of a THF/methanol (2:1)
mixture was added slowly 0.62 g (16.6 mmol) of NaBH4 for 1
Bis(2,3-d im eth yl-1H-cyclop en ta [b][1]ben zoth ien -1-yl)-
(d im eth yl)sila n e (26). To a solution of 18.2 g (90.7 mmol) of
11 in 180 mL of a toluene/THF (10:1) mixture was added 64.8
mL of 1.4 M n-BuLi in hexanes at -80 °C. This mixture was
stirred for 10 h at room temperature and 4 h at 60 °C. To this
mixture was added 5.49 mL (45.3 mmol) of Me2SiCl2 at -40
°C. The resulting mixture was stirred for 10 h at room
temperature and 1 h at 60 °C. Then, 100 mL of water was
added; the organic layer was separated, dried over K2CO3, and
evaporated to dryness. The crude product was crystallized from
a hexane/pentane mixture. Yield: 4.83 g (23%) of a yellow solid
of a rac/meso mixture of 26. Anal. Calcd for C28H28SSi: C,
h
at 0 °C. This mixture was stirred for 10 h at room
temperature, then 20 mL of water and 10% HCl (to pH 1.0)
were added. The formed cyclopentanol was extracted by 3 ×
75 mL of CH2Cl2. The extract was washed with a saturated
aqueous solution of Na2CO3, dried over K2CO3, and evaporated
to dryness. Toluene (75 mL) and a catalytic quantity of
p-toluenesulfonic acid were added to the resulting yellow oil.
This mixture was refluxed for 10 min, then passed through
short column with silica gel using hexanes/methyl-tert-butyl
ether (10:1) as eluent. The combined organic extract was
evaporated to dryness. Yield: 1.68 g (76%) of a beige solid of
a mixture of the title isomers. Anal. Calcd for C13H12S: C,
1
73.63; H, 6.18. Found: C, 73.55; H, 6.12. H NMR (CDCl3): δ
7.81 (m), 7.79 (m), 7.64 (m), 7.50 (m), 7.25-7.09 (m), 3.99 (m),
3.88 (m), 2.19 (m), 2.11 (m), 2.11 (m), 2.10 (s), -0.24 (s), -0.27
(s), -0.41 (s). 13C NMR (CDCl3): δ 147.2, 147.0, 142.0, 141.6,
141.5, 138.7, 138.5, 134.6, 134.5, 129.6, 129.5, 124.0, 123.6,
123.5, 123.4, 123.3, 121.4, 121.3, 121.0, 120.9, 45.9, 45.8, 15.4,
15.3, 11.5, 11.4, -4.5, -4.7, -5.5.
Mixtu r e of r a c- a n d m eso-31. To a solution of 2.00 g (4.38
mmol) of 26 in 100 mL of toluene was added 3.50 mL (8.76
mmol) of 2.5 M n-BuLi in hexanes at -40 °C. This mixture
was stirred for 10 h at room temperature, then 1.65 g (4.38
mmol) of ZrCl4(THF)2 was added at -40 °C. The resulting
mixture was stirred for 12 h at room temperature and refluxed
for an additional 5 h. The precipitate containing the product
and LiCl was filtered off (G3), washed with 3 × 10 mL of THF
to dissolve LiCl, and dried in vacuo. Yield: 0.98 g (36%) of
yellow crystals of a rac/meso mixture of 31. An exact ratio of
rac to meso isomers cannot be defined because of their low
solubility in all common solvents. Anal. Calcd for C28H26Cl2S2-
SiZr: C, 54.52; H, 4.25. Found: C, 54.44; H, 4.19. 1H NMR
(CD2Cl2): meso δ 8.12 (m, 2H, 5,5′-H in C13H10S), 7.38 (m, 2H,
8,8′-H in C13H10S), 7.09 (m, 2H, 7,7′-H in C13H10S), 7.02 (m,
2H, 6,6′-H in C13H10S), 2.24 (s, 6H, 3,3′-Me in C13H10S), 2.18
(s, 6H, 2,2′-H in C13H10S), 1.63 (s, 3H, MeSi), 1.25 (s, 3H,
Me′Si).
1
77.95; H, 6.04. Found: C, 77.88; H, 6.11. H NMR (CDCl3): δ
7.94 (m), 7.80 (m), 7.67 (m), 7.32 (m), 7.22 (m), 7.16 (m), 7.64
(m), 3.35-3.27 (m), 2.29 (m), 2.11 (m), 2.05 (m), 1.39 (d, J )
7.7 Hz). 13C NMR (CDCl3): δ 145.8, 144.8, 144.7, 143.7, 143.1,
139.7, 137.9, 134.8, 133.2, 131.0, 124.2, 123.9, 123.8, 123.5,
122.8, 122.0, 121.0, 120.9, 119.8, 45.0, 40.6, 29.7, 15.1, 15.0,
13.8, 12.2.
Com p lex 19. To a solution of 0.78 g (3.90 mmol) of 14 in
70 mL of toluene was added 1.56 mL (3.90 mmol) of 2.5 M
n-BuLi in hexanes at room temperature. This mixture was
stirred for 10 h at room temperature, then 1 h at 100 °C. To
this mixture was added 1.30 g (3.90 mmol) of Cp*ZrCl3 at -70
°C. It was stirred for 24 h at room temperature, then refluxed
for 5 h. This hot reaction mixture was filtered; the filtrate was
evaporated to dryness. Then, 100 mL of hexane was added.
The formed precipitate was filtered off (G3), washed with 15
mL of cold hexane, and dried in vacuo. Yield: 0.68 g (35%) of
a yellow solid. Anal. Calcd for C23H26Cl2SZr: C, 55.62; H, 5.28.
(2E)-1-(1-Ben zoth ien -2-yl)-2-m eth yl-2-bu ten -1-on e (12).
The respective cuprate was prepared analogously to the
procedure described for the synthesis of 10 starting from 2.00
g (15.0 mmol) of 1-benzothiophene in 20 mL of THF, 12.4 mL
(15.0 mmol) of 1.21 M n-BuLi in hexanes, and 0.67 g (7.5 mmol)
of CuCN. To this mixture was added 1.78 g (15.0 mmol) of
(2E)-2-methyl-2-butenoyl chloride at -80 °C. The resulting
mixture was stirred for 10 h at room temperature, then 10
mL of 10% HCl was added. The organic layer was separated,
and the aqueous one was extracted by 3 × 50 mL of CH2Cl2.
The combined extract was washed with a saturated aqueous
solution of Na2CO3, dried over K2CO3, and evaporated to
dryness. The product was isolated using flash chromatography
over silica gel with a hexane/CH2Cl2 (4:1) mixture as eluent.
Yield: 2.47 g (76%) of beige solid. Anal. Calcd for C13H12OS:
1
Found: C, 55.77; H, 5.30. H NMR (CD2Cl2): δ 7.88 (m, 1H,
5-H in C13H11S), 7.62 (m, 1H, 8-H in C13H11S), 7.39 (m, 1H,
6-H in C13H11S), 7.30 (m, 1H, 7-H in C13H11S), 5.84 (s, 1H, 1-H
in C13H11S), 2.42 (s, 3H, 1-Me in C13H11S), 2.00 (s, 3H, 2-Me
in C13H11S), 1.95 (s, 15H, C5Me5). 13C NMR (CD2Cl2): δ 139.4,
134.8, 131.7, 127.5, 126.3, 125.8, 125.5, 124.5, 121.7, 121.1,
107.3, 100.3, 15.7, 13.8, 13.6.
Bis(1,2-d im eth yl-3H-cyclop en ta [b][1]ben zoth ien -3-yl)-
(d im eth yl)sila n e (27). To a solution of 20.3 g (102 mmol) of
14 in 200 mL of toluene/THF (10:1) mixture was added 73 mL
(102 mmol) of 1.4 M n-BuLi in hexanes at -80 °C. This mixture
was stirred for 10 h at room temperature and 4 h at 60 °C,
then 6.16 mL (51 mmol) of Me2SiCl2 was added at -40 °C.
The mixture was stirred for 10 h at room temperature and 1
h at 60 °C. To the resulting mixture was added 100 mL of
water at room temperature. The organic layer was separated
and evaporated to dryness. The residue was washed with 70
mL of hexane and dried in vacuo. Yield: 19.2 g (83%) of pure
meso-30 as a yellow solid. Anal. Calcd for C28H28S2Si: C, 73.65;
1
C, 72.19; H, 5.59. Found: C, 71.96; H, 5.50. H NMR (CDCl3):
δ 7.85-7.82 (m, 2H, 4,7-H in C8H5S), 7.75 (m, 1H, 3-H in
C8H5S), 7.44-7.34 (m, 2H, 5,6-H in C8H5S), 6.68 (m, 1H, MeCd
CHMe), 1.99 (m, 3H, MeCdCHMe), 1.92 (m, 3H, MeCdCHMe).
13C NMR (CDCl3): δ 191.5, 143.3, 142.4, 139.1, 138.9, 137.7,
130.3, 127.1, 125.9, 125.0, 122.9, 14.9, 12.9.

Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p lexes 16, 17, 20, 21, 24, 28, 29, 31, a n d 32
16
17
20‚(C7H8)4
21
24
28
29
31
32
formula
fw
color
cryst syst
space group
a (Å)
C
19H24Cl2SZr
C19H24Cl2SZr
446.56
white
triclinic
P1h
9.644(2)
14.207(4)
14.786(4)
100.396(4)
97.017(4)
105.615(4)
1887.7(8)
4
C68H94Cl12Li2Zr4 C47H58Cl4S2Zr2
C22H28S2Si
384.65
white
triclinic
P1h
8.7053(9)
10.5026(10)
12.2813(12)
98.354(2)
102.703(2)
106.605(2)
1023.35(18)
2
C20H22Cl2S2SiZr C20H22Cl2S2SiZr C28H26Cl2S2SiZr C28H26Cl2S2SiZr
446.56
white
1715.60
yellowish
monoclinic
C2/c
1011.29
beige
triclinic
P1h
516.71
yellow
triclinic
P1h
9.18(2)
9.38(2)
13.194(19)
81.74(7)
81.43(7)
63.39(6)
1001(4)
2
516.71
yellow
triclinic
P1h
8.7712(15)
9.1736(15)
14.473(2)
79.752(4)
88.813(4)
63.715(3)
1025.3(3)
2
616.82
yellow
triclinic
P1h
9.2891(15)
11.8935(15)
24.581(4)
97.633(4)
94.147(3)
110.442(3)
2501.4(7)
4
616.82
yellow
triclinic
P1h
9.792(4)
10.288(4)
13.532(6)
81.450(8)
86.535(8)
71.289(7)
1276.6(9)
2
orthorhombic
Pca2(1)
16.763(3)
8.9146(14)
25.051(4)
90
23.849(4)
14.147(2)
22.314(3)
90
91.768(12)
90
8.536(10)
8.644(8)
17.563(16)
86.96(3)
79.14(3)
61.21(3)
1114.4(19)
1
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
90
90
3743.6(10)
8
1.585
0.981
1824
7525.0(19)
4
Fcalcd (g cm-3
)
1.571
0.973
912
1.514
1.507
1.248
0.321
412
1.715
1.674
1.638
1.605
µ (mm-1
F(000)
)
1.003
0.834
1.088
1.062
0.886
0.868
3488
520
524
524
1256
628
no. of reflns collected 33704
no. of ind reflns 11 837
17 801
8154
9326
9117
9288
5889
8503
5847
9619
12 242
5927
29 969
14 464
13 111
6128
9641a
[R(int) ) 0.0427] [R(int) ) 0.0295] [R(int) ) 0.0238] [R(int) ) 0.0510] [R(int) ) 0.0138]
[R(int) ) 0.1105] [R(int) ) 0.0506] [R(int) ) 0.0487]
no. of data/restraints/ 11 806/1/415
params
8154/0/415
9117/0/392
5839/0/272
5847/0/334
9641/176/248
5909/1/258
14464/0/821
6095/0/411
goodness-of-fit on F2 0.980
1.155
1.050
0.948
1.100
0.861
0.745
0.881
0.855
final R indices
[I>2σ(I)]
R1 ) 0.0522,
R1 ) 0.0785,
R1 ) 0.0298,
R1 ) 0.0610,
R1 ) 0.0499,
R1 ) 0.0838,
R1 ) 0.0674,
R1 ) 0.0545,
R1 ) 0.0464,
wR2 ) 0.1236
R1 ) 0.0654,
wR2 ) 0.1349
wR2 ) 0.1861
R1 ) 0.0986,
wR2 ) 0.1988
wR2 ) 0.0729
R1 ) 0.0421,
wR2 ) 0.0765
wR2 ) 0.1450
R1 ) 0.0830,
wR2 ) 0.1756
wR2 ) 0.1376
R1 ) 0.0574,
wR2 ) 0.1477
wR2 ) 0.2036
R1 ) 0.1314,
wR2 ) 0.2279
wR2 ) 0.1280
R1 ) 0.1531,
wR2 ) 0.1708
wR2 ) 0.1164
R1 ) 0.0878,
wR2 ) 0.1269
wR2 ) 0.0963
R1 ) 0.0858,
wR2 ) 0.1171
R indices (all data)
largest diff. peak and 3.227 and -1.057 2.272 and -0.757 0.828 and -0.608 1.840 and -1.407 1.277 and -0.351 1.542 and -1.043 1.006 and -0.709 2.332 and -0.801 1.489 and -0.730
hole, e‚Å-3
a
The refinement of 28 was carried out against twinned data (HKLF 5), and thus the Rint was not calculated.

Zirconium Complexes with Cyclopentadienyl Ligands
Organometallics, Vol. 21, No. 14, 2002 2855
H, 6.18. Found: C, 73.58; H, 6.11. 1H NMR (CDCl3): δ 7.99
(m, 2H, 5,5′-H), 7.80 (m, 2H, 8,8′-H), 7.36 (m, 2H, 6,6′-H), 7.24
(m, 2H, 7,7′-H), 3.83 (m, 2H, 3,3′-H), 2.40 (s, 6H, 1,1′-Me), 2.21
analysis of the reciprocal lattice in 28 by means of the RLAT
program has revealed the twinning which was solved using
GEMINI 1.0.28 The refinement of 28 was carried out taking
into consideration the possible overlap of the reflections from
two components of the twin crystal. The structures were solved
by direct methods and refined by full-matrix least-squares
against F2 in the anisotropic approximation for all non-
hydrogen atoms. All hydrogen atoms were placed in geo-
metrically calculated positions and included in the refinement
procedure using a riding model. The H(1M) atom in the
structure 20 was refined in isotropic approximation. All
calculations were performed using SHELXTL-97 software29 on
an IBM PC/AT.
(s, 6H, 2,2′-Me), -0.21 (s, 3H, MeSi), -0.29 (s, 3H, Me′Si). 13
C
NMR (CDCl3): δ 144.7, 144.2, 140.7, 138.8, 133.2, 130.9, 123.9,
123.3, 122.7, 120.9, 46.3, 15.1, 12.4, -6.4, -8.2.
Mixtu r e of r a c- a n d m eso-32. To a solution of 17.3 g (37.9
mmol) of 27 in 380 mL of toluene was added 54.1 mL (75.8
mmol) of 1.4 M n-BuLi in hexanes at -40 °C. This mixture
was stirred for 10 h at room temperature, then 9.27 g (39.8
mmol) of ZrCl4 was added at -40 °C. The resulting mixture
was srirred for 12 h at room temperature and refluxed for an
additional 5 h. The precipitate containing the product and LiCl
was filtered off (G3), washed with 4 × 40 mL of THF to dissolve
LiCl, and dried in vacuo. Yield: 7.62 g (33%) of yellow crystals
of a rac/meso mixture of 32. An exact ratio of rac to meso
isomers cannot be defined because of their low solubility in
all common solvents. Anal. Calcd for C28H26Cl2S2SiZr: C, 54.52;
H, 4.25. Found: C, 54.69; H, 4.32. 1H NMR (CD2Cl2): rac δ
7.86 (m, 2H, 5, 5′-H), 7.64 (m, 2H, 8,8′-H), 7.39 (m, 2H, 6,6′-
H), 7.32 (m, 2H, 7,7′-H), 2.36 (s, 6H, 1,1′-Me), 2.13 (s, 6H, 2,2′-
Me), 1.21 (s, 6H, Me2Si); meso δ 7.77 (m, 2H, 5,5′-H), 7.54 (m,
2H, 8,8′-H), 7.28 (m, 2H, 6,6′-H), 7.21 (m, 2H, 7,7′-H), 2.47 (s,
6H, 1,1′-Me), 2.10 (s, 6H, 2,2′-Me), 1.22 (s, 3H, MeSi), 1.11 (s,
3H, Me′Si).
Ack n ow led gm en t. Financial support from the Rus-
sian Foundation for Basic Research (Grant No. 01-03-
32699), President of the Russian Federation (Grant No.
02-03-99352), International Science and Technology
Center (Grant No. 1036/99), and ExxonMobil Chemical
Company is gratefully acknowledged. We thank the
Crystallography Center of the Institute of Organoele-
ment Compounds of RAS for help in the X-ray measure-
ments and refinements. We also thank Prof. I. P.
Beletskaya.
X-r a y Str u ctu r a l Deter m in a tion s of 16, 17, 20, 21, 24,
28, 29, 31, a n d 32. Intensities of reflections were measured
with a SMART 1000 CCD diffractometer (graphite monochro-
mated Mo KR radiation, λ ) 0.71073 Å) at 110(2) K for all
complexes exept 20. Data collection for 20 was performed using
a Syntex P21 diffractometer at 120(2) K. Crystallographic data
for 16, 17, 20, 21, 24, 28, 29, 31, and 32 are listed in Table 1
(see also Supporting Information).
Reflection intensities were integrated using SAINT soft-
ware26 and corrected for absorption by semiempirical methods
(SADABS program27) for all complexes exept 20. Data reduc-
tion for 20 was performed using Siemens P3 software. The
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, data collection, structure solution and refinement pa-
rameters, atomic coordinates, anisotropic thermal parameters,
and bond lengths and angles for 16, 17, 20, 21, 24, 28, 29, 31,
and 32. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM010810Z
(27) Sheldrick, G. M. SADABS; Bruker AXS Inc.: Madison, WI,
1997.
(28) Gemini 1.0, The program package for the twining solution, v.
1.0; Bruker AXS, Madison, WI, 1998.
(26) SMART, Version 5.051, and SAINT, Version 5.00, Area detector
control and integration software; Bruker AXS Inc.: Madison, WI, 1998.
(29) Sheldrick, G. M., SHELXTL-97, Version 5.10; Bruker AXS Inc.,
Madison, WI, 1997.