Chiral-at- ansa -bridged group 4 metallocene complexes {(R 1R2C)-(3,6- T Bu2Flu)(3-R3-5-Me- C5H2)}MCl2: Synthesis, structure, stereochemistry, and use in highly isoselective prop

Article abstract of DOI:10.1021/om100897j

New chiral racemic, sterically crowded fluorenyl-cyclopentadienyl compounds having monoaryl-substituted methylene bridges (R¹R ²C)-((3,6-tBu₂Flu)H)(3-R³-5-Me-C ₅H₃) (R¹ = H, R

Full text of DOI:10.1021/om100897j

Organometallics 2011, 30, 263–272 263
DOI: 10.1021/om100897j
Chiral-at-ansa-Bridged Group 4 Metallocene Complexes
{(R1R2C)-(3,6-tBu2Flu)(3-R3-5-Me-C5H2)}MCl2: Synthesis, Structure,
Stereochemistry, and Use in Highly Isoselective Propylene Polymerization
Evgeny Kirillov,*,†,‡ Nicolas Marquet,† Manuela Bader,† Abbas Razavi,§
Vincenzo Belia,§ Frank Hampel,‡ Thierry Roisnel,† John A. Gladysz,*,‡,^ and
Jean-Franc-ois Carpentier*,†
†
ꢀ
Organometalliques et Catalyse, UMR 6226 CNRS-Universite de Rennes 1, 35042 Rennes Cedex, France,
Institut fu€r Organische Chemie, Friedrich-Alexander Universitat Erlangen-Nurnberg, Henkestrasse 42,
‡
€
€
91054 Erlangen, Germany, §Total Petrochemicals, Zone IndustrielleC, 7181 Feluy, Belgium, and ^Department
of Chemistry, Texas A&Μ University, P.O. Box 30012, College Station, Texas 77842-3012, United States
Received September 17, 2010
New chiral racemic, sterically crowded fluorenyl-cyclopentadienyl compounds having monoaryl-
substituted methylene bridges (R1R2C)-((3,6-tBu2Flu)H)(3-R3-5-Me-C5H3) (R1=H, R2=Ph, R3=tBu:
2a; R1=H, R2=2,4,6-Me3C6H2 (Mes); R3=CMe2Ph (cumyl): 2b; R1=H, R2=3,5-(CF3)2C6H3, R3=
tBu: 2c) or a disubstituted (R1=CF3, R2=Ph, R3=tBu: 2d) as well as an unsubstituted (nonstereogenic)
methylene bridge (R1=R2=H, R3=tBu: 2e) were synthesized via nucleophilic additions to substituted
fulvenes. The zirconium and hafnium dichloro complexes derived from proligands 2a, 2b, and 2e, namely,
{Ph(H)C-(3,6-tBu2Flu)(3-tBu-5-Me-C5H2)}ZrCl2 (3a), {Ph(H)C-(3,6-tBu2Flu)(3-tBu-5-Me-C5H2)}-
HfCl2 (4a), {Mes(H)C-(3,6-tBu2Flu)(3-cumyl-5-Me-C5H2)}ZrCl2 (3b), and {H2C-(3,6-tBu2-Flu)(3-
tBu-5-Me-C5H2)}ZrCl2 (3e), were prepared (63-88% yields). Attempted metalations at the fluorinated
proligands 2c and 2d were not successful. Due to the presence of the stereogenic center of the ansa-bridge,
3a, 4a, and 3b exist as mixtures of two diastereomers in which the most bulky substituent in the
methylenebridgeiseitheranti (major product in the case of 3a and 4a) orsyn (only one observed for 3b) to
the 5-methyl substituent in the Cp ring. Diastereomerically pure anti-3a, anti-4a and syn-4a, and syn-3b
were isolated and characterized by elemental analysis, NMR spectroscopy, and X-ray crystallography.
When activated with MAO, metallocene complex anti-3a showed very high activity in the polymeriza-
tion of propylene (14 000 kg(PP) mol(Zr)-1 h-1, toluene, 60 ꢀC) to yield highly isotactic polypropylene
3
3
(iPP) with [m]4 =95.8% and Tm =153 ꢀC. Both diastereomers of hafnium analogues exhibited lower
activities (260-270 kg(PP) mol(Hf)-1 h-1) but distinct catalytic behavior: anti-4a yielded low
3
molecular weight and moderately isotactic PP ([m]4=88.8%), while highly isotactic PP ([m]4=94.0%)
with a bimodal distribution wasproduced with syn-4a. Precursor syn-3b was inactive under standard
polymerization conditions, presumably due to deactivation of the cationic metal center by the
cumyl Cp substituent. Methylene-bridged 3e produced highly isotactic PP ([m]4 =96.9%; Tm =
154 ꢀC) with moderate activity (2 320 kg(PP) mol(Zr)-1
h
-1).
3
3
Introduction
in the academic and industrial communities because of the
remarkably high catalytic activity and stereoselectivity that
some group 4 metal complexes derived therefrom feature
in olefin polymerization.1,2 In a previous study, we have
investigated the preparation of new C1-symmetric ansa-
zirconocene complexes bearing diaryl-substituted methylene-
bridged {R1R2C-(Flu)(Cp)}2- ligands (I-R1R2, Scheme 1)
that produce isotactic polypropylene via an enantiomorphic-
site control mechanism.3 Special emphasis was given to the
Ph2C-bridged system (I-Ph2), which was anticipated to provide
improved catalytic performances but remained elusive for
years due to synthetic challenges. In fact, the latter com-
pound could be effectively prepared via an “activated ful-
vene” pathway and was shown to afford enhanced catalytic
Carbon-linked mixed fluorenyl-cyclopentadienyl ligands
(hereafterreferredtoas{Flu-Cp}2-) are of significant importance
*Corresponding authors. E-mail: evgueni.kirillov@univ-rennes1.fr,
gladysz@mail.chem.tamu.edu, jean-francois.carpentier@univ-rennes1.fr.
(1) For leading references, see: (a) Ewen, J. A.; Jones, R. L.; Razavi,
A. J. Am. Chem. Soc. 1988, 110, 6255. (b) Razavi, A.; Bellia, V.;
De Brauwer, Y.; Hortmann, K.; Peters, L.; Sirol, S.; Van Belle, S.; Thewalt,
U. Macromol. Chem. Phys. 2004, 205, 347.
(2) For reviews, see: (a) Alt, H.; Samuel, E. Chem. Soc. Rev. 1998,
323. (b) Alt, H. Macromol. Chem. Symp. 2001, 173, 65. (c) Razavi, A.
Coord. Chem. Rev. 2006, 250, 155. (d) Alt, H. G.; Koppl, A. Chem. Rev.
2000, 100, 1205. (e) Coates, G. W. Chem. Rev. 2000, 100, 1223. (f) Resconi,
L.; Cavallo, L.; Falt, A.; Piemontesi, F. Chem. Rev. 2000, 100, 1253.
(g) Gladysz, J. A. Special issue: Frontiers in Metal-Catalyzed Polymerization.
Chem. Rev. 2000, 100, 1167. (h) Price, C. J.; Irwin, L. J.; Aubry, D. A.;
Miller, S. A. Fluorenyl Containing Catalysts for Stereoselective Propylene
Polymerization. In Stereoselective Polymerization with Single Site Cata-
lysts; Baugh, L. S.; Canich, J. A. M., Eds.; CRC Press, 2000.
€
(3) Kirillov, E.; Marquet, N.; Razavi, A.; Belia, V.; Hampel, F.;
Roisnel, T.; Gladysz, J. A.; Carpentier, J.-F. Organometallics 2010,
29, 5073.
r
2010 American Chemical Society
Published on Web 12/22/2010
pubs.acs.org/Organometallics

264 Organometallics, Vol. 30, No. 2, 2011
Kirillov et al.
Scheme 1
most versatile and efficient routes for the synthesis of the
monocarbon-bridged proligands {R1R2C-(Flu)(Cp)}H2.6
Accordingly, a series of fulvene building blocks 1a-e were
prepared by the well-established pathway in Scheme 3. In a
previous study, we have investigated the synthesis of steri-
cally hindered diphenylmethylene-bridged proligands via
this route.3,7 However, the direct approach, involving reac-
tion between a fluorenyl anion and 6,60-diphenylfulvenes,
appeared to be inoperative for Ph2C-bridged systems having
a 5-methyl substituent in the cyclopentadienyl ring, due to
steric and electronic reasons. In this study, we have found
that the somewhat less congested 6-monoarene fulvenes 1a
and 1d can be treated with {3,6-tBu2Flu}-Liþ under mild
conditions (THF, room temperature; Scheme 3, protocol C)
to afford the corresponding adducts in satisfactory yields
(49-65%).8 The mesityl-substituted derivative 1b could be
induced to condense only in diethyl ether at 90 ꢀC (in an
autoclave) over several days (Scheme 3, protocol D), although
a satisfactory yield was attained under these conditions.9
This striking difference in efficiency obviously arises from
the presence of an ortho-methyl-substituted aryl ring, which
increases steric hindrance in the fulvene, as compared to
simple phenyl (1a, 1d). On the other hand, proligand 2c,
derived from meta-bis(trifluoromethyl)aryl-substituted ful-
vene (1c), could be obtained only in very small amounts
(isolated yield: 4%; protocol C).10 For comparison purposes,
the unsubstituted methylene-bridged proligand 2e was pre-
pared in 60% yield using the procedure disclosed by Alt
et al.,11 via the reaction of 6-dimethylaminofulvene 1e with
{3,6-tBu2Flu}-Liþ in THF solution at room temperature,
followed by treatment with LiAlH4. Proligands 2a-e were
isolated as air-stable crystalline solids, and their identities were
authenticated by NMR spectroscopy and elemental analysis.
Synthesis and Structure of ansa-Metallocene Complexes.
Zirconium and hafnium ansa-metallocene complexes were
obtained from the corresponding tetrachlorides MCl4 and
ligand dianions, prepared in situ via addition of 2 equiv of
n-butyllithium, using a regular salt metathesis protocol in
diethyl ether (see the Experimental Section). Analytically
pure zirconium complexes 3a, 3b, and 3e (pink crystalline
solids) and hafnium complex 4a (yellow-orange crystalline
solid) were thus isolated in good yields (Scheme 4). On the
other hand, all attempts to prepare ansa-metallocene com-
plexes based on fluorinated proligands 2c and 2d led to
mixtures of compounds that could not be purified.
Scheme 2
activity (2-3-fold increase as compared to the correspond-
ing isopropylidene-bridged system I-Me2) for the highly
isoselective polymerization of propylene under homogeneous
conditions.3 Yet, the complicated and relatively costly syn-
thetic approach required for preparing I-Ph2 prompted us
to seek other more synthetically attainable ansa-metallocene
systems {R1R2C-(Flu)(Cp)}MCl2 that contain phenyl sub-
stituent(s) in the ligand methylene bridge.
Our attention was directed toward ligand assemblies (and
corresponding metallocene complexes) having a single aryl
substituent at the methylene bridge. Syndioselective zirco-
nocene systems with a Ph(H)C bridge in the Cs-symmetric
{R1R2C-(Flu)(Cp)} ligand skeleton (Scheme 2) were first
reported by Alt (II)4 and subsequently developed by Lee et al.
(III).5 However, similar isoselective systems with a Ph(H)C
bridge in C1-symmetric ligand skeletons remain undocumented
to the best of our knowledge.2
We report herein new C1-symmetric group 4 metallocene
complexes supported by {R1R2C-(Flu)(Cp)}2- ligands that
incorporate monoaryl-substituted or unsubstituted methy-
lene bridges. The central objective of this investigation was to
assess the impact of such bridges on the catalytic performances
for the production of isotactic polypropylene; in particular,
it was of interest to evaluate (i) the effect of a single aryl
substituent upon reactivity, in comparison with diaryl-
substituted systems, and (ii) the influence of the stereogenic
center present in the bridge that induces the formation of two
diastereomeric ansa-metallocene species, which may have
distinct catalytic behaviors. Thus, the title complexes have,
after activation by MAO, been investigated as homogeneous
catalysts for the polymerization of propylene. Their perfor-
mances are compared to those of the prototype precatalyst
{Me2C-(3,6-tBu2Flu)(3-tBu-5-MeC5H2)}ZrCl2 (I-Me2) and
its more sterically encumbered variant {Ph2C-(3,6-tBu2Flu)-
(3-tBu-5-MeC5H2)}ZrCl2 (I-Ph2), which we have recently
investigated.3
(6) For relevant procedures, see: (a) Day, J. H. Chem. Rev. 1953, 53,
167. (b) Alt, H.; Jung, M. J. Organomet. Chem. 1998, 568, 87. (c) Alt, H. G.;
Jung, M.; Kehr, J. J. Organomet. Chem. 1998, 562, 153. (d) Miller, S. A.;
Bercaw, J. E. Organometallics 2002, 21, 934. (e) Miller, S. A.; Bercaw, J. E.
Organometallics 2004, 23, 1777.
ꢀ
(7) Carpentier, J.-F.; Kirillov, E.; Razavi, A. (Universite de Rennes 1
and Total Petrochemicals Co.) Eur. Pat. Appl. EP06121181.9,Sept 25,
2006.
(8) (a) Kirillov, E.; Gladysz, J. A.; Razavi, A. (Friedrich-Alexander
€
€
Universitat Erlangen-Nurnberg and Atofina Co.) Eur. Pat. Appl.
EP05105162.1, June 13, 2005.
(9) Solvent effects in the nucleophilic addition of the fluorenyl anion
to sterically protected fulvenes have been noticed in our previous study;
see ref 3.
Results and Discussion
(10) The small amount of proligand 2c isolated was sufficient to
explore its metalation and coordination onto Zr, which eventually
turned out unsuccessful (vide infra). Optimization of the synthesis of
this compound, e.g., using protocol D, was therefore not further
investigated.
Synthesis of Proligands. Nucleophilic additions of fluor-
enyl-type anions to fulvenes have been shown to provide the
(4) Alt, H. G.; Zenk, R. J. Organomet. Chem. 1996, 518, 7.
(5) Won, Y. C.; Kwon, H. Y.; Lee, B. Y.; Park, Y.-W. J. Organomet.
Chem. 2003, 677, 133.
(11) (a) Zenk, R.; Alt, H. G.; Welch, B. M.; Palackal, S. J. (Philips
Petroleum Co.) U.S. Patent 5420320, 1995. (b) Alt, H. G.; Zenk, R.
J. Organomet. Chem. 1996, 526, 295.

Article
Organometallics, Vol. 30, No. 2, 2011 265
Scheme 3. Synthesis of Fulvenes 1a-e and {R1R2C-(Flu)(Cp}H2 Proligands 2a-e
Scheme 4. Syntheses and Isolated Yields of Group 4 ansa-Metallocene Complexes Derived from Proligands 2a, 2b, and 2ea
a Only one enantiomer is shown for each diastereomer.
Since 3a, 3b, 3e, and 4a were derived from racemic pro-
ligands, they were presumed to be racemates. Their solution
structures were investigated by 1H and 13C NMR spectros-
copy. The NMR spectra of racemic 3e, the only complex with
an unsubstituted methylene bridge, featured only one set
of resonances, consistent with the presence of a single
C1-symmetric species in solution. On the other hand, due
to the existence of an additional element of chirality, i.e., the
stereogenic center in the substituted methylene bridge of 3a,
4a, and 3b, two diastereomers for each of these compounds
which two sets of resonances for unequal amounts of two
diastereomers were generally observed. Thus, the crude
zirconium complex 3a appeared to be a ca. 90:10 mixture
of two diastereomers. The predominant isomer would logi-
cally be that in which the phenyl substituent in the methylene
bridge is positioned anti to the methyl group in the Cp ring
(anti-3a, as further corroborated by X-ray analysis, vide
infra). Minimization of steric repulsion between these sub-
stituents is likely at the origin of the faster formation and/or
greater thermodynamic stability of the latter isomer, as opposed
to the syn isomer (syn-3a), in which the methyl and phenyl
groups are obviously much closer (vide infra). Also, crude
1
were anticipated (Scheme 4). This was corroborated by H
NMR spectra of crude (nonrecrystallized) complexes, for

266 Organometallics, Vol. 30, No. 2, 2011
Kirillov et al.
hafnium compound 4a was recovered in a quite different
(as compared to its zirconium congener, 3a) diastereomeric
ratio (anti-4a/syn-4a=70:30), despite the similar size of these
metal centers (ionic radius for six-coordinate metal centers,
4þ
12
Hf4þ: 0.71 A vs Zr : 0.72 A). This indicates that the
diastereomeric ratio in this metalation reaction is apparently
affected by the stereoelectronic environment of the metal
(precursor), but not by its ionic radius.
˚
˚
In contrast, for complex 3b, only one diastereomer was
detected by NMR spectroscopy. Further crystallographic
investigations (vide infra) revealed it is that in which the
bulky mesityl substituent in the methylene bridge is directed
to the same side as the methyl substituent in the Cp ring, that
is, cis-Me,Mes (syn-3b). There is no obvious explanation that
would rationalize the selective formation of this diastereo-
mer on steric grounds. Rather, this could imply that this is a
kinetically controlled process.
In addition to confirming the formation of these diastereo-
mers, 13C NMR spectroscopy revealed particularly upfield
chemical shifts for the C9-fluorenyl carbon (δ 70.3-76.6 ppm).
These data suggest reduced hapticity (η5fη3 ring slippage)
of the fluorenyl moiety in solution.13 Otherwise, the 13C
NMR data do not indicate significant differences in solution
structures in this series of ansa-metallocene complexes.
The pure diastereomer anti-3a was isolated in good yield
by recrystallization of the 90:10 anti/syn crude material.
With 4a, the less biased diastereomeric ratio (70:30) allowed
successful isolation of both anti-4a and syn-4a, also by
recrystallization. Single crystals of anti-3a, syn-3b, 3e, anti-4a,
and syn-4a suitable for X-ray diffraction studies were pre-
pared from concentrated solutions in dichloromethane/hexane
mixtures or neat hexane at room temperature. The molecular
structures of these metallocene compounds are depicted in
Figures 1-5, and selected crystallographic and geometrical
parameters are given in Tables 1 and 2, respectively. The
elementary units of the C1-symmetric complex 3e and dia-
stereomerically pure anti-3a, syn-3b, anti-4a, and syn-4a are
all composed of pairs of enantiomers. That of syn-4a contains
two independent molecules.
These compounds feature geometrical parameters similar
to those documented for other metallocene dichlorides in-
corporating Me2C-, Ph2C-, andPh(H)C-bridged{R1R2C-(Flu)-
(Cp)} ligands.5,14 In agreement with our previous observa-
tions on {Ph2C-(3,6tBu2Flu)(Cp)}MCl2 complexes,3 all the
new ansa-metallocene complexes reported herein display
a slight deviation of the η5-coordination of the fluorenyl
central five-membered ring to the metal atom toward a
reduced η3-mode, as evidenced by the significant differences
in the M-C(ring) distances. In line with the close ionic radii
of Zr and Hf metals, the Cpcent-M-Flucent bite angles in
anti-3a and anti-4a are quite similar (118.1(1)ꢀ and 118.7(3)ꢀ,
respectively). Note that the latter compounds are isostruc-
tural. The bite angle in syn-4a is modestly larger (119.6(2)ꢀ),
possibly as a consequence of the steric repulsion between the
bridge and Cp substituents. Also, a significant constraint at
the bridging carbon atom in this ansa-metallocene complex is
evidenced from the value of 98.7(2)ꢀ for the C(1)-C(6)-C(9)
angle; the latter angle is ca. 3ꢀ tighter than those observed in
Figure 1. Crystal structure of anti-{Ph(H)C-(3,6-tBu2Flu)-
(3-tBu-5-Me-C5H2)}ZrCl2 (anti-3a) (ellipsoids drawn at the 50%
probability level; all hydrogen atoms, except that of the bridge,
are omitted for clarity; only one enantiomer is depicted).
Figure 2. Crystal structure of anti-{Ph(H)C-(3,6-tBu2Flu)-
(3-tBu-5-Me-C5H2)}HfCl2 (anti-4a) (ellipsoids drawn at the 50%
probability level; all hydrogen atoms, except that of the bridge,
are omitted for clarity; only one enantiomer is depicted).
Figure 3. Crystal structure of one of the two independent mole-
cules of crystalline syn-{Ph(H)C-(3,6-tBu2Flu)(3-tBu-5-Me-
C5H2)}HfCl2 (syn-4a) (ellipsoids drawn at the 50% probability
level; all hydrogen atoms, except that of the bridge, are omitted
for clarity; only one enantiomer is depicted).
(12) Shannon, R. D. Acta Crystallogr. 1976, A32, 751.
(13) (a) Irwin, L. J.; Reibenspies, J. H.; Miller, S. A. Polyhedron 2005,
24, 1314. (b) Drago, D.; Pregosin, P. S.; Razavi, A. Organometallics 2000,
19, 1802.
(14) Razavi, A.; Thewalt, U. J. Organomet. Chem. 2001, 621, 267, and
references therein.
its congeners. In contrast, the Cpcent-Zr(1)-Flucent bite angle
in syn-3b is somewhat more constrained (116.7(2)ꢀ), that is,

Article
Organometallics, Vol. 30, No. 2, 2011 267
the reference systems I-Me2 and I-Ph2 (14 000 vs 1710 and
3580 kg PP mol-1
h
-1 at 60 ꢀC; compare entries 1, 2, and 4
3
3
in Table 3). This high activity generated significant exother-
micity, so that reactions with anti-3a/MAO performed at an
initial temperature of 40 ꢀC (entry 3) rapidly rose to 55-60 ꢀC.
Polymerizations with this catalyst system were better con-
ducted with low catalyst loadings (ca. 10 μmol) at a setting
temperature of 60 ꢀC (entries 4, 6); under such conditions, the
exothermicity could be limited to 5-10 ꢀC. On the other hand,
the isotactic polypropylenes produced with I-Me2, I-Ph2,
and anti-3a had similar characteristics. Replacement of the
Me2C or Ph2C bridge for a Ph(H)C bridge did not induce
significant changes in the molecular weight, molecular weight
distribution, or stereoselectivity of the resultant polymer, as
assessed by the GPC data, high pentad [m]4 content, and Tm
values (compare entries 1, 2, and 4). This was not unexpected
in terms of stereoselectivity, because of the structural analogy
of ansa-metallocene compounds I-Me2, I-Ph2, and anti-3a
(and of the corresponding active species derived thereof). We
also observed no major change either in activity or in properties
of the polypropylenes produced when a 40:60 molar mixture
of anti-3a and syn-3a diastereomers was used (entry 6).16 This
fact suggests that either the active species derived from both
diastereomers of zirconocene complex 3a have uniform
catalytic properties or the activation of isomer syn-3a
with MAO generates poorly active or completely inactive
species. The latter hypothesis seems unlikely since the system
anti/syn-3a/MAO behaved very similarly in terms of activity
as the one composed of pure anti-3a.
Figure 4. Crystal structure of syn-{Mes(H)C-(3,6-tBu2Flu)-
(3-Cumyl-5-Me-C5H2)}ZrCl2 (syn-3b) (ellipsoids drawn at the
50% probability level; all hydrogen atoms, except that of the
bridge, are omitted for clarity; only one enantiomer is depicted).
Further raising the polymerization temperature to 80 ꢀC
did not improve the catalytic activity of the anti-3a/MAO
system (entry 5), but rather resulted in a significant decrease
of the molecular weight of polypropylene (at least by 3 times,
attributable to enhanced β-H elimination) and stereoselectivity
(from 95.8% down to 82.2% of isotactic pentads).
The activities of the systems based on hafnium analogues
(anti-4a and syn-4a) were found to be much lower, even when
much larger catalyst loadings were used (activities up to 260
and 270 kg PP mol-1 h-1, respectively, entries 7 and 8). The
3
3
latter observation is in line with the almost complete inactivity
in propylene polymerization recently reported for ansa-
hafnocene complexes {R2C-(Flu)(Cp)}HfCl2 (R=Me, Ph)
upon activation with commercial MAO.17 Yet, interestingly
enough despite the relatively low catalytic activities, the
polypropylenes obtained independently with the two haf-
nium precatalysts featured quite different properties, as
judged from their molecular weight distributions and micro-
structures. As compared to its structural ansa-zirconocene
analogue (anti-3a), precatalyst anti-4a gave lower molecular
weight PP (72 vs 171 kDa) with significantly lower isotacti-
city ([m]4 = 88.8 vs 94.8% and Tm = 142 vs 153 ꢀC,
respectively) (compare entries 7 and 4). At the same time,
the syn-4a/MAO system yielded PP with a high isotactic
content ([m]4=94.0%), yet featuring a bimodal distribution,
as evidenced by GPC and the observation of two endotherms
Figure 5. Crystal structure of {H2C-(3,6-tBu2-Flu)(3-tBu-5-Me-
C5H2)}ZrCl2 (3e) (ellipsoids drawn at the 50% probability level;
all hydrogen atoms, except those of the bridge, are omitted for
clarity; only one enantiomer is depicted).
ca. 2-3ꢀ smaller than those in the latter ansa-metallocene
compounds.
Propylene Polymerization Catalysis. Diastereomerically
pure ansa-metallocene complexes anti-3a, anti-4a, syn-4a,
and syn-3b, as well as methylene-bridged 3e, in combination
with MAO, were evaluated in the homogeneous polymeri-
zation of propylene (toluene solutions, 5 bar constant pres-
sure, Tpol = 40-60 ꢀC).15 For comparison purposes, the
catalytic performances of the reference isopropylidene- and
diphenylmethylene-bridged metallocene precatalysts I-Me2
3
and I-Ph2 were determined under identical conditions.
Selected polymerization results are summarized in Table 3.
Gratifyingly, the activity of the catalyst system based on
anti-3a was found to be significantly higher than those of
(16) This 40:60 molar diastereomeric mixture was obtained by eva-
poration/crystallization of the mother liquor obtained after the isolation
of anti-3a diastereomer.
(17) The quite low polymerization activity of these hafnocene catalyst
systems is a function of the remarkable propensity of cationic species of
the type [{R2C-(Flu)(Cp)}HfMe]þ to form inactive “dormant” bimetal-
lic species of the type [{R2C-(Flu)(Cp)}Hf(μ-Me)2AlMe2]þ through
reaction with trimethylaluminium present in commercial MAO toluene
solutions; see: Busico, V.; Cipullo, R.; Pellecchia, R.; Talarico, G.;
Razavi, A. Macromolecules 2009, 42, 1789.
(15) Each polymerization experiment was independently repeated
three times under the same conditions, revealing good reproducibility
in terms of activity (gas uptake), productivity (polymer yield), and
physicochemical properties (Mw, Mn, Tm, isotacticity) of the isolated
polymer.

268 Organometallics, Vol. 30, No. 2, 2011
Kirillov et al.
Table 1. Summary of Crystal and Refinement Data for ansa-Metallocene Complexes anti-3a, anti-4a, syn-4a, syn-3b, and 3e
anti-3a
anti-4a
syn-4a
syn-3b
3e
empirical formula
fw
C
662.85
173(2)
0.71073
monoclinic
P21/c
11.0734(2)
26.3223(4)
11.6259(2)
101.831(1)
3316.70(10)
4
38H44Cl2Zr
C38H44Cl2Hf
750.12
100(2)
0.71073
monoclinic
P21/c
11.0044(8)
26.201(2)
11.5564(9)
101.670(2)
3263.1(4)
4
C76H88Cl4Hf2
1500.24
100(2)
0.71073
triclinic
P1
11.5420(10)
13.2190(10)
22.043(3)
97.850(10)
3290.6(6)
2
C46H52Cl2Zr
767.00
100(2)
0.71073
monoclinic
P21/n
10.1294(4)
18.5232(9)
20.7106(9)
95.147(2)
3870.2(3)
4
C32H40Cl2Zr
586.76
173(2)
0.71073
monoclinic
P21/c
10.4377(2)
21.6825(6)
13.6979(3)
106.509(1)
2972.25(12)
4
temp, K
wavelength, A
˚
cryst syst
space group
˚
a, A
˚
b, A
˚
c, A
β, deg
volume, A
3
˚
Z
density (calcd), Mg/m3
absorp coeff,mm-1
cryst size, mm3
1.327
0.517
1.527
3.386
1.514
3.357
1.316
0.453
1.311
0.568
0.20 ꢀ 0.20 ꢀ 0.15
0.55 ꢀ 0.50 ꢀ 0.45
0.20 ꢀ 0.15 ꢀ 0.15
0.27 ꢀ 0.25 ꢀ 0.17
0.25 ꢀ 0.20 ꢀ 0.15
reflns collected
indep reflns
14 977
7603
32 344
7489
44 214
13 182
38 826
8859
11 688
6802
data/restraints/params
final R indices [I > 2σ(I)]
7603/0/370
R1 = 0.0358,
wR2 = 0.0897
R1 = 0.0598,
wR2 = 0.1103
1.025
7489/0/370
R1 = 0.0402,
wR2 = 0.1048
R1 = 0.0443,
wR2 = 0.1080
1.041
13 182/0/740
R1 = 0.0199,
wR2 = 0.0419
R1 = 0.0410,
wR2 = 0.0443
0.881
8859/0/442
R1 = 0.0505,
wR2 = 0.1079
R1 = 0.0625,
wR2 = 0.1151
1.057
6802/0/326
R1 = 0.0335,
wR2 = 0.0836
R1 = 0.0512,
wR2 =0.0954
1.045
R indices (all data)
goodness-of-fit on F2
-3
˚
largest diff peak, e A
0.367 and -0.455
4.181 and -2.495
0.592 and -0.516
0.557 and -0.570
0.414 and -0.518
˚
Table 2. Selected Bond Distances (A) and Angles (deg) for Newly Prepared Metallocene Complexes anti-3a, anti-4a, syn-4a, syn-3b, 3e,
and Reference Systems
IIIc
a
b
anti-3a
anti-4a
syn-4a
syn-3b
3e
I-Me2
I-Ph2
M-Cl
2.4136(7)
2.4263(7)
2.436(2)
2.463(2)
2.601(2)
2.549(2)
2.481(2)
2.196(2)
2.407(2)
2.505(2)
2.677(2)
2.721(2)
2.576(2)
2.271(2)
118.29(16)
101.28(19)
107.7(2)
2.3852(10)
2.3973(10)
2.431(4)
2.448(4)
2.581(4)
2.518(4)
2.462(4)
2.175(4)
2.398(4)
2.484(4)
2.650(4)
2.706(4)
2.563(4)
2.253(4)
118.7(3)
101.7(3)
107.85(4)
2.3780(8)
2.4012(9)
2.420(3)
2.453(2)
2.588(3)
2.541(3)
2.465(3)
2.182(3)
2.401(3)
2.517(3)
2.681(3)
2.669(3)
2.532(3)
2.250(3)
119.6(2)
101.8(2)
106.5(2)
2.4083(8)
2.4276(7)
2.450(2)
2.492(3)
2.620(3)
2.539(3)
2.453(3)
2.203(3)
2.413(4)
2.503(3)
2.655(3)
2.679(3)
2.552(3)
2.253(3)
116.7(2)
98.7(2)
2.4078(6)
2.4336(6)
2.4388(19)
2.475(2)
2.616(2)
2.549(2)
2.465(2)
2.200(2)
2.423(2)
2.510(2)
2.654(2)
2.671(2)
2.565(2)
2.255(2)
118.08(11)
102.21(16)
109.2(2)e, f
2.8020(6)
2.639(1)d
2.427(3)
2.464(3)
2.611(4)
2.549(4)
2.461(4)
2.4227(10)
2.4283(10)
2.442(4)
2.492(3)
2.630(4)
2.547(4)
2.457(4)
2.204(4)
2.426(3)
2.497(4)
2.666(4)
2.712(4)
2.588(4)
2.269(4)
118.03(4)
98.60(3)
104.00(4) f
2.412(3)
2.421(3)
2.447(9)
2.488(11)
2.533(11)
M-C(1)
M-C(2)
M-C(3)
M-C(4)
M-C(5)
M-CpCent
M-C(9)
2.432(4)
2.512(4)
2.653(4)
2.688(4)
2.611(4)
2.401(9)
2.554(9)
2.659(8)
M-C(10)
M-C(11)
M-C(12)
M-C(13)
M-FluCent
CpCent-M-FluCent
C(1)-C(6)-C(9)
H(7)-C(6)-C(8)
118.5(3)
100.2(3)
105.3(3) f
117.15
101.6(7)
106.3(2)
a Data from ref 1b. b Data from ref 3. c Data from ref 5. d The crystal structure is for a mixed chloro-iodo-zirconocene complex, and the Zr-Cl bond
distances must be therefore consideredwith caution. e In the complexbearing a methylene-bridged ligand, the corresponding angle is H-C(6)-H. f In the
complex bearing a R2C-bridged ligand (where R = Me or Ph), the respective angle is C-C(6)-C.
in DSC (entry 8); these data suggest the participation of two
different active species.18,19 Although we cannot rationalize
at that time this strikingly different behavior between the two
diastereomeric precursors, this is, to our knowledge, a quite
unique observation for ansa-metallocene complexes.
No polymerization activity was found for zirconocene com-
plex 3b, which bears a cumyl group in the Cp ring (entry 9).
A similar inactivity was observed in the case of {Ph2C-(3,6-
tBu2Flu)(3-cumyl-5-Me-C5H2)}ZrCl2/MAO in our previous
study.3 In both cases, it is assumed that a similar deactivation
pathway operates, which involves coordination of the phenyl
ring of the cumyl group onto the cationic metal center and
subsequent C-H activation, yielding an inactive species.3
The methylene-bridgedansa-zirconocene complex 3e generated
(18) Propylene polymerization promoted by discrete but multisite
(pyridylamide)hafnium post-metallocenes was recently reported; see:
Busico, V.; Cipullo, R.; Pallecchia, R.; Rongo, L.; Talarico, G.; Macchioni,
A.; Zuccaccia, C.; Froese, R. D. J.; Hustad, P. D. Macromolecules 2009, 42,
4369.
(19) Activation of metallocenes with commercial MAO is known to
generate complex mixtures of species. For instance, activation of
Cp*2ZrMe2 with MAO containing 30 mol % of AlMe3 leads to mixtures
of at least four different species, namely, Cp*2Zr(Me)Mef[AlMe3-
(MAO)], [Cp*2Zr(Me)(μ-Me)(Me)ZrCp2]þ[Me(MAO)]-, [Cp*2Zr-
(μ-Me)2AlMe2]þ[Me(MAO)]-, and [Cp*2Zr(Me)]þr[Me-(MAO,
AlMe3)]-; see: (a) Babushkin, D. E.; Semikolenova, N. V.; Zakhar-
ov, V. A.; Tasli, E. Macromol. Chem. Phys. 2000, 201, 558. (b) Merle,
P. G.; Cheron, V.; Hagen, H.; Lutz, M.; Spek, A. L.; Deelman, B.-J.; Van
Koten, G. Organometallics 2005, 24, 1620. The use of diastereomeric
metallocenes may lead obviously to even more complex mixtures, with a
distinct behavior for each diastereomeric precursor.
a catalytic system with an activity (2320 kg PP mol-1 h-1
,
3
3
entry 10) comparable to that of the reference systems I-Me2
and I-Ph2, but ca. 1 order of magnitude lower than that based
on 3a. The PP produced with this system had similar mole-
cular weights and polydispersities to the other three afore-
mentioned catalysts, yet with a somewhat higher isotacticity
([m]4 = 96.9%) as revealed by 13C NMR spectroscopy and

Article
Organometallics, Vol. 30, No. 2, 2011 269
Table 3. Isoselective Propylene Polymerizationa
precatalyst MAO Tpolym
(μmol)
product.
activity
Tm
(ꢀC)c
Mw
[m]4 1,2-insert.
(equiv) (ꢀC)b miPP (g) (g/g of precatalyst) (kg mol-1 h-1
)
( ꢀ 103)d Mw/Mn (%)e
(%)e
d
entry
precatalyst
3
3
1
I-Me2
I-Ph2
anti-3a
11
9
5000 60 (61)
5000 60 (61)
1.39
2.42
1390
2420
13 500
10 550
12 760
10 680
170
1710
152
166
175
230
171
50
2.4
2.3
2.3
2.6
2.1
2.3
2.7
6.6f
95.2
94.0
94.8
95.8
82.2
94.0
88.8
94.0
>99.9
>99.9
>99.9
>99.9
99.8
2
3580
18 000
14 000
16 920
14 160
260
152
155
3
10
10
5000 40 (55) 13.50
5000 60 (64) 10.55
5000 80 (85) 12.76
4
anti-3a
anti-3a
153
133
5
10
9
6
anti/syn-3a (40:60)
anti-4a
syn-4a
5000 60 (70)
9.61
2.05
2.18
0
151
142
154
72
>99.9
>99.9
>99.9
7
200
200
200
11
1000
1000
1000
40
40
60
8
180
270
146, 153
239
9
10
syn-3b
3e
0
1980
0
2320
5000 60 (64)
1.98
154
180
2.4
96.9
>99.9
a Polymerization conditions: 300 mL high-pressureglass reactor;solvent: toluene, 150 mL; P(propylene) = 5 bar; time = 30 min. See also reference15.
b Data in brackets refer to the maximum temperature reached in the reactor. c Determined by DSC. d Determined by GPC. e Isotactic pentad content
determined by 13C NMR spectroscopy. f Bimodal distribution.
also the highest Tm value (154 ꢀC) within the series of iPPs
obtained in this study.
Experimental Section
General Considerations. All manipulations (except poly-
merizations) were performed under a purified argon atmosphere
using standard Schlenk techniques or in a glovebox. Solvents
were distilled from Na/benzophenone (THF, Et2O) and Na/K
alloy (toluene, pentane) under nitrogen, degassed thoroughly,
and stored under nitrogen prior to use. Deuterated solvents
(benzene-d6, toluene-d8, THF-d8; >99.5% D, Deutero GmbH
and Euroisotop) were vacuum-transferred from Na/K alloy into
storage tubes. CDCl3, CD2Cl2, and C2D2Cl4 were kept over
CaH2 and vacuum-transferred before use. The ligand precursor
3,6-di-tert-butylfluorene was generously provided by Total Petro-
chemicals. The precursors 3,6,60-trimethylfulvene, 1-tert-butyl-
3-methylcyclopentadiene (mixture of isomers), and 1-methyl-3-
tert-butylcyclopentadienyllithium were prepared according to
reported protocols21 and characterized by 1H NMR spectroscopy.
1-Cumyl-3-methylcyclopentadiene was synthesized as previously
described.3 The reference metallocene complex {Me2C-(3,6-
tBu2Flu)(3-tBu-5-MeC5H2)}ZrCl2 (I-Me2) was synthesized as
described in the patent literature.21 MAO (30 wt % solution
in toluene, Albermarle; contains ca. 10 wt % of free AlMe3) was
used as received. Other starting materials were purchased from
Acros, Strem, and Aldrich and used as received.
Conclusions
A new series of C1-symmetric group 4 ansa-metallocene
complexes incorporating monoaryl-substituted methylene-
bridged {Flu-Cp} ligands was obtained through an inexpen-
sive and effective synthetic approach. Neutral zirconium and
hafnium complexes were produced, in most cases, as mixtures of
diastereomers that depended on the nature of the ligand and
metal. Crystallizations afforded pure diastereomers (anti-3a,
anti-4a, syn-4a, and syn-3b), which were independently
authenticated and evaluated in propylene polymerization.
Precursor anti-3a, when activated with MAO, appeared to be
1 order of magnitude more active than systems based on
the reference precatalysts I-Me2 and I-Ph2, while providing
the same level of stereocontrol for the production of highly
isotactic polypropylene. Such differences in the catalytic
behavior are even more pronounced in the case of ansa-
hafnocene precursors, where a multisite catalytic system is
generated upon activation of syn-4a with MAO, while anti-4a
leads to a single-site catalytic system.
NMR spectra were recorded on Bruker AC-200, AC-300,
AM-400, and AM-500 spectrometers in Teflon-valved NMR
tubes at 25 ꢀC, unless otherwise indicated. 1H and 13C chemical
shifts are reported in ppm vs SiMe4 or determined by reference
to the residual solvent peaks. 19F chemical shifts were deter-
mined by external reference to an aqueous solution of NaBF4.
Assignments of resonances for organometallic complexes were
made from 2D 1H-13C HMQC and HMBC NMR experiments.
Coupling constants are given in hertz. Elemental analyses
(C, H, N) were performed using a Flash EA1112 CHNS Thermo
Electron apparatus and are the average of two independent
determinations. FAB-HRMS spectra were recorded on a high-
resolution MS/MS Micromass ZABSpecTOF spectrometer.
DSC measurements were performed on a SETARAM Instru-
mentation DSC 131 differential scanning calorimeter at heating
rate of 10 ꢀC/min; first and second runs were recorded after
cooling to 30 ꢀC; the reported melting temperatures correspond
to the second run. GPC analyses of iPP samples were carried out
in 1,2,4-trichlorobenzene at 135 ꢀC at the Total Petrochemicals
research center in Feluy (Belgium), using polystyrene standards
for universal calibration. 13C NMR analyses of iPP samples
were run on a AM-500 Bruker spectrometer (Total Petrochem-
icals, Feluy, Belgium) as follows: solutions of ca. 200 mg of PP
polymer in a trichlorobenzene/C6D6 mixture at 135 ꢀC in 10 mm
tubes, inverse gated experiment, pulse angle 90ꢀ, delay 11 s,
acquisition time 1.25 s, number of scans 6000.
The geometrical parameters of the molecules within this
series of ansa-metallocene precursors are very similar; hence,
the reason for the enhanced catalytic activity in complexes
featuring a Ph(H)C bridge, as compared to CH2- and CPh2-
bridged analogues, is not obvious. At this time, we can only
hypothesize that the activation step of the propylene polym-
erization reaction mediated by anti-3a/MAO may produce
active species dissimilar in nature from those derived from
I-Me2 or I-Ph2.20 Such a phenomenon may also account for
the strikingly different catalytic behavior observed between
the diastereomeric ansa-hafnocene complexes syn- and anti-4a.
Investigations aimed at clarifying the nature of the active
species generated from Ph(H)C-bridged ansa-metallocene
precatalysts as well as other structural modifications of this
class of metallocene compounds to further improve on cata-
lytic performance and control over iPP properties are under-
way and will be reported in due course.
(20) For instance, the stoichiometric reaction between Me(H)Si-
bridged metallocenes {Me(H)Si-(η5-C5Me4)(η1-NtBu)}TiMe2 and
{Me(H)Si-(η5-indenyl)2}ZrMe2 and 2 equiv of [Ph3C][B(C6F5)4] resulted
in simultaneous hydride and methide abstraction, to afford silylium-
metallocenium heterodicationic complexes. The latter species, being
highly electrophilic, appeared to be at least 2 times more active in
propylene polymerization than the corresponding metallocenium
monocations; see: Zhang, Y.; Chen, E. Y.-X. J. Organomet. Chem.
2010, 695, 1464.
(21) Razavi, A. (Atofina Co.) PCT Int. Appl. WO00/49029, 1999.

270 Organometallics, Vol. 30, No. 2, 2011
Kirillov et al.
6-Phenyl-2-methyl-4-tert-butylfulvene (1a). To a solution of
1-methyl-3-tert-butylcyclopentadiene (1.94 g, 14.24 mmol; mix-
ture of isomers) in diethyl ether (50 mL) was added n-butyl-
lithium (5.70 mL of a 2.50 M solution in hexane, 14.24 mmol)
at 0 ꢀC. The mixture was stirred for 2 h, and a solution of
benzaldehyde (1.44 mL, 14.24 mmol) in diethyl ether (30 mL)
was added dropwise. The reaction mixture turned orange. After
2 h, concentrated aqueous NH4Cl (50 mL) was added slowly.
This mixture was stirred overnight. The organic layer was sepa-
rated and dried over MgSO4, and the volatiles were removed
in vacuo. The orange residue was recrystallized from methanol
at -30 ꢀC to give 1a as a deep-red solid (1.00 g, 4.46 mmol, 31%).
1H NMR (CDCl3, 400 MHz, 25 ꢀC): δ 7.57 (m, 2H, Ph), 7.40 (m,
3H, Ph), 7.01 (s, 1H, CHPh), 6.24 (t, J= 1.7, 1H, CH), 6.14 (s,
1H, CH), 2.15 (s, 3H, CH3), 1.19 (s, 9H, CCH3). Anal. Calcd for
C17H20: C, 91.01; H, 8.99. Found: C, 91.18; H, 9.33.
1H NMR (CDCl3, 400 MHz, 25 ꢀC): δ 6.96 (s, 1H, CHN), 6.18
(s, 1H, CH), 6.12 (s, 1H, CH), 3.22 (s, 6H, NCH3), 2.24 (s, 3H,
CH3), 1.27 (s, 9H, CCH3). Anal. Calcd for C13H21N: C, 81.61;
H, 11.06. Found: C, 82.04; H, 11.79.
3,6-Di-tert-butyl-9-[(3-tert-butyl-5-methylcyclopenta-1,4-dienyl)-
phenylethyl]-9H-fluorene (2a). To a solution of 1a (1.75 g, 7.80
mmol) in THF (20 mL) was added at room temperature a
solution of 3,6-di-tert-butylfluorenyllithium (30 mL) prepared
from 3,6-di-tert-butylfluorene (1.95 g, 7.00 mmol) and n-butyl-
lithium (2.80 mL of a 2.50 M solution in hexane, 7.00 mmol).
The mixture was stirred for 4 h at room temperature, quenched
with saturated aqueous NH4Cl (50 mL), and diluted with diethyl
ether (50 mL). The organic layer was separated, washed with
water (2 ꢀ 200 mL), and dried over CaCl2. The volatiles were
removed in vacuo. The residue was dissolved in hot methanol
(50 mL). The solution was cooled to -30 ꢀC, and a white pre-
cipitate formed. The precipitate was filtered, washed with cold
methanol (-30 ꢀC), and dried in vacuo overnight to give 2a as a
white powder (2.30 g, 4.57 mmol, 65%). 1H NMR (CDCl3, 300
MHz, 25 ꢀC): δ 7.70 (m, 2H, Flu), 7.35 (m, 5H, Ph), 7.08 (dd, J=
2.5, J=10.8, 1H, Flu), 6.95 (dd, J=2.5, J=10.8, 1H, Flu), 6.83
(d, J = 10.8, 1H, Flu), 6.29 (m, 2H, Cp), 4.48 (d, 1H, J = 10.6,
CHPh), 3.68 (d, 1H, 3J=10.6, 9-Flu), 2.79 (s, 2H, CH2, Cp), 1.60
(s, 3H, CH3), 1.37 (s, 9H, CCH3-Flu), 1.33 (s, 9H, CCH3-Flu), 1.14
(s, 9H, CCH3-Cp). Anal. Calcd for C38H46: C, 90.78; H, 9.22.
Found: C, 90.69; H, 9.11.
3,6-Di-tert-butyl-9-{mesityl[2-methyl-4-(1-methyl-1-phenylethyl)-
cyclopenta-1,3-dien-1-yl]methyl}-9H-fluorene (2b). To a solution
of 1b (1.10 g, 3.35 mmol) in diethyl ether (20 mL) was added at
room temperature 30 mL of a solution of 3,6-di-tert-butylfluor-
enyllithium prepared from 3,6-di-tert-butylfluorene (0.93 g, 3.34
mmol) and n-butyllithium (1.34 mL of a 2.50 M solution in
hexane, 3.34 mmol). The mixture was refluxed for 5 days and
quenched with saturated aqueous NH4Cl (50 mL). The organic
layer was separated, washed with water (2ꢀ200 mL), and dried
over MgSO4. The volatiles were removed in vacuo, and the
residue was recrystallized from hot methanol to give white
crystals of 2b (1.35 g, 2.22 mmol, 67%). 1H NMR (CDCl3,
200 MHz, 25 ꢀC): δ 7.80 (m, 2H), 7.50-7.18 (m, 7H), 6.96
(dd, J=1.6, 1H), 6.85 (m, 3H), 6.14 (d, J=8.0, 1H), 4.78 (d, J=
10.4, 1H), 4.10 (d, J=10.4, 1H), 2.74 (s, 2H, CH2, Cp), 2.34 (s,
3H, CH3), 2.13 (br s, 6H, CH3-Mes), 1.65 (s, 3H, CCH3CH3Ph),
1.64 (s, 3H, CCH3CH3Ph), 1.49 (s, 3H, CH3-Mes), 1.48 (s, 9H,
CCH3-Flu), 1.40 (s, 9H, CCH3-Flu). Anal. Calcd for C38H46: C,
90.78; H, 9.22. Found: C, 90.69; H, 9.11.
9-[[3,5-Bis(trifluoromethyl)phenyl](4-tert-butyl-2-methylcyclo-
penta-1,4-dien-1-yl)methyl]-3,6-di-tert-butyl-9H-fluorene (2c).
Using a protocol similar to that described above for 2a, com-
pound 2c was obtained from 1c (2.60 g, 7.21 mmol) and 3,6-di-tert-
butylfluorenyllithium (prepared from 3,6-di-tert-butylfluorene
(2.00 g, 7.20 mmol) and n-butyllithium (2.88 mL of a 2.50 M
solution in hexane, 7.20 mmol)). A similar workup afforded 2c
(0.200 g, 0.31 mmol, 4%) as an off-white solid. 1H NMR
(CDCl3, 300 MHz, 25 ꢀC): δ 7.70 (m, 3H, Ph), 7.20-6.30
(m, 6H, Flu), 6.20 (s, 1H, CH), 5.91 (s, 1H, CH), 4.48 (m, 1H,
CHPh), 3.95 (m, 1H, 9-Flu), 3.19-2.73 (m, 2H, CH2), 1.59-1.52
(s, 3H, CH3), 1.36-1.33 (s, 18H, CCH3-Flu), 1.16-1.14
(s, 9H, CCH3-Flu). 19F NMR (CDCl3, 282 MHz, 25 ꢀC):
δ -62.41, -62.45. Anal. Calcd for C40H44F6: C, 75.21; H,
6.94. Found: C, 75.84; H, 7.01.
3,6-Di-tert-butyl-9-[1-(5-tert-butyl-2-methylcyclopenta-1,4-dien-
1-yl)-2,2,2-trifluoro-1-phenylethyl]-9H-fluorene (2d). Using a
protocol similar to that described above for 2a, compound 2d
was obtained from 1d (2.10 g, 7.18 mmol) and 3,6-di-tert-
butylfluorenyllithium (prepared from 3,6-di-tert-butylfluorene
(1.90 g, 6.82 mmol) and n-butyllithium (2.73 mL of a 2.50 M
solution in hexane, 6.82 mmol)). A similar workup gave 2d (2.00 g,
3.50 mmol, 49%) as a yellowish solid. 1H NMR (CDCl3, 200 MHz,
25 ꢀC): δ 7.85-7.65 (m, 3H), 7.60-7.30 (m, 4H), 7.28-6.90 (m,
5H), 6.14 (s, 1H, CH), 4.95 (s, 1H, 9-Flu) 3.09 (br s, 2H, CH2),
6-Mesityl-2-methyl-3-cumylfulvene (1b). To a 50 mL round-
bottom flask containing 1-cumyl-3-methylcyclopentadiene (1.00 g,
5.05 mmol; mixture of isomers) was added 2,4,6-trimethyl-
benzaldehyde (0.76 g, 5.23 mmol) and absolute ethanol (20 mL).
Once the solids had dissolved, NaOMe (0.55 g, 10.18 mmol) was
added and the mixture was stirred for 7 days. The yellow pre-
cipitate was filtered, washed with methanol (2ꢀ5 mL), and dried
in vacuo to yield 1b as a yellow solid (1.10 g, 3.35 mmol, 66%). 1H
NMR (CDCl3, 200 MHz, 25 ꢀC): δ 7.40-7.10 (m, 5H, Ph), 6.96
(m, 3H, Ph), 5.86 (s, 1H, CH), 5.72 (s, 1H, CH), 2.35 (s, 3H, CH3),
2.27 (s, 6H, CH3), 2.11 (s, 3H, CH3), 1.49 (s, 6H, CH3). Anal.
Calcd for C25H28: C, 91.41; H, 8.59. Found: C, 91.99; H, 9.02.
6-(3,5-Bis(trifluoromethyl)phenyl)-3-tert-butyl-5-methylfulvene
(1c). A protocol similar to that described above for 1a was used,
starting from 1-methyl-3-tert-butylcyclopentadiene (2.81 g, 20.63
mmol; mixture of isomers), n-butyllithium (8.20 mL of a 2.50 M
solution in hexane, 20.63 mmol), and 3,5-bis(trifluoromethyl)-
benzaldehyde (5.00 g, 20.65 mmol). Workup afforded 1c as a red
1
solid (2.60 g, 7.22 mmol, 35%). H NMR (CDCl3, 300 MHz,
25 ꢀC): δ 7.92 (s, 2H, Ph), 7.79 (s, 1H, Ph), 6.95 (s, 1H, CHPh),
6.25 (t, J=1.7, 1H, CH), 5.92 (s, 1H, CH), 2.11 (s, 3H, CH3), 1.15
(s, 9H, CCH3). 19F NMR (CDCl3, 282 MHz, 25 ꢀC): δ -62.6.
Anal. Calcd for C19H18F6: C, 63.33; H, 5.03. Found: C, 63.67; H, 5.58.
6-Trifluoromethyl-60-phenyl-2-methyl-3-tert-butylfulvene (1d).
To a solution of 1-methyl-3-tert-butylcyclopentadiene (4.00 g,
29.36 mmol; mixture of isomers) in THF (50 mL) was added
n-butyllithium (18.40 mL of a 1.60 M solution in hexane, 29.44
mmol) at 0 ꢀC. The mixture was stirred for 2 h, and a solution
of trifluoromethyl phenyl ketone (5.00 g, 28.71 mmol) in THF
(20 mL) was added dropwise. After 2 h, HCl (50 mL of a 2 M
aqueous solution) was added slowly. This mixture was stirred
overnight. The organic layer was separated and dried over
MgSO4, and the volatiles were removed in vacuo. The orange
residue was redissolved in pentane, and the resulting solution
was passed through a short silica column and concentrated to
give after crystallization at -30 ꢀC 1d as an orange solid (2.10 g,
7.18 mmol, 25%). 1H NMR (CDCl3, 200 MHz, 25 ꢀC): δ
7.46-7.25 (m, 5H, Ph), 6.22 (m, 1H, dCH), 6.14 (m, 1H, CH),
1.25 (s, 3H, CH3), 1.19 (s, 9H, CCH3). 19F NMR (CDCl3, 188
MHz, 25 ꢀC): δ -56.3. Anal. Calcd for C18H19F3: C, 73.95; H,
6.55. Found: C, 73.84; H, 6.87.
6-Dimethylamino-2-methyl-4-tert-butylfulvene (1e). DMF
(5.40 g, 73.80 mmol) and dimethylsulfate (9.21 g, 73.80 mmol)
were stirred overnight at room temperature. To this mixture
was added a solution of 1-methyl-3-tert-butylcyclopentadienyl
potassium (prepared from the corresponding cyclopentadiene
(10.0 g, 73.42 mmol; mixture of isomers) and KH (3.20 g,
80.00 mmol)). The mixture was stirred for 4 h at room
temperature, and the volatiles were then removed under re-
duced pressure. The oily residue was distilled (ca. 120-140 ꢀC/
10-2 Torr) to give 1e (3.20 g, 16.73 mmol, 23%) as an orange-
yellow oil, which crystallized at room temperature. This com-
pound rapidly decomposes in the presence of moisture, and it is
recommended that it be stored and handled in the glovebox.

Article
Organometallics, Vol. 30, No. 2, 2011 271
1.45 (s, 3H, CH3), 1.40 (s, 18H, CCH3-Flu), 1.16 (s, 9H, CCH3-Flu).
19F NMR (CDCl3, 188 MHz, 25 ꢀC): δ -59.1. Anal. Calcd for
C39H45F3: C, 82.07; H, 7.95. Found: C, 82.13; H, 7.63.
Subsequent concentration under reduced pressure of the result-
ing mother liquor gave pure syn-4a (0.30 g, 0.40 mmol, 18%). 1H
NMR (CD2Cl2, 300 MHz, 25 ꢀC): δ 8.08 (s, 1H), 8.04 (s, 1H),
7.88 (d, J=8.4 Hz, 2H), 7.55 (m, 2H), 7.52-7.43 (m, 3H), 7.12
(dd, J=1.7 Hz, J=9.8 Hz, 1H), 7.04 (d, J=9.2 Hz, 1H), 6.55
(s, 1H, PhHC), 6.05 (d, 1H, 4J=2.6 Hz, Cp), 5.52 (d, 1H, 4J=
2.6 Hz, Cp), 1.98 (s, 3H, CH3), 1.51 (s, 9H, CCH3-Flu), 1.44 (s,
9H, CCH3-Flu), 1.15 (s, 9H, CCH3-Cp). 13C NMR (CD2Cl2,
75 MHz, 25 ꢀC): (three signals from quaternary carbons in the
aromatic region were not observed) 149.5, 148.9, 143.7, 128.5,
128.3, 127.4, 127.3, 126.4, 125.3, 121.9, 120.5, 120.3, 120.2, 119.6,
119.4, 119.2, 119.1, 103.6, 101.6, 72.2 (9-Flu), 43.0 (CCH3), 35.0
(CCH3), 34.9 (CCH3), 32.5 (CCH3), 31.6 (CCH3), 29.5 (CCH3),
28.3 (CCH3), 17.8 (CH3). Anal. Calcd for C38H44Cl2Hf: C,
60.84; H, 5.91. Found: C, 61.05; H, 5.99.
{Mes(H)C-(3,6-tBu2Flu)(3-CMe2Ph-5-Me-Cp)}ZrCl2 (3b).
Using a protocol similar to that described above for 3a, com-
pound 3b was prepared from 2b (1.35 g, 2.22 mmol) and ZrCl4
(0.52 g, 2.23 mmol) and isolated as a pink solid (1.07 g, 1.40
mmol, 63%). 1H NMR (CD2Cl2, 300 MHz, 25 ꢀC): δ 8.14
(s, 1H), 8.06 (s, 1H), 7.51 (s, 2H), 7.30-6.98 (m, 8H), 6.95 (s, 1H),
6.50 (s, 1H, MesCH), 6.01(d, 1H, J=3.1, Cp), 5.63 (d, 1H, J=
3.1, Cp), 2.56 (s, 3H, Me), 2.40 (s, 3H, CH3), 2.15 (s, 3H, CH3),
1.87 (s, 3H, CH3), 1.74 (s, 3H, CH3), 1.53 (s, 9H, CCH3-Flu),
1.45 (s, 9H, CCH3-Flu), 1.42 (s, 3H, CH3). 13C NMR (CD2Cl2,
75 MHz, 25 ꢀC): δ 152.1, 150.2, 149.7, 142.1, 137.9, 137.7, 136.5,
131.4, 130.6, 130.5, 127.9, 127.1, 125.5, 125.4, 125.0, 122.9, 122.1,
121.8, 121.5, 120.1, 119.9, 119.4, 119.1, 105.2, 102.5, 76.5 (9-Flu),
41.3 (CCH3), 35.2 (CCH3), 35.0 (CCH3), 31.7 (CCH3), 27.1
(CCH3), 25.8 (CCH3), 22.9 (CH3), 21.9 (CH3), 20.4 (CH3), 17.4
(CH3). Anal. Calcd for C46H52Cl2Zr: C, 72.03; H, 6.83. Found:
C, 72.86; H, 7.07.
3,6-Di-tert-butyl-9-[(3-tert-butyl-5-methylcyclopenta-1,4-dien-
1-yl)methyl]-9H-fluorene (2e). To a solution of 1e (3.20 g, 16.70
mmol) in THF (50 mL) was added at room temperature a
solution of 3,6-di-tert-butylfluorenyllithium (50 mL) prepared
from 3,6-di-tert-butylfluorene (4.65 g, 16.7 mmol) and n-butyl-
lithium (6.70 mL of a 2.50 M solution in hexane, 16.7 mmol).
The mixture was stirred for 12 h at room temperature. LiAlH4
(1.17 g, 30.8 mmol) was added, and the resulting mixture was
refluxed for another 12 h. The mixture was carefully quenched
with saturated aqueous NH4Cl (50 mL) and diluted with
diethyl ether (100 mL). The organic layer was separated,
washed with water (2 ꢀ 200 mL), and dried over CaCl2. The
volatiles were removed in vacuo, and the crude product was
purified by flash chromatography (thin pad of silica gel,
pentane as eluent) to give 2e as a yellow solid (4.27 g, 10.0
mmol, 60%). 1H NMR (CDCl3, 300 MHz, 25 ꢀC): δ 7.78 (s, 2H,
Flu), 7.40-7.10 (m, 4H, Flu), 6.18 (s, 1H, CH), 5.97 (s, 1H,
CH), 4.00 (m, 1H, 9-Flu), 3.00 (m, 2H, CH2), 2.70 (m, 2H,
CH2), 1.73, 1.66 (s, 3H, CH3), 1.42 (s, 18H, CCH3-Flu), 1.21 (s,
9H, CCH3-Flu). Anal. Calcd for C32H42: C, 90.08; H, 9.92.
Found: C, 90.50; H, 9.99.
{Ph(H)C-(3,6-tBu2Flu)(3-tBu-5-Me-Cp)}ZrCl2 (3a). To a solu-
tion of 2a (1.03 g, 2.04 mmol) in diethyl ether (40 mL) was added
n-butyllithium (1.67 mL of a 2.50 M solution in hexane, 4.08 mmol)
at 0 ꢀC with stirring. After 12 h, anhydrous ZrCl4 (0.48 g, 2.04 mmol)
was added to the sample in the glovebox. The resulting pink
reaction mixture was stirred at room temperature overnight. Then
volatiles were evaporated in vacuo, and hexane (ca. 40 mL) was
vacuum-transferred under reduced pressure. The mixture was
filtered, and the solvent was removed from the filtrate to give 3a
as a pink powder (1.18 g, 1.78 mmol, 88%); this material contained
90% of the anti isomer, as determined by 1H NMR spectroscopy.
The product was recrystallized from hexane (20 mL) at room
temperature to yield pure anti-3a isomer (0.53 g, 8.80 mmol, 40%
yield). Crystals suitable for X-ray diffraction studies were obtained
by slow concentration of a CH2Cl2/hexane (1:9 v/v) solution. 1H
NMR (CD2Cl2, 300 MHz, 25 ꢀC): δ 8.03 (m, 2H, Flu), 7.78 (d, J=
7.8, 2H), 7.58 (d, J=9.1, 1H), 7.48 (m, 2H), 7.43 (m, 2H), 7.08 (dd,
J=1.8, J= 9.0, 1H, Flu), 6.57 (d, J=9.0, 1H, Flu), 6.50 (s, 1H,
CHPh), 6.12 (d, 1H, J=2.6, Cp), 5.57 (d, 1H, J=2.6, Cp), 2.21 (s,
3H, CH3), 1.45 (s, 9H, CCH3-Flu), 1.38 (s, 9H, CCH3-Flu), 1.05 (s,
9H, CCH3-Cp). 13C NMR (CD2Cl2, 75 MHz, 25 ꢀC): δ 150.2,
150.0, 147.1, 140.1, 129.2, 128.9, 128.6, 128.4, 128.2, 127.6, 126.7,
125.9, 125.3, 124.8, 122.8, 122.5, 121.5, 120.0, 119.5, 119.3, 116.9,
103.2, 100.9, 74.6 (9-Flu), 40.2 (CCH3), 35.5 (CCH3), 35.4 (CCH3),
33.2 (CCH3), 32.0 (CCH3), 29.7 (CCH3), 15.8 (CH3). Anal. Calcd
for C38H44Cl2Zr: C, 68.85; H, 6.69. Found: C, 69.01; H, 6.78.
{Ph(H)C-(3,6-tBu2Flu)(3-tBu-5-Me-Cp)}HfCl2 (4a). Using a
procedure similar to that described above for 3a, crude 4a was
obtained from 2a (1.11 g, 2.21 mmol), n-butyllithium (1.76 mL
of a 2.50 M solution in hexane, 4.08 mmol), and anhydrous
HfCl4 (0.71 g, 2.21 mmol) in Et2O (40 mL). The orange solid
obtained after workup contained ca. 70% of the anti isomer, as
estimated by 1H NMR spectroscopy. Pure anti-4a was obtained
by recrystallization from hexane (0.91 g, 1.21 mmol, 55%). 1H
NMR (CD2Cl2, 300 MHz, 25 ꢀC): δ 8.07 (m, 2H, Flu), 7.81 (d,
J=8.3, 2H), 7.65 (d, J=9.2, 1H), 7.60-7.43 (m, 3H), 7.42 (dd,
J=1.7, J=9.0, 1H), 7.11 (dd, J=1.7, J=9.0, 1H, Flu), 6.68 (d,
J=9.2, 1H, Flu), 6.57 (s, 1H, PhHC), 6.10 (d, 1H, J=2.6, Cp),
5.57 (d, 1H, J=2.6, Cp), 2.36 (s, 3H, CH3), 1.50 (s, 9H, CCH3-
Flu), 1.44 (s, 9H, CCH3-Flu), 1.11 (s, 9H, CCH3-Cp). 13C NMR
(CD2Cl2, 75 MHz, 25 ꢀC): δ 149.1, 149.0, 145.3, 140.0, 128.8,
128.1, 127.7, 127.2, 126.1, 123.9, 122.9, 122.4, 122.1, 122.0,
119.5, 119.3, 118.9, 117.8, 115.5, 105.7, 98.1, 74.1 (9-Flu), 39.7
(CCH3), 35.1 (CCH3), 34.9 (CCH3), 32.8 (CCH3), 31.6 (CCH3),
31.5, 29.3 (CCH3), 15.2 (CH3). Anal. Calcd for C38H44Cl2Hf: C,
60.84; H, 5.91. Found: C, 60.92; H, 5.90.
{H2C-(3,6-tBu2Flu)(3-tBu-5-Me-Cp)}ZrCl2 (3e). Using a pro-
tocol similar to that described above for 3a, compound 3e was
prepared from 2e (1.67 g, 3.91 mmol) and ZrCl4 (0.91 g, 3.90
mmol) and isolated as a pink solid (1.48 g, 2.52 mmol, 64%).
Crystals suitable for X-ray diffraction studies were obtained by
1
slow concentration of a CH2Cl2/hexane (3:7 v/v) solution. H
NMR (CD2Cl2, 300 MHz, 25 ꢀC): δ 8.01 (s, 1H, Flu), 7.97 (s, 1H,
Flu), 7.52 (s, 1H, Flu), 7.40 (m, 2H, Flu), 7.37 (m, 1H, Flu), 6.02
(d, 1H, J=2.8, Cp), 5.52 (d, 1H, J=2.8, Cp), 4.74 (m, 2H, CH2),
2.16 (s, 3H, CH3), 1.44 (s, 9H, CCH3-Flu), 1.43 (s, 9H, CCH3-Flu),
1.05 (s, 9H, CCH3-Flu). 13C NMR (CD2Cl2, 75 MHz, 25 ꢀC): δ
150.1, 150.0, 146.4, 127.9, 127.6, 124.8, 124.1, 124.0, 123.3, 121.8,
120.7, 120.6, 120.2, 119.7, 118.2, 102.4, 97.0, 70.3 (9-Flu), 35.6
(CCH3), 33.3 (CCH3), 32.2 (CCH3), 32.1 (CCH3), 32.0 (CCH3),
30.0 (CCH3), 22.5 (CH2), 16.1 (CH3). Anal. Calcd for C32H40Cl2Zr:
C, 65.50; H, 6.87. Found: C, 66.01; H, 6.99.
Propylene Polymerization. Polymerization experiments were
performed in a 300 mL high-pressure glass reactor equipped
with a mechanical stirrer (Pelton turbine) and externally heated
with a double mantle with a thermostated circulating water
bath. The reactor was charged with toluene (80 to 150 mL) and
MAO (1.5 mL of a 30 wt % solution in toluene), and propylene
(5 bar, Air Liquide, 99.99%) was introduced. The reactor was
thermally equilibrated at the desired temperature for 30 min.
Propylene pressure was decreased to 1 bar, and a solution of the
catalyst precursor in toluene (ca. 2 mL) was added by syringe.
The propylene pressure was immediately increased to 5 bar (kept
constant with a back regulator), and the solution was stirred for
the desired time. The temperature inside the reactor was mon-
itored using a thermocouple. The polymerization was stopped
by venting the vessel and quenching with a 10 wt % solution of
aqueous HCl in methanol (ca. 3 mL). The polymer was pre-
cipitated in methanol (ca. 200 mL), and 35 wt % aqueous HCl
(ca. 1 mL) was added to dissolve possible catalyst residues. The
polymer was collected by filtration, washed with methanol
(ca. 200 mL), and dried under vacuum overnight.
Crystal Structure Determination of anti-3a, syn-3b, anti-4a,
syn-4a, and 3e. Diffraction data were collected at 100(2) or

272 Organometallics, Vol. 30, No. 2, 2011
Kirillov et al.
173(2) K using a Bruker APEX CCD diffractometer with graphite-
˚
asymmetric unit is composed of two independent molecules,
each with the corresponding enantiomer. Detailed crystallo-
graphic data (excluding structure factors) are available as
Supporting Information, as cif files.
monochromatized Mo KR radiation (λ=0.71073 A). A combi-
nation of ω and φ scans was carried out to obtain a unique data set.
The crystal structures were solved by direct methods; remaining
atoms were located from difference Fourier synthesis followed
by full-matrix least-squares refinement based on F2 (programs
SIR97 and SHELXL-97).22 Many hydrogen atoms could be
located from the Fourier difference analysis. Other hydrogen
atoms were placed at calculated positions and forced to ride on
the attached atom. The hydrogen atom positions were calcu-
lated but not refined. All non-hydrogen atoms were refined with
anisotropic displacement parameters. Crystal data and details
of data collection and structure refinement for the different
compounds are given in Table 1. Note that in syn-4a the
Acknowledgment. This work was financially supported
by Total Petrochemicals (grant to E.K., J.A.G., N.M.,
and M.B.). J.F.C. thanks the Institut Universitaire de France
for a Junior IUF fellowship (2005-2009). Dr. Loic Toupet
(IPR) and S. Sinbandhit (CRMPO) are gratefully acknow-
ledged for technical assistance with X-ray diffraction and
NMR spectroscopy experiments, respectively.
Supporting Information Available: Representative 1H NMR
(22) (a) Sheldrick, G. M. SHELXS-97, Program for the Determina-
tion of Crystal Structures; University of Goettingen: Germany, 1997.
(b) Sheldrick, G. M. SHELXL-97, Program for the Refinement of Crystal
Structures; University of Goettingen: Germany, 1997. (c) Sheldrick, G. M.
Acta Crystallogr. 2008, A64, 112.
spectra of fulvenes, proligands, and metallocene complexes, 13
C
NMR spectrum of an iPP, and crystallographic data for anti-3a,
syn-3b, anti-4a, syn-4a, and 3e as CIF files. This material is
available free of charge via the Internet at http://pubs.acs.org.