Spirane-bridged ansa η5-cyclopentadienyl-η5-fluorenyl-zirconocene precatalysts

Article abstract of DOI:10.1016/j.jorganchem.2006.03.023

Synthesis of rigid ansa-zirconocene precatalyst systems with a C₂-bridge embedded in a spirane scaffold is described. Fulvenes were key intermediates in regio- and stereoselective preparation of the appropriate spirane ligands. Substitution in

Full text of DOI:10.1016/j.jorganchem.2006.03.023

Journal of Organometallic Chemistry 691 (2006) 3089–3097
www.elsevier.com/locate/jorganchem
Spirane-bridged ansa g5-cyclopentadienyl-g5-fluorenyl-zirconocene
precatalysts
*
Geir Langli, Christian Rømming, Kjell Undheim
Department of Chemistry, University of Oslo, Oslo, Norway
Received 4 February 2006; received in revised form 13 March 2006; accepted 13 March 2006
Available online 18 March 2006
Abstract
Synthesis of rigid ansa-zirconocene precatalyst systems with a C2-bridge embedded in a spirane scaffold is described. Fulvenes were
key intermediates in regio- and stereoselective preparation of the appropriate spirane ligands. Substitution in the cyclopentadienyl group
in the ligand was effected by fulvene methodology. The zirconocenes were active precatalysts for the polymerisation of propene when
activated with MAO. The structure of the parent zirconocene dichloride has been verified by X-ray crystal analysis.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: C2-spirane-bridged zirconocenes; Spirane scaffold; Rigid ansa-zirconocenes; Metallocenes; Stereoselective synthesis
1. Introduction
2. Results and discussion
In a recent report we have described a method for the
preparation of a rigid C2-bridged zirconocene precata-
lyst system, 2-(g5-cyclopentadienyl)-10,20,30,40-tetrahydro-
spiro[cyclobutane-1,10-(g5-fluorenyl)]zirconium dichloride
(Fig. 1; A), where the C2-bridge is embedded in a rigid spi-
rane scaffold [1]. A preliminary study of the zirconocene
complex as a propene polymerisation precatalyst showed
the product to be largely atactic PP resulting from little ste-
reocontrol from the ligand. Inspection of simple models
suggested that a regioisomeric fluorenyl zirconocene (Fig
1; B) might exert stronger stereocontrol on the course of
the polymerisation. When the benzene ring is moved
towards the spirobridge, one side of the zirconocene would
resemble the isoselective ethylene bridged bisindenyl zircon-
ocene [2]. In this report, we describe a method for the prep-
aration of the zirconocene B in Fig. 1, and isopropyl
homologues substituted in the cyclopentadienyl moiety of
the parent zirconocenes A and B.
The synthesis of the targeted spirane ligand 6 is outlined
in Scheme 1. The substrate was the 4-fluorenone 1 [3],
which was to be converted into the spirocyclobutanone 4
via an intermediate cyclopropane 2 and a ring expansion.
Lithiated cyclopropyl phenyl sulfide [4], reacted preferen-
tially as a base by extraction of an acidic indene proton.
With the less basic reagent derived from the lithiated spe-
cies and cerium trichloride [5], however, chemoselective
addition to the carbonyl carbon was achieved. The 1H
NMR spectra of the crude product showed full conversion
to the desired product, but part of this material was lost
during chromatographic purification probably because of
ready elimination of water. Attempts to effect rearrange-
ment of the cyclopropyl phenyl sulfide 2 moiety into a
cyclobutanone spirane 4 in the presence of fluoroboric acid
according to the methodology reported by Trost et al. [6],
failed to provide the cyclobutanone 4. Instead preferential
endo elimination of water furnished the dihydrofluorene 3.
Presumably both reaction paths proceed through closely
related carbonium ion intermediates after initial hydroxyl
elimination. Conditions adapted to Lewis acid catalysis,
however, furnished the cyclobutanone 4 in 19% yield using
*
Corresponding author.
E-mail address: kjell.undheim@kjemi.uio.no (K. Undheim).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.03.023

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G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
sive interaction with the larger part of the fluorene compo-
Cl
H
H
Cl
nent, and is thermodynamically the less favourable
structure of the two geometrical isomers. The cyclobutadie-
nyl substituent is thereby forced into the cis-configuration,
structure 6.
Cl
Cl
Zr
Zr
B
A
The subsequent conversion of the ligand 6 into the zirc-
onocene 8 is shown in Scheme 2. For the zirconocene for-
mation, the ligand was lithiated. One molar equivalent with
n-BuLi in diethyl ether produced a clear solution. Addition
of a second molar equivalent of n-BuLi led to precipitation
of a tan powder which was isolated by filtration and
washed with pentane. The dilithiated species 7 was added
to toluene without any further characterisation and treated
with solid ZrCl4, which had been purified by sublimation.
The zirconocene 8 was isolated in 21% yield. The product
was very sensitive to oxygen and moisture, and the reac-
tions were run in a glove box in preference to the Schlenk
equipment.
Fig. 1. Rigidly bridged zirconocenes in a spirane scaffold.
SnCl4 whereas the presence of the Meerwein salt Me3OBF4
increased the yield to 75%. The ketone 4 was in a subse-
quent step converted into a fulvene derivative 5 in a modest
yield with cyclopentadiene as a reactant in the presence of
pyrrolidine as a base.
A sandwich zirconocene structure with the zirconium
metal coordinated to the fluorenyl and cyclopentadienyl
moieties (Fig. 1) requires stereoselective reduction of the
exocyclic fulvene double bond. In the structure 5, the ster-
ical shielding of the two faces of the fulvene moiety differs
significantly (Scheme 1). The face pointing away from the
major body of fluorene is the less shielded face. Chemose-
lective and stereoselective cis-reduction was achieved by the
use of a bulky metal hydride, lithium triethylborohydride.
The cis-configuration, however, leads to a significant repul-
The performance of the zirconocenes 8 and 9 as precat-
alysts in the polymerisation of propene was unsatisfactory
(vide infra). Attempts were therefore made to modify the
properties of the zirconocenes by carbylation in the cyclo-
pentadienyl moiety of the ligands. Initial attempts were
PhS
SPh
O
HO
SPh
CeCl2
35% (aq.) HBF4
PhH
70 oC, 14 h
THF
-78 oC
1
3
2 69%
Me3OBF4
CH2Cl2
20 oC, 20 h
H
O
LiBEt3H
Pyrrolidine
MeOH
20 oC, 96 h
THF
20 oC, 24 h
5 45%
Scheme 1.
6 91%, de > 90%
4 75%
Li+
H
H
Cl
ZrCl4
H
n-BuLi
Et2O
Cl
Zr
PhMe
Li+
20 oC, 20 h
0-20 oC, 24 h
6
8 21%
7 95%
H
Cl
Cl
Zr
9
Scheme 2.

G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
3091
made to react isopropylcyclopentadiene under conditions
for fulvene formation by analogy to the successful reaction
4 ! 5 in Scheme 1. The desired fulvene reaction with
substituted cyclopentadiene failed. However, when the pre-
formed cis-ligands 6 and 12 were subjected to the fulvene
methodology with acetone as a reactant and pyrrolidine
as base, the isopropylidine products 10 and 13 were
obtained in high yields (Scheme 3). The ligand 12 was
available from previous work [1]. The exclusive regiochem-
istry achieved in the substitution reaction is controlled by
steric interactions. The fulvene derivative 10 was chemi-
cally labile and was used as a crude product in the subse-
quent reduction. Its isomer 13 was more stable. Exocyclic
regiochemical reduction to the isopropyl derivatives 11
and 14 was effected in high yield by lithium triethylborohy-
dride. The NMR spectra of the isopropyl derivatives
showed that all the three cyclopentadienyl isomers were
present in the products 11 and 14.
Formation of substituted target zirconocenes is shown
in Scheme 4. The isopropyl homologues 11 and 14 were
dilithiated by nBuLi in diethyl ether in the same manner
as the parent compound 6 in Scheme 2. The oily dilithiated
products 15 and 17 solidified on trituration with pentane.
The lithiated species were further converted by zirconium
tetrachloride into the corresponding zirconocenes in 11%
and 12% yields, respectively. Isomerism is introduced into
the ligands 11 and 14 on metallation because of the unsym-
metrical substitution pattern in the cyclopentadienyl moi-
ety, in each case an isomeric pair 16a/16b (3:5) and 18a/
18b (4:5) was formed depending on which side of the cyclo-
pentadienyl ring was coordinated to the metal. Attempts to
increase the selectivity of the reactions by using Zr(NMe2)4
or ZrCl4(THF)2 were not successful [7,8]. The solubility of
the isopropyl products in toluene, hexane or pentane was
significantly higher than for the parent zirconocenes 8
and 9 (Scheme 2). Attempts to separate the individual
members in each isomer pair failed. The modest yield in
the zirconation may in part be explained by face selectivity.
A sandwich complex requires an intramolecular reaction
where the zirconium reactant becomes attached to the
inner face of the fluorene ring. When the zirconium
becomes attached to the other outer face of the ring, inter-
molecular products are likely to be formed.
The zirconocene structure for the parent molecule 8 has
been verified by a single-crystal X-ray analysis. Crystals
suitable for X-ray analysis were obtained by slow evapora-
tion of a toluene solution of the zirconocene at room tem-
perature. The ORTEP plots of the crystal structure is
shown in Fig. 2.
The bite angle between the two Cp-moieties is 126.6ꢁ.
For comparison, this value is very close to the bite angle
125.8ꢁ of the regioisomeric zirconocene 9 [1] (Scheme 2),
and the bite angle 125.3ꢁ in the ethylene bridged bisindenyl
zirconocene [2]. The bite angle between the cyclopentadie-
nyl units in the two g5-coordinated aromatic ligands in
ansa-zirconocene dichloride complexes have a profound
influence on the catalytic properties of such complexes
[9–11].
2.1. Propene polymerisation
The parent zirconocenes 8 and 9 (Scheme 2) as well as
their isopropyl isomers 16 and 18 (Scheme 4) were all
active precatalysts for the polymerisation of propene
when the catalyst system was activated with a large excess
of MAO (1:1000). The polymerisation reactions were per-
formed in toluene at 30 ꢁC with propene, pressure 1.1 bar.
The parent precatalyst 9 (Scheme 2) yielded essentially an
atactic oligomer with an average of 15 monomer units.
The other parent precatalyst 8 (Scheme 2) yielded a viscous
oily PP which was slightly isotactic ([mmmm] = 17.6%)
with an average of 100 units [1]. The zirconocene 8
showed a twofold increase in activity over the regioiso-
meric system 9. The isomeric pairs 16a/16b and 18a/18b
were used as such. The results were much better than
for the unsubstituted zirconocenes, but uncertainties are
H
H
Pyrrolidine
Acetone
H
LiBEt3H
THF
MeOH/CH2Cl2
20 oC, 48 h
0 oC, 2 h
6
10 84%
11 97%
H
H
H
Pyrrolidine
Acetone
LiBEt3H
MeOH/CH2Cl2
20 oC, 20 h
THF
0 oC, 2 h
13 84%
14 88%
12
Scheme 3.

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G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
Cl
H
Cl
Zr
Li
16a
H
H
ZrCl4
n-BuLi
PhMe
Et2O
Cl
H
20 oC, 20 h
Cl
Zr
0-20 oC, 24 h
Li
11%
95%
15
11
16b
H
H
Li
Zr
Cl
Cl
Cl
H
H
n-BuLi
ZrCl4
18a
_
PhMe
Et2O
20 oC, 20 h.
0-20 oC, 24 h
Li
Zr
Cl
12 %
90%
14
17
18b
Scheme 4.
ucts which were extracted with diethyl ether to remove
atactic PP (40–60%). The ether extractions will increase
the apparent isotacticity values due to the removal of
the atactic PP. The zirconocene pair 16 yielded a crystal-
line powder with a relatively high isotacticity ([mmmm] =
81.6%), while the zirconocene pair 18 yielded a waxy PP
with intermediate isotacticity. The molecular weights for
both polymers were low.
3. Conclusion
In conclusion, a method for the preparation of C2-rigid-
ified ansa-zirconocene precatalysts is described. The C2-
bridge is part of a spirane system which is substituted by
a cyclopentadienyl and a fluorenyl moiety. cis-Spirane
ligands appropriate for conversion into metallocenes were
prepared by stereochemically controlled reactions. The pre-
catalyst zirconocenes together with a large excess of MAO
constitute a moderately active catalyst system for PP
formation.
Fig. 2. The ORTEP plot of compound 8. Ellipsoids are shown at 50%
˚
probability. Selected bond lengths (A) and angles (ꢁ) in the molecules:
4. Experimental
Zr(1)–Cl(1) = 2.431, Zr(1)–Cl(2) = 2.443, Zr(1)–X(1A) = 2.201, Zr(1)–
The 1H NMR spectra were recorded at 500 MHz with a
Bruker DPX 500, at 300 MHz with a Bruker DPX 300
instrument. The 13C NMR spectra were recorded at 125
X(1B) = 2.224; X(1A)–Zr(1)–X(1B) = 126.6, Cl(1)–Zr(1)–Cl(2) = 97.8.
Estimated standard deviations are 0.001 A in bond lengths and 0.1ꢁ in
angles.
˚
1
or 75 MHz using the above instruments. H and 13C spec-
associated with which regioisomer in each pair is the more
active, and which isomer is the more stereoselective. Both
catalyst systems produced complex polypropylene prod-
tra were referenced to residual protons in the solvent. Mass
spectra were recorded at 70 eV ionising voltage and are
presented as m/z (% rel. int.).

G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
3093
All organometallic reactions were run under an argon
atmosphere using Schlenk or glovebox techniques. THF,
Et2O and toluene were distilled from sodium/benzophe-
none, and CH2Cl2 from CaH2. CeCl3 was bought as
the heptahydrate and dried according to the literature
[12].
(65%) of a light yellow oil. HRMS(EI): M 334.1385. Calc.
for C22H22OS: 334.1391. H NMR (CDCl3, 300 MHz): d
1
0.92–0.97 (m, 1H), 1.26–1.41 (m, 3H), 1.73–1.86 (m, 2H),
1.95–2.13 (m, 1H), 2.45–2.50 (m, 3H), 2.60–2.68 (m, 1H),
3.25 (dd, J = 22.5, 22.5 Hz, 2H), 7.13–7.39 (m, 6H), 7.55–
7.59 (m, 2H), 7.84 (d, J = 7.6 Hz, 1H). 13C NMR (CDCl3,
75 MHz): d 11.9, 17.0, 19.7, 25.7, 34.2, 37.7, 40.8, 75.1,
121.8, 123.1, 123.5, 125.8, 126.2, 128.2, 130.4, 136.1,
137.3, 142.0, 143.8, 146.5. MS(EI): 334 (M+, 18%), 316
(59), 207 (77), 185 (100), 165 (37), 150 (57), 129 (19).
4.1. X-ray crystallographic analysis for zirconocene 8
X-ray data were collected on a Siemens SMART CCD
diffractometer [13] using graphite monochromated Mo
˚
Ka radiation (k = 0.71073 A). Data collection method: x-
4.4. 2,3-Dihydro-4-[1-(phenylthio)cyclopropyl]-1H-
fluorene (3)
scan, range 0.6ꢁ, crystal to detector distance 5 cm. Data
reduction and cell determination were carried out with
the SAINT and XPREP programs [13]. Absorption corrections
were applied by the use of the SADABS program [14]. The
structures were determined and refined using the SHELXTL
program package [15]. The non-hydrogen atoms were
refined with anisotropic thermal parameters; hydrogen
atoms were located from difference Fourier maps and
refined with isotropic thermal parameters.
The structure was found to contain one disordered mol-
ecule of toluene per unit cell. Structural data have been
deposited at the Cambridge Crystallographic Data Centre
with Deposition No. CCDC 269765.
The product (3) (yield 78%) was a viscous dark yellow
oil. HRMS(EI):
M
316.1284. Calc. for C22H20S:
1
316.1286. H NMR (CDCl3, 300 MHz): d 1.06–1.24 (m,
1H), 1.41–1.55 (m, 2H), 1.61–1.76 (m, 1H), 1.80–1.98 (m,
2H), 6.46 (s, 1H), 6.98–7.03 (m, 1H), 7.19–7.22 (m, 2H),
7.25–7.34 (m, 3H), 7.46 (dd, 1H, J = 0.47, 7.6 Hz), 7.60–
7.63 (m, 2H). 13C NMR (CDCl3, 75 MHz): d 24.6, 25.2,
31.2, 31.6, 65.7, 119.3, 122.9, 123.3, 124.5, 126.6, 128.57,
128.63, 132.5, 133.6, 135.2, 137.4, 140.0, 143.4, 146.5.
MS(EI): 316 (M+, 62%), 283 (5), 239 (6), 207 (100), 191
(27), 178 (23), 165 (33), 152 (9).
4.2. Crystal data for C21H20Cl2Zr (8) + C3.5
4.5. 10,20,30,40-Tetrahydro-90H-spiro[cyclobutane-1,40-
fluoren]-2-one (4)
˚
ꢀ
M = 476.52, triclinic, P1, a = 8.227(2) A, b =
˚
˚
˚
10.746(3) A, c = 12.956(3) A, a = 114.30(1)ꢁ, b = 97.05(1)ꢁ,
Triethyloxonium tetrafluoroborate (99 mg, 0.52 mmol)
was added to a solution of 2,3,4,9-tetrahydro-4-[1-(phenyl-
thio)cyclopropyl]-1H-fluoren-4-ol (2) (167 mg, 0.5 mmol)
in anhydrous dichloromethane (15 mL) under argon at
room temperature. The mixture was stirred at room tem-
perature for 20 h before water (20 mL) and diethyl ether
(100 mL) were added. The organic layer was collected,
washed with saturated NaHCO3 (20 mL), dried (MgSO4),
the solution evaporated and the residual material subjected
to flash chromatography on silica gel using EtOAc:hexane
1:10; yield 84 mg (75%) of a light yellow solid. HRMS(EI):
M 224.1209. Calc. for C16H16O: 224.1201. 1H NMR
(CDCl3, 300 MHz): d 1.69–1.82 (m, 1.5H), 1.89–2.05 (m,
3.5H), 2.41–2.45 (m, 2H), 2.51–2.61 (m, 1H), 3.16–3.39
(m, 4H). 13C NMR (CDCl3, 75 MHz): d 20.0, 23.5, 25.9,
33.0, 40.7, 43.1, 64.9, 118.6, 123.8, 124.0, 126.0, 134.1,
142.7, 143.2, 144.6, 213.9. MS(EI): 224 (M+, 10%), 196
(8), 182 (100), 167 (29), 152 (14), 128 (10), 115 (7).
3
ꢀ3
c = 96.63(1)ꢁ, V = 1018.5(5) A , Z = 2, Dx = 1.554 Mg m
,
l = 0.809 mmꢀ1, T = 103(2) K, measured 11,096 reflections
in 2h range 4.2–52.8ꢁ, Rint = 0.129. 325 Parameters refined
against 4166F2, R = 0.046 for I0 > 2r (I0) and 0.079 for all
data.
4.3. 2,3,4,9-Tetrahydro-4-[1-(phenylthio)cyclopropyl]-1H-
fluoren-4-ol (2)
1.6 M n-BuLi in hexane (113 mL, 180 mmol) was added
to a solution of cyclopropyl phenyl sulfide (26.8 g,
180 mmol) in THF (250 mL) at 0 ꢁC, and the mixture stir-
red at this temperature for 90 min. The temperature was
lowered to ꢀ78 ꢁC, and the solution cannulated into a solu-
tion of anhydrous CeCl3(51.8 g, 210 mmol) in THF
(500 mL) at ꢀ78 ꢁC. The CeCl3/THF mixture had been
vigorously stirred overnight. The mixture was stirred at
ꢀ78 ꢁC for 3 h before a solution of 3,4-dihydro-2H-fluo-
ren-1(9H)-one (1) (24.9 g, 135 mmol) in THF (80 mL)
was added dropwise, and the reaction mixture allowed to
reach room temperature overnight. Water (50 mL) was
added, the organic phase collected, evaporated to dryness
and the residual material triturated with dichloromethane
(1.0 L). The organic solution was washed with water
(3 · 100 mL), dried (MgSO4), the solution evaporated
and the residual material subjected to flash chromatogra-
phy on silica gel using EtOAc:hexane 1:10; yield 29.3 g
4.6. 2-(Cyclopenta-2,4-dienylidene)-10,20,30,40-tetrahydro-
90H-spiro[cyclobutane-1,40-fluorene] (5)
Pyrrolidine (6.4 mL, 74 mmol) was added dropwise to a
solution of 10,20,30,40-tetrahydro-90H-spiro[cyclobutane-
1,40-fluoren]-2-one (4) (2.05 g, 9.2 mmol) and cyclopentadi-
ene (6.1 mL, 74 mmol) in a 1:5 mixture of dichloromethane
and methanol (50 mL) at 0 ꢁC. The mixture was stirred at
room temperature for 96 h and was subsequently poured

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G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
into 0.5 M HCl (100 mL) at 0 ꢁC. The mixture was
extracted with hexane (3 · 150 mL), the extracts dried
(MgSO4), evaporated and the residual material subjected
to flash chromatography on silica gel with EtOAc:hexane
1:100; yield 1.12 g (45%) of a dark yellow oil. HRMS(EI):
M 272.1558. Calc. for C21H20: 272.1565. 1H NMR (CDCl3,
300 MHz): d 1.70–1.84 (m, 1H), 1.91–2.00 (m, 1H), 2.00–
2.13 (m, 2H), 2.23–2.31 (m, 1H), 2.50–2.56 (m, 2H), 2.6–
2.72 (m, 1H), 3.23–3.45 (m, 4H), 5.98 (dt, J = 1.7, 5.2 Hz,
1H), 6.19–6.21 (m, 1H), 6.37 (dt, J = 1.7, 5.1 Hz, 1H),
6.41–6.44 (m, 1H), 7.07–7.19 (m, 3H), 7.40 (d,
J = 6.6 Hz, 1H). 13C NMR (CDCl3, 75 MHz): d 20.1,
26.3, 27.0, 29.1, 38.3, 40.7, 49.6, 119.7, 119.88, 119.92,
123.3, 123.4, 125.8, 130.1, 130.3, 138.8, 139.6, 142.3,
142.7, 143.9, 164.0. MS(EI): 272 (M+, 100), 257 (17), 243
(70), 229 (28), 215 (65), 202 (23), 182 (15), 165 (29), 115
(18), 49 (5).
(5 mL), dried in vacuo and stored in a glovebox; yield:
860 mg (98%). Solid, sublimated zirconium tetrachloride
(233 mg, 1.0 mmol) was added to a suspension of the
dilithiated product (286 mg, 1.0 mmol) in toluene
(20 mL) at ꢀ20 ꢁC. The mixture was stirred at room tem-
perature overnight, filtered through a glass sinter and the
clear dark yellow filtrate concentrated to 1 mL before
addition of pentane (20 mL). A light yellow solid precip-
itate was formed. The solid was filtered off, washed with a
small amount of pentane and dried in vacuo; yield: 90 mg
(21%), of a light yellow solid. The product was crystal-
lised for X-ray analysis by slow evaporation of a solution
in toluene. HRMS(EI):
M
431.9978. Calc. for
C21H20Cl2Zr: 431.9989. 1H NMR (CD2Cl2, 300 MHz):
d = 1.65 (dt, J = 3.0, 13.6, 1H), 1.94–2.25 (m, 4H),
2.50–2.68 (m, 2H), 2.95–3.09 (m, 2H), 3.19 (dd, J = 5.1,
17.0 Hz, 1H), 4.04 (t, J = 8.7 Hz, 1H), 6.20 (q, J = 2.4,
3.1 Hz, Cp, 1H), 6.29 (s, fluorene, 1H), 6.30–6.37 (m,
Cp, 2H), 6.43 (q, J = 2.5, 2.8 Hz, Cp, 1H), 7.16–7.31
(m, Ar, 2H), 7.58 (dd, J = 1.2, 8.3 Hz, Ar, 1H), 8.26
(dd, J = 0.6, 8.5 Hz, Ar, 1H). 13C NMR (CD2Cl2,
75 MHz): d 19.3, 20.3, 27.0, 27.8, 41.0, 50.5, 52.1, 107.1,
107.5, 114.4, 119.2, 120.1, 123.9, 124.3, 124.8, 125.2,
125.8, 126.4, 133.2, 135.7, 139.6. MS(EI): 432 (M+,
68%), 341 (54), 303 (10), 251 (100), 215 (18), 181 (32),
165 (56), 152 (21).
4.7. cis-2-(Cyclopentadienyl)-10,20,30,40-tetrahydro-90H-
spiro[cyclobutane-1,40-fluorene] (6)
1.0 M LiBEt3H in THF (0.4 mL) was added dropwise
to a solution of 2-(cyclopenta-2,4-dienylidene)-10,20,30,40-
tetrahydro-90H-spiro[cyclobutane-1,40-fluorene] (5) (71 mg,
0.26 mmol) in THF (5 mL) at 0 ꢁC. The mixture was stir-
red at room temperature for 22 h, poured into a mixture
of water/ice (50 mL) and dichloromethane (50 mL). The
layers were separated, the water phase extracted with
dichloromethane (2 · 30 mL), the combined organic solu-
tions washed with water (3 · 10 mL), dried (MgSO4), and
the solution evaporated to furnish the crude title com-
pound which was used as such in the subsequent reaction;
yield 65 mg (91%) of a light yellow oil as a 1:1 mixture of
two double bond isomers in the cyclopentane ring.
4.9. cis-2-(3-Isopropylidenecyclopenta-2,4-dienyl)-
10,20,30,40-tetrahydro-90H-spiro[cyclobutane-1,40-fluorene]
(10)
Acetone (1.5 mL, 17.7 mmol) and pyrrolidine (1.8 mL,
20.7 mmol) were added to a solution of cis-2-(cyclopenta-
dienyl)-10,20,30,40-tetrahydro-90H-spiro[cyclobutane-1,40-
fluorene] (6) (1.62 g, 5.9 mmol) in methanol (40 mL) and
dichloromethane (10 mL) under argon at 0 ꢁC. The mix-
ture was allowed to reach room temperature and stirred
for 48 h before the mixture was poured into ice/water
(100 mL). The resultant mixture was extracted with hex-
ane (3 · 50 mL), the organic phase collected and washed
with water (3 · 10 mL). The dried (MgSO4) solution
was evaporated to leave a dark yellow oil which was used
in the subsequent reaction without further purification;
yield 1.57 g (84%). HRMS(EI): M 314.2025. Calc. for
C24H26: 314.2034. 1H NMR (CD2Cl2, 300 MHz): d
1.75–1.96 (m, 5H), 2.02 (s, CH3, 3H), 2.05 (s, CH3,
3H), 2.15–2.25 (m, 2H), 2.43–2.63 (m, 4H), 2.87–3.00
(m, 1H), 3.16 (d, J = 3.0 Hz, 1H), 6.05–6.08 (m, Cp,
1H), 6.14–6.18 (m, Cp, 2H), 7.03 (dt, J = 1.0, 7.4 Hz,
Ar, 1H), 7.15 (dt, J = 1.3, 7.6 Hz, Ar, 1H), 7.31 (dd,
J = 0.5, 7.3 Hz, Ar, 1H), 7.66 (d, J = 7.7 Hz, Ar, 1H).
13C NMR (CD2Cl2, 75 MHz): d 19.9, 21.8, 22.7 (double,
CH3), 27.0, 29.0, 41.0, 42.2, 45.7, 48.0, 115.9, 120.6,
121.5, 123.2, 123.4, 125.8, 132.7, 139.9, 142.3, 143.4,
143.5, 146.1, 146.2, 148.5. MS(EI): 314 (M+, 20%), 272
(12), 182 (100), 167 (27), 154 (11), 141 (16), 132 (46),
115 (12), 91 (10).
1
HRMS(EI): M 274.1710. Calc. for C21H22: 274.1721. H
NMR (CDCl3, 200 MHz): d 1.70–3.30 (m, 1.5H), 6.03–
6.14 (m, 1.5H), 6.25–6.29 (m, 1H), 6.49–6.55 (m, 0.5H),
7.00–7.66 (m, 4H). 13C NMR (CDCl3, 50 MHz): d 19.3,
19.4, 20.6, 21.5, 26.5, 26.6, 28.3, 28.5, 40.4, 40.6, 40.7,
41.1, 41.6, 42.9, 44.6, 45.4, 46.6, 48.3, 120.0, 121.2,
122.6, 122.8, 123.0, 123.1, 125.1, 125.5, 125.9, 126.6,
131.2, 131.6, 132.3, 134.4, 139.3, 139.4, 139.7, 142.6,
142.7, 142.9, 145.2, 145.6, 148.3, 150.9. MS(EI): 274
(M+, 8%), 195 (12), 182 (100), 167 (17), 153 (7), 141
(7), 91 (7).
4.8. 2-(g5-Cyclopenta-2,4-dienyl)-10,20,30,40-
tetrahydrospiro[cyclobutane-1,40-(g5-fluorenyl)]zirconium
dichloride (8)
1.6 M n-BuLi in hexane (4.6 mL, 7.4 mmol) was added
to solution of cis-2-(cyclopenta-dienyl)-10,20,30,40-tetrahy-
dro-90H-spiro[cyclobutane-1,40-fluorene]
(6)
(842 mg,
3.1 mmol) in diethyl ether (20 mL) under argon at 0 ꢁC.
The reaction mixture was allowed to reach room temper-
ature overnight. A dilithium salt was precipitated as a tan
yellow solid which was filtered off, washed with pentane

G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
3095
4.10. cis-2-(3-Isopropylcyclopentadienyl)-10,20,30,40-
THF (40 mL) under argon at 0 ꢁC. The stirring was contin-
ued at this temperature for 1.5 h and the mixture poured
into ice/water (100 mL) and dichloromethane (50 mL).
The organic phase was separated, the water phase extracted
with dichloromethane (2 · 50 mL) and the combined
organic solutions washed with water (3 · 20 mL). The
dried (MgSO4) solution was evaporated to leave a light yel-
low oil which was used in the subsequent reaction without
any further purification; yield 753 mg (88%). HRMS (EI):
M 316.2199. Calc. for C24H28: 316.2191. MS (EI): m/z
(%) 316 (M+, 9), 182 (100), 167 (14), 154 (6), 141 (7), 119
(9).
tetrahydro-90H-spiro[cyclobutane-1,40-fluorene] (11)
A 1.0 M solution of LiBEt3H in THF (6.3 mL,
6.3 mmol) was added to a solution of cis-2-(3-isopropy-
lidenecyclopentadienyl)-10,20,30,40-tetrahydro-90H-spiro[cyc-
lobutane-1,40-fluorene] (10) (1.31 g, 4.2 mmol) in THF
(40 mL) under argon at 0 ꢁC. The mixture was stirred
at 0 ꢁC for 2 h and poured into ice/water (100 mL) and
dichloromethane (50 mL). The organic phase was sepa-
rated, the water phase extracted with dichloromethane
(2 · 50 mL) and the combined organic solutions washed
with water (3 · 20 mL). The dried (MgSO4) solution
was evaporated to leave a light yellow oil which was
used in the subsequent reaction without any further puri-
fication; yield 1.28 g (97%). HRMS(EI): M 316.2192.
Calc. for C24H28: 316.2191. MS(EI): 316 (M+, 15%),
273 (6), 182 (100), 167 (25), 141 (10), 134 (48), 119
(22), 91 (6).
4.13. 2-(g5-3-Isopropylcyclopenta-2,4-dienyl)-10,20,30,40-
tetrahydrospiro[cyclobutane-1,40-(g5-fluorenyl)]zirconium
dichloride (16)
1.6 M n-BuLi in hexane (5.6 mL, 8.9 mmol) was added
to cis-2-(3-isopropylcyclopenta-2,4-dienyl)-10,20,30,40-tetra-
hydro-90H-spiro[cyclobutane-1,40-fluorene] (11) (1.28 g,
3.9 mmol) in diethyl ether (40 mL) under argon at 0 ꢁC.
The reaction mixture was allowed to reach room tem-
perature overnight. The solvent was decanted from the
precipitated red syrup. The sirup was triturated with pen-
tane (15 mL). The dilithiated light yellow solid was
isolated by filtration, and dried in vacuo; yield 1.30 g
(98%). Freshly sublimed solid zirconium tetrachloride
(466 mg, 2.0 mmol) was added to a suspension of the
dilithiated product (632 mg, 1.9 mmol) in toluene
(40 mL) at ꢀ20 ꢁC. The mixture was stirred at room
temperature overnight, filtered through a glass sinter,
and the filtrate evaporated. The residual material was
extracted with pentane (3 · 15 mL), the pentane solu-
tion concentrated to ca. 3 mL and cooled to ꢀ20 ꢁC.
A light yellow solid was precipitated, filtered off and
dried in vacuo; yield 100 mg (11%). The product was
a 3:5 mixture of the two isomeric products 16a and
16b. HRMS(EI): M 474.0464. Calc. for C24H26Cl2Zr:
474.0459. 1H NMR (CD2Cl2, 300 MHz): d 0.84 (d,
J = 6.8 Hz, CH3, major), 0.97 (d, J = 6.9 Hz, CH3,
major), 1.08 (d, J = 6.8 Hz, CH3, minor), 1.12 (d,
J = 6.9 Hz, CH3, minor), 1.2–4.0 (series of m, 19.2 H),
5.92 (t, J = 2.7 Hz, Cp, major, 1H), 6.02–6.06 (m, Cp
double intensity of minor, 1.2H), 6.23–6.25 (m, Cp and
fluorene major, 2H), 6.27 (t, J = 2.9 Hz, major, 1H),
6.30 (s, fluorene minor, 0.6H), 6.41 (t, J = 3.0 Hz, Cp
minor, 0.6H), 7.16–7.27 (m, Ar, 3.2H), 7.56–7.62 (m,
Ar, 1.6H), 8.26 (d, J = 8.6 Hz, Ar major, 1H), 8.31 (d,
J = 8.6 Hz, Ar minor, 0.6H). 13C NMR (CD2Cl2,
75 MHz): d 18.9, 19.1, 20.2, 20.5, 22.6 (2 shifts), 23.5,
23.8, 24.3, 25.3, 28.7, 29.2, 29.9, 30.6, 37.3, 38.4, 48.9,
49.3, 51.1, 51.4, 95.1, 95.5, 107.4, 107.7, 113.1 (2 shifts),
116.5, 118.9, 119.4, 119.6, 123.4, 125.0 (2 shifts), 125.6,
126.0, 126.2, 126.3, 126.6, 128.6, 129.4, 132.2, 132.6,
137.2, 138.2, 140.9, 141.8, 141.9, 144.6. MS(EI): 474
(M+, 43%), 341 (11), 293 (100), 255 (13), 181 (16), 165
(23), 91 (6).
4.11. cis-2-(3-Isopropylidenecyclopenta-2,4-dienyl)-
10,20,30,40-tetrahydro-90H-spiro[cyclobutane-1,10-fluorene]
(13)
Acetone (0.44 mL, 5.9 mmol) and pyrrolidine (0.6 mL,
7.2 mmol) were added to a solution of cis-2-(cyclopenta-
dienyl)-10,20,30,40-tetrahydro-90H-spiro[cyclobutane-1,10-
fluorene] (12) [1] (1.0 g, 3.6 mmol) in methanol (20 mL)
and dichloromethane (5 mL) under argon at 0 ꢁC. The
mixture was allowed to reach room temperature overnight
and poured into ice/water (50 mL). The mixture was
extracted with hexane (3 · 20 mL), the hexane solution
washed with water (2 · 10 mL), dried (MgSO4) and evap-
orated to leave a dark yellow oil which was used in the
subsequent reaction without further purification; yield
954 mg (84%). HRMS (EI): M 314.2026. Calc. for
C24H26: 314.2034. 1H NMR (CD2Cl2, 300 MHz): d
1.77–2.01 (m, 5H), 2.09 (s, CH3, 3H), 2.14 (s, CH3, 3H),
2.29–2.64 (m, 6H), 3.29–3.44 (m, 2H), 6.14 (dd, J = 1.4,
5.3 Hz, 1H), 6.24 (dd, J = 2.0, 3.9 Hz, 1H), 6.34 (dd,
J = 2.2, 5.2 Hz, 1H), 7.07 (dt, J = 2.0, 7.1 Hz, 1H),
7.17–7.22 (m, 2H), 7.30 (d, J = 7.4 Hz, 1 H). 13C NMR
(CD2Cl2, 75 MHz): d 20.4, 21.5, 22.9, 23.0 (2 shifts),
32.3, 38.8, 40.0, 46.6, 47.9, 115.2, 118.1, 121.6, 123.5,
124.0, 126.2, 132.1, 136.9, 142.3, 143.7, 146.5 (2 shifts),
147.1, 148.6. MS (EI): m/z (%) 314 (M+, 21), 195 (7),
182 (100), 167 (34), 153 (11), 141 (14), 132 (21), 117 (8),
91 (5).
4.12. cis-2-(3-Isopropylcyclopentadienyl)-10,20,30,40-
tetrahydro-90H-spiro[cyclobutane-1,10-fluorene] (14)
A 1.0 M solution of LiBEt3H in THF (4.5 mL,
4.5 mmol) was added to a solution of cis-2-(3-isopropylid-
enecyclopenta-2,4-dienyl)-10,20,30,40-tetrahydro-90H-spiro
[cyclobutane-1,10-fluorene] (13) (900 mg, 2.7 mmol) in

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G. Langli et al. / Journal of Organometallic Chemistry 691 (2006) 3089–3097
4.14. 2-(g5-3-Isopropylcyclopenta-2,4-dienyl)-10,20,30,40-
tetrahydro-spiro[cyclobutane-1,10-(g5-fluorenyl)]zirconium
dichloride (18)
the propene pressure at 1.1 bar during the reaction. A
solution of 1% HCl in MeOH (200 mL) was added after
1 h to quench the reaction. The polymers from the par-
ent zirconocenes 8 and 9 (Scheme 2) were separated from
methanol by decantation, washed with methanol and
dried at 60 ꢁC in a rotary evaporator overnight. The
polymers from the isopropyl substituted isomers 16 and
18 were collected by filtration, washed with methanol,
dried and extracted with Et2O (50 mL) to remove atactic
PP.
1.6 M n-BuLi in hexane (3.0 mL, 4.8 mmol) was added
to
a
solution of cis-2-(3-isopropylcyclopentadienyl)-
10,20,30,40-tetrahydro-90H-spiro[cyclobutane-1,10-fluorene]
(14) (695 mg, 2.2 mmol) in diethyl ether (20 mL) under
argon at 0 ꢁC. The reaction mixture was allowed to reach
room temperature overnight. A red syrup-like precipitate
was formed. The solvent was decanted off, the residue trit-
urated with hexane (10 mL), and a light yellow solid was
formed. The solid was filtered off and dried in vacuo;
yield 686 mg (95%). Freshly sublimed zirconium tetrachlo-
ride (466 mg, 2.0 mmol) was added to a suspension of the
dilithiated ligand (656 mg, 2.0 mmol) in toluene (40 mL)
under argon at room temperature. The mixture was stir-
red at room temperature overnight, filtered through a
glass sinter and the solution evaporated. The residual
material was extracted with pentane (3 · 15 mL), the pen-
tane extracts concentrated to ca. 3 mL and cooled to
ꢀ20 ꢁC. A light yellow solid was precipitated and was fil-
tered off and dried in vacuo; yield 114 mg (12%) of a 4:5
mixture of two isomeric products 18a and 18b. HRMS
(EI): M 474.0479. Calc. for C24H26Cl2Zr: 474.0459. 1H
NMR (CD2Cl2, 300 MHz): d 1.06 (d, J = 6.8 Hz, CH3,
minor), 1.07 (d, J = 6.9 Hz, CH3, major), 1.11 (d,
J = 7.0 Hz, CH3, minor), 1.15 (d, J = 6.9 Hz, CH3,
major), 1.20–2.50 (m, 11.2H), 2.64–2.83 (m, 3.6H), 2.95–
3.09 (m, 1.8H), 3.19–3.32 (m, 1.8H), 3.73–3.79 (m,
1.8H), 5.81 (t, J = 2.6 Hz, Cp–H, minor, 0.8H), 6.05–
6.09 (m, Cp–H, double intensity of major, 2H), 6.42 (t,
J = 2.8 Hz, Cp–H, minor, 0.8H), 6.54 (t, J = 2.6 Hz,
Cp–H, major, 1H), 6.81 (t, J = 3.0 Hz, Cp–H, minor,
0.8H), 6.86 (s, fluorene-H, major, 1H), 6.98 (s, fluorene-
H, minor, 0.8H), 7.14–7.30 (m, Ar–H, 3.6H), 7.42–7.61
(m, Ar–H, 3.6H). 13C NMR (CD2Cl2, 75 MHz): d 19.5,
19.6, 20.3, 20.6, 22.5, 22.7, 23.6, 23.9, 24.2, 25.5, 28.9,
29.2, 30.4, 30.6, 38.3, 38.6, 49.3, 49.5, 50.6, 50.7, 95.2,
95.4, 107.6, 107.8, 113.0, 113.2, 117.0, 119.2, 119.4,
119.8, 123.5, 124.9, 125.1, 125.6, 126.0, 126.2, 126.3,
126.6, 128.6, 129.4, 132.2, 132.6, 137.2, 138.2, 140.9,
141.7, 142.0, 145.7. MS (EI): m/z (%) 474 (M+, 64), 312
(35), 293 (66), 269 (23), 239 (28), 182 (76), 178 (95), 165
(100), 91 (33).
4.16. Polymer analysis
The properties of the zirconocene complexes as a pro-
pene polymerisation precatalyst were briefly studied with
MAO in toluene under a propene pressure of 1.1 bar at
30 ꢁC. Molecular weights and molecular weight distribu-
tions were determined by gel-permeation chromatography
(GPC, Waters 150CVplus, 140 ꢁC in 1,2,4-trichloroben-
zene) for the polymers from the isopropyl substituted iso-
mers 16 and 18. The molecular weights for polymers
from 8 and 9 (Scheme 1) were calculated by 1H NMR
1
end-group analysis [16]. H NMR spectra were recorded
at 300 MHz on a Bruker DPX 300 instrument (C2D2Cl4,
363 K and 256 scans). 13C NMR spectra were recorded
at 75 MHz on the same instrument (C2D2Cl4, 363 K,
3000 scans and a delay time of 12 s) and analysed by
known methods [17].
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4.15. Polymerisation reactions
The polymerisation experiments in toluene were car-
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The reactor was evacuated, filled with propene, and
charged with 200 mL of dry toluene. The precatalysts
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merisation was started by injection of the active catalyst
into the reactor. The temperature was kept at 30 ꢁC and

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