Synthesis of chiral unbridged zirconocene complexes: Applications in the polymerization of ethylene and propylene

Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

Synthesis of chiral unbridged zirconocene complexes: Applications

in the polymerization of ethylene and propylene

a

Dorian Polo-Ceron , Santiago Gomez-Ruiz , Sanjiv Prashar^a,∗, Mariano Fajardo^a,

´

b

b,∗∗

b

c

˜

´

, Isabel Lopez-Solera , Manuel L. Reyes

Antonio Antinolo , Antonio Otero

^aDepartamento de Qu´ımica Inorga´nica y Anal´ıtica, E.S.C.E.T., Universidad Rey Juan Carlos, 28933 Mo´stoles (Madrid), Spain

^bDepartamento de Qu´ımica Inorga´nica, Orga´nica y Bioqu´ımica, Universidad de Castilla-La Mancha, Facultad de Qu´ımicas,

Campus Universitario, 13071 Ciudad Real, Spain

^cCentro de Tecnolog´ıa Repsol-YPF, Carretera de Extremadura A5, Km. 18, 28931 Mo´stoles (Madrid), Spain

Received 9 November 2006; received in revised form 20 December 2006; accepted 26 December 2006

Available online 5 January 2007

Abstract

The lithium derivatives of the chiral substituent bearing cyclopentadienyl ligands, Li{C₅H₄(CHRR^ꢀ)} (R = Prⁱ, R^ꢀ= Me (1); R = Prⁱ, R^ꢀ= Ph (2);

R = Bu^t, R^ꢀ= Me (3); R = Bu^t, R^ꢀ= Ph (4)), were prepared via the reaction of alkyllithium compounds with the corresponding fulvene reagent. The

mixed cyclopentadienyl zirconocene complexes [Zr(␩⁵-C₅H₅)(␩⁵-C₅H₄{CHRR^ꢀ})Cl₂] (R = Prⁱ, R^ꢀ= Me (5); R = Prⁱ, R^ꢀ= Ph (6); R = Bu^t, R^ꢀ= Me

(7); R = Bu^t, R^ꢀ= Ph (8)) were prepared via the reaction of the lithium precursors 1–4 with [Zr(␩⁵-C₅H₅)Cl₃]. The symmetrical zirconocene

complexes, [Zr(␩⁵-C₅H₄{CHRR^ꢀ})₂Cl₂] (R = Prⁱ, R^ꢀ= Me (9); R = Prⁱ, R^ꢀ= Ph (10); R = Bu^t, R^ꢀ= Me (11); R = Bu^t, R^ꢀ= Ph (12)), were synthesized

from the reaction of two molar equivalents of 1–4 with ZrCl₄. When the mono(cyclopentadienyl) complexes [Zr(␩⁵-C₅H₄{CHRR^ꢀ})Cl₃] (R = Prⁱ,

R^ꢀ= Me (17); R = Prⁱ, R^ꢀ= Ph (18); R = Bu^t, R^ꢀ= Me (19); R = Bu^t, R^ꢀ= Ph (20)) were reacted with Li(C₉H₇) the zirconocene derivatives, [Zr(␩⁵-

C₉H₇)(␩⁵-C₅H₄{CHRR^ꢀ})Cl₂] (R = Prⁱ, R^ꢀ= Me (21); R = Prⁱ, R^ꢀ= Ph (22); R = Bu^t, R^ꢀ= Me (23); R = Bu^t, R^ꢀ= Ph (24)), were obtained. The

molecular structure of 11 has been determined by single-crystal X-ray diffraction studies. 5–12 and 21–24 have been tested as catalysts in the

polymerization of ethylene and propylene. Isotactic polypropylene with [mmmm] pentads between 20 and 40% were obtained and their tacticity

can be related directly to the structure of the catalyst.

Keywords: Metallocenes; Zirconium; Polymerization; Polyethylene; Polypropylene

1. Introduction

Kaminsky and Steiger made the ﬁrst report of an isospeciﬁc

unbridged zirconocene polypropylene catalyst [4]. Subse-

quently Erker et al. have synthesized unbridged zirconocene

complexes containing bulky substituents and observed them to

be isoselective in the polymerization of propylene at low tem-

peratures [5]. Waymouth et al. have studied similar metallocene

systems containing substituted indenyl ligands and reported that

the conformational dynamics of the catalysts give conversion

between stereoselective and non-stereoselective conformations

leading to atactic/isotactic block polymers in the polymerization

of propylene [6]. Mixed indenyl–cyclopentadienyl unbridged

zirconocene systems have received less attention than their

symmetrical counterparts. Alt et al. have synthesized different

zirconocene complexes with indenyl and substituted cyclopen-

tadienyl ligands and observed high catalytic activity in the

polymerization of ethylene [3c,7]. Recently Huang and cowork-

ers reported the synthesis of a series of similar compounds [8].

Since the discovery of metallocene/MAO catalytic systems

in the polymerization of oleﬁns by Sinn and Kaminsky [1], there

has been a rapid development in this ﬁeld at both academic and

industrial level [2].

It is well established that the structural make up of the met-

allocene complex directly inﬂuences the catalytic activity and

selectivity in oleﬁn polymerization [2c] and this is made evident

by the large number of metallocene complexes with different

substituents on the cyclopentadienyl ring that have been reported

[3].

∗

∗∗

Corresponding author. Tel.: +34 914887186; fax: +34 914888143.

Corresponding author. Tel.: + 34 926295326; fax: +34 926295318.

E-mail addresses: sanjiv.prashar@urjc.es (S. Prashar),

antonio.otero@uclm.es (A. Otero).

doi:10.1016/j.molcata.2006.12.040

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

265

As part of our ongoing studies in the design of oleﬁn polymer-

2.2. Synthesis and characterization of zirconocene

complexes

ization catalysts [9] we present in this paper a series of unbridged

bis(cyclopentadienyl) and indenyl–cyclopentadienyl zirconium

complexes with chiral substituents, and their catalytic behaviour

in the polymerization of ethylene and propylene.

The reaction of 1–4 with [Zr(␩⁵-C₅H₅)Cl₃] yielded the zir-

conocene compounds [Zr(␩⁵-C₅H₅)(␩⁵-C₅H₄{CHRR^ꢀ})Cl₂]

(R = Prⁱ, R^ꢀ= Me (5); R = Prⁱ, R^ꢀ= Ph (6); R = Bu^t, R^ꢀ= Me (7);

R = Bu^t, R^ꢀ= Ph (8)) (Eq. (2)) which were isolated as white crys-

talline solids and characterized spectroscopically. The pair of ␣,

and likewise the pair of ␤ protons, of the cyclopentadienyl unit

of 5–8 are diastereotopic due to the presence of the chiral sub-

stituent and thus four multiplets, between 5.9 and 7.0 ppm, were

observed in the ¹H NMR spectra. In addition, one singlet at ca.

6.0 pp mwasassignedtotheunsubstitutedcyclopentadienylring.

The signals for the corresponding cyclopentadienyl substituent

were observed with similar chemical shifts and identical spectral

2. Results and discussion

2.1. Synthesis and characterization of cyclopentadienyl

precursors

The alkyllithium reagents, LiR^ꢀ(R^ꢀ= Me, Ph), react with 6-

(iso-propyl)- or 6-(tert-butyl)-fulvene via nucleophilic addition

attheexocyclic double bond to givethelithium cyclopentadienyl

compounds, Li{C₅H₄(CHRR^ꢀ)} (R = Prⁱ, R^ꢀ= Me (1); R = Prⁱ,

R^ꢀ= Ph (2); R = Bu^t, R^ꢀ= Me (3); R = Bu^t, R^ꢀ= Ph (4)) (Eq. (1))

[10].

patterns as those recorded in the spectra of 1–4. The ¹³C{ H}

1

NMR spectra of 5–8 showed in all cases ﬁve signals between

100 and 145 ppm for the substituted C₅ring and one signal

at ca. 115 ppm corresponding to the unsubstituted cyclopen-

tadienyl ligand. The signals for the different cyclopentadienyl

substituents are similar to those described for the compounds

1–4.

(1)

1

1–4 were characterized by H and ¹³C NMR spectroscopy

(see Section 4). Two multiplets were observed between 5.5 and

1

5.7 ppm in the H NMR spectra of 1–4 and assigned to the

cyclopentadienyl ring protons. In 1 and 2, two doublets and

a multiplet were observed for the two diastereotopic methyl

groups and proton of the iso-propyl fragment, respectively. For

1, a multiplet at 2.67 ppm and a doublet at 1.33 ppm, were

observed, corresponding to the proton and methyl group bonded

to the stereocentre carbon atom of the cyclopentadienyl sub-

stituent, respectively. For2, theprotonbondedtothestereocentre

carbon atom gave a doublet signal at 3.30 ppm. Three multiplets

(between 7.0 and 7.3 ppm) were recorded for the phenyl moiety.

(2)

The metallocene complexes, [Zr(␩⁵-C₅H₄{CHRR^ꢀ})₂Cl₂]

(R = Prⁱ, R^ꢀ= Me (9); R = Prⁱ, R^ꢀ= Ph (10); R = Bu^t, R^ꢀ= Me

(11); R = Bu^t, R^ꢀ= Ph (12)), were prepared by the reaction of

two molar equivalents of 1–4 with ZrCl₄(Eq. (3)). 9–12 were

isolated as white crystalline solids and characterized spectro-

scopically. The existence of two stereocentres in the molecules

leads to formation of the rac- and meso-isomers. NMR spec-

troscopy conﬁrmed the presence of the two diastereomers in the

ﬁnal product in a 1:1 ratio. Our attempts to separate them by

1

The tert-butyl signal in 3 and 4 was observed in the H NMR

spectra as a singlet at 0.9 ppm. For 3, a quartet, at 2.53 ppm, and

a doublet, at 1.28 ppm, were observed corresponding to the pro-

ton and methyl group bonded to the stereocentre carbon atom of

the cyclopentadienyl substituent, respectively. For 4, the proton

bonded to the stereocentre carbon atom gave a singlet signal at

3.58 ppm and three multiplets (between 7.0 and 7.4 ppm) which

1

were assigned to the phenyl moiety. The ¹³C{ H} NMR spectra

1

for 1–4 showed the expected signals (stereocentre carbon atom,

one signal at ca. 42.0 ppm for 1 and 46.3 ppm for 3 and 57.6 ppm

for 2 and 60.9 ppm for 4; methyl, one signal at ca. 19 ppm; iso-

propyl, three signals at ca. 20, 21 and 36 ppm; tert-butyl, two

signals at ca. 29 and 35 ppm; phenyl, four signals at ca. 125,

128, 129 and 150 ppm; cyclopentadienyl, three signals at ca.

101, 103, and 124 ppm).

fractional recrystallization proved to be unsuccessful. The H

NMR spectra of 9–12 are similar in nature to those recorded

for the parent lithium derivatives 1–4. However, 9–12 differ in

the fact that the ring protons are more sensitive to the chiral

environment of the alkyl substituent giving four multiplets for

each isomer in the ¹H NMR spectra compared with two signals

observed in 1–4.

266

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

(3)

Although we were unable to satisfactorily separate the meso-

and rac-isomers of 9–12 we were, however, able to isolate, by

crystallization from toluene, a small amount of crystals of 11,

which proved to be, by single-crystal X-ray diffraction analy-

sis, the meso-isomer. The molecular structure of 11 and atomic

numbering scheme are shown in Fig. 1. Selected bond lengths

and angles are given in Table 1.

The molecular structure of 11 revealed that both C₅rings

5

are bound to the metal in an ␩ mode. The usual bent metal-

locene conﬁrmation was observed with the geometry around the

metal atom being pseudo-tetrahedral as deﬁned by the two chlo-

rine atoms and the two cyclopentadienyl moieties. The centroids

of the cyclopentadienyl rings form an angle with the zirconium

atom of 128.9^◦which is typical for zirconocene dichloride com-

plexes.

Fig. 1. Molecular structure and atom-labeling scheme for meso-[Zr(␩⁵-

C₅H₄{CHBu^tMe})₂Cl₂] (11), with thermal ellipsoids at 20% probability.

Therefore the synthetic strategy to obtain the mixed ring

compound was changed to that of the reaction of the

mono(cyclopentadienyl) zirconium trichloride with indenyl-

lithium.

The cyclopentadienyl substituents are positioned, with

respect to each other, in such a way as to give a near C₂

symmetrical arrangement. In addition, the tert-butyl groups are

orientated away (outwards) from, and the methyl groups towards

(inwards), thezirconiumatom. Thistypeofarrangementhaspre-

viously been reported by Erker et al. in a similar metallocene

complex and was attributed to steric factors [5a]. The stereocen-

tre carbon atoms (C(6) and C(17)) of the alkyl substituent are

located only 0.12(1)^◦and 0.15(1)^◦out of the plane deﬁned by

the cyclopentadienyl unit. The structure corresponds to that of

the meso-isomer with the stereocentre carbon atoms (C(6) and

C(17)) bonded to the two different cyclopentadienyl rings hav-

ing alternate absolute conﬁgurations. Selected structural data of

11 can be compared with similar zirconocene complexes using

Table 2.

In order to prepare [Zr(␩⁵-C₅H₄{CHRR^ꢀ})Cl₃], the tri-

methylsilyl cyclopentadienyl precursors C₅H₄(CHRR^ꢀ)(SiMe₃)

(R = Prⁱ, R^ꢀ= Me (13); R = Prⁱ, R^ꢀ= Ph (14); R = Bu^t, R^ꢀ= Me

(15); R = Bu^t, R^ꢀ= Ph (16)) were synthesized by the reaction of

one equivalent of the corresponding lithium derivative 1–4 and

one equivalent of SiMe₃Cl (Eq. (4)). 13–16 were isolated as iso-

meric mixtures. The predominant isomer was characterized by

¹H NMR spectroscopy.

The reaction of 1–4 with [Zr(␩⁵-C₉H₇)Cl₃] was carried out in

order to obtain the mixed cyclopentadienyl–indenyl zirconocene

complexes. However this synthetic route led to an inseparable

mixture of products containing, as well as the desired product,

the bis(cyclopentadienyl) and bis(indenyl) zirconium deriva-

tives.

(4)

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

267

Table 1

three signals at ca. 18, 20 and 34 ppm in 17 and 18; two signals at

ca. 28 and 34 ppm for the tert-butyl in 19 and 20; for the phenyl

group in 18 and 20, four signals between 125 and 135 ppm; ﬁve

signals between 115 and 145 ppm for the cyclopentadienyl ring

carbon atoms.

◦

˚

Selected bond lengths (A) and angles ( ) for 11

Zr(1)–Cent(1)

Zr(1)–Cent(2)

av Zr(1)–C[C(1)–C(5)]^a

av Zr(1)–C[C(12)–C(16)]^a

Zr(1)–Cl(1)

Zr(1)–Cl(2)

C(1)–C(6)

C(12)–C(17)

C(6)–C(7)

2.212

2.209

2.513(6)

2.510(6)

2.445(2)

2.449(1)

1.508(7)

1.503(7)

1.538(8)

1.560(8)

1.544(8)

1.561(8)

C(6)–C(8)

C(17)–C(18)

C(17)–C(19)

Cent(1)–Zr(1)–Cent(2)

Cl(1)–Zr(1)–Cent(1)

Cl(1)–Zr(1)–Cent(2)

Cl(2)–Zr(1)–Cent(1)

Cl(2)–Zr(1)–Cent(2)

Cl(1)–Zr(1)–Cl(2)

C(1)–C(6)–C(7)

C(1)–C(6)–C(8)

C(7)–C(6)–C(8)

C(12)–C(17)–C(18)

C(12)–C(17)–C(19)

C(18)–C(17)–C(19)

C(6)–C(1)–Cent(1)

C(17)–C(12)–Cent(2)

128.9

107.0

105.1

105.6

(5)

108.5

The cyclopentadienyl–indenyl mixed ring metallocene com-

plexes, [Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄(CHRR^ꢀ))Cl₂] (R = Prⁱ, R^ꢀ= Me

(21); R = Prⁱ, R^ꢀ= Ph (22); R = Bu^t, R^ꢀ= Me (23); R = Bu^t,

R^ꢀ= Ph (24)), were prepared by the reaction of Li(C₉H₇) with

17–20, respectively (Eq. (6)). 21–24 were isolated as crystalline

solids and characterized spectroscopically. The ¹H NMR spectra

of 21–24 are similar to those observed for 17–20, with in addi-

tion four multiplets, between 5.0 and 8.0 ppm, being observed

97.37(6)

110.6(5)

112.0(5)

112.2(5)

110.5(5)

112.7(5)

175.8

174.9

and assigned to the indenyl ligand protons. The ¹³C{ H} NMR

1

Cent(1) and Cent(2) are the centroids of C(1)–C(5) and C(12)–C(16), respec-

tively.

spectra of 21–24 gave ﬁve signals between ca. 100–130 ppm

a

Average bond distance between Zr(1) and the carbon atoms of the C₅ring

corresponding to the indenyl ligand carbon atoms.

of the corresponding cyclopentadienyl moiety.

The mono(cyclopentadienyl) trichloride complexes, [Zr(␩⁵-

C₅H₄{CHRR^ꢀ})Cl₃] (R = Prⁱ, R^ꢀ= Me (17); R = Prⁱ, R^ꢀ= Ph

(18); R = Bu^t, R^ꢀ= Me (19); R = Bu^t, R^ꢀ= Ph (20)) were then

prepared by the reaction of 13–16 with ZrCl₄in toluene and

the subsequent elimination of SiMe₃Cl (Eq. (5)). 17–20 have

1

been characterized by H and ¹³C NMR spectroscopy. In the

¹H NMR spectra of 17–20 four multiplets between 6.0 and

7.0 ppm were observed and assigned to the cyclopentadienyl

protons. In 17 and 18, two doublets for the two diastereotopic

methyl groups and a multiplet for the proton of the iso-propyl

fragment, were observed. For 17, a multiplet at 3.23 ppm and

a doublet at 1.32 ppm, were observed, corresponding, respec-

tively, to the proton and methyl group bonded to the stereocentre

carbon atom of the cyclopentadienyl substituent. For 18, the

proton bonded to the stereocentre carbon atom gave a dou-

blet signal at 4.55 ppm and three multiplets (between 7.0 and

7.3 ppm) were recorded for the phenyl moiety. The tert-butyl

(6)

2.3. Polymerization of ethylene

The polymerization of ethylene using the zirconocene deriva-

tives, 5–12 and 21–24, as catalyst (in the case of 9–12 the

1:1 rac/meso isomer mixture) with a MAO–metal catalyst ratio

of 1000:1, has been carried out. The polymerization experi-

ments were conducted at 20 ^◦C and at an oleﬁn pressure of

2 bar during 30 min. The polymerization was also carried out

with the reference compound [Zr(␩⁵-C₅H₅)₂Cl₂], under the

same experimental conditions. The catalytic activities and poly-

mer molecular weight and distribution values are given in

Table 3.

The catalytic activities recorded for all the complexes, with

the exception of 9 and 11, are lower than that of the ref-

erence compound [Zr(␩⁵-C₅H₅)₂Cl₂]. In all cases, markedly

lower activities were observed for the phenyl substituted com-

pounds (6, 8, 10, 12, 22 and 24) in comparison with the methyl

1

signal in 19 and 20 was observed in the H NMR spectra as

a singlet at ca. 0.9 ppm. For 19, a quartet at 2.96 ppm and a

doublet at 1.30 ppm, were observed and assigned, respectively,

to the proton and methyl group bonded to the stereocentre car-

bon atom of cyclopentadienyl substituent. For 20, the proton

bonded to the stereocentre carbon atom gave a singlet signal at

4.08 ppm and the phenyl moiety three multiplets (between 7.0

and 7.3 ppm).

1

The ¹³C{ H} NMR spectra for 17–20 showed one signal at

ca. 45 ppm for the stereocentre carbon atom; one signal for the

methyl group at ca. 14 ppm in 17 and 19; for the iso-propyl group

268

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

Table 2

Selected structural data of some zirconocene complexes^a

b

˚

Complex

Zr–Cp (A)

Zr–Cl (A)

Cp–Zr–Cp (^◦)

Cl–Zr–Cl(^◦)

Reference

[11]

2.20(1)

2.21(1)

2.20(1)

2.44

2.45

129.5(1)

129.1(1)

97.0(1)

97.1(1)

[Zr(␩⁵-C₅H₅)₂Cl₂]^c

[Zr(␩⁵-C₅H₄Prⁱ)₂Cl₂]

[Zr(␩⁵-C₅H₄Bu^t)₂Cl₂]

[Zr(␩⁵-C₅H₄Ph)₂Cl₂]

2.207

2.217

2.22(1)

2.448(3)

2.457(1)

2.45

96(1)

94.2(6)

95.2(1)

[12]

[13]

[14]

128.6

129.3(2)

2.212

2.209

2.445(2)

2.449(1)

128.9

97.37(6)

meso-[Zr(␩⁵-C₅H₄{CHBu^tMe})₂Cl₂]

rac-[Zr(␩⁵-C₅H₄{CHPhMe})₂Cl₂]

This work

[5a]

2.462(2)

2.456(2)

96.6(1)

[Zr(␩⁵-C₅H₄{CH₂Ph})₂Cl₂]

2.16

2.205

2.461(6)

2.4448(6)

2.441(1)

2.4529(5)

126

94.4(1)

[15]

[16]

[17]

[18]

[Zr(␩⁵-C₅H₄{CH₂CH₂PPh₂})₂Cl₂]

rac-[Zr(␩⁵-C₅H₄{CHMePPh₂})₂Cl₂]

rac-[Zr(␩⁵-C₅H₄{CHnBuNMe₂})₂Cl₂]

130.9

130.6

131.7

99.69(3)

98.85(6)

97.70(3)

2.442(1)

2.440(1)

[Zr(␩⁵-C₅H₄{C( CH₂)C₆H₃Me-2})₂Cl₂]

[19]

96.5(1)

[Zr(␩⁵-C₅H₄{CMe₂CHMe₂})₂Cl₂]

2.223

2.224(1)

2.4546(6)

2.457(1)

129.4

93.95(3)

93.5(1)

[20]

[21]

[Zr(␩⁵-C₅H₄{C(C₅H₁₀)Me})₂Cl₂]

2.196

2.180

2.200

2.214

2.190

2.198

2.448(7)

2.470(5)

2.440(7)

2.473(6)

2.459(4)

2.464(8)

133.7

131.5

130.1

94.2(2)

95.1(2)

94.2(2)

rac-[Zr(␩⁵-C₅H₄{CH(Me)CH₂OMe})₂Cl₂]^d

[22]

[Zr(␩⁵-C₅H₄{methylestratrienyl})₂Cl₂]

[Zr(␩⁵-C₅H₄{C( CH₂)C₆H₁₁})₂Cl₂]

[Zr(␩⁵-C₅H₄{C(CH₂)₅CH₂CH₂CHMe₂})₂Cl₂]

[Zr(␩⁵-C₅H₄{SiMe₃})₂Cl₂]

2.2

128.7

130.1

130.1(1)

129.1

95.2

[23]

[5b]

[24]

[25]

2.215(1)

2.224(1)

2.21

2.437(1)

2.460(1)

2.49

98.0(1)

93.7(1)

94

2.210(2)

2.224(2)

2.4253(9)

2.4337(8)

[Zr(␩⁵-C₅H₄{SiPh₂Me})₂Cl₂]

[26]

130.2(2)

95.90(3)

2.209(1)

2.216(1)

2.4571(6)

2.4379(6)

[Zr(␩⁵-C₅H₄{SiMe₂CH₂C₆F₅})₂Cl₂]

[27]

[28]

127.94(4)

129.61(5)

99.48(2)

96.50(3)

[Zr(␩⁵-C₅H₄{SiMe₂CH₂CH₂C₆F₁₃})₂Cl₂]

2.199(1)

2.4524(7)

2.2

105.7

99.5

[Zr(␩⁵-C₅H₄{SiMe₂N(SiMe₃)₂})₂Cl₂]^c

a

Blank spaces in this table indicate that this data were not reported; ESD values are given when reported.

Cp refers to the C₅H₄R moiety.

There are two independent molecules in the asymmetric cell.

There are three independent molecules in the asymmetric cell.

b

c

d

substituted analogues (5, 7, 9, 11, 21 and 23). This observation

ind–cp^ꢀmetallocene systems. For the phenyl substituted cata-

lysts little difference was observed in the activities between the

different metallocene systems.

The polymer molecular weights are, in all the cases, higher

than for the reference complex and are between 300,000 and

600,000, except for 7 and 23 which give values of approximately

1,200,000.

The complexes 5–12 and 21–24 produced broad poly-

mer molecular weight distributions with polydispersity values

between 4 and 9. This phenomenon has previously been

explained considering the rotation of the C₅ring to be slower

than the propagation of the polymer chain creating different

can be explained by the more than likely intramolecular coordi-

nation of the phenyl moiety to the zirconium active centre during

the polymerization [29].

The activities for the iso-propyl substituted compounds (5, 6,

9 and 10), were higher than their tert-butyl analogues (7, 8, 11

and 12). In the case of the indenyl derivatives, 21–24, this trend

was reversed. A correlation in the catalytic activities between

the different metallocene systems (cp–cp^ꢀ= 5–8, cp₂^ꢀ= 9–12, and

ind–cp^ꢀ= 21–24) is not easy. The catalysts with the methyl sub-

stituent (5 and 7) gave higher activities (approximately triple)

for the cp^ꢀ₂system compared with those for both the cp–cp^ꢀand

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

269

Table 3

Ethylene polymerization results for 5–12, 21–24 and [Zr(␩⁵-C₅H₅)₂Cl₂]^a

Catalyst

Activity^b

M_w

169,000

M_w/M_n

[Zr(␩⁵-C₅H₅)₂Cl₂]

23,300

16,747

8,707

13,233

4,820

40,747

7,333

34,960

3,347

12,033

4,033

13,347

8,607

2.3

5.0

4.2

7.5

4.2

7.9

8.1

7.1

8.8

4.1

6.8

4.2

[Zr(␩⁵-C₅H₅)(␩⁵-C₅H₄{CHPrⁱMe})Cl₂] (5)

[Zr(␩⁵-C₅H₅)(␩⁵-C₅H₄{CHPrⁱPh})Cl₂] (6)

[Zr(␩⁵-C₅H₅)(␩⁵-C₅H₄{CHBu^tMe})Cl₂] (7)

[Zr(␩⁵-C₅H₅)(␩⁵-C₅H₄{CHBu^tPh})Cl₂] (8)

[Zr(␩⁵-C₅H₄{CHPrⁱMe})₂Cl₂] (9)

331,000

421,000

1,212,000

3,83,000

4,87,000

5,42,000

4,22,000

609,000

3,71,000

494,000

1,149,000

458,000

[Zr(␩⁵-C₅H₄{CHPrⁱPh})₂Cl₂] (10)

[Zr(␩⁵-C₅H₄{CHBu^tMe})₂Cl₂] (11)

[Zr(␩⁵-C₅H₄{CHBu^tPh})₂Cl₂] (12)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHPrⁱMe})Cl₂] (21)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHPrⁱPh})Cl₂] (22)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHBu^tMe})Cl₂] (23)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHBu^tPh})Cl₂] (24)

a

At 20 ^◦C, 2 bar monomer pressure, 200 mL toluene, [Al] = 3 × 10⁻²mol L⁻¹, [Zr] = 3 × 10⁻⁵mol L⁻¹, t_Pol= 30 min.

b

In kg Pol (mol Zr h)⁻¹

.

rotamers of the catalyst which act as distinct active centres

[8,30].

The polymer molecular weights are in all the cases much

higher than that obtained for the reference complex and are in

the order of 50,000. Catalyst 23 produced polypropylene with

the highest molecular weight, approximately 100,000.

The polydispersities of the polypropylenes obtained with the

metallocene catalysts are also of a high nature and again can be

explained by different rotamers of the same complex acting as

active centres in the polymerization [8,30].

The isotacticity of the polymers was measured by the pen-

tad method using ¹³C NMR spectroscopy. The [mmmm] pentad

measured for the polypropylene obtained with the catalysts 9–12

and 21–24 were between 20 and 40% and are comparable with

those previously reported for similar unbridged metallocene

complexes [5a,b].

Considering 9–12 as conformationally dynamic systems in

which the two extremes are described when the cyclopen-

tadienyl substituents are eclipsed or orientated in opposite

directions, then the two possible rotamers should produce

either non-selective (atactic) or isoselective coordination of

the monomer (Fig. 2a). The greater steric imposition of the

substituents will make the syn conformation less stable than

the anti conformations and thus make the catalyst more

isoselective. Indeed the phenyl containing complexes 10 and

2.4. Polymerization of propylene

The polymerization of propylene using the zirconocene

derivatives, 9–12 and 21–24, as catalyst (in the case of 9–12 as

the 1:1 rac/meso isomer mixture) with a MAO cocatalyst–metal

catalyst ratio of 3000:1 has been carried out. The polymeriza-

tion experiments were conducted at 0 ^◦C and at an oleﬁn pressure

of 2.5 bar during 60 min. The polymerization was also carried

out with the reference compound [Zr(␩⁵-C₅H₅)₂Cl₂] under the

same experimental conditions. The catalytic activities, poly-

mer molecular weight and distribution values and tacticity are

given in Table 4. Pentad distribution percentages are shown in

Table 5.

The catalytic activities of the complexes 9–12 are higher than

that recorded for the reference compound. Lower activities were

observed for the phenyl substituted compounds (10, 12, 22 and

24) in comparison with their methyl substituted analogues (9,

11, 21 and 23). The cp^ꢀ₂system (9–12) catalysts gave higher

activities (approximately double) compared with the ind–cp^ꢀ

metallocene system catalysts (21–24).

Table 4

Propylene polymerization results for 9–12, 21–24 and [Zr(␩⁵-C₅H₅)₂Cl₂]^a

Catalyst

Activity^b

M_w

2,000

M_w/M_n

[mmmm] (%)

[Zr(␩⁵-C₅H₅)₂Cl₂]

121

211

162

264

132

111

67

1.8

7.4

10.1

7.0

9.2

7.3

12.9

4.9

9.1

4.0

20.4

36.5

20.6

37.4

19.3

40.7

16.7

28.1

[Zr(␩⁵-C₅H₄{CHPrⁱMe})₂Cl₂] (9)

49,000

45,000

55,000

51,000

66,000

52,000

102,000

26,000

[Zr(␩⁵-C₅H₄{CHPrⁱPh})₂Cl₂] (10)

[Zr(␩⁵-C₅H₄{CHBu^tMe})₂Cl₂] (11)

[Zr(␩⁵-C₅H₄{CHBu^tPh})₂Cl₂] (12)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHPrⁱMe})Cl₂] (21)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHPrⁱPh})Cl₂] (22)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHBu^tMe})Cl₂] (23)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHBu^tPh})Cl₂] (24)

102

97

a

At 0 ^◦C, 2.5 bar monomer pressure, 200 mL toluene, [Al] = 9 × 10⁻²mol L⁻¹, [Zr] = 3 × 10⁻⁵mol L⁻¹, t_Pol= 60 min.

In kg Pol (mol Zr h)⁻¹

.

b

270

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

Table 5

1

Pentad distribution, calculated from ¹³C{ H} NMR spectroscopy, for polypropylene synthesized from 9–12 and 21–24

Catalyst

[mmmm]

(%)

[mmmr]

(%)

[rmmr]

(%)

[mmrr]

(%)

[mmrm] +

[rmrr] (%)

[mrmr]

(%)

[rrrr]

(%)

[mrrr]

(%)

[mrrm]

(%)

[Zr(␩⁵-C₅H₄{CHPrⁱMe})₂Cl₂] (9)

20.4

36.5

20.6

37.4

19.3

40.7

16.7

28.1

16.5

15.8

16.8

15.5

17.1

15.4

15.8

17.5

5.8

3.7

5.5

3.9

5.3

3.5

5.5

4.3

10.7

11.4

11.1

11.3

10.4

10.1

14.2

9.2

18.3

14.1

20.2

13.8

20.7

13.2

18.4

18.3

12.2

7.4

10.4

7.3

12.0

7.9

10.7

9.4

4.0

2.3

3.6

2.5

3.2

1.2

3.9

2.8

5.6

3.4

4.7

3.3

6.1

2.9

8.1

4.7

6.5

5.4

7.1

5.0

5.9

5.1

6.7

5.7

[Zr(␩⁵-C₅H₄{CHPrⁱPh})₂Cl₂] (10)

[Zr(␩⁵-C₅H₄{CHBu^tMe})₂Cl₂] (11)

[Zr(␩⁵-C₅H₄{CHBu^tPh})₂Cl₂] (12)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHPrⁱMe})Cl₂] (21)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHPrⁱPh})Cl₂] (22)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHBu^tMe})Cl₂] (23)

[Zr(␩⁵-C₉H₇)(␩⁵-C₅H₄{CHBu^tPh})Cl₂] (24)

Fig. 2. Possible conformational dynamics in 9–12.

12 give higher [mmmm] values than the methyl substituted ana-

logues 9 and 11. Analogous behaviour was also observed for

the indenyl–cyclopentadienyl complexes 21–24. Interconver-

sion between the stereoselective anti and the non-stereoselective

syn conformations has previously been proposed, by Waymouth

et al., as a means of generating blocks of atactic and isotac-

tic stereosequences in a single polymer chain [5]. However,

Busico et al. have recently put in doubt this reasoning. They

propose that the isoselective centre does not invert its con-

ﬁguration and the non-stereoselective centre is not the syn

conformation but instead a C₁symmetric species (Fig. 2b)

[31].

3. Conclusions

New zirconocene complexes incorporating chiral alkyl sub-

stituents in different metallocene systems have been prepared

and structurally characterized. The complexes are active as

catalysts in the polymerization of ethylene and propylene. Cat-

alytic activities in the polymerization were shown to be directly

related to the metallocene system and the substituents present

in the zirconocene catalyst. The stereoselective polymerization

of propylene gave polymers with low to moderate isotacticity

which again can be directly related to the cyclopentadienyl sub-

stituent. Conformational dynamics in the unbridged metallocene

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

271

iso-propyl-fulvene (2.50 g, 20.80 mmol). Yield 3.86 g, 91%. ¹H

NMR (400 MHz, d₈-THF): δ 0.73 (3H), 0.88 (3H) (d, CHMe₂)

2.23 (m, 1H, CHMe₂), 3.30 (d, 1H, CHPrⁱPh), 5.55 (2H), 5.61

(2H) (m, C₅H₄), 6.98 (1H), 7.15 (2H), 7.33 (2H) (m, Ph).

complexes allows the interconversion between stereoselective

and non-stereoselective rotamers thus forming stereoblocks of

isotactic and atactic polypropylene. The rate of this conversion

and the stability of the respective rotamers depend directly on

the steric impositions of the alkyl substituent, which translates

in higher tacticities being obtained for the bulkier substituents.

The work presented in this paper should allow the rational

election of substituents in unbridged zirconocene complexes to

permit, in the polymerization of oleﬁns, an increase in catalytic

activity and/or modulate stereoselectivity.

1

¹³C{ H} NMR (100 MHz, d₈-THF): δ 22.8, 22.9, 35.7 (Prⁱ),

57.6 (CpC), 102.1, 102.9, 123.9 (C₅H₄), 125.0, 128.3, 128.8,

150.9 (Ph). Anal. Calc. for C₁₅H₁₇Li: C, 88.21; H, 8.39. Found

C, 88.10; H, 8.33%.

4.2.3. Li{C₅H₄(CHBu^tMe)} (3)

The synthesis of 3 was carried out in an identical manner

to 1. LiMe (1.6 M in Et₂O) (11.6 mL, 18.63 mmol) and 6-tert-

butyl-fulvene (2.50 g, 18.63 mmol). Yield 2.79 g, 96%. ¹H NMR

(400 MHz, d₈-THF): δ 0.94 (s, 9H, Bu^t), 1.28 (d, 3H, Me), 2.53

4. Experimental

4.1. General procedures

(q, 1H, CHBu^tMe), 5.59 (2H), 5.60 (2H) (m, C₅H₄). ¹³C{ H}

1

All reactions were performed using standard Schlenk tube

techniques in an atmosphere of dry nitrogen. Solvents were dis-

tilled from the appropriate drying agents and degassed before

use.

NMR (100 MHz, d₈-THF): δ 18.6 (Me), 28.9, 34.8 (Bu^t), 46.3

(CpC), 101.1, 103.6, 123.4 (C₅H₄). Anal. Calc. for C₁₁H₁₇Li:

C, 84.59; H, 10.97. Found C, 84.32; H, 10.96%.

LiBuⁿ(1.6 M in hexane), LiMe (1.6 M in Et₂O), MAO,

indene, SiMe₃Cl, and ZrCl₄, were purchased from Aldrich

4.2.4. Li{C₅H₄(CHBu^tPh)} (4)

The synthesis of 4 was carried out in an identical manner

n

2

and used directly. LiPh (2.0 M in Bu O) was purchased

from Acros Organics and used without further puriﬁcation.

6-iso-Propyl-fulvene [32], 6-tert-butyl-fulvene [32], Li(C₉H₇)

[33] and [Zr(␩⁵-C₅H₅)Cl₃] [34] were prepared as previously

reported.

n

2

to 1. LiPh (2.0 M in Bu O) (9.3 mL, 18.63 mmol) and 6-tert-

butyl-fulvene (2.50 g, 18.63 mmol). Yield 3.62 g, 90%. ¹H NMR

(400 MHz, d₈-THF): δ 0.87 (s, 9H, Bu^t), 3.58 (s, 1H, CHBu^tPh),

5.53 (2H), 5.69 (2H) (m, C₅H₄), 6.98 (1H), 7.10 (2H), 7.43 (2H)

1

(m, Ph). ¹³C{ H} NMR (100 MHz, d₈-THF): δ 29.8, 36.1 (Bu^t),

1

¹H and ¹³C{ H} NMR spectra were recorded on a Varian

60.9 (CpC), 101.9, 105.1, 121.0 (C₅H₄), 125.1, 127.6, 130.8,

148.6 (Ph). Anal. Calc. for C₁₆H₁₉Li: C, 88.05; H, 8.77. Found

C, 87.88; H, 8.67%.

Mercury FT-400 spectrometer and referenced to the resid-

ual deuterated solvent. Microanalyses were carried out with a

Perkin-Elmer 2400 or LECO CHNS-932 microanalyzer. Mass

spectroscopic analyses were preformed on a Hewlett-Packard

5988A (m/z 50–1000) instrument. Polymer molecular weights

anddistributionsweredeterminedbyGPC(Waters150CPlus)in

1,2,4-trichlorobenzene at 145 ^◦C. Polymer isotacticity was cal-

culated from ¹³C NMR spectra of polymer samples dissolved in

1,2,4-trichlorobenzene and C₆D₆(1:1).

4.2.5. [Zr(η⁵-C₅H₅)(η⁵-C₅H₄{CHPrⁱMe})Cl₂] (5)

Li{C₅H₄(CHPrⁱMe)} (1) (1.00 g, 7.03 mmol) in THF

(50 mL) was added dropwise during 15 min to a solution of

[Zr(␩⁵-C₅H₅)Cl₃] (1.89 g, 7.03 mmol) in THF (50 mL) at 0 ^◦C.

The reaction mixture was allowed to warm to room temperature

and stirred for 2 h. Solvent was removed in vacuo and hexane

(125 mL) added to the resulting solid. The mixture was ﬁltered

and the ﬁltrate concentrated (20 mL) and cooled to −30 ^◦C to

give crystals of the title complex. Yield 0.82 g, 32%. ¹H NMR

(400 MHz, CDCl₃): δ 0.75 (3H), 0.87 (3H) (d, CHMe₂), 1.15

(d, 3H, Me), 1.86 (m, 1H, CHMe₂), 2.96 (m, 1H, CHPrⁱMe),

6.13 (1H), 6.20 (1H), 6.35 (1H), 6.50 (1H) (m, C₅H₄), 5.87 (s,

4.2. Preparation of compounds

4.2.1. Li{C₅H₄(CHPrⁱMe)} (1)

LiMe (1.6 M in Et₂O) (13.0 mL, 20.80 mmol) was added

dropwise to a solution of 6-iso-propyl-fulvene (2.50 g,

20.80 mmol) in Et₂O (50 mL) at −78 ^◦C. The reaction mixture

was allowed to warm to room temperature and stirred for 6 h.

Solvent was removed in vacuo to give a white solid which was

washed with hexane (2× 50 mL) and dried under vacuum to

yield a free ﬂowing white solid of the title complex (2.78 g,

1

5H, C₅H₅). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 14.0 (Me),

18.3, 20.0, 34.5 (Prⁱ), 39.7 (CpC), 107.7, 115.1, 115.7, 117.3,

140.1 (C₅H₄), 115.5 (C₅H₅). MS electron impact (m/e (% rel-

ative intensity)): 360 (2) [M⁺], 317 (19) [M⁺− Prⁱ], 283 (100)

[M⁺− Prⁱ–Cl], 225 (55) [M⁺− C₅H₄CHPrⁱMe]. Anal. Calc. for

C₁₅H₂₀Cl₂Zr: C, 49.71; H, 5.56. Found C, 49.33; H, 5.51%.

1

94%). H NMR (400 MHz, d₈-THF): δ 1.00 (3H), 1.01 (3H)

(d, CHMe₂), 1.33 (d, 3H, Me), 1.90 (m, 1H, CHMe₂), 2.67 (m,

1

1H, CHPrⁱMe), 5.74 (2H), 5.78 (2H) (m, C₅H₄). ¹³C{ H} NMR

(100 MHz, d₈-THF): δ 19.9 (CMe), 20.7, 21.5, 36.3 (Prⁱ), 42.0

(CpC), 101.7, 102.4, 124.8 (C₅H₄). Anal. Calc. for C₁₀H₁₅Li:

C, 84.48; H, 10.63. Found C, 84.01; H, 10.60%.

4.2.6. [Zr(η⁵-C₅H₅)(η⁵-C₅H₄{CHPrⁱPh})Cl₂] (6)

The synthesis of 6 was carried out in an identical manner

to 5. Li{C₅H₄(CHPrⁱPh)} (2) (1.00 g, 4.89 mmol), and [Zr(␩⁵-

1

C₅H₅)Cl₃] (1.27 g, 4.89 mmol). Yield 0.77 g, 37%. H NMR

4.2.2. Li{C₅H₄(CHPrⁱPh)} (2)

(400 MHz, CDCl₃): δ 0.81 (3H), 0.95 (3H) (d, CHMe₂), 2.19

(m, 1H, CHMe₂), 3.75 (d, 1H, CHPrⁱPh), 6.01 (1H), 6.20 (1H),

6.56 (1H), 6.78 (1H) (m, C₅H₄), 6.00 (s, 5H, C₅H₅), 7.32

The synthesis of 2 was carried out in an identical manner

n

2

to 1. LiPh (2.0 M in Bu O) (10.4 mL, 20.80 mmol) and 6-

272

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

1

(2H), 7.35 (2H), 7.42 (1H) (m, Ph). ¹³C{ H} NMR (100 MHz,

CDCl₃):δ21.3, 22.4, 35.0(Prⁱ), 54.1(CpC), 106.5, 112.5, 120.0,

124.0, 141.7 (C₅H₄), 116.1 (C₅H₅), 127.2, 128.5, 130.1, 135.8

(Ph). MS electron impact (m/e (% relative intensity)): 422 (1)

[M⁺], 380 (39) [M⁺− Prⁱ], 357 (70) [M⁺− C₅H₅], 344 (52)

[M⁺− Prⁱ–Cl], 225 (100) [M⁺− C₅H₄CHPrⁱPh]. Anal. Calc. for

C₂₀H₂₂Cl₂Zr: C, 56.59; H, 5.22. Found C, 56.55; H, 5.20%.

(1.00 g, 4.90 mmol). Yield 0.91 g, 67%. H NMR (400 MHz,

CDCl₃; two isomers): δ 0.75 (6H), 0.77 (6H), 0.89 (6H), 0.91

(6H) (d, CHMe₂), 2.14 (2H), 2.29 (2H) (m, CHMe₂), 3.73 (2H),

3.88 (2H) (m, CHPrⁱPh), 4.64 (2H), 5.59 (2H), 5.88 (4H), 6.26

(2H), 6.28 (2H), 6.32 (2H), 6.37 (2H) (m, C₅H₄), 7.15 (4H), 7.29

(8H), 7.33 (8H) (m, Ph). ¹³C{ H} NMR (100 MHz, CDCl₃;

1

two isomers): δ 19.7, 20.9, 22.0, 22.1, 33.2, 34.6 (Prⁱ), 52.7,

53.5 (CpC), 106.3, 108.8, 111.9, 115.7, 116.6, 117.9, 119.2,

123.1, 135.9, 136.1 (C₅H₄), 126.4, 126.6, 127.7, 127.9, 129.8,

129.9, 140.9, 141.3 (Ph). MS electron impact (m/e (% rela-

tive intensity)): 556 (2) [M⁺], 519 (4) [M⁺− Cl], 357 (100)

[M⁺− C₅H₄CHPrⁱPh]. Anal. Calc. for C₃₀H₃₄Cl₂Zr: C, 64.72;

H, 6.16. Found C, 64.99; H, 6.17%.

4.2.7. [Zr(η⁵-C₅H₅)(η⁵-C₅H₄{CHBu^tMe})Cl₂] (7)

The synthesis of 7 was carried out in an identical manner to

5. Li{C₅H₄(CHBu^tMe)} (3) (1.00 g, 6.40 mmol), and [Zr(␩⁵-

1

C₅H₅)Cl₃] (1.68 g, 6.40 mmol). Yield 0.83 g, 35%. H NMR

(400 MHz, CDCl₃): δ 0.85 (s, 9H, Bu^t), 1.18 (d, 3H, Me), 2.74 (q,

1H, CHBu^tMe), 6.10 (1H), 6.15 (1H), 6.40 (1H), 6.55 (1H) (m,

C₅H₄), 6.48 (s, 5H, C₅H₅). ¹³C{ H} NMR (100 MHz, CDCl₃):

1

4.2.11. [Zr(η⁵-C₅H₄{CHBu^tMe})₂Cl₂] (11)

δ 15.0 (Me), 27.9, 34.2 (Bu^t), 44.5 (CpC), 106.4, 114.8, 116.4,

118.3, 138.9 (C₅H₄), 115.6 (C₅H₅). MS electron impact (m/e

(% relative intensity)): 374 (3) [M⁺], 317 (16) [M⁺− Bu^t], 282

(100) [M⁺− Bu^t–Cl], 225 (32) [M⁺− C₅H₄CHBu^tMe]. Anal.

Calc. for C₁₆H₂₂Cl₂Zr: C, 51.04; H, 5.89. Found C, 50.92; H,

5.87%.

The preparation of 11 was carried out in an identical manner

to 5. ZrCl₄(0.75 g, 3.20 mmol) and Li{C₅H₄(CHBu^tMe)} (3)

1

(1.00 g, 6.40 mmol). Yield 1.06 g, 72%. H NMR (400 MHz,

CDCl₃; two isomers): δ 0.84 (18H), 0.85 (18H) (s, Bu^t), 1.19

(6H), 1.21 (6H) (d, CMe), 2.73 (2H), 2.76 (2H) (q, CHBu^tMe),

6.00 (4H), 6.02 (4H), 6.37 (2H), 6.45 (4H), 6.54 (2H) (m, C₅H₄).

¹³C{ H} NMR (100 MHz, CDCl₃; two isomers): δ 14.9, 15.0

1

(CMe), 27.8, 27.9, 34.2, 34.3 (Bu^t), 44.4, 44.5 (CpC), 105.4,

106.7, 115.6, 115.9, 116.1, 116.2, 117.4, 118.3, 137.7, 139.0

(C₅H₄). MS electron impact (m/e (% relative intensity)): 460

(2) [M⁺], 401 (14) [M⁺− Bu^t], 365 (89) [M⁺− Bu^t, −Cl]. Anal.

Calc. for C₂₂H₃₄Cl₂Zr: C, 57.36; H, 7.44. Found C, 57.55; H,

7.38%.

4.2.8. [Zr(η⁵-C₅H₅)(η⁵-C₅H₄{CHBu^tPh})Cl₂] (8)

The synthesis of 8 was carried out in an identical man-

ner to 5. Li{C₅H₄(CHBu^tPh)} (4) (1.00 g, 4.58 mmol), and

[Zr(␩⁵-C₅H₅)Cl₃] (1.20 g, 4.58 mmol). Yield 0.66 g, 33%. H

1

NMR (400 MHz, CDCl₃): δ 0.96 (s, 9H, Bu^t), 3.88 (s, 1H,

CHBu^tPh), 5.87 (s, 5H, C₅H₅), 6.02 (1H), 6.52 (1H), 6.55

(1H), 6.87 (1H) (m, C₅H₄), 7.32 (2H), 7.37 (1H), 7.41 (2H)

(m, Ph). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 29.2, 36.2 (Bu^t),

1

4.2.12. [Zr(η⁵-C₅H₄{CHBu^tPh})₂Cl₂] (12)

58.0 (CpC), 105.4, 112.4, 120.1, 120.2, 141.0 (C₅H₄), 115.9

(C₅H₅), 126.1, 126.9, 128.1, 132.9 (Ph). MS electron impact

(m/e (% relative intensity)): 436 (3) [M⁺], 379 (12) [M⁺− Bu^t],

371 (31) [M⁺− C₅H₅], 344 (49) [M⁺− Bu^t–Cl], 225 (100)

[M⁺− C₅H₄CHBu^tPh]. Anal. Calc. for C₂₁H₂₄Cl₂Zr: C, 57.51;

H, 5.52. Found C, 57.09; H, 5.49%.

The preparation of 12 was carried out in an identical manner

to 5. ZrCl₄(0.53 g, 2.29 mmol) and Li{C₅H₄(CHBu^tPh)} (4)

1

(1.00 g, 4.58 mmol). Yield 0.95 g, 71%. H NMR (400 MHz,

CDCl₃; two isomers): δ 0.86 (18H), 0.87 (18H) (s, Bu^t), 3.77

(2H), 3.81 (2H) (s, CHBu^tPh), 3.98 (2H), 5.21 (2H), 5.89

(2H), 6.11 (2H), 6.19 (2H), 6.28 (2H), 6.30 (2H), 6.36 (2H)

(m, C₅H₄), 7.21 (4H), 7.23 (8H), 7.29 (8H) (m, Ph). ¹³C{ H}

1

4.2.9. [Zr(η⁵-C₅H₄{CHPrⁱMe})₂Cl₂] (9)

NMR (100 MHz, CDCl₃; two isomers): δ 29.3, 29.4, 36.4, 36.5

(Bu^t), 58.1, 58.2 (CpC), 105.8, 105.9, 108.4, 108.5, 111.8, 111.9,

118.0, 118.9, 132.5, 134.0 (C₅H₄), 119.2, 120.1, 126.5, 126.9,

127.1, 128.1, 141.3, 141.6 (Ph). MS electron impact (m/e (%

relative intensity)): 582 (1) [M⁺], 527 (7) [M⁺− Bu^t], 371 (60)

[M⁺− C₅H₄CHBu^tPh]. Anal. Calc. for C₃₂H₃₈Cl₂Zr: C, 65.72;

H, 6.55. Found C, 65.24; H, 6.50%.

The preparation of 9 was carried out in an identical manner

to 5. ZrCl₄(0.81 g, 3.51 mmol) and Li{C₅H₄(CHPrⁱMe)} (1)

1

(1.00 g, 7.02 mmol). Yield 1.05 g, 69%. H NMR (400 MHz,

CDCl₃; two isomers): δ 0.73 (6H), 0.75 (6H), 0.87 (6H), 0.89

(6H) (d, CHMe₂), 1.15 (6H), 1.17 (6H) (d, CMe), 1.87 (2H), 1.88

(2H) (m, CHMe₂), 2.96 (2H), 2.97 (2H) (m, CHPrⁱMe), 6.09

(4H), 6.14 (4H), 6.32 (2H), 6.36 (2H), 6.45 (2H), 6.50 (2H) (m,

C₅H₄). ¹³C{ H} NMR (100 MHz, CDCl₃; two isomers): δ 13.8,

1

4.2.13. C₅H₄(CHPrⁱMe)(SiMe₃) (13)

13.9 (CMe), 18.2, 18.3, 20.0, 20.1, 34.5, 34.6 (Prⁱ), 39.6, 39.7

(CpC), 107.1, 107.8, 114.5, 114.7, 115.5, 115.8, 116.4, 116.5,

139.5, 139.9 (C₅H₄). MS electron impact (m/e (% relative inten-

sity)): 432 (4) [M⁺], 394 (40) [M⁺− Cl], 351 (100) [M⁺− Cl,

−Prⁱ]. Anal. Calc. for C₂₀H₃₀Cl₂Zr: C, 55.53; H, 6.99. Found

C, 55.10; H, 7.06%.

SiMe₃Cl (2.28 g, 14.06 mmol) in THF (10 L) was added to

a solution of Li{C₅H₄(CHPrⁱMe)} (1) (2.00 g, 14.06 mmol) in

THF (50 mL) at −78 ^◦C. The reaction mixture was allowed

to warm to room temperature and stirred for 15 h. Solvent

was removed in vacuo and hexane (150 mL) was added to the

resulting dark yellow oil. The mixture was ﬁltered and solvent

removed from the ﬁltrate under reduced pressure to yield the

title compound as dark yellow oil. Yield 2.66 g, 91%. ¹H NMR

(400 MHz, CDCl₃; for the predominant isomer): δ 0.04 (s, 9H,

SiMe₃), 0.93 (d, 6H, CHMe₂), 1.17 (d, 3H, Me), 1.81 (m, 1H,

4.2.10. [Zr(η⁵-C₅H₄{CHPrⁱPh})₂Cl₂] (10)

The preparation of 10 was carried out in an identical manner

to 5. ZrCl₄(0.57 g, 2.45 mmol) and Li{C₅H₄(CHPrⁱPh)} (2)

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

273

CHMe₂), 2.46 (m, 1H, CHPrⁱMe), 3.27 (1H), 6.10 (1H), 6.47

(1H), 6.54 (1H) (m, C₅H₄). MS electron impact (m/e (% rel-

ative intensity)): 208 (24) [M⁺], 137 (100) [M⁺− CHPrⁱMe],

135 (44) [M⁺− SiMe₃]. Anal. Calc. for C₁₃H₂₄Si: C, 74.92; H,

11.61. Found C, 74.65; H, 11.88%.

142.3 (C₅H₄). Anal. Calc. for C₁₀H₁₅Cl₃Zr: C, 36.09; H, 4.54.

Found C, 35.92; H, 4.49%.

4.2.18. [Zr(η⁵-C₅H₄{CHPrⁱPh})Cl₃] (18)

The synthesis of 18 was carried out in an identical manner to

17. C₅H₄(CHPrⁱPh)(SiMe₃) (14) (1.50 g, 5.54 mmol) and ZrCl₄

1

(1.29 g, 5.54 mmol). Yield 1.07 g, 49%. H NMR (400 MHz,

4.2.14. C₅H₄(CHPrⁱPh)(SiMe₃) (14)

CDCl₃): δ 0.80 (3H), 0.91 (3H) (d, CHMe₂), 2.79 (m, 1H,

CHMe₂), 4.55 (d, 1H, CHPrⁱPh), 5.93 (1H), 6.37 (1H), 6.51

(1H), 6.62 (1H) (m, C₅H₄), 7.05 (2H), 7.14 (2H), 7.25 (1H)

The synthesis of 14 was carried out in an identical manner to

13. SiMe₃Cl (1.06 g, 9.79 mmol) and Li{C₅H₄(CHPrⁱPh)} (2)

1

(2.00 g, 9.79 mmol). Yield 2.51 g, 95%. H NMR (400 MHz,

1

(m, Ph). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 13.6, 18.4, 20.8

CDCl₃; for the predominant isomer): δ −0.08 (s, 9H, SiMe₃),

1.05 (d, 6H, CHMe₂), 2.38 (m, 1H, CHMe₂), 3.40 (m, 1H,

CHPrⁱPh), 3.26 (1H), 6.24 (1H), 6.45 (1H), 6.57 (1H) (m, C₅H₄),

7.18(1H), 7.26(2H), 7.30(2H)(m, Ph). MSelectronimpact(m/e

(% relative intensity)): 270 (12%) [M⁺], 197 (69) [M⁺− SiMe₃],

137 (100) [M⁺− CHPrⁱPh]. Anal. Calc. for C₁₈H₂₆Si: C, 79.93;

H, 9.69. Found C, 79.34; H, 9.58%.

(Prⁱ), 40.6 (CpC), 116.5, 117.3, 117.7, 121.0, 140.2 (C₅H₄),

126.2, 127.4, 128.3, 133.4 (Ph). Anal. Calc. for C₁₅H₁₇Cl₃Zr:

C, 45.62; H, 4.34. Found C, 45.29; H, 4.27%.

4.2.19. [Zr(η⁵-C₅H₄{CHBu^tMe})Cl₃] (19)

The synthesis of 19 was carried out in an identical man-

ner to 17. C₅H₄(CHBu^tMe)(SiMe₃) (15) (1.50 g, 6.74 mmol)

1

and ZrCl₄(1.57 g, 6.74 mmol). Yield 0.98 g, 42%. H NMR

4.2.15. C₅H₄(CHBu^tMe)(SiMe₃) (15)

(400 MHz, CDCl₃): δ 0.85 (s, 9H, Bu^t), 1.30 (d, 3H, Me), 2.96

(q, 1H, CHBu^tMe), 5.95 (1H), 6.27 (1H), 6.36 (1H), 6.56 (1H)

The synthesis of 15 was carried out in an identical manner to

13. SiMe₃Cl (1.39 g, 12.80 mmol) and Li{C₅H₄(CHBu^tMe)}

(3) (2.00 g, 12.80 mmol). Yield 2.67 g, 94%. ¹H NMR

(400 MHz, CDCl₃; for the predominant isomer): δ 0.02 (s, 9H,

SiMe₃), 0.91 (s, 9H, Bu^t), 1.15 (d, 3H, Me), 2.47 (m, 1H,

CHBu^tMe), 3.23 (1H), 6.07 (1H), 6.40 (1H), 6.50 (1H) (m,

C₅H₄). MS electron impact (m/e (% relative intensity)): 222

(38)[M⁺], 149(42)[M⁺− SiMe₃], 137(100)[M⁺− CHBu^tMe].

Anal. Calc. for C₁₄H₂₆Si: C, 75.59; H, 11.78. Found C, 75.19;

H, 11.78%.

1

(m, C₅H₄). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 14.0 (Me),

28.1, 34.3 (Bu^t), 44.7 (CpC), 116.3, 116.8, 117.3, 122.8, 141.1

(C₅H₄). Anal. Calc. for C₁₁H₁₇Cl₃Zr: C, 38.09; H, 4.94. Found

C, 37.72; H, 4.88%.

4.2.20. [Zr(η⁵-C₅H₄{CHBu^tPh})Cl₃] (20)

The synthesis of 20 was carried out in an identical man-

ner to 17. C₅H₄(CHBu^tPh)(SiMe₃) (16) (1.50 g, 5.27 mmol)

1

and ZrCl₄(1.22 g, 5.27 mmol). Yield 0.84 g, 39%. H NMR

(400 MHz, CDCl₃): δ 1.00 (s, 9H, Bu^t), 4.08 (s, 1H, CHBu^tPh),

5.99 (1H), 6.29 (1H), 6.33 (1H), 6.54 (1H) (m, C₅H₄), 7.09

4.2.16. C₅H₄(CHBu^tPh)(SiMe₃) (16)

1

(2H), 7.17 (1H), 7.28 (2H) (m, Ph). ¹³C{ H} NMR (100 MHz,

The synthesis of 16 was carried out in an identical manner

to 13. SiMe₃Cl (1.00 g, 9.16 mmol) and Li{C₅H₄(CHBu^tPh)}

(4) (2.00 g, 9.16 mmol). Yield 2.55 g, 98%. ¹H NMR (400 MHz,

CDCl₃; for the predominant isomer): δ 0.01 (s, 9H, SiMe₃), 1.03

(s, 9H, Bu^t), 3.67 (m, 1H, CHBu^tPh), 3.23 (1H), 6.32 (1H), 6.42

(1H), 6.69 (1H) (m, C₅H₄), 7.18 (1H), 7.25 (2H), 7.32 (2H)

(m, Ph). MS electron impact (m/e (% relative intensity)): 284

(78)[M⁺], 211(37)[M⁺− SiMe₃], 137(1 0 0)[M⁺− CHBu^tPh].

Anal. Calc. for C₁₉H₂₈Si: C, 80.21; H, 9.92. Found C, 79.99; H,

9.78%.

CDCl₃): δ 27.6, 33.7 (Bu^t), 42.9 (CpC), 115.4, 116.9, 117.2,

123.1, 143.4 (C₅H₄), 125.9, 127.1, 128.2, 134.0 (Ph). Anal.

Calc. for C₁₆H₁₉Cl₃Zr: C, 47.00; H, 4.68. Found C, 46.75; H,

4.65%.

4.2.21. [Zr(η⁵-C₉H₇)(η⁵-C₅H₄{CHPrⁱMe})Cl₂] (21)

The synthesis of 21 was carried out in an identical

manner to 5. Li(C₉H₇) (0.18 g, 1.50 mmol) and [Zr(␩⁵-

C₅H₄{CHPrⁱMe})Cl₃] (17) (0.50 g, 1.50 mmol). Yield 0.23 g,

38%. ¹H NMR (400 MHz, CDCl₃): δ 0.70 (3H), 0.83 (3H) (d,

CHMe₂), 1.07 (d, 3H, Me), 1.79 (m, 1H, CHMe₂), 2.89 (m,

1H, CHPrⁱMe), 5.46 (1H), 5.96 (1H), 6.02 (1H), 6.28 (1H)

(m, C₅H₄), 6.53 (2H), 6.94 (1H), 7.30 (2H), 7.69 (2H) (m,

4.2.17. [Zr(η⁵-C₅H₄{CHPrⁱMe})Cl₃] (17)

A

solution of C₅H₄(CHPrⁱMe)(SiMe₃) (13) (1.50 g,

7.20 mmol) in toluene (25 mL) was added dropwise to a suspen-

sion of ZrCl₄(1.67 g, 7.20 mmol) in toluene (15 mL) at 0 ^◦C.

The reaction mixture was allowed to warm to room tempera-

ture and stirred for 6 h and subsequently heated to 80 ^◦C and the

reaction continued for an additional hour. Solvent was removed

in vacuo to give a red solid which was washed with hexane (2×

50 mL), dried under vacuum and recrystallized in toluene. Yield

1

C₉H₇). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 13.9 (Me), 18.3,

20.0, 34.4 (Prⁱ), 39.9 (CpC), 102.3, 109.8, 115.5, 123.9, 140.5

(C₅H₄), 103.0, 117.6, 125.3, 126.0, 126.4 (C₉H₇). MS elec-

tron impact (m/e (% relative intensity)): 410 (2) [M⁺], 295

(100) [M⁺− C₉H₇], 275 (43) [M⁺− C₅H₄CHPrⁱMe], 252 (29)

[M⁺− C₉H₇–Prⁱ]. Anal. Calc. for C₁₉H₂₂Cl₂Zr: C, 55.32; H,

5.38. Found C, 54.93; H, 5.30%.

1

1.03 g, 43%. H NMR (400 MHz, CDCl₃): δ 0.72 (3H), 0.90

(3H) (d, CHMe₂), 1.32 (d, 3H, Me), 1.96 (m, 1H, CHMe₂), 3.23

(m, 1H, CHPrⁱMe), 6.11 (1H), 6.34 (1H), 6.37 (1H), 6.47 (1H)

4.2.22. [Zr(η⁵-C₉H₇)(η⁵-C₅H₄{CHPrⁱPh})Cl₂] (22)

The synthesis of 22 was carried out in an identical

manner to 5. Li(C₉H₇) (0.15 g, 1.27 mmol) and [Zr(␩⁵-

1

(m, C₅H₄). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 13.3 (Me),

18.4, 20.7, 35.2 (Prⁱ), 40.2 (CpC), 116.9, 117.4, 117.9, 121.4,

274

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

and washed with ethanol and dried under vacuum at 90 ^◦C for

16 h.

C₅H₄{CHPrⁱPh})Cl₃] (18) (0.50 g, 1.27 mmol). Yield 0.17 g,

29%. ¹H NMR (400 MHz, CDCl₃): δ 0.79 (3H), 0.92 (3H) (d,

CHMe₂), 2.18 (m, 1H, CHMe₂), 3.76 (d, 1H, CHPrⁱPh), 5.19

(1H), 5.51 (1H), 6.06 (1H), 6.36 (1H) (m, C₅H₄), 6.38 (2H), 6.43

(1H), 7.37 (2H), 7.53 (2H) (m, C₉H₇), 7.21 (2H), 7.27 (2H), 7.38

4.3.2. Polymerization of propylene

The zirconocene catalyst (15 ␮mol), MAO (10% in toluene)

(45,000 ␮mol) and toluene (200 mL) were mixed together for

15 min in a 1 L glass autoclave. The N₂pressure inside the auto-

clave was reduced by applying vacuum. Propylene pressure of

2.5 bar was then applied and maintained to the autoclave and

stirring of the mixture commenced (1000 rpm). After exactly

60 min, stirring was halted and the propylene pressure released.

Excess MAO was then destroyed by cautiously adding a mix-

ture of methanol/HCl (90:10). Solvent was then removed under

reduced pressure and a mixture of acetone/methanol (50:50)

(200 mL) added. The mixture was stirred for 16 h and then ﬁl-

tered to isolate the polymer which was washed with ethanol and

dried under vacuum at 25 ^◦C for 16 h.

1

(1H) (m, Ph). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 21.8, 22.5,

34.7(Prⁱ), 53.7 (CpC), 102.6, 109.3, 114.9, 123.2, 141.0 (C₅H₄),

102.8, 116.9, 124.9, 126.1, 126.5 (C₉H₇), 127.4, 128.7, 130.4,

136.2 (Ph). MS electron impact (m/e (% relative intensity)): 472

(4) [M⁺], 429 (39) [M⁺− Prⁱ], 357 (100) [M⁺− C₉H₇], 275 (43)

[M⁺− C₅H₄CHPrⁱPh]. Anal. Calc. for C₂₄H₂₄Cl₂Zr: C, 60.74;

H, 5.10. Found C, 60.21; H, 5.00%.

4.2.23. [Zr(η⁵-C₉H₇)(η⁵-C₅H₄{CHBu^tMe})Cl₂] (23)

The synthesis of 23 was carried out in an identical

manner to 5. Li(C₉H₇) (0.18 g, 1.44 mmol) and [Zr(␩⁵-

C₅H₄{CHBu^tMe})Cl₃] (19) (0.50 g, 1.44 mmol). Yield 0.27 g,

44%. ¹H NMR (400 MHz, CDCl₃): δ 0.81 (s, 9H, Bu^t), 1.13 (d,

3H, Me), 2.69 (q, 1H, CHBu^tMe), 5.29 (1H), 5.95 (1H), 6.12

(1H), 6.18 (1H) (m, C₅H₄), 6.53 (2H), 6.94 (1H), 7.30 (2H),

4.4. X-ray data collection

4.4.1. [Zr(η⁵-C₅H₄{CHBu^tMe})₂Cl₂] (11)

1

7.70 (2H) (m, C₉H₇). ¹³C{ H} NMR (100 MHz, CDCl₃): δ 14.9

(Me), 27.8, 34.1 (Bu^t), 44.4 (CpC), 102.5, 108.6, 115.7, 116.9,

139.6 (C₅H₄), 103.8, 118.2, 123.3, 125.3, 126.0 (C₉H₇). MS

electron impact (m/e (% relative intensity)): 424 (6) [M⁺], 409

(5) [M⁺− Me], 367 (18) [M⁺− Bu^t], 309 (15) [M⁺− C₉H₇],

275 (100) [M⁺− C₅H₄CHBu^tMe], 252 (28) [M⁺− C₉H₇–Bu^t].

Anal. Calc. for C₂₀H₂₄Cl₂Zr: C, 56.32; H, 5.67. Found C, 55.99;

H, 5.52%.

Data were collected on a Bruker X8 APPEX II CCD-based

diffractometer, equipped with a graphite monochromated Mo

˚

K␣ radiation source (λ = 0.71073 A). The crystal data, data

collection, structural solution, and reﬁnement parameters are

summarized in Table 6. Data were integrated using SAINT [35]

and an absorption correction was performed with the program

SADABS [36]. Thestructurewassolvedby directmethodsusing

SHELXTL [37], and reﬁned by full-matrix least-squares meth-

ods based on F². All non-hydrogen atoms were reﬁned with

4.2.24. [Zr(η⁵-C₉H₇)(η⁵-C₅H₄{CHBu^tPh})Cl₂] (24)

The synthesis of 24 was carried out in an identical

manner to 5. Li(C₉H₇) (0.15 g, 1.22 mmol) and [Zr(␩⁵-

C₅H₄{CHBu^tPh})Cl₃] (20) (0.50 g, 1.22 mmol). Yield 0.18 g,

Table 6

Crystal data and structure reﬁnement for 11

1

31%. H NMR (400 MHz, CDCl₃): δ 0.96 (s, 9H, Bu^t), 3.89

Formula

fw

C₂₂H₃₄Cl₂Zr

460.61

(s, 1H, CHBu^tPh), 5.03 (1H), 5.22 (1H), 5.88 (1H), 6.43 (1H)

(m, C₅H₄), 6.35 (2H), 6.59 (1H), 7.24 (2H), 7.52 (2H) (m,

T (K)

200(2)

Cryst. syst.

Space group

Monoclinic

P2(1)/n

1

C₉H₇), 7.30 (1H), 7.39 (2H), 7.50 (2H) (m, Ph). ¹³C{ H}

NMR (100 MHz, CDCl₃): δ 29.1, 36.2 (Bu^t), 57.9 (CpC), 100.6,

105.5, 113.2, 123.3, 141.3 (C₅H₄), 107.7, 120.0, 125.5, 125.9,

126.9 (C₉H₇), 125.2, 125.6, 127.5, 132.7 (Ph). MS electron

impact (m/e (% relative intensity)): 486 (1) [M⁺], 371 (100)

[M⁺− C₉H₇], 275 (74) [M⁺− C₅H₄CHBu^tPh]. Anal. Calc. for

C₂₅H₂₆Cl₂Zr: C, 61.45; H, 5.36. Found C, 61.22; H, 5.19%.

˚

a (A)

6.756(1)

˚

b (A)

15.178(3)

˚

c (A)

22.432(4)

94.806(4)

2292.1(8)

β (^◦)

3

˚

V (A )

Z

4

Dc (g cm⁻³

)

1.335

0.716

960

μ (mm⁻¹

F(0 0 0)

)

4.3. Polymerization reactions

Cryst. dimens. (mm)

θ range (^◦)

h k l ranges

0.20 × 0.09 × 0.05

1.62–22.62

−7 ≤ h ≤ 7, −16 ≤ k ≤ 15,

−24 ≤ l ≤ 24

11,610

4.3.1. Polymerization of ethylene

The zirconocene catalyst (6 ␮mol), MAO (10% in toluene)

(6000 ␮mol) and toluene (200 mL) were mixed together for

15 min in a 1 L glass autoclave. The N₂pressure inside the

autoclave was reduced by applying vacuum. Ethylene pressure

of 2 bar was then applied and maintained to the autoclave and

stirring of the mixture commenced (1000 rpm). After exactly

30 min, stirring was halted and the ethylene pressure released.

Excess MAO was then destroyed by cautiously adding a mixture

of methanol/HCl (90:10). The polymer was isolated by ﬁltration

Number of reﬂections measured

Number of reﬂections observed

Goodness-of-ﬁt on F²

2102

1.014

Final R indices [I > 2σ(I)]

R indices (all data)

Largest diff. peak and hole (einstein A

R1 = 0.0426, wR2 = 0.1041

R1 = 0.0708, wR2 = 0.1330

0.341 and −0.339

−3

˚

)

ꢁ

ꢃ

0.5

2

ꢀ

ꢂ

[w(Fo²− Fc²) ]

||Fo| − |Fc||

ꢀ

R₁

=

;

wR₂

=

.

ꢀ

[w(Fo²)²]

|Fo|

D. Polo-Cero´n et al. / Journal of Molecular Catalysis A: Chemical 268 (2007) 264–276

275

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Crystallographic data for the structural analysis of 11 have

been deposited with the Cambridge Crystallographic Data Cen-

tre, CCDC-615356. Copies of this information may be obtained

free of charge from The Director, CCDC, 12 Union Road,

Cambridge CB2 1EZ, UK (fax: +44 1223 336033; e-mail:

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[7] A.I. Licht, K.J. Schneider, H.G. Alt, J. Organomet. Chem. 688 (2003) 254.

[8] Y. Zhang, J. Huang, X. Yang, J. Zhang, Y. Qian, J. Polym. Sci. Part A:

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Villasen˜or, Organometallics 21 (2002) 2460;

We gratefully acknowledge ﬁnancial support from the

´

Ministerio deEducacion y Ciencia, Spain (Grants no. CTQ2005-

07918-C02-02/BQU and MAT2003-05345), the Comunidad de

Madrid (S-0505/PPQ-0328) and the Universidad Rey Juan Car-

los (GVC-2004-12 project and graduate fellowship for D.P-C.).

We would also like to thank Repsol YPF and LATEP (Univer-

sidad Rey Juan Carlos) for their assistance in polymer analysis.

(c) C. Alonso-Moreno, A. Antin˜olo, I. Lo´pez-Solera, A. Otero, S. Prashar,

A.M. Rodr´ıguez, E. Villasen˜or, J. Organomet. Chem. 656 (2002) 129;

(d) A. Antin˜olo, R. Ferna´ndez-Gala´n, I. Orive, A. Otero, S. Prashar, Eur. J.

Inorg. Chem. (2002) 2470;

(e) A. Antin˜olo, R. Ferna´ndez-Gala´n, B. Gallego, A. Otero, S. Prashar,

A.M. Rodr´ıguez, Eur. J. Inorg. Chem. (2003) 2626;

(f) A. Antin˜olo, M. Fajardo, S. Go´mez-Ruiz, I. Lo´pez-Solera, A. Otero, S.

Prashar, A.M. Rodr´ıguez, J. Organomet. Chem. 683 (2003) 11;

(g) A. Antin˜olo, M. Fajardo, S. Go´mez-Ruiz, I. Lo´pez-Solera, A. Otero, S.

Prashar, Organometallics 23 (2004) 4062;

(h) A. Antin˜olo, R. Ferna´ndez-Gala´n, A. Otero, S. Prashar, I. Rivilla, A.M.

Rodr´ıguez, M.A. Maestro, Organometallics 23 (2004) 5108;

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(j) C. Alonso-Moreno, A. Antin˜olo, F. Carrillo-Hermosilla, P. Carrio´n, I.

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Article Doi

Synthesis of chiral unbridged zirconocene complexes: Applications in the polymerization of ethylene and propylene

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