Fluorous Zirconocene(IV) complexes and their olefin polymerization activity in toluene and fluorous biphasic solvent systems

Article abstract of DOI:10.1021/om049507z

The synthesis (4a-d) and structure (4a,c) of the four crystalline, water-stable, hydrocarbon- and perfluorocarbon (PFC)-soluble fluorous zirconocene(IV) dichloride precatalysts [Zr-{ν⁵-C ₅H₄SiMe_3-n(R_F)_n} ₂Cl₂] (n = 1, R_F = CH₂CH ₂C₆F₁₃ (4a), C₈F₁₇ (4b), CH₂C₆F₅ (4c); n = 3, R_F = CH ₂C₆F₅ (4d)), possessing one to three fluorous alkyl or aryl groups attached to the cyclopentadienyl ligand through a silicon atom and an additional methylene (4c,d) or ethylene (4a) spacer or no spacer at all (4b), are reported. A nonfluorous analogue of 4a, [Zr{ν⁵- C₅H₄-SiMe₂C₈H₁₇} ₂Cl₂] (4e), was prepared for comparison, and 4a was easily converted to its dimethyl derivative [Zr{ν⁵-C₅H ₄SiMe₂CH₂CH₂C₆F ₁₃}₂Me₂] (5a). The ethylene polymerization activities of the zirconocene dichlorides were compared to those of the known bis-{(trimethylsilyl)cyclopentadienyl}zirconium dichloride [Zr{ν⁵- C₅ H₄SiMe₃}₂Cl₂] (4f), in both toluene and fluorous biphasic solvent (FBS) systems. In the case of 4b a PE with a bimodal molecular weight distribution and a significantly lower molecular weight was obtained. Polymerization data and polymer properties for 4a-d, compared to data for 4f, show a marked influence of the fluorous groups and the alkyl spacer (e.g. methylene in 4c or ethylene in 4a). FBS conditions result in PE with a higher average molecular weight. Evidence on the nature of the active species formed when these precatalysts were treated with an excess of methylaluminoxane (MAO) is presented.

Full text of DOI:10.1021/om049507z

1620
Organometallics 2005, 24, 1620-1630
Fluorous Zirconocene(IV) Complexes and Their Olefin
Polymerization Activity in Toluene and Fluorous
Biphasic Solvent Systems†
Philippe G. Merle,‡,§ Virginie Che´ron,‡ Henk Hagen,‡,| Martin Lutz,
Anthony L. Spek, Berth-Jan Deelman,*,# and Gerard van Koten‡
Debye Institute, Department of Metal Mediated Synthesis, and Bijvoet Center for Biomolecular
Research, Department of Crystal and Structural Chemistry, Utrecht University,
Padualaan 8, NL-3584 CH Utrecht, The Netherlands, and ARKEMA Vlissingen BV,
P.O. Box 70, NL-4380 AB Vlissingen, The Netherlands
Received July 4, 2004
The synthesis (4a-d) and structure (4a,c) of the four crystalline, water-stable, hydrocar-
bon- and perfluorocarbon (PFC)-soluble fluorous zirconocene(IV) dichloride precatalysts [Zr-
{η5-C5H4SiMe3-n(RF)n}2Cl2] (n ) 1, RF ) CH2CH2C6F13 (4a), C8F17 (4b), CH2C6F5 (4c); n ) 3,
RF ) CH2C6F5 (4d)), possessing one to three fluorous alkyl or aryl groups attached to the
cyclopentadienyl ligand through a silicon atom and an additional methylene (4c,d) or ethylene
(4a) spacer or no spacer at all (4b), are reported. A nonfluorous analogue of 4a, [Zr{η5-C5H4-
SiMe2C8H17}2Cl2] (4e), was prepared for comparison, and 4a was easily converted to its
dimethyl derivative [Zr{η5-C5H4SiMe2CH2CH2C6F13}2Me2] (5a). The ethylene polymerization
activities of the zirconocene dichlorides were compared to those of the known bis-
{(trimethylsilyl)cyclopentadienyl}zirconium dichloride [Zr{η5-C5H4SiMe3}2Cl2] (4f), in both
toluene and fluorous biphasic solvent (FBS) systems. In the case of 4b a PE with a bimodal
molecular weight distribution and a significantly lower molecular weight was obtained.
Polymerization data and polymer properties for 4a-d, compared to data for 4f, show a
marked influence of the fluorous groups and the alkyl spacer (e.g. methylene in 4c or ethylene
in 4a). FBS conditions result in PE with a higher average molecular weight. Evidence on
the nature of the active species formed when these precatalysts were treated with an excess
of methylaluminoxane (MAO) is presented.
Introduction
We are here interested in fluorous metallocene based
olefin polymerization precatalysts. Olefin polymeriza-
tion catalysts consisting of group 4 metallocene dichlo-
ride precatalysts and methylaluminoxane (MAO) have
received significant industrial interest.3 They belong to
the most highly active and selective classes of catalysts
for R-olefin polymerization, and they offer unique pos-
sibilities for controlling polymer structure and proper-
ties.4 While catalyst recovery is not a major issue in
coordination polymerization (low catalyst loading), we
reasoned that the fluorous character of the catalyst,
optionally supplemented by a fluorous reaction medium
(pure PFC solvent or FBS conditions), would affect the
polymerization mechanism and could possibly lead to
improved physical properties of the polymers produced.
Examples of coordination polymerization in PFC sol-
vents are extremely rare,5 despite their interesting
solvent properties that are related to those of super-
Fluorous phase catalysis using fluorinated catalysts
in a fluorous biphasic solvent system (FBS; i.e., a
mixture of hydrocarbon and perfluorocarbonsPFCs
solvents) is of considerable interest, mainly in relation
to catalyst recycling.1 In addition, PFC’s have also
received attention because of their unique solvent
properties (low polarity, inertness, low dielectric con-
stant, high solubility of gases, low heats of evaporation).
They offer advantages in terms of environmental con-
siderations (nontoxic) and, in the case of polymerization
reactions, improved properties of the polymers.2
* To whom correspondence should be addressed. Fax: +31 113
612984. E-mail: berth-jan.deelman@arkemagroup.com.
† Dedicated to Professor Jan H. Teuben at the occasion of his
retirement and in recognition of his important contributions to the field
of early-transition-metal chemistry and R-olefin polymerization ca-
talysis.
‡ Debye Institute, Utrecht University.
§ Current address: The CHEM Lab, Concordia University, 7141
Sherbrooke West, Montreal H4B 1R6, QC, Canada.
(2) Banks, R. E., Smart, B. E., Tatlow, J. C., Eds. Organofluorine
Chemistry, Principles and Commercial Applications; Plenum Press:
New York, 1994, Chapter 3, pp 57-67.
| Current address: Dow Benelux B.V, P.O. Box 48, 4530 AA
Terneuzen, The Netherlands.
(3) For recent reviews, see e.g.: (a) Marks, T. J., Stevens, J. C., Eds.
Topics in Catalysis; Baltzer: Amsterdam, 1999; Vol. 7, pp 1-208. (b)
Kaminsky, W., Ed. Metalorganic Catalysts for Synthesis and Polym-
erization; Springer-Verlag: Berlin, 1999. (c) Kaminsky, W.; Laban, A.
Appl. Catal. A: Gen. 2001, 222, 47-61. (d) Jordan, R. F. Ed. J. Mol.
Catal. 1998, 128, 1-337.
Bijvoet Center for Biomolecular Research, Utrecht University.
# ARKEMA Vlissingen BV.
(1) (a) De Wolf, E.; van Koten, G.; Deelman, B. J. Chem. Soc. Rev.
1999, 28, 37-41. (b) Hope, E. G.; Stuart, A. M. J. Fluorine Chem. 1999,
100, 75-83. (c) Horva´th, I. T. Acc. Chem. Res. 1998, 31, 641-650. (d)
Curran, D. P. Angew. Chem., Int. Ed. 1998, 37, 1175-1196. (e) Cornils,
B. Angew. Chem., Int. Ed. 1997, 36, 2057-2059. (f) Barthel-Rosa, L.
P.; Gladysz, J. A. Coord. Chem. Rev. 1999, 190-192, 587-605.
(4) (a) Coates, G. W. Chem. Rev. 2000, 100, 1223-1252 and
references therein. (b) Morse, P. M. Chem. Eng. News 1973, 51(July
6), 11-16.
10.1021/om049507z CCC: $30.25 © 2005 American Chemical Society
Publication on Web 02/24/2005

Fluorous Zirconocene(IV) Complexes
Organometallics, Vol. 24, No. 7, 2005 1621
Scheme 1
critical CO2 but available at atmospheric pressure (in
contrast to sc-CO2).1c,2,6
Finally, it should be noted that although the cyclo-
pentadienyl group is one of the most ubiquitous ligands
in organometallic chemistry, only a few such ligands
bearing fluorine or short fluoroalkyl substituents have
been reported.7 Notably in these complexes, the elec-
tronic effect of the fluorous group on the metal center
is significant, as it is directly bound to a metal-
coordinated carbon atom. We here report on the syn-
thesis (4a-d) and structure (4a,c) of the four crystal-
line, hydrocarbon- and PFC-soluble fluorous zircono-
cene(IV) dichlorides [Zr{η5-C5H4(SiMe3-n(RF)n)}2Cl2] (n
) 1, RF ) CH2CH2C6F13 (4a), C8F17 (4b), CH2C6F5 (4c);
n ) 3, RF ) CH2C6F5 (4d)) and some first investigations
into their olefin polymerization activity in both conven-
tional and fluorous biphasic systems (FBS) upon treat-
ment with MAO as cocatalyst. Part of this work was
previously communicated.8 More recently, the synthesis
of related titanium compounds was reported9 and there
has been work by the Gladysz group on (2-(perfluoro-
alkyl)ethyl)cyclopentadienyl complexes.10
Figure 1. One of the two independent molecules of
compound 2d. Displacement ellipsoids are drawn at the
50% probability level, and H atoms are omitted for clarity.
Symmetry operations: (i) 1 - y, 1 + x - y, z; (ii) -x + y, 1
- x, z. Selected bond lengths (Å): Si-Br ) 2.2192(15),
2.1971(14); Si-C11 ) 1.864(3), 1.876(3). Selected bond
angles (deg): Br-Si-C11 ) 108.37(10), 109.46(9), C11-
Si-C11i
)
110.55(9), 109.48(9); Si-C11-C12
)
114.41(19), 115.18(18).
The chlorosilane 2a (step i of Scheme 1) is prepared by
catalytic hydrosilylation of the 1,1,2-trihydroperfluo-
rooctene using fluorous biphasic extraction of 2a, al-
lowing complete recovery of the expensive rhodium
catalyst.11 The fluorous silanes 2b-d were obtained in
two steps from the commercially available perfluorooctyl
iodide (for 2b) or 2,3,4,5,6-pentafluorobenzyl bromide
(for 2c,d). The intermediate silanes 1b-d, obtained
through modified literature procedures12 (steps ii, iv,
and vi of Scheme 1, respectively), were brominated into
1b-d (steps iii, v, and vii of Scheme 1, respectively).
Crystallization of 2d from Et2O at -20 °C gave
colorless crystals suitable for single-crystal X-ray analy-
sis. The molecular structure is shown in Figure 1, along
with selected bond distances and angles. The asym-
metric unit contains one-third of each of the two
independent molecules, both of which have crystal-
lographic C3 symmetry with the symmetry axis along
the Si-Br bond. Despite the heavy fluorination at the
phenyl rings the Si-Br bond distances of 2.2192(15) and
2.1971(14) Å are comparable to those in Me3SiBr13 and
1,4-dibromo-1,4-disilabutane (2.2362(12) Å)14 but shorter
than in tris(bromodimethylsilyl)methane (2.251-2.263
Results and Discussion
Synthesis of the Fluorous Zirconocene Dichlo-
rides 4a-d and Non-Fluorous 4e. The chosen pre-
cursors for the zirconocene dichlorides 4a-e, the fluo-
rous halosilanes 2a-d and nonfluorous 2e, were
synthesized in good to quantitative yield (Scheme 1).
(5) (a) Malanga, M. T.; Newman, T. H. Eur. Pat. Appl. EP 361309
A2, 1990, (b) Jones, E.; Walker, J. Ger. Offen. DE 2501239, 1975. (c)
Mitani, M.; Furuyama, R.; Mohri, J.-I.; Saito, J.; Ishii, S.; Terao, H.;
Nakano, T.; Tanaka, H.; Fujita T. J. Am. Chem. Soc. 2003, 125, 4293-
4305.
(6) (a) De Vries, T. J.; Duchateau, R.; Vorstman, M. A. G.; Keurentjes,
J. T. F. Chem. Commun. 2000, 263-264. (b) Kendall, J. L.; Canelas,
D. A.; Young, J. L.; DeSimone, J. M. Chem. Rev. 1999, 99, 543-563.
(7) (a) Hughes, R. P.; Trujillo, H. A. Organometallics 1996, 15, 286-
294. (b) Herrera, V.; de Rege, P. J. F.; Horva´th, I. T.; Le Husebo, T.;
Hughes, R. P. Inorg. Chem. Commun. 1998, 1, 197-199. (c) Maldanis,
R. J.; Chien, J. C. W.; Rausch, M. D. J. Organomet. Chem. 2000, 599,
107-111. (d) Deck, P. A.; Jackson, W. F.; Fronczek, F. R. Organo-
metallics 1996, 15, 5287-5291. (e) Brˇ´ıza, T.; Kv´ıcˇala, J.; Paleta, O.;
Cˇ erma´k, J. Tetrahedron 2002, 58, 3841-3846.
(8) (a) Cheron, V.; Couturier, J.-L.; Hagen, H.; van Koten, G.;
Deelman, B. J. Int. Pat. Appl. WO/0214337 (publication date Feb 21,
2002) to ATOFINA. (b) Merle, P. G.; Deelman, B. J.; van Koten, G.
Fluorous metallocenes for R-olefin polymerisation in fluorous biphasic
systems. Second European Catalysis Symposium; Organic Catalysis
for a Sustainable Development; Sept 23-26, 2001, Pisa, Italy; Book of
Abstracts, Poster 48.
(9) Cˇ erma´k, J.; Sˇta´stna´, L.; Sy´kora, J.; C´ısarˇova´, I.; Kv´ıcˇala, J.
Organometallics 2004, 23, 2850-2854 and references therein.
(10) Dinh, L. V.; Gladysz, J. A. Chem. Commun. 2004, 998-999 and
references therein.
(11) De Wolf, E.; Spek, A. L.; Deelman, B. J.; van Koten, G.
Organometallics 2001, 20, 3686-3690.
(12) (a) Denson, D. D.; Smith, C. F.; Tamborski, C. J. Fluorine Chem.
1973/1974, 3, 247. (b) Smith, C. F.; Soloski, E. J.; Tamborski, C. J.
Fluorine Chem. 1974, 4, 35. (c) Thoai, N. J. Fluorine Chem. 1975, 5,
115. (d) Picard, J. P.; Ekouya, A.; Dunogues, J.; Duffaut, N.; Calas, R.
J. Organomet. Chem. 1975, 93, 51-70.
(13) Harmony, M. D.; Strand, M. R. J. Mol. Spectrosc. 1980, 81, 308-
315.
(14) Mitzel, N. W.; Riede, J.; Schmidbauer, H. Acta Crystallogr.
1996, C52, 980-982.

1622 Organometallics, Vol. 24, No. 7, 2005
Merle et al.
hydrocarbon-soluble, crystalline solids or as a brown oil
(4e) with satisfactory analyses and multinuclear ambi-
ent-temperature NMR spectra. Complex 4a was easily
converted to its dimethyl derivative [(η5-C5H4SiMe2CH2-
CH2C6F13)2ZrMe2] (5a).
Low-temperature NMR spectra (300 MHz) of toluene-
d8 solutions of 4a,c were recorded from 25 to -80 °C
(for assignments, see the Experimental Section) and
revealed that even at low temperature (-80 °C) the
fluxional M-Cp rotational processes are still operative
and fast on the NMR time scale.18 The spectra recorded
under the same conditions for the precatalyst 4b (i.e.
with the C8F17 tail; see the Experimental Section for
assignments) merit more explanations: the R- and
â-proton signals, of the monosubstituted-cyclopenta-
dienyl ligand (δ 6.30 and 5.70 at ambient temperature),
gradually disappear to the profit of four equal-intensity
signals (δ 6.34, 6.15, 5.64, and 5.46 at -80 °C); in the
meantime, the singlet observed for the SiMe2 protons
(δ 0.61 at ambient temperature) splits into two new
signals at δ 0.75 and 0.67 at - 80 °C, the fluxional
M-Cp rotational process becoming slower than the
NMR time scale, indicative of either a C2- or Cv-
symmetric isomer (rac or meso forms).
Figure 2. Stacking between the pentafluorophenyl rings
of the two independent molecules of 2d. The rings are
nearly parallel with a dihedral angle of 0.02°. The inter-
planar distance is approximately 3.14 Å. Because the rings
are shifted with respect to each other, the distance between
the ring centers is significantly longer (4.2098(17) Å). Due
to this shift, atom F16 of ring 1 is above the center of ring
2 (distance F16-Cg02 ) 3.121(2) Å). Atoms F25 and F26
of ring 2 are directly above carbon atoms C17 and C15 of
ring 1 (F25-C17 ) 3.158(4) Å; F26-C15 ) 3.176(4) Å).
Complexes 4a-d have a much higher hydrocarbon
solubility than the previously reported group 4 fluorous
metallocenes [M{η5-C5H4(C6F5)}2Cl2] (M ) Ti,7b Zr7c).
Moreover, in contrast to 4f, they clearly display, albeit
modest, solubility in PFC solvents: e.g., FC-72 (ca. 1
Scheme 2
g/L). The partition coefficient P (P ) Cfluorous phase
/
Corganic phase, where C is the concentration of the complex
in the solvent, i.e. c-C6F11CF3 and toluene, respectively)
for complexes 4a-c reflected a trend similar to that
observed in the case of fluorous phosphines,19 i.e., a
steady increase with the F weight percentage of the
molecule (cf. P4c ) 0.09, wt % F 24.7; P4a ) 0.23, wt %
F 44.9; P4b ) 0.78, wt % F 51.9); these values indicate
a relatively small affinity of the molecules for the
fluorous phase but possibly enough to induce surface
activity.20
Crystal Structures of 4a-c. Compounds 4a,c were
successfully subjected to structural characterization by
single-crystal X-ray crystallography. The single crystals
of 4a,c contained discrete [Zr{η5-C5H4(SiMe2RF)}2Cl2]
molecules (RF ) CH2CH2C6F13 (4a) CH2C6F5 (4c))
(Figures 3 and 4, respectively). Compound 4b could not
be refined satisfactorily, due to significant disorder in
the perfluorooctyl groups (R ) 22%); hence, the crystal-
lographic data are not reported here. However, we can
conclude from this analysis that 4b also has a regular
bent-metallocene structure, similar to that of 4a. The
asymmetric unit for 4c contained a single molecule,
whereas it contained half a molecule in 4a, the other
half being generated by a 2-fold rotation. The stereo-
chemistry around the Zr atom was invariably that found
in previously studied bent-sandwich complexes of the
type [ML2X2] (M ) Zr, Hf; L ) η5-cyclopentadienyl or
Å).15 Also, the tetrahedral hybridization of the Si atoms
with angles of 108.37(10)-110.55(9)° is comparable to
that in other bromotrialkylsilanes and compounds 4a,c
(vide infra). Interestingly, the pentafluorophenyl rings
of the two independent molecules of 2d are π-stacked
but with significant ring slippage (Figure 2).
The target compounds 4a-e were prepared (Scheme
2) by slight modification of a reported procedure for [Zr-
(η5-C5H4SiMe3)2Cl2] (4f).16 Addition of LiCp (Cp ) C5H5)
in THF to 2a-e gave in good yield the fluorous silyl-
substituted cyclopentadienes 3a-e as a mixture of the
1-, 2- and 5-silyl isomers (the last being the major
species by ca. 80%).17 Lithiation and reaction with solid
ZrCl4 produced the new fluorous zirconocene(IV) dichlo-
rides 4a-e in moderate to good yields as colorless (4a),
off-white (4c,d), or pale yellow (4b) air-stable, highly
(18) DSC analysis of crystalline 4a,c in the solid state, from ambient
temperature to the melting point, shows no evidence of polymorphism
as one could have expected with such fluxional groups (e.g. CH2-
CH2C6F13 as in 4a).
(19) Richter, B.; de Wolf, E.; van Koten, G.; Deelman, B. J. J. Org.
Chem. 2000, 65, 3885-3893.
(20) de Wolf, E.; Spek, A. L.; Kuipers, B. W. M.; Philipse, A. P.;
Meeldijk, J. D.; Boumans B. H. H.; Frederic, P. M.; Deelman, B. J.;
van Koten, G. Tetrahedron 2002, 58, 3911-3922.
(15) Friesen, D. M.; McDonald, R.; Rosenberg, L. Can. J. Chem.
1999, 77, 1931-1940.
(16) Lappert, M. F.; Pickett, C. J.; Riley, P. I.; Yarrow, P. I. W. J.
Chem. Soc., Dalton Trans. 1981, 3, 805-813.
(17) Abel, E. W.; Dunster, M. O. J. Organomet. Chem. 1971, 33,
161-167.

Fluorous Zirconocene(IV) Complexes
Organometallics, Vol. 24, No. 7, 2005 1623
Table 1. Polymerization Activities for 4a-d,f in
Toluenea
activity (kg of PE ((mol of Zr) h)-1
entry
precatalyst
t ) 5 min
t ) 30 min
1
2
3
4
5
4a
4b
4c
4d
4f
443
234
288
20
1196
1125
188b
a Polymerizations were conducted using [Zr] ) 2.5 × 10-4 mol
L-1, Al/Zr ) 500, p ) 1 bar, and T ) 20 °C. The reproducibility
determined from two experiments was better than 10%. b This
catalytic system is essentially deactivated after 5 min due to high
viscosity.
Figure 3. Molecular structure of compound 4a. Displace-
ment ellipsoids are drawn at the 50% probability level, and
H atoms are omitted for clarity. Symmetry operation: (i)
-x, y, 0.5 - z. Selected bond lengths (Å) and angles (deg):
Zr-Cl ) 2.4524(7), Zr-Cg01 ) 2.1987(12); Cl-Zr-Cl′ )
96.50(3), Cg01-Zr-Cg01′ ) 129.61(5).
metrically constrained [Zr{(η5-C5H4CH2)2CH2}Cl2].24 The
Cl-Zr-Cl bond angle is 99.48(2)° (cf. 93.7(1)° in 4f),
close to the 97° reported value in [Zr{(η5-C5H4CH2)2-
CH2}Cl2],24 while the Cg01-Zr-Cg02 bond angle is less
influenced at 127.94(4)° (cf. 129.1° in 4f).
Polymerization Experiments. Our next concern
was whether the fluorous zirconocene dichlorides 4a-d
would be at all active in ethylene polymerization using
MAO as the cocatalyst.25 Initial experiments were
carried out at p ) 6 bar, T ) 80 °C, [Zr] ) 50 µM, Al/Zr
) 500, and t ) 30 min. Under these conditions the
fluorous precatalysts 4a,b and nonfluorous 4e were
found to display similar activities, compared to the
known reference systems Cp2ZrCl2 and (CpBu)2ZrCl2
((1.6-2.0) × 103 kg of PE mol-1 bar-1 h-1). The fact that
4a,e displayed essentially equal activities indicates that
the perfluoroalkyl group is effectively insulated from the
cyclopentadienyl ligand by the -SiMe2CH2CH2- spacer
functionality. Due to the high activity of these precata-
lysts, the reproducibility and temperature control during
the polymerization runs was too poor to allow an
accurate comparison of the molecular weights of the
polymers obtained. We therefore studied complexes 4a-
d,f under less forcing conditions at 1 bar of ethylene
pressure, room temperature, and [Zr] ) 25 mM. The
activities that were obtained are an order of magnitude
lower, but the reproducibility and temperature control
were significantly better, allowing comparison of the
performance of the different complexes and the proper-
ties of the resulting polymers.
Table 1 compares the measured activities for 4a-d,f
in toluene. The polymerization times employed are
rather long, as we were interested in the evolution of
the catalytic activity over time. Remarkably, complex
4f, which was used as the reference system, shows very
high activity over the first 5 min, after which stirring
became hindered, resulting in significant mass transfer
limitation and a reduced activity over 30 min. Com-
plexes 4a-c, although less active by a factor of 2,
remained active during this 30 min, resulting in higher
overall productivity. The highest activity over 30 min
was observed for ethylene-spaced 4a. Substitution of the
ethylene function by a tetrafluoroethylene bridge as in
4b induced a 2-fold drop in activity. Apparently an
ethylene spacer is needed to leave the delicate electronic
balance on the Zr center, required for ethylene com-
Figure 4. Molecular structure of compound 4c. Displace-
ment ellipsoids are drawn at the 50% probability level, and
H atoms are omitted for clarity. Selected bond lengths (Å)
and angles (deg): Zr-Cl1
) 2.4571(6), Zr-Cl2 )
2.4379(6), Zr-Cg01 ) 2.2091(11), Zr-Cg02 ) 2.2157(11);
Cl1-Zr-Cl2 ) 99.48(2), Cg01-Zr-Cg02 ) 127.94(4).
an analogue)21 and can be conveniently described as a
distorted tetrahedron by considering the ligand L- as a
sterically demanding unidentate moiety. The cyclopen-
tadienyl ring is slightly asymmetrically η5-bonded to the
Zr atom (with Zr-C distances ranging from 2.480(3) to
2.530(3) Å in 4a and from 2.489(2) to 2.545(2) Å in 4c,
the shift resulting from the steric hindrance of the bulky
SiMe2CH2CH2C6F13 group) with similar Zr-centroid
distances (Zr-Cg ) 2.1987(12) Å in 4a and 2.2091(11)
and 2.2157(11) Å in 4c).
Compound 4a possess 2-fold symmetry in the solid
state (Figure 3) with the Si atoms pointing in opposite
directions, as observed for the related complex 4f with
a smaller SiMe3 substituent.22 The fluorous tails lie on
one side of the molecule, the two chlorine atoms occupy-
ing the other one. The Si atoms are pushed above the
cyclopentadienyl plane by 0.335(1) Å, resulting in a
Cg01-Zr-Cg01′ angle of 129.61(5)° (cf. 129.1° for 4f).22
The Cl-Zr-Cl′ angle of 96.50(3)° is wider than in 4f
(93.7°) but close to the 97° measured for the catalytically
highly active zirconocene dichloride complex [Zr{η5-
C5H5}2Cl2].
Triclinic 4c crystallized as the rac conformer with C1
symmetry (Figure 4). In contrast to 4a, the Si atoms on
the Cp rings in 4c are eclipsed with astride Cl atoms,
as observed for [Zr{η5-C5H4CH2Ph}2Cl2]23 or the geo-
(21) Cardin, D. J., Lappert, M. F., Raston, C. L., Eds. Chemistry of
Organo Zirconium and Hafnium Compounds; Ellis Hoorwood: Chich-
ester, U.K., 1986.
(22) Antin˜olo, A.; Lappert, M. F.; Singh, A.; Winterborn, D. J. W.;
Engelhardt, L. M.; Raston, C. L.; White, A. H.; Carty, A. J.; Taylor, N.
J. J. Chem. Soc., Dalton Trans. 1987, 1463-1472.
(23) Dusausoy, Y.; Protas, J.; Renaut, P.; Gautheron, B.; Tainturier,
G. J. Organomet. Chem. 1978, 157, 167-172.
(24) Saldarriaga-Molina, C. H.; Clearfield, A.; Bernal, I. J. Orga-
nomet. Chem. 1974, 80, 79-90.
(25) For an overview of the role of MAO see, e.g.: Abel, E. W., Stone,
F. G. A., Wilkinson, G., Eds. Comprehensive Organometallic Chemistry
II; Pergamon: Oxford, U.K., 1995; Chapter 12, pp 1193-1208.

1624 Organometallics, Vol. 24, No. 7, 2005
Merle et al.
Table 2. GPC Data for the Polymer Prepared from
4a-c,f in Toluene and FBSa
Mn (103 g mol-1) (Mw/Mn)
entry
precatalyst
toluene
toluene/FC 72 (1/1 v/v)
1
2
3
4
5
4ab
4ac
4b
119 (2.7)
21 (8.1)
33 (6.5)
69 (2.7)
86 (2.2)
n.d.
79 (3.2)
43 (6.3)
99 (4.3)
109 (2.7)
4c
4fd
a Polymerization conditions: [Zr] ) 2.5 × 10-4 mol L-1, Al/Zr
) 500, t ) 30 min, p ) 1 bar, and T ) 20 °C unless stated
otherwise. b t ) 15 min. c Polymerization conditions: [Zr] ) 5.8 ×
10-5 mol L-1, Al/Zr ) 400, t ) 30 min, p ) 6 bar, and T ) 40 °C.
In both cases the temperature of the reaction mixture rose to 80
°C. d t ) 5 min.
plexation-insertion processes, intact.1a The effective-
ness of a spacer is also exemplified by 4c, where a
methylene spacer is used between the Si atom and the
pentafluorophenyl ring. It is noteworthy that, measured
over the first 5 min, 4c has an activity that is essentially
identical with that of 4f (1196 and 1125 kg of PE ((mol
of Zr) bar h)-1, respectively). For 4d, in which all three
methyl groups are replaced by CH2C6F5, the activity was
poor, probably because of the steric shielding of the
metal center.
GPC analyses of the polymers showed that their
number-averaged molecular weight (Mn) was reasonably
high and that the molecular weight distributions were
broad (Table 2). Due to the long polymerization times
employed, the polydispersity indexes are higher than
those predicted by Flory’s most probable distribution
(Mw/Mn ) 2), but they are not exceptional for metal-
locene catalysts and can be explained by significant
heterogenization of the reaction mixtures due to the
precipitating polymer (both low solubility of the PE at
the low reaction temperature and the relatively long
reaction time play a role) and local temperature fluctua-
tions.28
The activities measured fit well within the range of
activities reported in the literature for zirconocene
precatalysts.26 The observation that the activities and
molecular weight drop when more electron-withdrawing
substituents are used parallels recent observations for
pentafluorophenyl-substituted zirconocenes.27
Figure 5. Differential pressure chromatograms for PE
samples prepared from 4b/MAO in toluene (a) and toluene/
FC 72 (b) compared to the PE obtained from 4f/MAO in
toluene (c). Note that the low retention volume corresponds
to a high-molecular-weight polymer.
investigations and pentane extractions of the quenched
reaction mixtures indicate that the zirconocene moiety
itself is unaffected when reacted with MAO (vide infra).
Although this turned out to be hard to verify experi-
mentally, a more likely explanation is that the hindered
rotation around the Zr-Cp axis, which was already
observed for the parent dichloride 4b (vide supra), is
sufficiently slow to afford species with different kp/kt
ratios (kp ) rate constant for chain propagation, kt )
rate constant for chain termination). The steric crowding
around the Zr center supplemented by the rigidity of
the -C8F19 tails30 may contribute to this phenomenon.
Another possibility suggested by one of the reviewers
of this paper, i.e. chain transfer to aluminum, appears
to be less likely, as it generally leads to a lower
molecular weight fraction and becomes important only
at high Al/Zr ratios.28b,c,31 The GPC curves of the
polymers obtained from the other catalysts in toluene
were all unimodal.
A tempting explanation for the increased productivity
of the fluorous precatalyst at longer polymerization
times, which at this moment is purely speculative, is
that the fluorous systems remain active after precipita-
tion of the growing polymer chain. Precipitation nor-
mally results in liquid-to-solid mass transfer of ethylene
followed by ethylene starvation and consequently chain
termination.28a Occlusion of the active site in the
precipitated PE may well become enthalpically less
favorable for the fluorous complexes compared to non-
fluorous precatalysts, resulting in continued availability
and activity of the active site.32
The extremely broad molecular weight distribution
obtained for 4b is remarkable, however, and closer
inspection of the GPC data (Figure 5) indicated that in
fact a bimodal distribution was obtained with the second
molecular weight fraction located at higher average
molecular weight (Mn ) 2 × 106) relative to the PE
obtained for 4f (Mn ) 86 × 103). The low-molecular-
weight fraction was found to be comparable to that of
4f. Although such a distribution could signify that the
catalyst is not stable under the reaction conditions,
resulting in the creation of multiple sites,29 NMR
Exploratory polymerization experiments with 4a-c,f
under FBS conditions (1:1 volumetric mixtures of tolu-
ene and FC-72 as well as of hexane and FC72) were
undertaken to probe the possible effect of the fluorous
(26) Mo¨hring, P. C.; Coville, N. J. J. Organomet. Chem. 1994, 479,
1-29.
(30) Bunn, C. W.; Howells, E. R. Nature 1954, 174, 549.
(31) (a) Scollard, J. D.; McConville, D. H.; Vittal, J. J.; Payne N. C.
J. Mol. Catal. A: Chem. 1998, 128, 201-214. (b) Britovsek, G. J. P.;
Bruce, M.; Gibson, V. C.; Kimberley, B. S.; Maddox, P. J.; Mastroianni,
S.; McTavish, S. J.; Redshaw, C.; Solan, G. A.; Stro¨mberg, S.; White,
A. J. P.; Williams, D. J. J. Am. Chem. Soc. 1999, 121, 8728.
(27) Thornberry, M. P.; Reynolds, N. T.; Deck, P. A. Organometallics
2004, 23, 1333-1339.
(28) (a) Lahti, M.; Koivumaeki, J.; Seppaelae, J. V. Angew. Makro-
mol. Chem. 1996, 236, 139-153. (b) Leino, R.; Luttikhedde, H. J. G.;
Lehmus, P.; Wile´n C.-E.; Sjo¨holm, R.; Lehtonen, A.; Seppa¨la¨, J. V.;
Na¨sman, J. H. Macromolecules 1997, 30, 3477-3483. (c) Liu, J.;
Støvneng, J. A.; Rytter, E. J. Polym. Sci. A: Polym. Chem. 2001, 39,
3566-3577.
(29) For example, one could envision nucleophilic attack by MAO
or AlMe3, which is contained in MAO, on the Si atom replacing the
1H,1H,2H,2H-perfluoroalkyl group by a regular Me group.
(32) This would be another demonstration of fluorous biphasic
separation behavior in the solid state caused by the inability of the
fluorous metallocene fragment to enter into enthalpically favorable
interactions with the PE that could otherwise compensate for the loss
of intramolecular van der Waals interactions in the partly crystalline
PE. Related phase separation phenomena in the solid state have been
observed in the X-ray structure of a fluorous Rh complex.20

Fluorous Zirconocene(IV) Complexes
Organometallics, Vol. 24, No. 7, 2005 1625
polymerization.34b,35 For the Cp2ZrMe2-MAO systems,
these are the heterodinuclear [Cp2Zr(µ-Me)2AlMe2]+[Me-
MAO]- and the unsymmetrical methyl-bridged complex
[Cp2ZrMe]+[Me-MAO]- ion pairs along with other in-
termediates (especially at low Al/Zr ratio) such as the
neutral [Cp2ZrMe2][MAO] adduct or the dimeric sym-
metric (on the cationic part) binuclear [Cp2ZrMe]2-
(µ-Me)+[Me-MAO]- ion pair.35a
Scheme 3
biphasic conditions on the activities. It was found that
that the activities remained essentially unaffected,
demonstrating that FC-72 is compatible with both MAO
and the polymerization conditions and that the biphasic
conditions did not result in problems with mass trans-
port limitation. More importantly, under biphasic condi-
tions the relative ranking of the activities of the fluorous
complexes and nonfluorous 4f that was observed in
toluene was essentially reproduced, suggesting that
partitioning of the active species into the fluorous phase
is not yet significant at this level of fluorous character
of the metallocene precatalysts. However, when the
molecular weights of the resulting polymers are com-
pared (Table 2), a general trend toward significantly
higher average molecular weight is observed under the
biphasic conditions.
In trying to rationalize the effect of replacing part of
the toluene solvent by FC-72, it should be noted that
the ionic catalyst system is essentially insoluble in the
FC-72 phase. This could be easily concluded from
experiments in pure FC-72 that resulted in poor activity
(<10 kg of PE ((mol of Zr) bar h)-1) as well as visually
observable poor solubility of the catalyst components.
Although the solubility of ethylene in FC-72 is ca. 20%
higher than in toluene,33 this is of relatively low
importance, as the polymerization reaction takes place
predominantly in the toluene phase. Some surface
activity cannot be ruled out in the case of the am-
phiphilic fluorous metallocene systems. However, by
partial dissolution in the toluene layer (ca. 5 vol %), the
main effect of the perfluorocarbon solvent is to lower
the dielectric constant of the toluene phase. The latter
will promote tight ion pairing of the catalytic system,
which in turn may be expected to suppress the rate of
â-hydrogen transfer to the metal center.34 The observed
increase in polymer molecular weight can thus be
rationalized qualitatively.
Solutions of precatalysts 4a-c and MAO (benzene-
d6, Al/Zr ) 100) were studied by 1H NMR spectroscopy
at ambient temperature (see Table 3 for NMR data and
assignments). A remarkable feature for each experiment
with precatalysts 4a-c and MAO is the presence in the
1H NMR spectrum of four broad signals for the mono-
substituted-cyclopentadienyl group protons, which be-
long to the unsymmetrical methyl-bridged [(CpSiMe2RF)2-
ZrMe]+[X-MAO]- (X ) Me, Cl, RF ) CH2CH2C6F13 (4a′),
C8F17 (4b′), CH2C6F5 (4c′)) contact and separated ion
pairs rather than to the heterodinuclear complex
[(CpSiMe2RF)2Zr(µ-Me)2AlMe2]+[X-MAO]- (X ) Me, Cl),
for which only two Cp H signals (symmetrical cationic
part) would be expected.35a Nevertheless, the formation
of the [(CpSiMe2RF)2Zr(µ-Me)2AlMe2]+[X-MAO]- (X )
Me, Cl) ion pair cannot be excluded, as its NMR signals
could be non-resolved from the broad [(CpSiMe2RF)2-
ZrMe]+[X-MAO]- (X ) Me, Cl) signals at ambient
temperature. It is noteworthy that species 4′ is observed
in solution in equilibrium with the starting precatalyst
4 (in a 2:1 molar ratio) for complexes 4a,f, whereas 4′
is the only species observed when 4b,c were treated with
MAO. At lower Al/Zr ratio (Al/Zr ) 20), a similar pattern
for the Cp protons was observed, but at lower field,
which is attributed to the unsymmetrical monomethy-
lated [(CpSiMe2RF)2Zr(Me)Cl] (RF ) C8F17 (4b′′), CH2C6F5
(4c′′)). These monomethyl complexes were observed
along with unreacted precatalyst (3:1 ratio).
These observations are in accordance with previous
observations for [Cp2ZrCl2]-MAO and 4f-MAO35a,e,36
and also correlate, at least qualitatively, with recent
work by Deck et al.,37 where it was found that electron-
withdrawing C6F5 groups stabilize mononuclear cationic
[(CpC6F5)2ZrMe]+[X-MAO]- species. From these NMR
studies no indications were obtained that precatalyst
4b behaves differently from the other precatalysts,
leaving the origin of the bimodality of the polyethylene
obtained with 4b unclear. Attempts to study solutions
of complexes 4a-c,f and MAO at low temperatures were
hampered by severe line broadening.
When the shape of the GPC chromatogram for 4b was
inspected, it was found that the higher molecular weight
distribution gets more pronounced under the fluorous
biphasic conditions (Figure 5), whereas the GPC curves
for the other catalysts remained unimodal. Apparently
the species with the highest kp/kt ratio is favored by the
presence of the fluorocarbon solvent.
Most remarkably, hydrolysis of the fluorous species
4′ by aqueous alcoholic HCl regenerated the fluorous
zirconocene dichlorides (characterized by both their 1H
and 19F NMR spectra) whereas hydrolysis of a 4f-MAO
solution led to decomposition of the catalyst, free HCp-
SiMe3 being the only product observed by 1H NMR.
Catalyst Analysis by 1H NMR Spectroscopy. The
Lewis acid role of MAO in the formation of coordinately
unsaturated cationic zirconocene alkyl species from the
zirconocene dichloride precursor is now well established
(Scheme 3); NMR spectroscopy has proven to be a useful
technique for the characterization of these species,
which are thought to be the actual catalysts for
(35) (a) Babushkin, D. E.; Semikolenova, N. V.; Zakharov, V. A.;
Talsi, E. P. Macromol. Chem. Phys. 2000, 201, 558. (b) Tritto, I.;
Donetti, R.; Sacchi, M. C.; Locatelli, P.; Zannoni, G. Macromolecules
1997, 30, 1247-1252. (c) Tritto, I.; Donetti, R.; Sacchi, M. C.; Locatelli,
P.; Zannoni, G. Macromolecules 1999, 32, 264-269. (d) Harlan, C. J.;
Bott, S. G.; Barron, A. R. J. Am. Chem. Soc. 1995, 117, 6465-6474.
(e) Cam, D.; Giannini, U. Makromol. Chem. 1992, 193, 1049-1055.
(36) Nekhaeva, L. A.; Bondarenko, G. N.; Rykov, S. V.; Nekhaev,
A. I.; Krentsel, B. A.; Mar’in, V. P.; Vyshinskaya, L. I.; Khrapova, I.
M.; Polonskii, A. V.; Korneev, N. N. J. Organomet. Chem. 1991, 406,
139-146.
(33) Derived from a plot of log x versus δ (x ) mole fraction of
ethylene, δ ) Hildebrand parameter of the solvent): Jolley, J. E.;
Hildebrand, J. H. J. Am. Chem. Soc. 1958, 80, 1050-1054.
(34) (a) Stehling, U.; Diebold, J.; Kirsten, R.; Ro¨ll, W.; Brintizinger,
H.-H. Organometallics 1994, 13, 964-970. (b) Pe´deutour, J.-N.;
Radhakrishnan, K.; Cramail, H.; Deffieux, A. Macromol. Rapid Com-
mun. 2001, 22, 1095-1123.
(37) Hawrelak, E. J.; Deck, P. A. Organometallics 2003, 22, 3558-
3565.

1626 Organometallics, Vol. 24, No. 7, 2005
Merle et al.
apparatus and are uncorrected. Mass spectra (nanoES-Q-TOF-
MS) were performed by C. Versluis (Department of Bio-
molecular Mass Spectrometry, Utrecht University, NL) using
a Micromass Q-Tof hybrid tandem mass spectrometer and the
MassLynx software, version 3.0. GPC analyses (against poly-
styrene standard in 1,2-dichlorobenzene at 140 °C) were
performed by Rapra Technology Ltd (U.K.). Cyclopentadiene
was obtained by cracking of dicyclopentadiene and distilled
prior to use, CpLi was prepared by directly cracking dicyclo-
pentadiene over a solution of LiBun (1.6 mol L-1 in hexane).
Chlorodimethyl(1H,1H,2H,2H-perfluorooctyl)silane was pre-
pared by following reported methods.11,38 All other reagents
were purchased from commercial sources and used without
further purification. For all the polymerization tests, a 10 wt
% solution of MAO in toluene from WITCO (d20 ) 0.885, total
Al content 4.8 wt %) and ethylene (3.0, >99.9%, Hoek Loos)
were used as received.
Moreover, pentane extraction of the quenched
polymerization filtrate, from polymerization experi-
ments with precatalysts 4a-d and MAO, allowed, after
removal of the solvent, recovery of the starting precata-
lyst. These results confirm the enhanced stability of the
fluorous precatalyst. Also, they open up the possibility
of (pre)catalyst recycling in metallocene polymerization
even though there might not be a practical need for it,
given the low catalyst loadings of industrial metal-
locene-based olefin polymerization processes.
Conclusions
In conclusion, four new crystalline, highly stable
zirconocene(IV) dichlorides, substituted with one fluo-
rous silyl group per cyclopentadienyl ring, have been
prepared. They are hydrocarbon soluble and even
moderately soluble in perfluorocarbons (PFC’s). Three
of these four fluorous complexes (4a-c) form active
ethylene polymerization catalysts when reacted with an
excess of methylaluminoxane (MAO, Al/Zr ) 500) in
pure toluene but also in fluorous biphasic solvent
systems (e.g. toluene/perfluorohexanes). The most im-
portant observation is that these fluorous zirconocene
systems display increased robustness and consequently
increased productivity over prolonged polymerization
times in comparison to the nonfluorous reference system
[Zr(η5-C5H4SiMe3)2Cl2] (4f). This phenomenon may well
be related to phase segregation of the fluorous metal-
locene moiety from the polyethylene matrix and will be
investigated further in future studies.
Dimethyl(perfluoroctyl)silane (1b). LiBun (80 mL of a
1.6 mol L-1 solution in hexane, 50 mmol) and hexane (90 mL)
were added dropwise over a period of 4.5 h to a solution of
C8F17I (26.52 g, 48.6 mmol) and HSiMe2Cl (6.8 mL, 85 mmol)
in Et2O (150 mL) at -78 °C. After the mixture was warmed
to ambient temperature, a white suspension had formed, and
water (50 mL) and Et2O (150 mL) were added. The layers were
separated, and the ethereal layer was washed with brine (30
mL) and dried on MgSO4. Removal of the volatiles using a
rotary evaporator gave a yellow oil (19.8 g). Fractional distil-
lation (11 mbar, 57-59 °C) using a 10 cm Vigreux column gave
HSiMe2C8F17 (1b) as a colorless liquid (10.14 g, 44%), which
according to 19F NMR contained approximately 5% C8F17I. 1H
3
NMR (δ, CDCl3): 0.38 (d, 6 H, JH,H ) 4 Hz, SiMe2), 4.24 (br,
1
1 H, Si-H). 13C{19F} NMR (δ, CDCl3): -7.9 (q, JH,C ) 125
Hz, SiMe2), 108.6, 110.5, 111.0, 111.7, 117.4 (t, 2JF,C ) 19 Hz,
CF3), 122.7 (CF2Si). 19F NMR (δ, CDCl3): -81.9 (t, 3 F, 4JF,F
)
The more electron-withdrawing fluorinated hydrocar-
byl substituents on the cyclopentadienyl ligand result
in lower initial polymerization activity and a decreased
molecular weight of the polyethylene obtained, probably
as a result of a decreased propagation rate. Remarkably,
fluorous biphasic conditions during the polymerization
reaction in general result in higher polymer molecular
weight. This phenomenon was even observed for non-
fluorous 4f and is most likely caused by a suppression
of the rate of â-H transfer to the metal center in these
relatively nonpolar solvent combinations. For the most
fluorous zirconocene complex bearing two -SiMe2C8F17
tails (4b) a polyethylene with a bimodal molecular
weight distribution was obtained, the higher molecular
weight part of which became more pronounced under
9 Hz, CF3), -120.8 (br s, 2 F, F2), -122.6 (br s, 2 F, F3), -122.8
(br s, 4 F, F4 and F5), -123.6 (br s, 2 F, F6), -127.1 (br s, 2 F,
F7), -127.6 (d, 2 F, 3JH,F ) 12 Hz, F1). 29Si{1H} NMR (δ, CDCl3):
2
3
-8.3 (tt, JF,Si ) 30 Hz, JF,Si ) 6 Hz).
(2,3,4,5,6-Pentafluorobenzyl)dimethylsilane (1c). A so-
lution of BrCH2C6F5 (10.55 g, 40.4 mmol) and HSiMe2Cl (4.11
g, 43.4 mmol) in Et2O (150 mL) was added over a period of 4
h to magnesium turnings (2.65 g, 109 mmol) on suspension in
Et2O (50 mL). The greenish suspension was stirred at ambient
temperature for ca. 15 h and quenched with H2O (50 mL). The
aqueous layers was extracted with Et2O (3 × 50 mL), the
organic layers were washed with brine (50 mL) and dried over
MgSO4, and solvent was removed in vacuo to yield the desired
1
product as a colorless oil (8.66 g, 89%). H NMR (δ, CDCl3):
0.17 (m, 6 H, SiMe2), 2.20 (m, 2H, CH2), 4.01 (m, 1 H, H-Si).
13C{1H} NMR (δ, CDCl3): -4.6 (SiMe2), 10.1 (CH2), 114.2 (t,
2JF,C ) 240 Hz, ipso-C6F5), 137.8 (dm, 1JF,C ) 280 Hz, m-C6F5),
138.4 (dm, 1JF,C ) 240 Hz, p-C6F5), 144.4 (dm, 1JF,C ) 250 Hz,
1
fluorous biphasic conditions. H NMR experiments on
benzene-d6 solution of the precatalysts and MAO (Al/
Zr ) 100) have shown the formation of unsymmetrical
[(CpSiMe2RF)2ZrMe]+[Me-MAO]- ion pairs rather than
the heterodinuclear [(CpSiMe2RF)2Zr(µ-Me)2AlMe2]+-
[MeMAO]- ion pairs as the predominant species.
3
o-C6F5). 19F NMR (δ, CDCl3): -144.5 (dd, 2 F, JF,F ) 23 Hz
3
4JF,F ) 8 Hz, o-C6F5), -161.9 (dd, 2 F, JF,F ) 22 Hz, p-C6F5),
-164.5 (dd, 2 F, 3JF,F ) 21 Hz 4JF,F ) 9 Hz, m-C6F5). 29Si{1H}
NMR (δ, CDCl3): -11.5 (s). Anal. Calcd for C9H9F5Si: C, 44.99;
H, 3.78. Found: C, 45.16; H, 3.86.
Tris(2,3,4,5,6-pentafluorobenzyl)silane (1d). A solution
of BrCH2C6F5 (9.74 g, 37.3 mmol) and HSiCl3 (1.2 mL, 12
mmol) in Et2O (150 mL) was added over a period of 4.5 h to
magnesium turnings (2.20 g, 90 mmol) in suspension in Et2O
(100 mL). The greenish suspension was refluxed for 1 h and
then quenched with H2O (50 mL). The aqueous layers was
extracted with Et2O (3 × 50 mL), and the organic layers were
washed with brine (50 mL), dried over MgSO4, and concen-
trated to dryness in vacuo to yield the title compound as a
yellowish solid (5.83 g, 86%). 1H NMR (δ, CDCl3): 2.30 (m,
6H, CH2), 4.06 (m, 1 H, Si-H). 13C{1H} NMR (δ, CDCl3): 7.3
Experimental Section
General Considerations. All experiments were carried out
under dry nitrogen using standard Schlenk techniques. Sol-
vents were dried and distilled prior to use following literature
procedures. Elemental analyses were performed by Dornis und
Kolbe, Mikroanalytisches Laboratorium (Mu¨lheim, Germany).
1H (300.1 MHz), 13C (75.5 MHz), 29Si (59.6 MHz), and 19F (282.4
MHz) NMR spectra were recorded on a Varian INOVA 300
spectrometer at 25 °C, unless otherwise stated, and were
referenced internally (1H, 13C) to residual solvent resonances
or externally (to SiMe4 for 29Si and CFCl3 for 19F). Melting
points were measured in sealed capillaries on a Tottoli
(38) Ameduri, B.; Boutevin, B.; Nouiri, M.; Talbi, M. J. Fluorine
Chem. 1995, 74, 191-197.

Fluorous Zirconocene(IV) Complexes
Organometallics, Vol. 24, No. 7, 2005 1627
1
(CH2), 111.4 (ipso-C6F5), 137.8 (dm, JF,C ) 250 Hz, m-C6F5),
isomer), 6.63 and 6.53 (m, R- + â-H 5-(RFSiMe2)C5H5 isomer),
6.87 and 6.71 (m, R- + â-H of 1- and 2-(RFSiMe2)C5H5 isomers).
Anal. Calcd for C15H15F13Si: C, 38.30; H, 3.19; F, 52.55; Si,
5.96. Found: C, 38.08; H, 3.29; F, 52.74; Si, 5.81.
139.3 (dm, 1JF,C ) 250 Hz, p-C6F5), 144.5 (dm, 1JF,C ) 250 Hz,
o-C6F5). 19F NMR (δ, CDCl3): -143.2 (dd, 2 F, JF,F ) 21 Hz
3
4JF,F ) 6 Hz, o-C6F5), -158.5 (t, 1 F, JF,F ) 21 Hz, p-C6F5),
3
-162.5 (dt, 2 F, JF,F ) 21 Hz JF,F ) 6 Hz, m-C6F5). 29Si{1H}
NMR (δ, CDCl3): -6.4 (s). Anal. Calcd for C21H7F15Si: C, 44.07;
H, 1.23. Found: C, 43.94; H, 1.30.
3
4
[Dimethyl(perfluorooctyl)silyl]cyclopentadiene (3b).
A solution of CpLi (0.93 g, 12.9 mmol) in THF (50 mL) was
added dropwise to a stirred solution of BrSiMe2C8F17 (2b; 7.32
g, 13.1 mmol) in THF (50 mL) at 0 °C. The brownish solution
was stirred for 1 h at ambient temperature and quenched with
water (200 mL). The aqueous layer was extracted with pentane
(200 mL), and the organic layer was washed with water (2 ×
50 mL) and brine (30 mL) and dried over MgSO4. Solvent was
removed in vacuo using a rotary evaporator. The resulting
liquid was Kugelrohr-distilled (10-2 mbar, 100 °C) to yield the
Bromodimethyl(perfluorooctyl)silane (2b). A mixture
of HSiMe2C8F17 (1b; 7.56 g, 15.8 mmol) and Br2 (3.2 mL, 62
mmol) in CCl4 (25 mL) was stirred for 18 h at 60 °C in a
Schlenk flask which had been fitted with a condenser and a
CaCl2 tube. After removal of the volatiles in vacuo, the
resulting liquid was flash-distilled to yield the title compound
as a pale pink liquid (8.35 g, 95%). 19F NMR spectroscopy
showed that it contained approximately 5% C8F17I and was
used as such. 1H NMR (δ, CDCl3): 0.84 (s). 13C{19F} NMR (δ,
CDCl3): -0.1 (q, 1JH,C ) 124 Hz, SiMe2), 108.6 (partly resolved
q, JF,C ) 12 Hz), 110.4, 111.0 (s, 2 C), 111.6, 113.0, 117.4 (t,
2JF,C ) 21 Hz, CF3), 119.3 (CF2Si). 19F NMR (δ, CDCl3): -82.0
(t, 3 F, 4JF,F ) 9 Hz, CF3), -118.8 (br s, 2 F, F1), -122.5 (br s,
2 F, F3), -122.9 (br s, 4 F, F4 and F5), -123.7 (br s, 2 F, F6),
-127.2 (m, 4 F, F1 and F7). 29Si{1H} NMR (δ, CDCl3): 17.7 (t,
2JF,Si ) 35 Hz).
1
title compound as a clear yellow liquid (5.00 g, 70%). H and
19F NMR analysis showed the product to be a mixture of at
least two isomers (minor) with the 5-silyl isomer (major, ca.
80%) along with ca. 3% of C8F17I. 1H NMR (δ, CDCl3): 0.13 (s,
4.8 H, SiMe2, major), 0.51 (s, 1.2 H, SiMe2, minor), 3.18 (d, 0.3
H, J ) 1.5 Hz, C5H5, minor), 3.7 (br, 0.7 H, C5H5, major), 6.4-
4
7.2 (m, 3.5 H, C5H5). 19F NMR (δ, CDCl3): -81.9 (t, 3 F, JF,F
) 10 Hz, C8F3), -119.2 (br s, 2 F, C2F2), -122.5 (br s, 2 F,
C3F2), -122.7 (br s, 4 F, C4,5F2), -123.6 (br s, 2 F, C6F2), -126.8
4
(t, 1.5 F, JF,F ) 15 Hz, C1F2), -127.1 (m, 2 F, C7F2), -127.3
Bromo(2,3,4,5,6-pentafluorobenzyl)dimethylsilane (2c).
A solution of HSiMe2(CH2C6F5) (1c; 8.66 g, 36.0 mmol) and
Br2 (3.6 mL, 70 mmol) in pentane (30 mL) was stirred at
ambient temperature for a period of 3 days. The dark brown
solution was concentrated to dryness to afford the desired
product as a clear orange oil (11.36 g, 98%). 1H NMR (δ,
CDCl3): 0.62 (m, 6 H, SiMe2), 2.53 (t, 2H, 4JF,H ) 2 Hz, CH2).
13C{1H} NMR (δ, CDCl3): 2.5 (SiMe2), 15.5 (CH2), 135.3, 140.2,
142.0, and 144.4 (C6F5). Anal. Calcd for C9H8BrF5Si: C, 33.87;
H, 2.53. Found (duplicate analysis): C, 34.35; H, 2.66.
Bromotris(2,3,4,5,6-pentafluorobenzyl)silane (2d). A
solution of HSi(CH2C6F5)3 (1c; 6.97 g, 12.2 mmol) and Br2 (1.2
mL, 23.3 mmol) in hexane (40 mL) was stirred at ambient
temperature for a period of 6 days. The dark brown solution
was concentrated to dryness in vacuo and the brown sticky
solid extracted with pentane (50 mL); crystallization at -20
°C gave the title compound as beige microcrystals (6.0 g, 76%,
4
(t, 0.5 F, JF,F ) 15 Hz, C1F2).
[(2,3,4,5,6-Pentafluorobenzyl)dimethylsilyl]cyclo-
pentadiene (3c). A solution of LiCp (1.33 g, 18.46 mmol) in
THF (20 mL) was added dropwise to a cooled (0 °C) solution
of BrSiMe2(CH2C6F5) (2c; 5.78 g, 18.11 mmol) in THF (50 mL).
The deep red solution was maintained at 0 °C for 30 min and
then allowed to come to ambient temperature and left as such
overnight. Volatiles were removed in vacuo, and the brown
solid was extracted with pentane (3 × 20 mL). Filtrate was
concentrated in vacuo to give the crude product as an orange
oil which was Kugelrohr-distilled (120 °C, 10-2 mbar) to yield
a light yellow oil (4.72 g, 86%). 1H and 13C NMR spectra in
CDCl3 were extremely complicated, due to the presence of the
three isomers. 1H NMR (δ, CDCl3): 0.04-0.87 (3bs, 6 H,
SiMe2), 1.7-2.30 (3m, 2H, CH2), 6.50 and 6.66 (2bs, 5H, C5H5).
Anal. Calcd for C14H13F5Si: C, 55.25; H, 4.31. Found: C, 55.20;
H, 4.28.
first crop). H NMR (δ, CDCl3): 2.65 (m, 6H, CH2). 13C{19F}
1
NMR (δ, CDCl3): 12.8 (t, 1JC,H ) 127 Hz, CH2), 109.8 (t, 2JC,H
) 7 Hz, ipso-C6F5), 138.0 (m, m-C6F5), 139.7 (m, p-C6F5), 144.6
[Tris(2,3,4,5,6-pentafluorobenzyl)silyl]cyclopenta-
diene (3d). A solution of LiCp (0.69 g, 9.5 mmol) in THF (10
mL) was added dropwise to a cooled (0 °C) solution of BrSi-
(CH2C6F5)3 (2d; 5.96 g, 9.15 mmol) in THF (50 mL). The deep
red solution was maintained at 0 °C for 30 min and then
allowed to come to ambient temperature and left as such
overnight. Solvent was removed in vacuo, and pentane (50 mL)
was added. The brown suspension was quenched by water (50
mL). The aqueous layer was extracted with pentane (3 × 20
mL), and the organic layers were rinsed with brine (50 mL),
dried over MgSO4, and concentrated in vacuo; the oily crude
product was crystallized from pentane (15 mL) to yield orange
microcrystals of the product (4.71 g, 81%). 1H NMR (δ,
(m, o-C6F5). 19F NMR (δ, CDCl3): -141.9 (dd, 2 F, JF,F ) 21
3
Hz, 4JF,F ) 8 Hz, o-C6F5), -157.2 (t, 1 F, 3JF,F ) 21 Hz, p-C6F5),
-162.1 (dt, 2 F, 3JF,F ) 21 Hz, 4JF,F ) 8 Hz, m-C6F5). 29Si{1H}
NMR (δ, CDCl3): 19.2 (s). Anal. Calcd for C21H6BrF15Si: C,
38.73; H, 0.93. Found: C, 39.11; H, 1.01.
[Dimethyl(1H,1H,2H,2H-perfluoroctyl)silyl]cyclopen-
tadiene (3a). Freshly distilled cyclopentadiene (2.40 mL, 29.1
mmol) was added to a cooled (0 °C) solution of LiBun (50 mL
of a 1.6 mol L-1 solution in hexane, 31.3 mmol) in hexane (100
mL). The reaction mixture was stirred for 3 h at ambient
temperature. After removal of the solvent in vacuo, the solid
was washed with pentane (3 × 50 mL) and dried under
vacuum. The Li[C5H5] was dissolved in THF (100 mL) at -78
°C and the solution added dropwise by cannula over 0.5 h to
a solution of C6F13C2H4SiMe2Cl (2a; 13 g, 29.5 mmol) in THF
(100 mL) at 0 °C. The reaction mixture was stirred overnight
at ambient temperature. Volatiles were removed in vacuo, the
solid was extracted with pentane (100 mL), and the filtrate
was concentrated to dryness in vacuo to give an orange oil.
The pure title compound was obtained as a colorless oil (10.94
g, 80%) by distillation (75-80 °C at 5 10-1 mbar). The 1H NMR
spectrum is complicated by the presence of 1- and 2-silyl
isomers (minor) next to the 5-silyl isomer (major, ca. 80%). 1H
NMR (δ, CDCl3): 0.03 (s, SiMe2, 5-(RFSiMe2)C5H5 isomer), 0.21
(s, SiMe2, 1- and 2-(RFSiMe2)C5H5 isomers), 0.68 (m, CH2-Si,
5-(RFSiMe2)C5H5 isomer), 0.88 (m, CH2-Si, 1- and 2-(RFSiMe2)-
C5H5 isomers), 1.98 (m, CH2-CF2, all isomers), 3.04 (m, CH2
of 1- and 2-(RFSiMe2)C5H5), 3.40 (m, CH2 of 5-(RFSiMe2)C5H5
3
CDCl3): 1.66 (m, 6H, CH2), 3.02 (d, 1H, JH,H ) 1 Hz, C5H5),
6.05 (m, 2H, C5H5) and 6.37 (m, 2H, C5H5). 13C{1H} NMR (δ,
CDCl3): 7.7 (CH2), 111.7, 130.9, 133.7, 135.2, 140.2, 141.9, and
146.8 (C6F5 and C(sp2) from C5H5). 19F NMR (δ, CDCl3): -142.4
(bd, 2 F, o-C6F5), -158.9 (t, 1 F, 3JF,F ) 21 Hz, p-C6F5), -162.8
3
4
(dt, 2 F, JF,F ) 22 Hz JF,F ) 7 Hz, m-C6F5). Anal. Calcd for
C26H11F15Si: C, 49.07; H, 1.74. Found: C, 48.98; H, 1.67.
[Dimethyloctylsilyl]cyclopentadiene (3e). Freshly dis-
tilled cyclopentadiene (2 mL, 24.3 mmol) was added dropwise
to a stirred solution of n-BuLi (24.2 mmol) in n-hexane (100
mL) that was kept at 0 °C. The reaction mixture was stirred
for 3 h at room temperature. Then, the solvent was removed
and the product was washed with pentane (3 × 50 mL) and
dried under vacuum. The Li(C5H5) was then dissolved in THF
(75 mL) at -78 °C and the solution added dropwise by cannula
to chlorodimethyl(octyl)silane (4.55 g, 22.0 mmol) in THF (75
mL) at 0 °C over a period of 0.5 h. The reaction mixture was

1628 Organometallics, Vol. 24, No. 7, 2005
Merle et al.
stirred overnight at room temperature. Volatiles were removed
under vacuum, and the product was extracted with pentane
(3 × 50 mL), filtered, and then dried under vacuum, affording
3.41 g (66%) of the pure product as a yellow liquid. GC-MS
(70 eV): m/z 236 (M+). As was observed for C5H5SiMe2C6F13,
Hz, 3 F, CF3), -118.0 (bs, 2 F, R-CF2), -121.6 (br s, 2 F, â-CF2),
-121.9 (br s, 4 F, γ,δ-CF2), -122.8 (br s, 2 F, ú-CF2), -126.3
(br s, 2 F, ꢀ-CF2).
Bis[{(2,3,4,5,6-Pentafluorobenzyl)dimethylsilyl}-
cyclopentadienyl]zirconium Dichloride (4c). LiBun (3.4
mL of 1.6 mol L-1 solution in hexane, 5.44 mmol) was added
to a cooled solution (0 °C) of {C5H5SiMe2(CH2C6F5)} (3c; 1.59
g, 5.22 mmol) in hexane (20 mL). The beige suspension was
left at 0 °C for 30 min and then allowed to come to ambient
temperature and left for 2 h as such. The solvent was removed
by filtration and the solid rinsed with pentane (20 mL) and
dried in vacuo. The compound was dissolved in diethyl ether
(60 mL), and solid ZrCl4 (0.48 g, 2.05 mmol) was added, leading
to the exothermic formation of a thick suspension, which was
left at ambient temperature overnight. The suspension was
filtered off and solvent removed in vacuo to yield the product
as an off-white microcrystalline solid (1.53 g, 97%). Mp: 133-
134 °C. 1H NMR (δ, C6D6): 0.33 (bs, 6 H, SiMe2), 2.04 (bs, 2H,
CH2), 5.73 (t, 2H, 3JH,H ) 2 Hz, R-C5H4), 6.19 (t, 2H, 3JH,H ) 2
1
this ligand appears as a mixture of three isomers in the H
NMR spectrum, the 5-isomer being the major compound at
room temperature (ca. 80%). 1H NMR (200.1 MHz, acetone-
d6): δ 6.85 and 6.65 (2 × m, CHd, 1- and 2-[C8H17(Me)2Si]-
C5H5, 6.55 (m, CHd, 5-[C8H17(Me)2Si]C5H5), 3.47 (m, 5-CH,
5-[C8H17(Me)2Si]C5H5), 3.03 (m, 5-CH2, 1- and 2-[C8H17(Me)2-
Si]C5H5), 1.29 (m, CH3C6H12CH2Si, 1-, 2-, and 5-[C8H17(Me)2-
Si]C5H5), 0.88 (m, CH3C6H12CH2Si, 1-, 2-, and 5-[C8H17(Me)2-
Si]C5H5), 0.67 (m, CH2Si, 1- and 2-[C8H17(Me)2Si]C5H5), 0.56
(m, CH2Si, 5-[C8H17(Me)2Si]C5H5), 0.15 (s, SiMe2, 1- and
2-[C8H17(Me)2Si]C5H5), -0.09 (s, SiMe2, 5-[C8H17(Me)2Si]C5H5).
Bis[{dimethyl(1H,1H,2H,2H-perfluorooctyl)silyl}-
cyclopentadienyl]zirconium Dichloride (4a). LiBun (50
mL of a 1.6 mol L-1 solution in hexane, 80 mmol) was added
to a cooled (0 °C) solution of C5H5SiMe2C2H4C6F13 (3a; 37 g,
78.7 mmol) in hexane (200 mL). The resulting reaction mixture
was stirred for 3 h at ambient temperature. The solvent was
removed, and the product was washed with pentane (3 × 50
mL) and dried in vacuo. Li[C5H5SiMe2C2H4C6F13] was dissolved
in precooled (-78 °C) THF (100 mL) and was added dropwise
over 0.5 h to a cooled (0 °C) solution of ZrCl4 (9.08 g, 38.2 mmol)
in THF (100 mL). The resulting solution was stirred for 48 h
at ambient temperature. Volatiles were removed in vacuo, and
the residue was extracted with boiling toluene (100 mL). The
filtrate was concentrated in vacuo to afford white thin crystal-
line needles of pure product (31.50 g, 75%). Mp: 119-120 °C.
1H NMR (δ, C6D6): 0.23 (s, 6 H, SiMe2), 0.91 (m, 2 H, CH2Si),
1.96 (bm, 2 H, CH2-CF2), 5.78 (t, 3JHH ) 2.5 H, 2H z, R-C5H4),
1
Hz, â-C5H4). H NMR (δ, toluene-d8): 0.32 (bs, 6 H, SiMe2),
2.10 (bs, 2H, CH2), 5.75 (bs, 2H, R-C5H4), 6.19 (bs, 2H, â-C5H4).
1H NMR (δ, toluene-d8, -80 °C): 0.40 (bs, 6 H, SiMe2), 2.10
(bs, 2H, CH2), 5.55 (bs, 2H, R-C5H4), 6.12 (bs, 2H, â-C5H4). 13
C
NMR (δ, C6D6): -2.5 (s, SiMe2), 13.3 (s, CH2), 114.6, 126.1,
128.3, and 143.0 (C6F5). 19F NMR (δ, C6D6): -143.1 (d, 3JF,F
)
20 Hz, 2F, o-F), -160.8 (t, 3JF,F ) 20 Hz, 1F, p-F), -163.9 (dt,
3JF,F ) 20 Hz, 2F, m-F), Anal. Calcd for C28H24Cl2F10Si2Zr: C,
43.74; H, 3.15. Found: C, 44.02; H, 3.35
Bis[{tris(2,3,4,5,6-pentafluorobenzyl)silyl}cyclopenta-
dienyl]zirconium Dichloride (4d). LiBun (2.3 mL of 1.6 mol
L-1 solution in hexane, 3.68 mmol) was added to a cooled
solution (0 °C) of {C5H5Si(CH2C6F5)3} (3d; 2.14 g, 3.36 mmol)
in hexane (50 mL). The light beige suspension was left at 0
°C for 30 min and then allowed to come to ambient tempera-
ture and left for 2 h as such. The solvent was removed by
filtration and the solid rinsed with pentane (20 mL) and dried
in vacuo. The compound was dissolved in diethyl ether (40 mL),
and solid ZrCl4 (0.31 g, 1.33 mmol) was added, leading to the
exothermic formation of a thick suspension, which was left at
ambient temperature overnight. The suspension was filtered
off and solvent removed in vacuo to yield the product as an
off-white microcrystalline solid (1.71 g, 93%). Mp: 55-56 °C.
3
1
6.24 (t, JHH ) 2.5 Hz, 2H, â-C5H4). H NMR (δ, toluene-d8):
0.23 (s, 6 H, SiMe2), 0.92 (m, 2 H, CH2Si), 1.97 (bm, 2 H, CH2-
3
3
CF2), 5.79 (t, JHH ) 2.5 Hz, 2H, R-C5H4), 6.22 (t, JHH ) 2.5
1
Hz, 2H, â-C5H4). H NMR (δ, toluene-d8, -80 °C): 0.21 (s, 6
H, SiMe2), 0.94 (vbs, 2 H, CH2Si), 1.97 (vbs, 2 H, CH2-CF2),
5.65 (bs, 2H, R-C5H4), 6.08 (bs, 2H, â-C5H4) 13C{1H} NMR (δ,
2
acetone-d6): -2.3 (SiMe), 6.77 (CH2Si), 26.5 (t, JC,F ) 23.28
Hz, CH2CF2), 117.2 (R-C C5H4), 125.36 (ipso-C C5H4), 127.24
(â-C C5H4). 19F{1H} NMR (δ, toluene-d8): -81.2 (t, JF,F ) 9
3
3
3
1H NMR (δ, C6D6): 2.34 (bs, 6H, CH2), 5.36 (t, 2H, JH,H ) 3
Hz, CF3), -115.6 (t, JF,F ) 15 Hz, R-CF2), -122.0 (s, γ-CF2),
-123.0 (s, δ-CF2), -123.1 (bs, â-CF2), -126.3 (bs, ꢀ-CF2). 29Si
NMR (acetone-d6): δ 1.70 (s). Anal. Calcd for C30H28Cl2F26Si2-
Zr: C, 32.73; H, 2.55; Cl, 6.45; F, 44.91; Si, 5.09. Found: C,
32.58; H, 2.56; Cl, 6.35; F, 44.78; Si, 5.39. MS (TOF-ES): m/z
1123 ([M + Na]+, 100), 2223 ([2M + Na]+).
3
Hz, R-C5H4), 6.13 (t, 2H, JHH ) 3 Hz, â-C5H4). 13C NMR (δ,
C6D6): 8.8 (CH2), 111.9, 114.2, 122.4, 125.3, 140.2, 141.9, and
146.8 (C6F5 and C5H4). Anal. Calcd for C52H20Cl2F30Si2Zr: C,
43.58; H, 1.41. Found: C, 43.45; H, 1.33
Bis[(dimethyloctylsilyl)cyclopentadienyl]zirconium
Dichloride (4e). To a stirred solution of LiBun (14.2 mmol,
in 8.9 mL of n-hexane) in Et2O (150 mL) was added C5H5-
SiMe2C8H17 (3.37 g, 14.2 mmol) at -78 °C. The resulting
reaction mixture was stirred for 3 h at room temperature.
Volatiles were removed under vacuum. The yellow viscous
liquid obtained could not be washed with pentane or hexane,
because it gave a gel instead of a precipitate in these solvents.
The lithiated product was dissolved in THF (75 mL) at -78
°C. A solution of ZrCl4 (1.64 g, 6.90 mmol) in THF (75 mL)
was prepared, and the THF solution of the lithiated ligand
was added dropwise over 0.5 h at 0 °C. The mixture was stirred
for 48 h at room temperature. Volatiles were removed under
vacuum, and the residue was extracted with pentane (2 × 50
mL). Concentration of the orange extract under vacuum
afforded a brown oil (4.43 g, 98%). 1H NMR (300.1 MHz,
acetone-d6): δ 6.76 (m, 4H, CHd), 1.31 (m, 12 H, CH3C6H12-
CH2Si), 0.91 (m, 3 H, CH3C6H12CH2Si), 0.80 (m, 2H, CH2Si),
0.34 (s, 6 H, (CH3)2Si). 13C{1H} NMR (75.5 MHz, acetone-d6):
126.85 (CHd), 126.70 (Cd), 117.23 (CHd), 34.30, 32.70, 30.03
(high intensity, probably two overlapping signals), 24.56, 23.39
(CH3C6H12CH2Si), 17.43, 14.46 (2 C, CH3C6H12CH2Si), -1.78
(Si(CH3)2). 29Si NMR (59.6 MHz, acetone-d6): δ 0.37 (s, SiMe2).
29Si NMR (59.6 MHz, benzene-d6): δ -4.76 (s, SiMe2). Anal.
Bis[{dimethyl(perfluorooctyl)silyl}cyclopentadienyl]-
zirconium Dichloride (4b). LiBun (4 mL of a 1.6 mol L-1
solution in hexane, 6.4 mmol) was added to a solution of C5H5-
SiMe2C8H17 (3b; 3.41 g, 6.3 mmol) in hexane (50 mL) at
ambient temperature. The resulting reaction mixture was
stirred for ca. 15 h at ambient temperature. Solvent was
removed by filtration, and the beige solid was rinsed with
hexane (10 mL) and dried in vacuo. The compound was then
dissolved in diethyl ether (30 mL) and solid ZrCl4 (0.73 g, 3.13
mmol) was added. A cloudy suspension immediately formed
and was left at ambient temperature for ca. 20 h. The
suspension was filtered and cooled to -20 °C to yield pale
yellow needles of 4b (1.62 g, 42%). Anal. Calcd for C30H20Cl2F34-
Si2Zr: C, 28.95; H, 1.62; Cl, 5.70; Zr, 7.33; Found: C, 29.06;
H, 1.54; Cl, 5.76; Zr, 7.26. Mp: 136-137 °C. 1H NMR (δ,
C6D6): 0.62 (s, 6 H, SiMe2), 5.65 (bs, 2H, R-C5H4), 6.31 (s, 2 H,
â-C5H4). 1H NMR (δ, toluene-d8): 0.61 (s, 6 H, SiMe2), 5.70 (t,
JFF ) 2.5 Hz, 2H, R-C5H4), 6.30 (t, JFF ) 2.5 Hz, 2 H, â-C5H4).
1H NMR (δ, toluene-d8, -80 °C): 0.64 and 0.75 (2 bs, total 6
H, SiMe2), 5.46 and 5.64 4 (2 bs, total 2H, R-C5H4), 6.15 and
6.34 (2 bs, total 2H, â-C5H4). 13C{1H} NMR (δ, THF-d8): -5.2
(SiMe2), 117.2, 128.5 (R, â-C of C5H4), ipso-C of C5H4 and C8F17
signals not observed. 19F NMR (δ, C6D6): -81.1 (t, JFF ) 10

Fluorous Zirconocene(IV) Complexes
Table 3. Catalyst NMR Analysis of (4a-c,f)-MAO
1H (δ, ppm)a
CH2
Organometallics, Vol. 24, No. 7, 2005 1629
compd
Cp
SiMe2
Zr-Me
MAO
-0.16 (bs)
4a
6.24 (t), 5.78 (t)
1.96 (m), 0.91 (m)
2.01 (s), 1.94 (s),
0.95 (s), 0.91(s)
0.23 (s)
4a + MAOb
6.28 (s), 6.24 (s), 5.85 (s), 5.78 (s),
5.75 (s), 5.51 (s)
0.24 (s), 0.18 (s)
0.42 (bs)
4b
6.31 (t), 5.65 (t)
0.62 (s)
4b + MAOb
4b + MAOc
4c
6.48 (b), 5.93 (b), 5.62 (b), 5.42 (b)
6.55 (s), 5.97 (s), 5.65 (s), 5.45 (s)
6.19 (t), 5.73 (t)
0.57 (s)
0.50 (s)
0.39 (s)
-0.33 (bs)
-0.27 (bs), 0.49 (s)
0.57 (s)
2.04 (s)
2.02 (s)
2.08 (s)
0.33 (s)
4c + MAOb
4c + MAOc
4f
6.22 (b), 5.89 (b), 5.79 (b), 5.58 (b)
6.31 (s), 5.90 (s), 5.77(s), 5.12 (s)
6.35 (t), 5.90 (t)
0.26 (s)
0.44 (s)
0.42 (s)
-0.32 (bs), -0.56 (s)
-0.26 (bs), -0.50 (s)
0.26 (s)
0.28 (s)
4f + MAOb
6.32 (b), 6.02 (s), 5.89 (s), 5.78 (s), 5.66 (s)
0.24 (s), 0.11 (s)
0.49 (s)
-0.22 (bs)
a
1H NMR in C6D6 at ca. 25 °C. b Al/Zr ) 100. c Al/Zr ) 20.
Table 4. Crystallographic Data for 2d and 4a,c
Calcd for C30H54Cl2Si2Zr: C, 56.88; H, 8.53; Cl, 11.22; Si, 8.85.
Found: C, 56.68; H, 8.46; Cl, 11.27; Si, 8.88.
2d
4a
4c
Bis[{dimethyl(1H,1H,2H,2H-perfluorooctyl)silyl}-
cyclopentadienyl]zirconium Dimethyl (5a). To a stirred
solution of 4a (6.39 g, 5.8 mmol) in diethyl ether (100 mL) was
added a solution of LiMe (11.68 mmol) in diethyl ether at -78
°C. The solution was warmed to room temperature and stirred
overnight. The volatiles were removed under vacuum, and the
product was extracted with pentane (150 mL) and then dried
under vacuum. The pure product (5.31 g, 86%) was obtained
empirical formula
C
21H6BrF15
-
C
30H28Cl2F26- C28H24Cl2F10-
Si
Si2Zr
Si2Zr
768.77
triclinic
formula wt
cryst syst
space group
a, Å
651.26
trigonal
1100.82
monoclinic
R3h (No. 148) C2/c (No. 15) P1h (No. 2)
15.9230(12) 46.3678(10) 7.8842(1)
b, Å
c, Å
15.9230(12) 6.5983(2)
29.4013(16) 14.2962(4)
13.4155(2)
15.1449(3)
73.4706(7)
R, deg
90
90
1
as a white powder and recrystallized from pentane. H NMR
â, deg
90
106.4326(14) 80.0282(8)
(200.14 MHz, benzene-d6): δ 5.95 and 5.84 (dt, 4H, JAX ) JAX′
) 2.45 Hz, CHd), 1.94 (m, 2 H, CH2-CF2), 0.81 (m, 2 H, CH2-
Si), 0.07 (s, 6 H, Me2Si), - 0.21 (s, 3 H, Me2Zr). 13C{1H} NMR
(50.33 MHz, benzene-d6): δ 118.42 (CHd), 117.22 (Cd), 113.91
γ, deg
120
90
4195.2(2)
4
1.743
0.586
2176
87.9965(7)
1512.31(4)
2
V, Å3
6455.8(8)
12
Z
Dcalcd, g cm-3
µ(Mo KR), mm-1
F(000)
2.010
2.106
3792
1.688
0.701
2
(CHd), 31.57 (Me2Zr), 26.69 (t, JC,F ) 23.73 Hz, CH2-CF2),
768
7.51 (CH2-Si), -2.50 (Si(CH3)2). 29Si NMR (59.62 MHz,
benzene-d6): δ -4.71 (SiMe2). Anal. Calcd for C32H34Cl2F26-
Si2Zr: C, 36.26; H, 3.21; Cl, 0.00; F, 46.65; Si, 5.29. Found:
C, 36.15; H, 3.15; Cl, 0.00; F, 46.43; Si, 5.24.
no. of unique
reflns, Rint
2966, 0.064 4790, 0.065
5631, 0.041
no. of rflns (I > 2σ(I)) 2249
2810
0.033
0.089
0.80
4883
0.030
0.079
1.05
final R1 (I > 2σ(I))
final wR2
0.036
0.078
1.015
NMR Analysis of Precatalyst/MAO Mixtures. In a
typical experiment, ca. 5 µmol of the precatalyst was added
in a Schlenk to solid MAO (0.3 mL of a 10 wt % solution in
toluene evaporated to dryness in vacuo, 0.5 mmol, Al/Zr ≈ 100),
solvated with C6D6 (ca. 0.5 mL), and transferred under
nitrogen to an NMR tube, which was then capped. Hydrolysis
of the catalyst was carried out with 0.1 mL of a 1:20
concentrated HCl-D2O solution. See Table 3 for chemical
shifts and assignments.
Ethylene Polymerization. In a typical polymerization
experiment, a jacketed 150 mL glass reactor was fitted with a
gas action stirrer (1300 rpm) and inlet/outlet for ethylene/
vacuum/nitrogen. The reactor was thermostated at 20 °C using
a water bath, dried and degassed in vacuo for 30 min, and
then purged with nitrogen gas. The solvent was transferred
via syringe, and a solution (in toluene, hexane, or FC-72) of
the catalyst was added (the total volume of solvents was used
for calculation of the zirconium concentration). Finally MAO
(10 wt % solution in toluene or suspension in hexane) was
transferred to the reaction mixture, which was stirred for 5
min under nitrogen pressure. The reactor was briefly depres-
surized, and ethylene was allowed at 1.1 bar pressure (at t0).
The reaction was quenched (at tf) with 50 mL of a 1:1 mixture
of EtOH and aqueous 2 M HCl and stirred for 15 min. The
suspension was filtered off, and the solid was rinsed with 10%
aqueous HCl and then EtOH and dried in vacuo for ca. 15 h
at ambient temperature.
goodness of fit
estimate of the experimental error in the partition coefficient
is (1 in the last digit.
Crystallography. Colorless, X-ray-quality, single crystals
of the zirconocene dichloride were grown from cooled (ca. -20
°C) concentrated Et2O (2d), THF (4a), or Et2O (4c) solution of
the pure compound and were mounted under a flow of cold
nitrogen (150 K) on an Enraf-Nonius CAD4T (2d) or a Nonius
KappaCCD (4a,c) diffractometer, both equipped with a rotat-
ing anode. Crystal data and details on data collection are
collected in Table 4. Data were collected using graphite-
monochromated Mo KR radiation (λ ) 0.710 73 Å). The
structures were solved by direct methods (2d39 and 4a40) or
Patterson methods (4c41) and refined with SHELXL-9742
against F2 of all reflections. All geometrical calculations and
illustrations were done with PLATON.43
Acknowledgment. We thank the European Com-
mission for the award of a RTN fellowship to P.G.M.
(Contract HPRN-CT-2000-00010), ELF SA for a CSN
(39) Sheldrick, G. M. SHELXS-86; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1986.
(40) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna,
R. J. Appl. Crystallogr. 1999, 32, 115-119.
Determination of Partition Coefficients. The partition
coefficients were determined by dissolving a known amount
of complex (typically 50 µmol) in a fluorous biphasic system
consisting of c-C6F11CF3 (2.00 ( 0.01 mL) and toluene (2.00 (
0.01 mL). The resulting mixture was stirred at 20 °C for 1 h,
and then an aliquot of each layer was removed for ICP-AAS
analysis on silicon with an accuracy of (3 ppm. A conservative
(41) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O., Smits, J. M. M.; Smykalla, C. The
DIRDIF99 program system; Technical Report of the Crystallography
Laboratory, University of Nijmegen, Nijmegen, The Netherlands, 1999.
(42) Sheldrick, G. M. SHELXL-97; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1997.
(43) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7-13.

1630 Organometallics, Vol. 24, No. 7, 2005
Merle et al.
Supporting Information Available: CIF files with atomic
coordinates, bond lengths and angles, and thermal parameters
for 2d and 4a,c and figures giving 1H NMR spectra of solutions
of 4a-c with MAO (Al/Zr ) 100) in benzene-d6. This material
is available free of charge via the Internet at http://pubs.acs.org.
studentship to V.C., and ARKEMA Vlissingen for other
support. M.L. and A.L.S. were supported by The Neth-
erlands Organization for Scientific Research (NWO/
CW). We thank Professors J. H. Teuben and B. Hessen
(COP Centre, University of Groningen) for initial screen-
ing of polymerization activity.
OM049507Z