Synthesis and cyclic voltammetry of 1,2,3-trisubstituted bis(cyclopentadienyl)zirconium dichlorides

Article abstract of DOI:10.1016/S0022-328X(02)01665-0

The synthesis of the 1,2,3-trisubstituted cyclopentadienes 3-10 and their corresponding zirconocene dichlorides 11-18 from commercially available internal alkynes is presented. The solid state structures of the differently substituted zirconocenes 11-13 and 15-17 were examined by means of X-ray analysis. The bite angles have shown not to be dependent on the substitution pattern of the cyclopentadienyl ligand. Cyclic voltammetry was used to measure the effect of introducing electron withdrawing and donating groups at the five membered ligand on the Lewis acidity of the zirconium central atom.

Full text of DOI:10.1016/S0022-328X(02)01665-0

Journal of Organometallic Chemistry 658 (2002) 242ꢀ250
/
www.elsevier.com/locate/jorganchem
Synthesis and cyclic voltammetry of 1,2,3-trisubstituted
bis(cyclopentadienyl)zirconium dichlorides
Bernhard J. Rausch, Rolf Gleiter *, Frank Rominger
Organisch-Chemisches Institut, Universitat Heidelberg, INF 270, D-69120 Heidelberg, Germany
¨
Received 18 March 2002; accepted 7 June 2002
Abstract
The synthesis of the 1,2,3-trisubstituted cyclopentadienes 3ꢀ
commercially available internal alkynes is presented. The solid state structures of the differently substituted zirconocenes 11ꢀ
15ꢀ17 were examined by means of X-ray analysis. The bite angles have shown not to be dependent on the substitution pattern of the
/
10 and their corresponding zirconocene dichlorides 11ꢀ
/18 from
/13 and
/
cyclopentadienyl ligand. Cyclic voltammetry was used to measure the effect of introducing electron withdrawing and donating
groups at the five membered ligand on the Lewis acidity of the zirconium central atom. # 2002 Published by Elsevier Science B.V.
Keywords: Zirconocene dichloride; Cyclic voltammetry; Cyclopentadiene; PausonꢀKhand reaction
/
1. Introduction
However, most zirconocene based catalysts incorpo-
rate many different substituents at the same time at the
cyclopentadienyl unit and therefore we found it of
interest to take a closer look at the influence of the
specific electronic nature of each substituent at the five-
membered ligand. Since especially the stereoselective
synthesis of bis(trisubstituted) metallocenes has seen
rising attention in recent publications [8], we envisioned
to elucidate the effect of the electronic nature of the
substituents in these kind of catalyst systems.
The synthesis of substituted cyclopentadienyls, which
were often used as ligands in organometallic chemistry,
is strongly connected with the search for modified
stereospecific and highly versatile metallocene catalysts
for olefin polymerization. The substitution pattern of
the ligand core has proven to be crucial for the reactivity
of metallocene dichlorides (Cp2MCl2) [1] like zircono-
cene [2,3b] or titanocene [3] derivatives.
In this work we report the synthesis of several 1,2,3-
trisubstituted cyclopentadienes and their zirconocene
dichlorides. Additionally, the study of the redoxpoten-
tials of the corresponding metallocenes by means of
cyclic voltammetry is presented.
The stability of the active species in the polymeriza-
tion reaction can be mainly attributed to steric and
electronic effects. Especially, the steric influence of
cyclopentadienyl ring substituents on the stereospecifi-
city of olefin polymerization by zirconocenes has been
extensively examined in experimental studies [4] as well
as model calculations [5]. To investigate the electronic
effects of the substitution pattern at the ligand core of
metallocenes ESCA [6] as well as cyclic voltammetry [7]
have been used. For instance, it has been shown that the
redox potential of zirconocene dichlorides is depending
on the number of trimethylsilyl-groups [7c] at the
cyclopentadienyl ligand.
2. Results
To generate an easy access to 1,2,3-trisubstituted
cyclopentadienes we had to develop a straight forward
synthesis of 1,2-disubstituted cyclopentenones which are
allowed to react with differently substituted aryllithium
reagents in a Grignard type reaction to yield the
corresponding cyclopentadienes. Even though many
methods have been reported in the literature for the
synthesis of cyclopentenones, they often suffer from not
* Corresponding author. Tel.: ꢁ
/
49-6221-548-400; fax: ꢁ49-6221-
/
544-205
E-mail address: rolf.gleiter@urz.uni-heidelberg.de (R. Gleiter).
0022-328X/02/$ - see front matter # 2002 Published by Elsevier Science B.V.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 6 5 - 0

B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ
/250
243
being general [9] as well as from producing mostly
moderate yields [10] or isomeric mixtures [11]. There-
fore, we synthesized the ketones from commercially
available twofold substituted alkynes (2-butyne and 3-
hexyne) and applied the PausonꢀKhand [12] protocol
/
using ethylene [13] as olefin component in toluene
solution in the presence of DMSO as promotor (Scheme
1). The cyclopentenones 1 and 2 were isolated in 68ꢀ
/
99% yield.
To generate the corresponding cyclopentadienes, 1
and 2 were allowed to react with several aryllithium
reagents [14] in diethyl ether at ꢂ
acidic hydrolysis the cyclopentadienes 3ꢀ
lated in very high yields (Scheme 2).
Treatment of 3ꢀ10 in toluene solution with 1 equiva-
/
78 8C and after mild
/
10 were iso-
Scheme 2.
/
lent of n-butyllithium yielded the corresponding 1,2,3-
trisubstituted cyclopentadienyl ligands. Subsequently,
0.5 equivalents of ZrCl4(thf)2 were added and after 3
days stirring under reflux the corresponding zirconocene
dichlorides 11ꢀ/18 were obtained as mixtures of stereo-
isomeres (rac/meso, 85ꢀ/70% yield of crude metallocene
products). By iterative recrystallization from mixtures of
n-hexane and toluene the isomerically pure metallocenes
were isolated in 2ꢀ21% yield (Scheme 3). Increasing
/
solubility of the zirconocenes in n-hexane led to
decreasing yields obtained after purification, e.g. rather
unpolar 18 could only be isolated in poor yield (2%),
while isomerically pure 11 was isolated in 21% yield after
recrystallization.
The stereochemistry of 11ꢀ
/
13 and 15ꢀ17 was deduced
/
Scheme 3.
by X-ray analysis on single crystals, for the p-
(Me3C)C4H4-substituted derivatives 14 and 18 no single
crystals could be obtained. For 15 the meso-metallocene
and for 12, 13, 16 and 17 the rac-compounds were
isolated isomerically pure. Only for 11 both stereoi-
somers could be separated.
Fig. 1 shows the solid state structures of the 1-
naphthyl- (rac-13) and the o-fluorphenyl-substituted
zirconocenes (meso-15). The bite angles a, Cp(cen-
To substantiate the view that each substituent at the
cyclopentadienyl ligand influences the Lewis acidity of
the zirconium metal center, we examined the reduction
peak potentials of compounds 11ꢀ
/
13 and 15ꢀ17 by
/
means of cyclic voltammetry [16]. This correlation
between Lewis acidity and reduction peak potential is
based on the results of quantum chemical calculations
which predict a large 4d character of the lowest
unoccupied molecular orbital (LUMO) of zirconocene
dichloride [17]. In Table 2 we list the results obtained at
a scan rate of 100 mV sꢂ1 in tetrahydrofuran. The
reduction peak potentials (Ered) were scaled to the
standard potential of ferrocene (Fc) which was found
troid)-ZrꢀCp(centroid), are 130.3 and 129.78, respec-
/
tively, thus only slightly depending on the substitution
pattern at the cyclopentadienyl ligand and on differences
of the electronic nature of the substituents. Similar bite
angle values have been reported in the literature [8,15].
Further selected angles and bond lengths are given in
Table 1.
to be 0.589
0.01 V (Fc/Fcꢁ). Additionally, we refer to
/
unsubstituted zirconocene dichloride 19 as standard
compound [7c,18] to assure comparability of data.
Fig. 2 shows a shift of the reduction peak potentials
towards more negative values from the unsubstituted
zirconocene dichloride (19) to bis(1,2-diethyl-3-(4-
methylphenyl)cyclopentadienyl)zirconium
dichloride
(17). We ascribe this shift to the ability of the alkyl
substituents to donate electron density. In view of this
interpretation, it is interesting to compare the various
Scheme 1.

244
B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ250
/
Table 2
Reduction peak potentials (Ered) for 11, 12, 13, 15, 16, 17 and
zirconocene dichloride 19 (Cp2ZrCl2)
a
Compound
R
R?
Ered [ꢂV]
11
12
13
15
16
17
19
Me
Me
Me
Me
Et
Ph
p-MeC4H4
1-naphthyl
2.3590.01
2.3690.01
2.3390.01
2.3190.01
2.4090.01
2.4490.01
2.2890.01
o-Fꢀ/C4H4
Ph
p-MeC4H4
Et
H
H
a
Scan rate 100 mV sꢂ1, concentration 1 mmol lꢂ1 in tetrahydro-
furan.
fluorine atom (15, DEꢃ/40 mV). A comparison between
11 and 16 as well as 12 and 17 reveals that the
replacement of two methyl groups by two stronger
electron donating ethyl groups at the Cp ligand shows a
shift to more negative values (DEꢃ
/
50ꢀ80 mV). These
/
examples demonstrate that the Lewis acidity of the
metal center can not only be tuned by the number of
substituents introduced at the ligand core, but also by
varying the donor capacity or acceptors at the cyclo-
pentadienyl ring.
3. Conclusion
In this paper, we present an easy access to 1,2,3-
trisubstituted cyclopentadienes via the PausonꢀKhand
/
reaction of an alkyne with ethylene and subsequent
treatment with organolithium compounds. These li-
gands could be transformed into 1,2,3-substituted
bis(cyclopentadienyl)zirconium dichlorides by reaction
with ZrCl4(thf)2. The stereochemistry of six out of eight
zirconocene dichlorides could be deduced by X-ray
analysis. Investigations by means of cyclic voltammetry
suggest that the Lewis acidity of zirconocene dichlorides
can be tuned by introducing electron withdrawing or
electron donating substituents not only at the cyclopen-
tadienyl ring itself but also at the aryl substituent. We
have demonstrated that the magnitude of the electronic
interaction of the differently 1,2,3-trisubstituted ligands
can be compared by cyclic voltammetry. This might
enable us to predict the changes in reactivity of the
metallocenes and therefore to help us to modify
specifically metallocene based catalyst for olefin poly-
merization in the future.
Fig. 1. Molecular structures of 13 (top) and 15 (bottom), hydrogen
atoms are omitted for the sake of clarity. Plots are presented at 50%
probability level of the thermal ellipsoids.
Table 1
Selected structural data for 11, 12, 13, 15, 16 and 17
Compound
Angles (8)
Bond lengths (pm)
Zrꢀ Zrꢀ
244.0
a
a
Clꢀ
/Zrꢀ/Cl
/
C
/Cl
meso-11
rac-11
rac-12
131.3 93.8
130.7 94.8
130.3 97.6
130.3 96.3
129.7 97.9
132.4 95.7
131.5 96.4
247.3ꢀ
245.3ꢀ
246.1ꢀ
246.1ꢀ
246.6ꢀ
246.9ꢀ
246.4ꢀ
/
256.5
261.6
259.9
262.3
260.9
262.1
260.6
/
242.9ꢀ
/
244.9
/
245.6
rac ꢀ/13
/
243.2ꢀ
242.1ꢀ
243.8ꢀ
244.1ꢀ
/
243.6
244.0
244.2
245.5
meso-15
rac-16
rac-17
/
/
/
/
/
/
a
Bite angle a, Cp(centroid)ꢀ
/
ZrꢀCp(centroid).
/
substituents in a more detailed fashion. A shift towards
smaller reduction potential is anticipated and found
when one methyl group at the aromatic ring in 12 is
4. Experimental
4.1. General remarks
replaced by the more electronegative fluorine (15, DEꢃ
50 mV). A similar shift is encountered when a hydrogen
atom at the aryl substituent in 11 is replaced by a
/
All melting points are uncorrected. The NMR spectra
were measured with a Bruker Avance 500 (1H-NMR at

B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ
/250
245
Fig. 2. Dependencies of the reduction peak potentials (Ered) [ꢂ
/
V] of 11ꢀ
/
13, 15ꢀ
17 and 19 at a scan rate of 100 mV sꢂ1 in tetrahydrofuran.
/
500 MHz and 13C-NMR at 125 MHz) and a Bruker
Avance 300 (1H-NMR at 300 MHz and 13C-NMR at 75
MHz) using the solvent as internal standard (d). The
mass spectra refer to data from a JEOL JMS-700
instrument. IR spectra were recorded with a Bruker
Vector 22. UV light absorption data were recorded
using a Hewlett Packard 8452A spectrometer. All
reactions were carried out in dried glassware under
argon atmosphere using dried and oxygen-free solvents.
The aryllithium reagents were synthesized according to
literature known procedures [14] except for phenyl-
lithium (Fluka).
4.2.3. 2,3-Diethylcyclopent-2-en-1-one (2)
Starting materials: 0.41 ml (5.0 mmol) of 1-hexyne,
1.71 g (5.0 mmol) of octacarbonyl dicobalt and 1.4 ml
(20 mmol) of DMSO. Yield: 68%. Colorless oil. B.p.
1
119 8C/18 mbar. H-NMR (CDCl3): d 2.49ꢀ
/
2.48 (m,
2.33 (m, 2H,
2.16 (m, 2H, CH2), 1.13 (s, 3H, CH3), 0.96
(s, 3H, CH3). 13C-NMR (CDCl3): d 210.6 (CO), 175.4
C), 34.9 (CH2), 29.2 (CH2), 24.8
2H, CH2), 2.45ꢀ
/
2.41 (m, 2H, CH2), 2.35ꢀ
/
CH2), 2.18ꢀ
/
(CÄ
/
C), 141.9 (CÄ
/
(CH2), 16.9 (CH2), 14.0 (CH3), 12.8 (CH3). For addi-
tional analytical data see literature. [9]
4.3. Syntheses of cyclopentadienes
4.2. Syntheses of cyclopentenones
4.3.1. Standard procedure
A solution of the cyclopentenone in 100 ml of diethyl
ether was treated with the aryllithium reagent at
4.2.1. Standard procedure
The alkyne was dissolved in 175 ml of toluene and
1.71 g of octacarbonyl dicobalt as well as 1.4 ml of
DMSO were added. The mixture was poured in a steel
vessel and pressurized with 50 bar of ethylene. After 40 h
at 110 8C the gas pressure was released, the solvent was
removed and the crude product was freed from cobalt
clusters by filtration through a thin layer of silica eluting
with light petroleum. Vacuum distillation yielded the
pure oily products.
ꢂ78 8C. The reaction mixture was allowed to warm
/
up to room temperature (r.t.) over night and was
hydrolysed by adding 50 ml of water. The organic phase
was separated and the aqueous phase was subsequently
extracted with diethyl ether (3ꢄ50 ml). The combined
/
organic phases were treated with 5 ml of 3 M HCl,
vigorously stirred for 10 minutes and neutralized by
washing with NaHCO3-solution (2ꢄ50 ml). After
/
drying (MgSO4) the solvent was removed and the crude
product was purified by filtration through a thin layer of
alumina (neutral, grade III) using light petroleum to
yield the desired oily product.
4.2.2. 2,3-Dimethylcyclopent-2-en-1-one (1)
Starting materials: 0.39 ml (5.0 mmol) of 1-butyne,
1.71 g (5.0 mmol) of octacarbonyl dicobalt and 1.4 ml
(20 mmol) of DMSO. Yield: 99%. Colorless oil. B.p.
1
102 8C/18 mbar. H-NMR (CDCl3): d 2.30ꢀ
/2.27 (m,
4.3.2. 1,2-Dimethyl-3-phenylcyclopentadiene (3)
2H, CH2), 2.16ꢀ
1.48 (s, 3H, CH3). 13C-NMR (CDCl3): d 210.0 (CO),
C), 34.5 (CH2), 31.8 (CH2), 17.5
(CH3), 8.1 (CH3). For additional analytical data see
literature [10b].
/
2.14 (m, 2H, CH2), 1.86 (s, 3H, CH3),
Starting materials: 0.75 g (6.8 mmol) of 2,3-dimethyl-
cyclopent-2-en-1-one (1) and 7.5 mmol of phenyllithium
(1.6 M in hexane solution). Yield: 95%. Colorless oil.
170.3 (CÄ
/
C), 136.5 (CÄ
/
MS(EI) 170 [Mꢁ], 155 [Mꢁꢂ
/
CH3]. HRMS(EI) Anal.
Calc. for [C13H14]: 170.1095. Found: 170.1074.

246
B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ250
/
4.3.3. 1,2-Dimethyl-3-(4-methylphenyl)cyclopentadiene
(4)
4.4. Syntheses of zirconocene dichlorides
Starting materials: 0.5 g (4.5 mmol) of 2,3-dimethyl-
cyclopent-2-en-1-one (1) and 4.7 mmol of p-methylphe-
nyllithium. Yield: 91%. Colorless oil. MS(EI) 184 [Mꢁ],
4.4.1. Standard procedure
The cyclopentadiene was dissolved in toluene, cooled
to ꢂ78 8C and treated with 1 equivalent of n-butyl-
/
169 [Mꢁꢂ
CH3]. HRMS(EI) Anal. Calc. for [C14H16]:
/
lithium (1.6 M solution in hexane) in a dropwise
fashion. After warming up to room temperature a white
slurry had formed, which was again cooled down to
184.1252. Found: 184.1231.
4.3.4. 1,2-Dimethyl-3-(1-naphthyl)cyclopentadiene (5)
Starting materials: 0.5 g (4.5 mmol) of 2,3-dimethyl-
cyclopent-2-en-1-one (1) and 4.7 mmol of 1-naphthyl-
lithium. Yield: 99%. Colorless oil. MS(EI) 220 [Mꢁ],
ꢂ78 8C. Addition of the solid ZrCl4(thf)2 complex and
/
stirring for an additional 3 days under reflux led to the
formation of a yellow-brownish reaction mixture. After
filtration through a pad of Celite the solvent was
removed and the crude product (rac/meso-mixture)
205 [Mꢁꢂ
CH3]. HRMS(EI) Anal. Calc. for [C17H16]:
/
220.1252. Found: 220.1256%.
was isolated in 85ꢀ70% yield. Recrystallization from
/
mixtures of n-hexane and toluene yielded the isomeri-
cally pure product (either rac- or meso-complex). The
yields given below refer to the isomerically pure
zirconocenes as determined by NMR spectra.
4.3.5. 1,2-Dimethyl-3-(4-tert-butylphenyl)cyclo-
pentadiene (6)
Starting materials: 0.5 g (4.5 mmol) of 2,3-dimethyl-
cyclopent-2-en-1-one (1) and 4.7 mmol of p-(tert-
butyl)phenyllithium. Yield: 90%. Colorless oil. MS(EI)
4.4.2. Bis(1,2-Dimethyl-3-phenylcyclopentadienyl)-
zirconium dichloride (11)
226 [Mꢁ], 211 [Mꢁꢂ
CH3]. HRMS(EI) Anal. Calc. for
/
[C17H22]: 226.1722. Found: 226.1717.
Starting materials: 1.2 g (6.8 mmol) of 1,2-dimethyl-3-
phenylcyclopentadiene (3), 4.25 ml (6.8 mmol) of n-
butyllithium and 1.28 g (3.4 mmol) of ZrCl4(thf)2
complex in 180 ml of toluene. Yield: 21% (meso).
Yellow solid. M.p. 179 8C. 1H-NMR (CDCl3): d
4.3.6. 1,2-Dimethyl-3-(2-fluorphenyl)cyclopentadiene
(7)
Starting materials: 0.5 g (4.5 mmol) of 2,3-dimethyl-
cyclopent-2-en-1-one (1) and 4.7 mmol of o-fluorphe-
nyllithium. Yield: 90%. Colorless oil. MS(EI) 189
7.29ꢀ7.23 (m, 10H, PhH), 6.07 (d, 2H, CpH), 5.74 (d,
/
2H, CpH), 2.20 (s, 6H, CH3), 2.13 (s, 6H, CH3). 13C-
NMR (CDCl3): d 134.5 (PhC), 130.1 (CpC), 128.7
(PhC), 128.5 (PhC), 128.5 (CpC), 128.0 (CpC), 127.4
(PhC), 112.6 (CpC), 109.3 (CpC), 14.1 (CH3), 13.0
(CH3). IR (KBr): 3102, 2920, 2092, 2056, 1630, 1508,
[Mꢁꢁ
H]. HRMS(EI) Anal. Calc. for [C13H14F]:
/
189.1079. Found: 189.1069.
1482, 1446, 1381 cmꢂ1. UVꢀ
vis (CH2Cl2, 0.02 mg
/
4.3.7. 1,2-Diethyl-3-phenylcyclopentadiene (8)
mlꢂ1) l [nm] (log o): 242 (4.48), 344 (3.65). Elemental
Anal. Calc.: C, 62.38; H, 5.24; Cl, 14.16. Found: C,
62.56; H, 5.39; Cl, 14.15%.
Starting materials: 0.62 g (4.5 mmol) of 2,3-diethylcy-
clopent-2-en-1-one (2) and 5.0 mmol of phenyllithium
(1.6 M in hexane solution). Yield: 99%. Colorless oil.
MS(EI) 198 [Mꢁ], 183 [Mꢁꢂ
/
CH3], 169 [Mꢁꢂ
C2H5].
/
HRMS(EI) Anal. Calc. for [C15H18]: 198.1408. Found:
198.1407.
4.4.3. Bis(1,2-Dimethyl-3-(4-methylphenyl)cyclo-
pentadienyl)zirconium dichloride (12)
Starting materials: 0.58 g (3.14 mmol) of 1,2-di-
methyl-3-(4-methylphenyl)cyclopentadiene (4), 1.96 ml
(3.14 mmol) of n-butyllithium and 0.59 g (1.57 mmol) of
ZrCl4(thf)2 complex in 120 ml of toluene. Yield: 19%
4.3.8. 1,2-Diethyl-3-(4-methylphenyl)cyclopentadiene
(9)
Starting materials: 0.62 g (4.5 mmol) of 2,3-diethylcy-
clopent-2-en-1-one (2) and 4.7 mmol of p-methylphe-
nyllithium. Yield: 99%. Colorless oil. MS(EI) 212 [Mꢁ],
1
(rac). Yellow solid. M.p. 128 8C. H-NMR (CDCl3): d
7.13ꢀ
/
7.08 (m, 4H, PhH), 7.07ꢀ7.04 (m, 4H, PhH), 6.04
/
197 [Mꢁꢂ
/
CH3], 183 [Mꢁꢂ
C2H5]. HRMS(EI) Anal.
/
(d, 2H, CpH), 5.71 (d, 2H, CpH), 2.34 (s, 6H, PhCH3),
2.18 (s, 6H, CH3), 2.12 (s, 6H, CH3). 13C-NMR
(CDCl3): d 137.1 (PhC), 131.6 (CpC), 129.7 (PhC),
129.1 (PhC), 128.5 (CpC), 128.5 (PhC), 127.9 (CpC),
112.3 (CpC), 109.1 (CpC), 21.3 (PhCH3), 14.4 (CH3),
12.9 (CH3). IR (KBr): 3022, 2919, 1622, 1524, 1449,
Calc. for [C16H20]: 212.1565. Found: 212.1571%.
4.3.9. 1,2-Diethyl-3-(4-tert-butylphenyl)cyclo-
pentadiene (10)
Starting materials: 0.62 g (4.5 mmol) of 2,3-diethylcy-
clopent-2-en-1-one (2) and 4.7 mmol of p-(tert-bu-
tyl)phenyllithium. Yield: 97%. Colorless oil. MS(EI)
1380 cmꢂ1. UVꢀvis (CH2Cl2, 0.027 mg mlꢂ1) l [nm]
/
(log o): 244 (4.81), 278 (4.52), 348 (4.08), 362 (4.07).
Elemental Anal. Calc.: C, 63.61; H, 5.72; Cl, 13.41.
Found: C, 63.39; H, 5.81; Cl, 13.61%.
254 [Mꢁ], 239 [Mꢁꢂ
[C19H26]: 254.2034. Found: 254.2014.
/CH3]. HRMS(EI) Anal. Calc. for

B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ
/250
247
4.4.4. Bis(1,2-Dimethyl-3-(1-naphthyl)cyclopenta-
dienyl)zirconium dichloride (13)
C, 58.20; H, 4.51; Cl, 13.21. Found: C, 58.28; H, 4.61;
Cl, 13.00%.
Starting materials: 1.0 g (4.54 mmol) of 1,2-dimethyl-
3-(1-naphthyl)cyclopentadiene (5), 2.83 ml (4.54 mmol)
of n-butyllithium and 0.85 g (2.27 mmol) of ZrCl4(thf)2
complex in 180 ml of toluene. Yield: 18% (rac). Yellow
4.4.7. Bis(1,2-Diethyl-3-phenylcyclopentadienyl)-
zirconium dichloride (16)
Starting materials: 1.1 g (5.4 mmol) of 1,2-diethyl-3-
phenylcyclopentadiene (8), 3.4 ml (5.4 mmol) of n-
butyllithium and 1.0 g (2.75 mmol) of ZrCl4(thf)2
complex in 180 ml of toluene. Yield: 14% (rac). Yellow
solid. M.p. 234 8C. 1H-NMR (CDCl3): d 7.84ꢀ
4H, ArH), 7.58ꢀ7.55 (m, 4H, ArH), 7.54ꢀ7.51 (m, 2H,
ArH), 7.27ꢀ7.23 (m, 4H, ArH), 5.93 (d, 2H, CpH), 5.86
/7.83 (m,
/
/
/
(d, 2H, CpH), 2.31 (s, 6H, CH3), 2.04 (s, 6H, CH3). 13C-
NMR (CDCl3): d 134.8 (ArC), 134.3 (ArC), 132.7
(ArC), 132.1 (CpC), 128.6 (ArC), 128.6 (ArC), 128.5
(CpC), 127.5 (CpC), 126.5 (ArC), 126.2 (ArC), 125.9
(ArC), 125.3 (ArC), 124.5 (ArC), 114.8 (CpC), 113.1
(CpC), 14.1 (CH3), 12.5 (CH3). IR (KBr): 3053, 2918,
solid. M.p. 138 8C. 1H-NMR (CDCl3): d 7.27ꢀ
10H, PhH), 6.09 (d, 2H, CpH), 5.80 (d, 2H, CpH), 2.69ꢀ
2.49 (s, 4H, CH2), 1.15 (t, 6H,
/7.24 (m,
/
2.65 (s, 4H, CH2), 2.56ꢀ
/
CH3), 0.83 (t, 6H, CH3). 13C-NMR (CDCl3): d 134.8
(PhC), 134.3 (CpC), 134.2 (PhC), 128.5 (PhC), 128.4
(CpC), 128.2 (PhC), 127.4 (CpC), 110.5 (CpC), 109.7
(CpC), 21.7 (CH2), 20.2 (CH2). 15.0 (CH3), 13.6 (CH3).
IR (KBr): 3061, 2969, 2934, 2873, 2019, 1631, 1507,
1623, 1594, 1510, 1442, 1388 cmꢂ1. UVꢀ
vis (CH2Cl2,
/
0.026 mg mlꢂ1) l [nm] (log o): 294 (4.25), 358 (3.66).
Elemental Anal. Calc.: C, 67.98; H, 5.03; Cl, 11.80.
Found: C, 67.97; H, 5.07; Cl, 11.65%.
1458, 1376 cmꢂ1. UVꢀvis (CH2Cl2, 0.017 mg mlꢂ1) l
/
[nm] (log o): 238 (4.25), 348 (3.45). Elemental Anal.
Calc.: C, 64.72; H, 6.16; Cl, 12.74. Found: C, 64.52; H,
6.15; Cl, 12.57%.
4.4.5. Bis(1,2-Dimethyl-3-(4-tert-butylphenyl)cyclo-
pentadienyl)zirconium dichloride (14)
4.4.8. Bis(1,2-Diethyl-3-(4-methylphenyl)cyclopenta-
dienyl)zirconium dichloride (17)
Starting materials: 0.92 g (4.0 mmol) of 1,2-dimethyl-
3-(4-tert-butylphenyl)cyclopentadiene (6), 2.54 ml (4
mmol) of n-butyllithium and 0.77 g (2.0 mmol) of
ZrCl4(thf)2 complex in 150 ml of toluene. Yield: 10%
Starting materials: 0.96 g (4.5 mmol) of 1,2-diethyl-3-
(4-methylphenyl)cyclopentadiene (9), 2.84 ml (4.5
mmol) of n-butyllithium and 0.86 g (2.25 mmol) of
ZrCl4(thf)2 complex in 180 ml of toluene. Yield: 7%
1
(single isomer). Yellow solid. M.p. 144 8C. H-NMR
(CDCl3): d 7.30ꢀ
/
7.28 (m, 4H, PhH), 7.18ꢀ7.15 (m, 4H,
/
1
(rac). Yellow solid. M.p. 196 8C. H-NMR (CDCl3): d
PhH), 6.04 (d, 2H, CpH), 5.74 (d, 2H, CpH), 2.19 (s, 6H,
CH3), 2.12 (s, 6H, CH3), 1.32 (s, 18H, CH3). 13C-NMR
(CDCl3): d 150.3 (PhC), 131.7 (PhC), 129.5 (CpC),
128.9 (PhC), 128.5 (CpC), 128.2 (CpC), 125.4 (PhC),
112.2 (CpC), 109.2 (CpC), 34.7 (C), 31.5 (CCH3), 14.5
(CH3), 13.0 (CH3). IR (KBr): 2962, 2867, 1628, 1526,
7.22ꢀ/7.16 (m, 8H, PhH), 5.64 (d, 2H, CpH), 5.47 (d, 2H,
CpH), 2.89-2.74 (m, 4H, CH2), 2.65ꢀ/2.51 (s, 4H, CH2),
2.40 (s, 6H, PhCH3), 1.18 (t, 6H, CH3), 0.79 (t, 6H,
CH3). 13C-NMR (CDCl3): d 137.3 (PhC), 136.2 (CpC),
133.6 (CpC), 132.6 (PhC), 129.7 (PhC), 127.7 (CpC),
124.2 (PhC), 110.5 (CpC), 109.7 (CpC), 21.4 (PhCH3),
21.3 (CH2), 20.4 (CH2). 15.3 (CH3), 13.8 (CH3). IR
(KBr): 3022, 2969, 2934, 2873, 1622, 1524, 1455, 1376,
1464, 1364 cmꢂ1. UVꢀvis (CH2Cl2, 0.015 mg mlꢂ1) l
/
[nm] (log o): 244 (4.42), 362 (3.49). HRMS(EI) Anal.
Calc. for [C34H4235Cl292Zr]: 612.1714. Found:
612.1697%.
1305 cmꢂ1. UVꢀvis (CH2Cl2, 0.038 mg mlꢂ1) l [nm]
/
(log o): 236 (4.81), 260 (4.70), 362 (4.04). HRMS(EI)
Anal. Calc. for [C32H3835Cl292Zr]: 584.1401. Found:
584.1397%. Elemental Anal. Calc.: C, 65.72; H, 6.55;
Cl, 12.13. Found: C, 65.04; H, 6.48; Cl, 11.94%.
HRMS(EI) Anal. Calc. for [C32H3835Cl292Zr]:
584.1401. Found: 584.1397.
4.4.6. Bis(1,2-dimethyl-3-(2-fluorphenyl)cyclopenta-
dienyl)zirconium dichloride (15)
Starting materials: 0.85 g (4.5 mmol) of 1,2-dimethyl-
3-(2-fluorphenyl)cyclopentadiene (7), 2.8 ml (4.5 mmol)
of n-butyllithium and 0.85 g (2.25 mmol) of ZrCl4(thf)2
complex in 120 ml of toluene. Yield: 17% (meso). White
4.4.9. Bis(1,2-Diethyl-3-(4-tert-butylphenyl)cyclo-
pentadienyl)zirconium dichloride (18)
solid. M.p. 188 8C. 1H-NMR (CDCl3): d 7.36ꢀ
2H, PhH), 7.31ꢀ7.26 (m, 2H, PhH), 7.15ꢀ7.09 (m, 4H,
/7.33 (m,
/
/
Starting materials: 1.0 g (4.0 mmol) of 1,2-diethyl-3-
(4-tert-butylphenyl)cyclopentadiene (10), 2.5 ml (4.0
mmol) of n-butyllithium and 0.75 g (2.0 mmol) of
ZrCl4(thf)2 complex in 150 ml of toluene. Yield: 2%
(single isomer). White solid. M.p. 198 8C. 1H-NMR
PhH), 6.23 (d, 2H, CpH), 5.90 (d, 2H, CpH), 2.14 (s, 6H,
CH3), 2.12 (s, 6H, CH3). 13C-NMR (CDCl3): d 161.0
(PhCF), 159.0 (PhC), 132.0 (CpC), 129.6 (PhC), 129.5
(CpC), 125.9 (CpC), 124.2 (PhC), 123.1 (PhC), 116.2
(PhC), 113.6 (CpC), 111.7 (CpC), 14.2 (CH3), 12.9
(CH3). IR (KBr): 2958, 2921, 1629, 1509, 1453, 1382
(CDCl3): d 7.40ꢀ
PhH), 5.67 (d, 2H, CpH), 5.46 (d, 2H, CpH), 2.90ꢀ
(m, 4H, CH2), 2.67ꢀ2.45 (m, 4H, CH2), 1.35 (s, 18H,
CH3), 1.16 (t, 6H, CH3), 0.79 (t, 6H, CH3). 13C-NMR
/
7.37 (m, 4H, PhH), 7.22ꢀ
/
7.18 (m, 4H,
/
2.73
cmꢂ1. UVꢀ
/
vis (CH2Cl2, 0.013 mg mlꢂ1) l [nm] (log o):
/
256 4.26), 280 (3.99), 340 (3.56). Elemental Anal. Calc.:

Table 3
Crystal data and structure refinement for 11, 12, 13, 15, 16 and 17
rac-11
meso-11
rac-12
rac-13
meso-15
rac-16
rac-17
Chemical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
C
500.59
26H26Cl2Zr
C26H26Cl2Zr
500.59
C28H30Cl2Zr
528.64
C34H30Cl2Zr
600.70
C28H30Cl2F2Zr
536.57
C30H34Cl2Zr
556.69
C32H36Cl2Zr
582.73
0.22ꢄ0.17ꢄ0.16
Orthorhombic
0.55ꢄ0.20ꢄ0.10
Triclinic
¯
P1
0.32ꢄ0.32ꢄ0.16
Orthorhombic
C2221
0.23ꢄ0.15ꢄ0.13
Triclinic
¯
P1
0.50ꢄ0.24ꢄ0.21
Monoclinic
P21/n
0.35ꢄ0.21ꢄ0.04
Monoclinic
P21/n
0.28ꢄ0.24ꢄ0.22
Orthorhombic
P212121
Aba2
4
Z
4
4
2
4
4
4
Unit cell dimensions
˚
a (A)
˚
17.0512(1)
20.4376(1)
6.6458(1)
90
10.7936(2)
12.2936(2)
16.6320(3)
84.542(1)
84.298(1)
88.822(1)
2185.92(7)
1.521
11.0679(1)
20.6220(2)
11.1717(2)
90
10.2720(1)
11.5260(1)
12.8450(1)
77.067(1)
74.037(1)
73.706(1)
1385.58(2)
1.440
9.5599(1)
12.3663(1)
19.7561(3)
90
10.9449(2)
12.6688(3)
19.4841(3)
90
11.8597(4)
12.3449(4)
19.6320(6)
90
b (A)
˚
c (A)
a (8)
b (8)
g (8)
90
90
90
90
94.574(1)
90
100.503(1)
90
90
90
3
˚
V (A )
2315.97(4)
1.436
0.715
2549.85(6)
1.377
0.654
2328.14(5)
1.531
0.729
2656.38(9)
1.392
0.631
2874.26(2)
1.347
0.587
Dcalc (g cmꢂ3
Absorption coefficient, m
(mmꢂ1
)
0.758
0.611
)
Min./max. transmission
Index ranges
0.81 and 0.91
ꢂ22Bh B21,
ꢂ26Bk B26,
ꢂ8Bl B8
11623
0.81 and 0.94
ꢂ13Bh B14,
ꢂ15Bk B15,
ꢂ21Bl B21
22632
0.79 and 0.91
ꢂ14Bh B14,
ꢂ26Bk B26,
ꢂ14Bl B14
13259
0.83 and 0.93
ꢂ13Bh B13,
ꢂ14Bk B14,
ꢂ16Bl B16
21613
0.42 and 0.88
ꢂ12Bh B12,
ꢂ15Bk B16,
ꢂ25Bl B25
23435
0.85 and 0.98
ꢂ14Bh B14,
ꢂ16Bk B16,
ꢂ25Bl B25
26960
0.83 and 0.89
ꢂ15Bh B15,
ꢂ15Bk B16,
ꢂ25Bl B25
30005
Reflections collected
Independent reflections
Observed reflections
Parameters
Goodness-of-fit on F2
R(F)
2650
2476
9908
8195
2936
2840
21613
16700
5328
4681
6082
4590
6582
6018
134
1.05
531
1.03
144
1.14
339
1.04
284
1.07
302
1.04
322
1.03
0.019
0.048
0.026
0.059
0.022
0.062
0.039
0.088
0.026
0.066
0.030
0.066
0.026
0.060
Rw(F2)
ꢂ3
˚
(Dr) max, min (e A
)
0.21, ꢂ0.29
0.40, ꢂ0.48
0.48, ꢂ0.32
0.85, ꢂ0.42
0.34, ꢂ0.39
0.72, ꢂ0.47
0.45, ꢂ0.30

B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ
/250
249
(CDCl3): d 150.2 (PhC), 135.7 (PhC), 133.4 (CpC),
132.1 (PhC), 127.1 (CpC), 125.3 (CpC), 124.0 (PhC),
112.9 (CpC), 111.7 (CpC), 34.3 (C), 31.1 (CCH3), 21.0
(CH2), 20.0 (CH2), 14.9 (CH3), 13.5 (CH3). IR (KBr):
Acknowledgements
We are grateful to the Deutsche Forschungsge-
meinschaft, the Fonds der Chemischen Industrie and
the BASF Aktiengesellschaft, Ludwigshafen, for finan-
cial support.
2966, 2872, 1628, 1521, 1462, 1365 cmꢂ1. UVꢀ
vis
/
(CH2Cl2, 0.066 mg mlꢂ1) l [nm] (log o): 238 (4.49),
262 (4.67), 360 (3.81). HRMS(EI) Anal. Calc. for
[C38H Cl922Zr]: 668.2340. Found: 668.2350%.
35
50
References
4.5. Cyclic voltammetry
[1] P.C. Mohring, N.J. Coville, J. Organomet. Chem. 479 (1994) 1
¨
and references cited therein.
The electrochemical measurements were performed
with the METROHM potentiostat system PGSTAT20.
As working electrode a METROHM disc electrode was
[2] (a) M.F. Lappert, C.J. Pickett, P.I. Riley, P.I.W. Yarrow, J.
Chem. Soc. Dalton Trans. (1981) 805;
(b) G. Erker, R. Nolte, R. Aul, S. Wilker, C. Kruger, R. Noe, J.
¨
used (radius ꢀ0.3 cm, glassy carbon). The Ag/AgCl
/
Am. Chem. Soc. 113 (1991) 7594;
(c) G. Fink, R. Muhlhaupt, H.-H. Brintzinger (Eds.), Ziegler
¨
reference electrode was separated from the solution by a
fine grid and a luggin capillary. A 0.1 M solution of n-
Bu4PF6 in THF was used as electrolyte. The potential of
ferrocene/ferrocenium (Fc/Fcꢁ) was recorded at 580
Catalysts, Springer, Berlin, 1995;
(d) H.-H. Brintzinger, D. Fischer, R. Muhlhaupt, B. Rieger, R.
¨
Waymouth, Angew. Chem. Int. Ed. Engl. 34 (1995) 1143;
(e) E. Negishi, J.-L. Montchamp, in: A. Togni, R.L. Halterman
mV with an error of 910 mV vs. Ag/AgCl. All
/
(Eds.), Metallocenes, VCH, Weinheim, 1998, pp. 241ꢀ319;
/
measurements were recorded at a scan rate of 100 mV
sꢂ1. Samples were measured at a concentration of 1
mmol lꢂ1 in tetrahydrofuran at room temperature.
Oxygen was removed from the solution by purging
argon through the cell.
(f) H.G. Alt, E. Samuel, Chem. Soc. Rev. 27 (1998) 323;
(g) W. Kaminsky, Pure Appl. Chem. 70 (1998) 1229;
(h) G.G. Hlatky, Coord. Chem. Rev. 181 (1999) 243;
(i) W. Kaminsky, Catal. Today 62 (2000) 23;
(j) G.G. Hlatky, Coord. Chem. Rev. 199 (2000) 235.
[3] (a) R. Beckhaus, in: A. Togni, R.L. Halterman (Eds.), Metallo-
cenes, VCH, Weinheim, 1998, pp. 153ꢀ
(b) R.L. Halterman, in: A. Togni, R.L. Halterman (Eds.),
Metallocenes, Weinheim: VCH, 1998, pp. 455ꢀ544;
/
239;
4.6. X-ray crystallography and structure solution
/
(c) R.J. Maldanis, J.C.W. Chien, M.D. Rausch, J. Organomet.
Chem. 599 (2000) 107 (and references cited therein).
[4] (a) W. Kaminsky, K. Kulper, H.-H. Brintzinger, F.R.W.P. Wild,
¨
The crystallographic data were recorded with a
Bruker Smart CCD diffractometer at 200 K at a
˚
wavelength l of 0.71073 A. Relevant crystal and data
Angew. Chem. Int. Ed. Engl. 24 (1985) 507;
(b) P. Courtot, R. Pichon, J.Y. Salaun, L. Toupet, Can. J. Chem.
69 (1991) 661;
collection parameters are given in Table 3. The struc-
tures were solved by using direct methods, least-squares
refinement and Fourier techniques. Structure solution
and refinement were performed with SHELXTL [19]. An
empirical absorption correction was carried out using
SADABS [20] based on the Laue symmetry of the
reciprocal space. Hydrogen atoms were included at
calculated positions. The crystal of 13 was a partially
merohedrical twin, which could be treated successfully
with an appropriate twinning model.
(c) C. Janiak, U. Versteeg, K.C.H. Lange, R. Weimann, E. Hahn,
J. Organomet. Chem. 501 (1995) 219;
(d) M. Bochmann, J. Chem. Soc. Dalton Trans. (1996) 255;
(e) S. Mansel, U. Rief, M.-H. Prosenc, R. Kirsten, H.-H.
Brintzinger, J. Organomet. Chem. 512 (1996) 225;
(f) P. Witte, T.K. Lai, R.M. Waymouth, Organometallics 18
(1999) 4147;
(g) H. Yamazaki, K. Kimura, M. Nakano, T. Ushioda, Chem.
Lett. (1999) 1311;
(h) E.J. Thomas, J.C.W. Chien, M.D. Rausch, Organometallics
18 (1999) 1439;
(i) Y.K. Kang, K.S. Shin, S.-G. Lee, I.S. Lee, Y.K. Chung,
Organometallics 18 (1999) 180;
(j) E.J. Thomas, J.C.W. Chien, M.D. Rausch, Macromolecules 33
(2000) 1546.
5. Supplementary material
[5] (a) P. Montag, Y. v. d. Leek, K. Angermund, G. Fink, J.
Organomet. Chem. 497 (1995) 201;
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 181334 (rac-11), 181335
(meso-11), 181336 (12), 181337 (13), 181338 (15),
181339 (16) and 181340 (17). Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(b) J.C. Green, Chem. Soc. Rev. 27 (1998) 263;
(c) M. Toto, L. Cavallo, P. Corradini, G. Moscardi, L. Resconi,
G. Guerra, Macromolecules 31 (1998) 3431;
(d) K. Thorshaug, J.A. Støvneng, E. Rytter, Macromolecules 33
(2000) 8136;
(e) A. Maiti, M. Sierka, J. Andzehm, J. Golab, J. Sauer, J. Phys.
Chem. A 104 (2000) 10932;
(f) J.N. Harvey, Organometallics 20 (2001) 4887;
(g) E. Zwek, T. Ziegler, Organometallics 21 (2002) 83 (and
references cited therein).
(Fax:
ac.uk or www: http://www.ccdc.cam.ac.uk).
ꢁ44-1223-336033; e-mail: deposit@ccdc.cam.
/

250
B.J. Rausch et al. / Journal of Organometallic Chemistry 658 (2002) 242ꢀ250
/
[6] (a) P.G. Gassmann, D.W. Macomber, J.W. Hershberger, Orga-
[13] (a) J.G. Donkervoort, A.R. Gordon, C. Johnstone, W.J. Kerr, U.
Lange, Tetrahedron 52 (1996) 7391;
nometallics 2 (1983) 1470;
(b) B.J. Rausch, R. Gleiter, Tetrahedron Lett. 42 (2001) 1651.
[14] L. Brandsma, H.D. Verkruijsse, Preparative Polar Organic
Chemistry, vol. 1, Springer, New York, 1987.
(b) P.G. Gassmann, C.H. Winter, Organometallics 10 (1991)
1592;
(c) P.G. Gassmann, P.A. Deck, C.H. Winter, D.A. Dobbs, D.H.
Cao, Organometallics 11 (1992) 959.
[15] (a) For further X-ray structures of substituted unbridged zirco-
nocene dichlorides see: J.L. Petersen, J.W. Egan, Jr, Inorg. Chem.
22 (1983) 3571;
[7] (a) M.F. Lappert, C.J. Pickett, P.I. Riley, P.I.W. Yarrow, J.
Chem. Soc. Dalton Trans. (1981) 805;
(b) R.G. Rodgers, M.M. Benning, L.K. Kurihara, K.J. Moriarty,
(b) J. Langmaier, Z. Samec, V. Varga, M. Hora´cek, K. Mach, J.
Organomet. Chem. 579 (1999) 348;
M.D. Rausch, J. Organomet. Chem. 293 (1985) 51ꢀ60;
/
(c) R. Bortolin, V. Patel, I. Munday, N.J. Taylor, A.J. Carty, J.
Chem. Soc. Chem. Commun. (1985) 456;
(c) J. Langmaier, Z. Samec, V. Varga, M. Hora´cek, R. Chouk-
roun, K. Mach, J. Organomet. Chem. 584 (1999) 323.
[8] (a) K. Kimura, K. Takaishi, T. Matsukawa, T. Yoshimura, H.
Yamazaki, Chem. Lett. (1998) 571;
(d) R.A. Howie, G.P. McQuillan, D.W. Thompson, G.A. Lock, J.
Organomet. Chem. 303 (1986) 213;
(e) J.C. Gallucci, B. Gautheron, M. Gugelchuk, P. Meunier, L.A.
Paquette, Organometallics 6 (1987) 15;
(f) A. Antinolo, M.F. Lappert, A. Singh, D.W. Winterborn, L.M.
˜
(b) B.Y. Lee, J.W. Han, Y.K. Chung, S.W. Lee, J. Organomet.
Chem. 587 (1999) 181;
(c) F. Zhang, Y. Mu, L. Zhao, Y. Zhang, W. Bu, C. Chen, H.
Zhai, H. Hong, J. Organomet. Chem. 613 (2000) 68.
[9] T. Takahashi, Z. Xi, Y. Nishihara, S. Huo, K. Kasai, K. Aoyagi,
V. Denisov, E. Negishi, Tetrahedron 53 (1997) 9123. (This
method cannot be used to synthesize 2,3-dimethylcyclopent-2-
en-1-one).
Engelhardt, C.L. Raston, A.H. White, A.J. Carty, N.J. Taylor, J.
Chem. Soc. Dalton Trans. (1987) 1463;
(g) P.B. Hitchcock, M.F. Lappert, G.A. Lawless, H. Olivier, E.J.
Ryan, J. Chem. Soc. Chem. Commun. (1992) 474;
(h) R. Choukroun, F. Dahan, Organometallics 13 (1994) 2097;
(i) M.T. Reetz, H. Brummer, M. Kessler, J. Kuhnigk, Chimia 49
¨
(1995) 501;
[10] (a) J. Ficini, J.-P. Geneˆt, Tetrahedron Lett. 12 (1971) 1565;
(b) M.A. Baig, D.V. Banthorpe, G. Carr, D. Whittaker, J. Chem.
Soc. Perkin Trans. 2 (1989) 1981;
(j) E. Polo, M.L.H. Green, F. Benetollo, G. Prini, S. Sostero, O.
Traverso, J. Organomet. Chem. 527 (1997) 173;
(k) A.S. Batsanov, B.M. Bridgewater, J.A.K. Howard, A.K.
Hughes, C. Wilson, J. Organomet. Chem. 590 (1999) 169;
(c) M.L.F. Cadman, L. Crombie, S. Freeman, J. Mistry, J. Chem.
Soc. Perkin Trans. 1 (1995) 1397.
[11] (a) S. Hirano, T. Hiyama, H. Nozaki, Tetrahedron Lett. 15 (1974)
1429;
(l) J. Pflug, A. Bertuleit, G. Kehr, R. Frohlich, G. Erker,
¨
Organometallics 18 (1999) 3818;
(b) S. Hirano, S. Tagaki, T. Hiyama, H. Nozaki, Bull. Chem. Soc.
Jpn. 53 (1980) 169.
(m) O.W. Lofthus, C. Slebodnick, P.A. Deck, Organometallics 18
(1999) 3702;
[12] (a) P.L. Pauson, Tetrahedron 41 (1985) 5855;
(b) P.L. Pauson, in: A. de Meijere, H. tom Dieck (Eds.),
Organometallics in Organic Synthesis, Springer, Berlin, 1988,
(n) P.L. Chirik, M.W. Day, J.E. Bercaw, Organometallics 18
(1999) 1873.
[16] J. Heinze, Angew. Chem. Int. Ed. Engl. 23 (1984) 831 (and
references cited therein).
pp. 233ꢀ
(c) N.E. Schore, in: B.M. Trost (Ed.), Comprehensive Organic
Synthesis, vol. 5, Pergamon, Oxford, 1991, pp. 1037ꢀ1064;
(d) N.E. Schore, Org. React. 40 (1991) 1;
/246;
[17] (a) J.L. Petersen, L.F. Dahl, J. Am. Chem. Soc. 97 (1975) 6422;
(b) J.W. Lauher, R. Hoffmann, J. Am. Chem. Soc. 98 (1976) 1729.
[18] (a) E. Samuel, D. Guery, J. Vedel, F. Basile, Organometallics 4
(1985) 1073;
/
(e) N.E. Schore, in: E.W. Abel, F.G.A. Stone, G. Wilkinson
(Eds.), Comprehensive Organometallic Chemistry II, vol. 12,
(b) A. Antinolo, G.S. Bristow, G.K. Campbell, A.W. Duff, P.B.
˜
Pergamon, Oxford, 1995, pp. 703ꢀ739;
(f) O. Geis, H.G. Schmalz, Angew. Chem. Int. Ed. Engl. 37 (1998)
/
Hitchcock, R.A. Kamarudin, M.F. Lappert, R.J. Norton, N.
Sarjudeen, D.J.W. Winterborn, J.L. Atwood, W.E. Hunter, H.
Zhang, Polyhedron 8 (1989) 1601.
911;
(g) Y.K. Chung, Coord. Chem. Rev. 188 (1999) 297;
(h) K.M. Brummond, J.L. Kent, Tetrahedron 56 (2000) 3263;
(i) A.J. Fletcher, S.D.R. Christie, J. Chem. Soc. Perkin Trans. 1
(2000) 1657.
[19] G.M. Sheldrick, Bruker Analytical X-ray Division, Madison, WI,
1997.
[20] G.M. Sheldrick, Bruker Analytical X-ray Division, Madison, WI,
1996.