Chiral indenes and group-4 metallocene dichlorides containing α- And β-pinenyl-derived ligand substituants: Synthesis and catalytic applications in polymerization and carboalumination reactions

FULL PAPER

Chiral Indenes and Group-4 Metallocene Dichlorides Containing α- and β-

Pinenyl-Derived Ligand Substituents: Synthesis and Catalytic Applications in

Polymerization and Carboalumination Reactions

Satu Silver,^[a]Arto Puranen,^[b]Rainer Sjöholm,^[a]Timo Repo,^[b]and Reko Leino*^[a]

Keywords: Homogeneous catalysis / Indenyl ligands / Metallocenes / Olefin polymerization / Carboalumination

The synthesis and characterization of chiral bis(indenyl)zir-

conium dichlorides containing β-pinenyl-derived ligand sub-

stituents is reported. Unbridged metallocene complexes

having the {[(1S,2S,5S)-6,6-dimethylbicyclo[3.1.1]hept-2-

yl]methyl}dimethylsilyl substituent in both 1- and 2-positions

of the indenyl moiety were prepared and isolated in moder-

ate to low yields by reaction of the corresponding indenylli-

thium salts with ZrCl₄followed by work-up and crystalli-

zation procedures. The corresponding tetrahydroindenyl

complexes were obtained in excellent yields by catalytic hy-

dehydropolymerization of phenylsilane upon activation with

nBuLi, for polymerization of ethylene and propylene upon

activation with methylaluminoxane (MAO) as well as for en-

antioselective carboalumination of 1-octene with triethyl-

and trimethylaluminum. The bis(indenyl) complexes cata-

lyzed the carboalumination reaction, albeit only low yields

(8–16%) and low enantioselectivities (ee = 0.5–10%) were

obtained. The 2-substituted bis(indenyl)zirconocene/MAO

catalyst system produced atactic low-molecular weight poly-

propylene with low polymerization activity whereas both 1-

drogenation of the indenyl six-membered rings. In a comple- and 2-substituted complexes showed high activities in ethyl-

mentary approach, a synthetic route to α-pinenyl-substituted

indenyl ligand analogues was briefly evaluated, which how-

ever, suffered from low yields. Selected β-pinenyl-substi-

tuted indenyl complexes were scanned as catalysts for the

ene polymerization producing polyethylenes with high mol-

ecular weights (M_wϾ 440000).

Germany, 2005)

work, we report here a detailed study on the utilization of

these new chiral ligand precursors for the preparation of

new chiral group-4 metallocene complexes as well as a brief

evaluation of the chiral metallocenes formed for catalytic

applications in olefin polymerization, dehydropolymeriza-

tion of phenylsilane and enantioselective carboalumination

reactions. As a complementary approach, the low-yield syn-

thesis of some α-pinenyl-substituted ligand analogues is bri-

efly described.

Introduction

Chiral group-4 metallocenes are widely used catalysts or

catalyst precursors for the stereoselective polymerization of

α-olefins,^[1–3]and enantioselective cyclopolymerization of

nonconjugated dienes,^[4,5]and are employed in various en-

antioselective organic transformations^[6,7]including car-

bon–carbon,^[8–13]carbon–hydrogen^[14–18]and carbon–oxy-

gen^[19,20]bond formation. Commonly employed chiral pre-

catalysts are the conformationally constrained racemic

ansa-metallocenes and their resolved single enantiomers,^[21]

but also unbridged bis(indenyl)metallocenes containing chi-

ral substituents^[22–27]have been utilized previously in a

number of applications in stereo- and/or enantioselective

synthesis.

Results and Discussion

Ligand Precursor and Metallocene Synthesis

The chiral zirconocene dichloride 2 was prepared by de-

protonation of the previously described chiral indene 1^[28]

with nBuLi followed by reaction with 0.5 equiv. ZrCl₄in

toluene (Scheme 1). Subsequent work-up and crystalli-

zation from pentane at –20 °C provided pure 2 in 37% iso-

lated yield. Due to the position of the chiral substituent,

the π-faces of the indenyl ligand are equivalent (i.e., homo-

topic) and only one product can be formed upon metall-

ation. Complex 2 was further hydrogenated at 50 bar H₂in

dichloromethane in the presence of PtO₂catalyst to provide

the corresponding chiral tetrahydroindenyl complex 3 in

86% isolated yield. The parent compound 2 is obtained as

In a recent communication, we presented a simple route

to new chirally substituted indenes by reaction of indenylli-

thium or 2-indenylmagnesium bromide with a β-pinenyl-de-

rived chlorosilane.^[28]As a continuation of the previous

[a] Department of Organic Chemistry, Åbo Akademi University,

20500 Åbo, Finland

Fax: +358-2-215-4866

E-mail: reko.leino@abo.fi

[b] Department of Chemistry, Laboratory of Inorganic Chemistry,

University of Helsinki,

P. O. Box 55, 00014 University of Helsinki, Finland

Supporting information for this article is available on the

WWW under http://ww w .eurjic.org or from the author.

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DOI: 10.1002/ejic.200400882

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Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

FULL PAPER

a yellow powder, whereas the hydrogenated congener 3 is a

Thus, when the previously described 1:1 diastereomeric

noncrystalline, pale green oil. Apparently, because of the mixture of the chiral 1-substituted indenes (1R)-4a and

large aliphatic pinenyl substituent, both complexes are re- (1S)-4b^[28]was deprotonated with nBuLi and the resulting

markably soluble in all common organic solvents including chiral indenyl anion lithium salt metallated with 0.5 equiv.

pentane and hexane. Consequently, all our attempts to grow of ZrCl₄(Scheme 2), a mixture of the metallocene com-

single crystals suitable for X-ray structure determination plexes 5a-c was obtained in variable ratios depending on

from either one of the complexes 2 or 3 failed.

the solvent employed in the metallation step, as shown by

¹H NMR analyses of the metallocene crude products

(Table 1, Figure 2). In all solvents investigated (toluene,

Et₂O, THF), the molar ratio between the C₂-symmetric dia-

stereomers (pR)(pR)-5a and (pS)(pS)-5b remained equi-

molar, consistent with their “pseudo-racemic” character.

Formation of the meso-like C₁-symmetric diastereomer

(pR)(pS)-5c was more favored in the coordinating solvents

Et₂O and THF. As observed for the 2-substituted analogue

2, also complexes 5a–c displayed unusually high solubilities

in all common organic solvents rendering their isolation

and purification very difficult. The pure, least soluble C₁-

symmetric diastereomer (pR)(pS)-5c was, however, obtained

in 11% isolated yield as a bright yellow powder from the

reaction carried out in Et₂O after subsequent work-up and

crystallization from dichloromethane at –20 °C. The meso-

like diastereomer (pR)(pS)-5c is easily distinguished from

the C₂-symmetric diastereomers (pR)(pR)-5a and (pS)(pS)-

1

5b by its H and ¹³C NMR spectra where, unlike in the

Scheme 1. Synthesis of the chiral metallocenes 2 and 3. (i) nBuLi,

Et₂O, 0 °C. (ii) ZrCl₄, toluene, 50 °C, 37%. (iii) H₂/50 bar/PtO₂,

CH₂Cl₂, 86%.

cases of 5a and 5b, separate signal sets are observed for

each of the (pR)- and (pS)-indenyl ligands coordinated to

the central metal atom. The corresponding tetrahydroinde-

The change in the position of the chiral substituent from

2- to 1- or 3-indenyl renders the π-faces of the ligand pre-

cursor inequivalent [planar chirality: (pR) vs. (pS)] thus po-

tentially resulting in the formation of three isomeric

metallocene complexes [combinations of (pR)/(pR), (pS)/

(pS) and (pR)/(pS)] upon metallation with group-4 metal

tetrahalides (Figure 1).

Figure 1. Metallocene diastereomers obtained upon metallation of

indenyl ligands with enantiotopic or diastereotopic ligand π-faces

[combinations of (pR)/(pR), (pS)/(pS) (A and B) and (pR)/(pS) (C).

If the 1- or 3-indenyl substituent is achiral (enantiotopic

ligand π-faces), a C₂symmetric racemic pair of two equi-

energetic enantiomers (A and B in Figure 1) is obtained to-

gether with a C_ssymmetric meso form (C). A statistical

1:1:2 ratio of the three isomers is observed in most cases.

When, as in the present case, the 1- or 3-indenyl substituent

is chiral (diastereotopic ligand π-faces), a mixture of three

diastereomers, two C₂symmetric “pseudo-racemic” or “ra-

cemic-like” complexes (A and B) and one C₁symmetric

“meso-like” diastereomer (C), is formed in a ratio de-

pending on the relative energies of the π-face metallation

(pR) vs. (pS) and the mono(indenyl)metallocene trichlorides

initially formed.

Scheme 2. Synthesis of the chiral metallocenes 5a–c and 6c. (i)

nBuLi, Et₂O, 0 °C. (ii) 0.5 ZrCl₄, toluene, 50 °C; or 0.5 ZrCl₄, Et₂O,

room temp.; or 0.5 ZrCl₄·2THF, –80 °C. (iii) H₂/50 bar/PtO₂,

CH₂Cl₂, 82%.

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S. Silver, A. Puranen, R. Sjöholm, T. Repo, R. Leino

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nyl analogue (pR)(pS)-6c was then obtained in 82% yield the ligand substitution pattern. Such complexes in turn

after hydrogenation at 50 bar over PtO₂catalyst in dichloro- could prove promising candidates for applications in enantio-

methane. Again, despite several attempts, crystals suitable selective catalysis. In a previous work, Halterman and co-

for X-ray structure determination could not be grown from workers demonstrated that for the chiral bis(2-menthyl-4,7-

either one of the highly soluble complexes 5c and 6c.

dimethylindenyl)zirconium dichloride one diastereomeric

conformation is slightly favored at 223 K (60:40) with a ro-

tational activation barrier of 12.5 0.5 kcal/mol.^[25]

Table 1. Relative ratios of the metallocene diastereomers 5a–c

formed in different solvents.

Solvent

rac-like 5a

rac-like 5b

meso-like 5c

Toluene

THF

Et₂O

42.4%

22.6%

28.4%

42.4%

22.6%

28.4%

15.2%

54.8%

43.2%

Scheme 3. Conformational equilibration of unbridged bis(indenyl)

zirconocenes with (A) achiral substituents (enantiomeric conforma-

tions), and (B) chiral substituents (diastereomeric conformations).

1

At ambient temperature, the H NMR spectra of com-

plexes 2 and 5c are consistent with unhindered ligand rota-

tion. Upon lowering the monitoring temperature to 213–

163 K, complex 2 displays dynamic behavior as indicated

by the broadening of the aromatic CH resonances at δ =

5.92 and 5.96 ppm in the five-membered indenyl ring. At

the estimated coalescence temperature of 163 K, the signals

start to split to the individual resonances resulting from the

equilibration of the two C₂symmetric diastereomeric con-

formers. However, due to the operational limits of the

NMR instrument at such low temperatures, neither the ex-

act point of coalescence nor the associated rotational en-

ergy barrier and the eventual predominance of either one

of the conformers could be reliably determined.

Next, as an attempt to modify the steric properties of the

complex family and as a further extension of the use of

the pinenyl group as a chiral indenyl ligand substituent, we

prepared the monomethylated analogues of compounds 1

and 4a/b. Thus, deprotonation of 1 with nBuLi and the sub-

sequent reaction of the lithium salt formed with excess

methyl iodide provided a diastereomeric mixture of the chi-

ral indenes (1R)-7a and (1S)-7b in 74% isolated yield after

Figure 2. Expansions of the crude product indenyl CH regions of

the H NMR spectra of complexes 5a–c.

1

Unbridged bis(indenyl)zirconocenes with bulky equato- purification by flash chromatography. Deprotonation of 7a/

rial or σ-ligand substituents may exhibit dynamic behavior 7b with nBuLi and the subsequent reaction with 0.5 equiv.

in their NMR spectra at subambient temperatures resulting ZrCl₄formed the expected mixture of the diastereomeric

from partially hindered rotation around the Zr–Cp(cen- metallocene complexes (pR)(pR)-8a, (pS)(pS)-8b and

troid) axis (Scheme 3).^[29]For complexes with achiral ligand (pR)(pS)-8c in good yield, as evidenced by ¹H NMR analy-

substituents the observed interconversion is likely to take sis of the crude product. All attempts to purify/isolate any

place between two C₂symmetric enantiomeric conforma- of the complexes 8a–c by fractional crystallization tech-

tions becoming frozen on the NMR time scale to form a niques failed due to their extremely high solubilities in all

racemic mixture of the interconverting conformational iso- common organic solvents. When, however, the crude pro-

mers.^[30–32]If, however, the ligand substituent is chiral, the duct was subjected to flash column chromatography using

interconverting conformational isomers become diastereo- silanized silica gel^[33]under argon, elution with pentane

meric, one of which could be favored by proper choice of provided a mixture of the pure metallocenes 8a–c in 53%

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Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

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yield (all fractions combined) as a yellow oil. Despite their umn chromatographic conditions (silanized silica gel under

very similar solubility properties, the diastereomers eluted argon atmosphere), yielding ligand precursor as the main

at slightly different retention times yielding fractions con- decomposition product upon elution with pentane

sisting of both 8a/8b and 8a/8b/8c in variable ratios. Small (Scheme 5).

differences in the elution properties were observed even be-

tween the racemic-like diastereomers 8a and 8b, however,

due to their high solubilities even in pentane, complete sep-

aration was impossible to achieve. Combination of all frac-

tions containing only the racemic-like diastereomers gave

an isolated yield of 18% for 8a/8b obtained as a yellow oil.

Crystallization of this mixture from cold pentane (–60 °C)

gave 54 mg (3%) of yellow crystals enriched in one of the

racemic-like diastereomers in a 53:47 ratio (Scheme 4).

Scheme 5. Synthesis of the chiral indenyl ligand precursor 9a/9b

and the chiral metallocenes 10a–c. (i) nBuLi, THF, 0 °C. (ii)

Chloro{[(1S,2S,5S)-6,6-dimethylbicyclo[3.1.1]hept-2-yl]methyl}di-

Scheme 4. Synthesis of the chiral indenyl ligand precursor 7a/7b

methylsilane, 53%. (iii) nBuLi, Et₂O, 0 °C. (iv) 0.5 ZrCl₄, product

and the chiral metallocenes 8a–c. (i) nBuLi, THF, 0 °C. (ii) MeI,

not isolated.

74%. (iii) nBuLi, Et₂O, 0 °C. (iv) 0.5 ZrCl₄, 53% (isolated mixture

8a–c), 18% (isolated mixture 8a/8b).

In addition, we briefly evaluated the metalation of the

A diastereomeric mixture of the 3-methyl-substituted ligand percursors 1 and (1R)-4a/(1S)-4b with other group-

chiral indenes (1R)-9a and (1S)-9b was in turn obtained in 4 metals. Treatment of the from 1 and (1R)-4a/(1S)-4b gen-

53% isolated yield by deprotonation of a 1-methylindene/3- erated lithium salts with 0.5 equiv. HfCl₄in diethyl ether or

methylindene mixture with nBuLi followed by quenching toluene yielded the desired metallocene complexes in mod-

with excess chloro{[(1S,2S,5S)-6,6-dimethylbicyclo[3.1.1]- erate (approximately 30%) yields as shown by ¹H NMR

hept-2-yl]methyl}dimethylsilane, work-up and purification analyses of the corresponding crude products. In contrast

by flash chromatography. Deprotonation of 9a/9b with to their zirconium analogues, these hafnium complexes

nBuLi and the subsequent reaction with 0.5 equiv. ZrCl₄proved highly unstable resulting in decomposition upon all

formed the expected mixture of the diastereomeric metall- purification attempts, even when manipulated under strictly

ocene complexes (pR)(pR)-10a, (pS)(pS)-10b and (pR)(pS)- inert atmosphere.

1

10c in good, approximately 70% yield, as evidenced by H

From both compounds 1 and (1R)-4a/(1S)-4b, a mixture

NMR analysis of the crude product. All attempts to purify/ of the trimethylsilyl-substituted derivatives (1R)-11a/(1S)-

isolate any of the complexes 10a–c by crystallization failed 11b and 12 and mixtures of (1R)-15a/(1S)-15b/(1R)-16a/

due to their high solubilities in all common organic sol- (1S)-16b were obtained in high yields by quenching the cor-

vents. In contrast to complexes 8a–c, the 1-silyl-substituted responding lithium salts with chlorotrimethylsilane

zirconocenes 10a–c were also unstable under the flash col- (Scheme 6 resp. Scheme 7). Treatment of these with one

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equivalent of TiCl₄in dichloromethane at –78 °C resulted

in competing elimination of both the trimethylsilyl- and the

pinenyl-substituted silyl groups providing approximately 1:1

mixtures of the mono(indenyl)titanium trichlorides carry-

ing either

a

trimethysilyl [(pR)-14a/(pS)-14b] or

{[(1S,2S,5S)-6,6-dimethylbicyclo[3.1.1]hept-2-yl]methyl}-

dimethylsilyl substituent [13 and (pR)-17a/(pS)-17b, respec-

tively]. In the case of the mixture of (1R)-11a/(1S)-11b and

12, conversion of the ligand to mono(indenyl)metallocene

appears to be nearly quantitative as evidenced by ¹H NMR,

whereas in the case of (1R)-15a/(1S)-15b/(1R)-16a/(1S)-16b

the yield of the metallation step is approximately 30%. Due

to the similar solubilities of the (trimethylsilylindenyl)-

titanium trichloride and the {{[(1S,2S,5S)-6,6-dimethylbi-

cyclo[3.1.1]hept-2-yl]methyl}dimethylsilylindenyl}titanium

trichlorides formed, these metallocene mixtures proved in-

separable by fractional crystallization techniques.

Scheme 7. Attempted synthesis of 1-chirally substituted mono(ind-

enyl)titanium trichlorides. (i) nBuLi, THF, 0 °C. (ii) Chlorodi-

methylsilane, 76%. (iii) TiCl₄·CH₂Cl₂, –78 °C, not purified/isolated.

In our previous communication,^[28]we also described the

preparation of the ethylene-bridged bis(indenyl) ligand ana-

logues of 1 and 4a/4b (compounds 18 and 19), as well as

the 1,3-chirally disubstituted indene analogue 20 (Figure 3).

When the dilithium salt of 18 was reacted with ZrCl₄in

Et₂O, no metallocene could be detected by ¹H NMR or

EIMS analysis of the crude product. Reaction of the dilith-

ium salt of 19 with ZrCl₄in THF showed no formation

of the desired bis(indenyl)metallocenes. By carrying out the

metallation in toluene only traces of zirconium complex

diastereomers could be detected together with large

amounts of impurities. In Et₂O, however, metallation of 19-

Li₂with ZrCl₄consumed all of the ligand precursor and

formation of zirconocene diastereomers could be proven by

both ¹H NMR and EIMS analyses, the latter of which gave

Scheme 6. Attempted synthesis of 2-chirally substituted mono(ind-

enyl)titanium trichlorides. (i) nBuLi, THF, 0 °C. (ii) Chlorodi-

methylsilane, 71%. (iii) TiCl₄·CH₂Cl₂, –78 °C, not purified.

When the lithium salts generated from 1 and (1R)-4a/ the observed isotope peak distibutions for [M⁺] in matching

(1S)-4b were treated with 0.5 equiv. FeCl₂, the desired ferro- ratios with the theoretically calculated values. Unfortu-

cenes were formed in approximately 25% and 40% yields, nately, again apparently due to the very high solubilities of

1

respectively, as evidenced by H NMR spectroscopy. Also the metallocene complexes formed, all attempts to isolate

these compounds proved to have extremely high solubilities pure compounds by crystallization from Et₂O, iPr₂O, hex-

in all common organic solvents rendering their purification ane, THF, toluene and dichloromethane failed.

by crystallization impossible. All attempts to purify the oily

All our attempts to metallate either the lithium or potas-

crude products by silica gel column chromatography like- sium salt of the 1,3-disubstituted indene 20 with ZrCl₄in

wise failed due to the apparent high sensitivity of these iron Et₂O, toluene and dichloromethane under various reaction

complexes.

conditions failed. In none of the attempts could we observe

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Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

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Scheme 8. Synthesis of the 2-chirally substituted indenyl ligand pre-

cursor 22. (i) THF, –72 °C, 3%.

Figure 3. Ethylene-bridged and 1,3-chirally disubstituted ligand

precursors 18–20.

any formation of the desired bis(indenyl)metallocene com-

plex. Considering that the analogous 1,3-bis(trimethylsilyl)-

indenyl and other 1,3-bis(trialkyl/arylsilyl)indenyl-derived

anions were recently successfully complexed with zirconium

and iron in moderately high yields by Chirik and co-

workers,^[34,35]the observation here is quite surprising and

hardly explained by steric factors only. Other examples of

both 1,2- and 1,3-trimethylsilyl-substituted bis(indenyl)-

iron(ii) complexes have also been reported recently.^[36]

Finally, in a complementary approach, we investigated

the possibility of using α-pinene as the chiral indenyl sub-

stituent. By deprotonation of α-pinene with nBuLi/tBuOK

at 50 °C using excess α-pinene^[37]and the subsequent reac-

tion of the obtained α-pinenyl potassium salt with 2-

(chlorodimethylsilyl)indene^[38]21 or 1-(chlorodimethylsilyl)-

indene^[39](1R)-23a/(1S)-23b, the corresponding 1- and 2-

chirally substituted indenes 22 and (1R)-24a/(1S)-24b/25

were obtained in low (3% and 21%, respectively) yields

(Scheme 8 and Scheme 9). The amount of the 3-silyl isomer

Scheme 9. Synthesis of the 1-chirally substituted indenyl ligand pre-

cursors (1R)-24a/(1S)-24b/25. (i) THF, –72 °C, 21%.

dehydrocoupling^[42]and during the past 20 years a number

of metallocene-based catalyst systems have been reported

to polymerize phenylsilane.^[43–50]Several shortcomings are,

however, still to be overcome. Firstly, catalysts producing

polyphenylsilanes with narrower polydispersities and with

higher molecular weights than the presently existing sys-

tems, which seldom yield polymers with M_w’s exceeding

5×10³, would be desirable. Secondly, cleaner reaction mix-

tures not containing intractable oligo-/polysilane mixtures

are required. Finally, the issue of stereocontrol in phenylsi-

lane polymerization remains largely unsolved and only es-

sentially atactic polymers are obtained regardless of chiral-

ity/achirality of the initiating catalyst system.

During the course of the present investigation, the chiral

metallocenes 2, 3, (pR)(pS)-5c and (pR)(pS)-6c were briefly

evaluated as catalysts for the dehydropolymerization of

phenylsilane using zirconocene dichloride ([Cp₂ZrCl₂]) as

reference catalyst (Scheme 10). The polymerization reac-

tions were carried out in neat phenylsilane under argon by

activation of 1 mol-% of the metallocene dichloride with 2

mol-% of nBuLi. The results are summarized in Table 2.

With the exception of the 1-substituted meso-like chiral

complex (pR)(pS)-5c, the silane polymerization activities of

the pinenyl-substituted systems were significantly lower

than obtained with the zirconocene dichloride reference.

The 2-substituted bis(indenyl) complex 2 gave polysilane

1

25 in the 24a/24b/25 mixture was estimated to 15% by H

NMR spectroscopy. All attempts to react α-pinenyl potas-

sium with either 2-indanone or 2-bromoindene failed. Due

to the low isolated yields and preparations in small scale,

further attempts to utilize the compounds 22 and (1R)-24a/

(1S)-24b/25 as ligand precursors for transition metal com-

plexes were not pursued.

Dehydropolymerization of Phenylsilane

Dehydropolymerization of phenylsilane to poly(phenylsi- with similar molecular weight to the reference catalyst

lane) with nBuLi activated transition-metal catalysts is a whereas both 1-substituted complexes 5c and 6c and the

well-known reaction.^[40,41]Harrod and co-workers reported 2-substituted tetrahydroindenyl analogue 3 produced lower

in 1985 the first effective transition-metal catalyst for silane molecular weight polymers. All catalysts investigated pro-

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pound 26. In the reaction catalyzed by the reference catalyst

only compounds 26 and 29 were formed.

Olefin Polymerization

Complexes 2 and (pR)(pS)-5c were activated with methyl-

aluminoxane (MAO) for polymerization of propylene in

toluene (T = 50 °C, P = 5.34 bar, [Al]:[Zr] = 2000:1). The

results are summarized in Table 3. Under the conditions in-

vestigated, the 2-pinenyl-substituted 2/MAO catalyst system

produced only low molecular weight atactic polypropylene

(aPP) (colorless oil) with low activity, whereas the 1-substi-

tuted 5c/MAO was totally inactive toward propylene intake,

most likely due to its greater steric hindrance toward mono-

mer coordination in the vicinity of the metal site induced

by placement of the bulky substituents. The experimental

pentad distribution for the a-PP obtained with 2/MAO as

determined by quantitative ¹³C NMR with inverse gated

¹H-decoupling is as follows: [mmmm] = 5.5%, [mmmr] =

Scheme 10. Zirconocene-catalyzed dehydropolymerization of phen-

ylsilane. (i) 1 mol-% 2, 3, (pR)(pS)-5c or (pR)(pS)-6c, 2 mol-%

nBuLi.

Table 2. Dehydropolymerization of phenylsilane over chiral

metallocenes 2, 3, (pR)(pS)-5c and (pR)(pS)-6c and the reference

catalyst [Cp₂ZrCl₂].

Catalyst^[a]Conv.^[b]A^[c]

M_w

M_n

MP^[d][e]PDI^[d][f]

[d]

Cp₂ZrCl₂

2

3

(pR)(pS)-5c 90

(pR)(pS)-6c 25

98

97

46

116.3 715

680

646

707

691

1.05

36.2

27.3

705

1.09

n.d.^[g]n.d.^[g]n.d.^[g]

n.d.^[g]

1.09

124.9 366^[h]336^[h]274

73.1

n.d.^[g]n.d.^[g]n.d.^[g]

n.d.^[g]

[a] 1 mol-% of metallocene activated with 2 mol-% nBuLi in 8.8%, [rmmr] = 5.5%, [mmrm] + [rmrr] = 25.3%, [mrmr] =

neat phenylsilane. [b] Conversion in % = (g of polymer)·(g of mono-

16.5%, [rrrr] = 8.8%, [rrrm] = 11.0% and [mrrm] = 7.7%.

mer)^–1. [c] Activity = (kg of polymer)·(mol of cat.)^–1·(mol of mono-

End group analysis by ¹³C NMR indicated the presence of

mer)^–1·h^–1. [d] Determined by GPC. [e] The place (g/mol) of the

n-propyl, vinylidene, isobutenyl, cis-2-butenyl and trans-2-

top of the molecular mass peak. [f] PDI = M_w/M_n. [g] Not deter-

butenyl chain ends (Figure 5).

mined. [h] The values reported are indicative only, due to the detec-

tion limit (500 g/mol) of the column employed.

Table 3. Polymerization of propylene over 2/MAO and (pR)(pS)-

5c/MAO.

duced atactic polysilanes as confirmed by ²⁹Si{¹H} NMR

analysis. As the sole significant difference between zir-

conocene dichloride and the investigated pinenyl-substi-

tuted complexes, it could be shown by ¹H NMR analysis of

the polysilanes produced that catalysts 2, 3, 5c and 6c pro-

duced only linear polysilanes whereas mixtures of cyclic and

linear poly-/oligomers were obtained with the Cp₂ZrCl₂/

nBuLi catalyst system. The formation of oligomers and

other coupling products was further investigated with GC-

MS with compounds detected shown in Figure 4. All by-

products 26–29 were detected in polymerizations catalyzed

by complexes 2 and (pR)(pS)-5c, whereas complex 3 only

yielded compounds 26 and 27 and complex 6c yielded com-

Catalyst^[a]A^[b]

M_w

M_n

M_v

PDI^[d]

[c]

2/MAO

5c/MAO

125

–

3670

–

1900

–

3110

–

1.93

–

[a] 20 μmol of 2 or (pR)(pS)-5c activated with 40 mmol of MAO

(30 vol-% in toluene) in 200 mL dry toluene at T = 50 °C, P = 5.34

bar, [Al]:[Zr] = 2000:1, t = 2 h. [b] Polymerization activity in (kg of

PP)·(mol of cat.)^–1·h^–1. [c] By GPC. [d] PDI = M_w/M_n.

Figure 5. End groups present in the atactic polypropylene produced

with 2/MAO

The MAO-activated bis(indenyl) complexes

2 and

(pR)(pS)-5c were further tested in the polymerization of

ethylene in toluene (T = 50 °C, P = 3.95 bar, [Al]:[Zr] =

2000:1). In contrast to the propylene polymerization experi-

ments, both catalysts 2/MAO and 5c/MAO polymerized

ethylene with fairly high activities (2300–2550 kg PE/mol

Zr/h) to high molecular weight polyethylene (M_w

Ͼ

440000), the latter being slightly more active of the two.

The polymerization results and characterization data are

Figure 4. Oligomers/by-products formed in the dehydropolymeriza-

tion of phenylsilane catalyzed by [Cp₂ZrCl₂], 2, 3, 5c and 6c/nBuLi collected in Table 4 with results of IR-analyses of the poly-

Eur. J. Inorg. Chem. 2005, 1514–1529

Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

FULL PAPER

mer end group composition in Table 5. Both catalysts pro- ylaluminum or trimethylaluminum in the presence of cata-

duced polyethylenes with vinylidene, terminal vinyl and lytic amounts of the chiral zirconocene complexes 2 and

trans-vinylene end groups (Figure 6) in slightly different ra- (pR)(pS)-5c, 2-ethyl-1-octanol and 2-methyl-1-octanol were

tios. The fact that the 5c/MAO catalyst polymerizes ethyl- indeed obtained after oxidation with O₂, albeit in disap-

ene with comparable activity to that of 2/MAO further sug- pointingly low yields ranging from 8 to 18% (Scheme 11).

gests that its inactivity toward propylene is most likely of Also enantiomeric excesses were low ranging from marginal

1

steric origin and a consequence of the orientation of the 1- to 10% as determined by H and ¹⁹F NMR analysis of the

indenyl substituents over the metal center.

corresponding Mosher esters.^[54]By measuring the optical

rotations of the enantiomeric product mixtures it could be

deduced that the 2-substituted complex 2 produced, in both

cases, a slight excess of the (+)-enantiomer of 2-alkyl-1-oc-

tanols whereas a slight excess of the (–)-enantiomers was

obtained with (pR)(pS)-5c. The hydrogenated congeners 3

and (pR)(pS)-6c proved totally inactive as carboalumi-

nation catalysts.

Table 4. Polymerization of ethylene over 2/MAO and (pR)(pS)-5c/

MAO.

A^[d]

M_w

M_n

M_v

PDI^[f]T_m

[e]

[g]

Cata-

lyst^[a]

2/

2300 489000 169000 428000 2.9

2550 449000 178000 395000 2.5

122–128

124–134

MAO^[b]

5c/

MAO^[c]

[a] 2 μmol of 2 or (pR)(pS)-5c activated with 4 mmol of MAO (30

vol-% in toluene) in 200 mL dry toluene at T = 50 °C, P = 3.95

bar, [Al]:[Zr] = 2000:1. [b] Polymerization time = 0.58 h. [c] Poly-

merization time = 0.75 h. [d] Polymerization activity in (kg of PE)-

(mol of cat.)^–1h^–1. [e] By GPC. [f] PDI = M_w/M_n. [g] Melting inter-

val in °C by DSC.

Table 5. End group distribution [C=C/1000] in polyethylenes pro-

duced by 2/MAO and (pR)(pS)-5c/MAO.

Scheme 11. Carboalumination of 1-octene with chiral zirconocene

catalysts. (i) Et₃Al or Me₃Al, 2 or (pR)(pS)-5c, dichloromethane.

(ii) O₂.

Catalyst^[a]

Vinylidene

Terminal vinyl trans-Vinylene

2/MAO

0.69

0.52

1.54

3.85

1.11

0.35

A simplified mechanistic scheme of the carboalumin-

ation reaction is displayed in Scheme 12. Based on the pre-

vious work by Negishi, Waymouth and others, the

NMI₂ZrCl₂catalyst appears to have an optimal disposal of

the chiral ligands coupled with conformational flexibility

driving the reaction towards the carboalumination product

which in turn can be oxidized to the chiral alcohol. With

other catalysts investigated previously, larger amounts of al-

kene products resulting from hydrometalation/carbometal-

ation and/or hydrogen transfer sequences are often pro-

duced. The ligands in 2 and (pR)(pS)-5c are apparently not

bulky enough for efficient blocking of the side reactions re-

sulting in low carboalumination yields and selectivities.

5c/MAO

[a] By IR.

Figure 6. End groups present in polyethylenes produced with 2/

MAO and 5c/MAO

Carboalumination Reactions

Catalytic asymmetric carboalumination of unactivated

terminal alkenes using chiral zirconocene catalysts has con-

siderable synthetic potential as oxidation of the organoalu-

minum products with molecular oxygen potentially pro-

vides access to the corresponding chiral alcohols.^[9–13]Re-

cently, this reaction, initially developed by Negishi and co-

workers, has been applied successfully e.g., in natural pro-

duct synthesis via the obtained chiral polypropionate build-

ing blocks.^[51–53]Of several zirconocene catalysts evaluated

previously, high yields and moderate enantioselectivities are

almost exclusively obtained by use of the chiral unbridged

bis(1-neomenthylindenyl)zirconium dichloride [(NMI)₂-

ZrCl₂], initially developed by Erker and co-workers.^[22]

Accordingly, we felt motivated to briefly investigate the ap-

plicability of the easily prepared chiral zirconocenes 2, 3,

(pR)(pS)-5c and (pR)(pS)-6c as catalysts for carboalumin-

Scheme 12. Simplified mechanism for zirconocene catalyzed car-

ation reactions. Thus, by reaction of 1-octene with trieth- boalumination.

Eur. J. Inorg. Chem. 2005, 1514–1529

www.eurjic.org

1521

S. Silver, A. Puranen, R. Sjöholm, T. Repo, R. Leino

FULL PAPER

was purified by passage through a series of activated 3-Å molecular

sieves and copper catalyst columns. Flash chromatography was per-

formed on silica gel 60 (40–63 μm). Silanized silica gel was pre-

pared according to a literature procedure.^[33]NMR spectra were

recorded at 298 K with a Bruker Avance 600 (¹H NMR 600 MHz,

¹³C NMR 150.9 MHz), Jeol JNM-A500 (¹H NMR 500 MHz, ¹³C

125.8 MHz), Jeol l-400 (¹H NMR 400 MHz, ¹³C 100.6 MHz, ²⁹Si

79.5 MHz) or Bruker 250 MHz (1H NMR 250 MHz) NMR spec-

Nevertheless, some enantiocontrol was obtained with the

simple ligand design presented in this work and the results

obtained could be considered promising. Unfortunately our

attempts to modify the steric properties of these precata-

lysts by additional methyl substituents were hampered by

the difficult (or impossible) isolation and purification of

complexes 8a–c and 10a–c. Furher variations in ligand

structure are currently in progress.

1

trometer. H NMR were referenced against residual H-impurities

in the solvent and ¹³C NMR to the solvent signals. In the ²⁹Si

NMR experiments TMS was used as external reference. The NMR

spectra were recorded in δ values with CDCl₃or CD₂Cl₂as the

solvent. Mass spectra were recorded with a high-resolution mass

spectrometer (Fison’s ZapSpec). A Hewlett–Packard Series II 5890/

Hewlett Packard 5971A Mass selective detector was used in GC-

MS analysis. Molecular weights and molecular weight distributions

Summary and Conclusions

In this paper we have reported the synthesis of some new

indenes containing a β-pinenyl-derived, chiral substituent

and investigated the metallation of these ligand precursors,

as well as some previously described ligand analogues,^[28]of polysilanes were measured at 30 °C in THF by size exclusion

chromatography (GPC) relative to polystyrene standards using a

Waters 515 high-pressure liquid chromatography pump, GPC fitted

with Styragel columns HR 2, HR 4, and HR 6, a UV detector

Waters 2487 and a refractive-index detector Waters 2410. Melting

intervals were measured with Perkin–Elmer DSC 7. Polyethylene

end group analyses were carried out with a Perkin–Elmer FT-IR

spectrometer Spectrum 1000. The optical rotation measurements

were made using Perkin–Elmer Polarimeter 241. The molecular

weights of the polyethylene and polypropylene samples were deter-

mined using a Waters Alliance 2000 GPC equipped with a refrac-

with group-4 metals. Due to the simple accessibility of the

ligand precursors and the successful metallations in some

of the cases, the route appears attractive for the preparation

of new chiral transition metal complexes. The main draw-

back of the complexes described are the high solubilities of

both the ligand precursors and the corresponding metallo-

cenes in nearly all common organic solvents which render

their isolation and purification unusually difficult in many

cases. The high solubilities in turn are likely a consequence

of the high rotational and conformational freedom of the tometer, viscometer, and three Waters Styragel HMW columns

covering the molecular weight range from 10²to 10⁸g/mol. 1,2,4-

pinenyl part in these molecules.

Trichlorobenzene was used as solvent and the chromatograms were

In addition, we have investigated the catalytic activity of

collected at 140 °C. The molecular weights were calculated with the

selected metal complexes in polymerization and carboalum-

ination reactions. Metal complexes 2 and (pR)(pS)-5c poly-

universal calibration based on 11 narrow polystyrene standards.

merized ethylene with high activity and polyethylene with

high molecular weight was obtained whereas only complex

2 was active in propylene polymerization producing atactic

Bis{2-[(7,7-dimethylnorpinanylmethyl)dimethylsilyl]indenyl}-

zirconium Dichloride (2): To 2-[(7,7-dimethylnorpinanylmethyl)di-

methylsilyl]indene (1) (2.4076 g, 7.8 mmol) in diethyl ether (35 mL)

polypropylene with low molecular weight. All of the cata- at 0 °C was added nBuLi (2.5 m in n-hexane, 3.2 mL, 7.8 mmol).

The yellow solution was stirred at room temperature for 4 h. The

solvent was removed under vacuum leaving a pale yellow foam.

Next, ZrCl₄(0.9634 g, 4.1 mmol) was added and the solids were

mixed a few minutes before 50 mL of toluene was added. After

stirring at 50 °C for 18 h, the suspension was filtered and the filtrate

was concentrated under vacuum. The product was crystallized from

n-pentane at –20 °C yielding 1.1157 g (37%) of pure 2 as a yellow

powder. ¹H NMR (400 MHz, CD₂Cl₂, 25 °C): δ = 7.81 (m, 4 H,

arom. CH in six-membered ring), 7.30 (m, 4 H, arom. CH in six-

membered ring), 5.97 (dd, J = 0.92 Hz, 2.14 Hz, 2 H, arom. CH in

five-membered ring), 5.94 (dd, J = 0.76 Hz, 2.14 Hz, 2 H, arom.

CH in five-membered ring), 1.92 (m, 2 H, aliph. CH in pinenyl

ring), 1.87 (m, 2 H, aliph. CH in pinenyl ring), 1.77 (m, 2 H, aliph.

CH in pinenyl ring), 1.65 (m, 4 H, aliph. CH₂in pinenyl ring), 1.55

(m, 2 H, aliph. CH in pinenyl ring), 1.35 (dt, J = 1.32 Hz, 5.57 Hz,

2 H, aliph. CH in pinenyl ring), 1.28 (d, J = 9.92 Hz, 2 H, aliph.

CH in pinenyl ring), 1.11 (m, 2 H, aliph. CH in pinenyl ring), 1.06

(s, 6 H, CH₃in pinenyl ring), 0.69 (s, 6 H, CH₃in pinenyl ring),

0.53 (dd, J = 7.55 Hz, 14.50 Hz, 2 H, aliph. CH between Si and

pinenyl ring), 0.45 (dd, J = 6.56 Hz, 14.50 Hz, 2 H, aliph. CH be-

tween Si and pinenyl ring), 0.11 (s, 6 H, CH₃attached to Si), 0.10

(s, 6 H, CH₃attached to Si) ppm. ¹³C NMR (100.6 MHz, CD₂Cl₂,

25 °C): δ = 141.83 (2 C_q), 130.02 (4 C_q), 126.32 (4 arom. CH in

six-membered ring), 126.06 (4 arom. CH in six-membered ring),

112.47 (2 arom. CH in five-membered ring), 112.30 (2 arom. CH

in five-membered ring), 49.44 (2 aliph. CH in pinenyl ring), 41.30

(2 aliph. CH in pinenyl ring), 39.93 (2 C_qin pinenyl ring), 31.46 (2

lysts investigated produced atactic poly(phenylsilane) with

low molecular weight. In catalytic carboalumination reac-

tions, complexes 2 and (pR)(pS)-5c showed to induce some

(0.5–10% ee) enantioselectivity in the carboalumination of

1-octene with triethyl- and trimethylaluminum whereas

their tetrahydroindenyl analogues 3 and (pR)(pS)-6c were

not active at all. Nevertheless, we believe that the simple

chiral catalyst structures described herein, may prove valu-

able starting points for further developoment by structural

modifications.

Experimental Section

General Comments: All air and moisture sensitive reactions were

conducted under argon using standard techniques. Commercially

available reagents were used without further purification. Methylin-

dene,^[55]α-pinenylpotassium,^[37]2-(chlorodimethylsilyl)indene^[38]

and 1-(chlorodimethylsilyl)indene^[39]were synthesized essentially

according to literature procedures. Chloro{[(1S,2S,5S)-6,6-dimeth-

ylbicyclo[3.1.1]hept-2-yl]methyl}dimethylsilane was prepared by

hydrosilylation of β-pinene with chlorodimethylsilane in the pres-

ence of Karstedt’s catalyst.^[56,57]Diethyl ether and tetrahydrofuran

were distilled from sodium/benzophenone ketyl prior to use.

Dichloromethane was distilled from calcium hydride and toluene

1522

www.eurjic.org

Eur. J. Inorg. Chem. 2005, 1514–1529

Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

FULL PAPER

aliph. CH in pinenyl ring), 27.15 (2 CH₃in pinenyl ring), 26.23 (4

aliph. CH in pinenyl ring), 25.31 (4 aliph. CH in pinenyl ring),

25.10 (2 aliph. CH₂between Si and pinenyl ring), 23.32 (4 aliph.

CH in pinenyl ring), 20.18 (2 CH₃in pinenyl ring), –1.16 (2 CH₃

1.27 (m, 2 H, aliph. CH in pinenyl ring), 1.15 (m, 2 H, aliph. CH

in pinenyl ring), 1.07 (s, 6 H, CH₃in pinenyl ring), 0.76 (m, 4 H,

aliph. CH₂between Si and pinenyl ring), 0.67 (s, 3 H, CH₃in pi-

nenyl ring), 0.64 (s, 3 H, CH₃in pinenyl ring), 0.44 (s, 3 H, CH₃

attached to Si), –1.47 (2 CH₃attached to Si) ppm. ²⁹Si NMR attached to Si), 0.42 (s, 3 H, CH₃attached to Si), 0.37 (s, 3 H, CH₃

(79.5 MHz, CD₂Cl₂, 25 °C): δ = –4.45 (2 Si) ppm. In the EIMS

attached to Si), 0.35 (s, 3 H, CH₃attached to Si) ppm. ¹³C NMR

(150.9 MHz, CDCl₃, 25 °C): δ = 145.59 (C_q), 144.37 (C_q), 136.05

(2 C_q), 134.73 (C_q), 134.41 (C_q), 127.35 (2 arom. CH in six-mem-

bered ring), 127.31 (2 arom. CH in five-membered ring), 126.42

(arom. CH in six-membered ring), 126.39 (arom. CH in six-mem-

bered ring), 126.01 (arom. CH in six-membered ring), 125.96

(arom. CH in six-membered ring), 125.24 (2 arom. CH in six-mem-

bered ring), 104.89 (arom. CH in five-membered ring), 104.86

(arom. CH in five-membered ring), 49.16 (aliph. C in pinenyl ring),

49.13 (aliph. C in pinenyl ring), 40.71 (2 aliph. C in pinenyl ring),

39.60 (C_qin pinenyl ring), 39.58 (C_qin pinenyl ring), 31.23 (2 aliph.

C in pinenyl ring), 26.98 (CH₃in pinenyl ring), 26.95 (CH₃in pi-

nenyl ring), 25.73 (aliph. C in pinenyl ring), 25.68 (aliph. C in pi-

nenyl ring), 25.15 (CH₂between Si and pinenyl ring), 25.12 (CH₂

between Si and pinenyl ring), 24.88 (2 aliph. C in pinenyl ring),

23.06 (aliph. C in pinenyl ring), 23.05 (aliph. C in pinenyl ring),

20.04 (CH₃in pinenyl ring), 20.00 (CH₃in pinenyl ring), 0.06

(CH₃–Si), –0.48 (CH₃–Si), –0.57 (CH₃–Si), –0.81 (CH₃–Si) ppm.

²⁹Si NMR (79.5 MHz, CDCl₃, 25 °C): δ = –4.82 (2 Si) ppm. In the

EIMS mass spectrum parent ions of composition C₄₂H₅₈Cl₂Si₂Zr⁺

were observed in the appropriate ratios at m/z = 778–786. ¹H NMR

(250 MHz, CDCl₃, 25 °C) analysis of the filtrate containing a mix-

ture of diastereomers (pR)(pS)-bis{1-[dimethyl(7,7-dimethylnorpin-

anylmethyl)silyl]indenyl}zirconium dichlorides (5a and 5b): δ =

7.73 (m, 4 H, arom. CH in six-membered ring in 5a and/or 5b),

7.54 (m, 4 H, arom. CH in six-membered ring in 5a and/or 5b),

7.28 (m, 8 H, arom. CH in six-membered ring in 5a and/or 5b),

6.49 (m, 4 H, arom. CH in five-membered ring in 5a and/or 5b),

6.15 (m, 4 H, arom. CH in five-membered ring in 5a and/or 5b),

1.07 (s, 12 H, CH₃in pinenyl ring in 5a and/or 5b), 0.67 (s, 6 H,

CH₃in pinenyl ring in 5a and/or 5b), 0.63 (s, 6 H, CH₃in pinenyl

ring in 5a and/or 5b), 0.47 (m, 12 H, CH₃attached to Si in 5a and/

or 5b), 0.40 (m, 12 H, CH₃attached to Si in 5a and/or 5b), 2.23–

0.75 (m, 44 H, aliph. CH in pinenyl substituent in 5a and 5b) ppm,

signals from the aliph. protons in pinenyl ring in 5a and 5b are

overlapping with each other and other signals in the region 2.23–

0.75 ppm.

mass spectrum parent ions of composition C₄₂H₅₈Cl₂Si₂Zr⁺were

observed in the appropriate ratios at m/z

=

778–786.

C₄₂H₅₈Cl₂Si₂Zr (781.18): calcd. C 64.57, H 7.48; found C 64.58, H

7.59.

Bis{2-[(7,7-dimethylnorpinanylmethyl)dimethylsilyl]4,5,6,7-tetrahy-

dro-1-indenyl}zirconium Dichloride (3): A suspension of 2 (0.1124 g,

0.1 mmol) and PtO₂(a catalytic amount) in dichloromethane

(50 mL) was hydrogenated in a steel autoclave under 50 bar H₂for

20 h at room temperature. The catalyst was filtered off and the

filtrate was evaporated yielding 0.095 g (86%) of the pure title com-

1

pound as a pale green oil. H NMR (400 MHz, CDCl₃, 25 °C): δ

= 6.22 (m, 4 H, arom. CH in five-membered ring), 2.78 (m, 4 H,

aliph. CH in six-membered ring), 2.59 (m, 4 H, aliph. CH in six-

membered ring), 1.86 (m, 10 H, aliph. CH in six-membered ring

and in pinenyl ring), 1.62 (m, 10 H, aliph. CH in six-membered

ring and in pinenyl ring), 1.45 (m, 2 H, aliph. CH in pinenyl ring),

1.29 (d, J = 9.92 Hz, 2 H, aliph. CH in pinenyl ring), 1.14 (m, 2

H, aliph. CH in pinenyl), 1.12 (s, 6 H, CH₃in pinenyl ring), 0.73

(s, 6 H, CH₃in pinenyl ring), 0.58 (m, 4 H, CH₂between Si and

pinenyl ring), 0.28 (s, 6 H, CH₃attached to Si), 0.27 (s, 6 H, CH₃

attached to Si) ppm. ¹³C NMR (100.6 MHz, CDCl₃, 25 °C): δ =

135.15 (2 C_q), 135.02 (2 C_q), 122.26 (2 C_q), 121.09 (2 arom. CH in

five-membered ring), 120.81 (2 arom. CH in five-membered ring),

48.85 (2 C, aliph. C in six-membered ring or in pinenyl ring), 40.54

(2 C, aliph. C in six-membered ring or in pinenyl ring), 39.44 (2 C_q

in pinenyl ring), 30.97 (2 C, aliph. C in six-membered ring or in

pinenyl ring), 26.91 (2 C, aliph. C in six-membered ring or in pi-

nenyl ring), 26.01 (2 C, aliph. C in six-membered ring or in pinenyl

ring), 25.59 (2 C, aliph. C in six-membered ring or in pinenyl ring),

25.40 (2 C, aliph. C in six-membered ring or in pinenyl ring), 25.12

(2 C, aliph. C in six-membered ring or in pinenyl ring), 24.71 (2 C,

aliph. C in six-membered ring or in pinenyl ring), 22.90 (2 C, aliph.

C in six-membered ring or in pinenyl ring), 22.26 (6 C, aliph. C in

six-membered ring or in pinenyl ring), 19.94 (2 C, aliph. C in six-

membered ring or in pinenyl ring), –0.45 (2 CH₃–Si), –0.88 (2 CH₃–

Si) ppm. ²⁹Si NMR (79.5 MHz, CDCl₃, 25 °C): δ = –4.71 (2 Si)

ppm. In the EIMS mass spectrum parent ions of composition

C₄₂H₆₆Cl₂Si₂Zr⁺were observed in the appropriate ratios at m/z =

786–794.

{pR)(pS)-Bis{1-[(7,7-dimethylnorpinanylmethyl)dimethylsilyl]-

4,5,6,7-tetrahydro-1-indenyl}zirconium Dichloride (6c): A suspen-

sion of 5c (0.1190 g, 0.2 mmol) and PtO₂(a catalytic amount)

dichloromethane (50 mL) was hydrogenated in a steel autoclave un-

der 50 bar H₂for 20 h at room temperature. The catalyst was fil-

tered off and the filtrate was evaporated yielding 0.096 g (82%) of

pure 6c as a pale green powder. Recrystallization from dichloro-

(pR)(pS)-Bis{1-[(7,7-dimethylnorpinanylmethyl)dimethylsilyl]-

indenyl}zirconium Dichlorides (5c): To a diastereomeric mixture of

1-[(7,7-dimethylnorpinanylmethyl)dimethylsilyl]indene

(4a/4b)

(5.5281 g, 17.8 mmol) in diethyl ether (100 mL) at 0 °C was added

nBuLi (2.5 m in n-hexane, 7.2 mL, 18.0 mmol). The yellow solution

was stirred at room temperature for 4.5 h. The reaction mixture

was cooled to 0 °C and ZrCl₄(2.0870 g, 9.0 mmol) was added. Af-

ter stirring the suspension at room temperature for 19 h, the sol-

vents were removed under vacuum. The residue was dissolved in

dichloromethane, filtered and the filtrate was concentrated.

Crystallization from dichloromethane at –20 °C provided 0.7782 g

(11%) of the pure (pR)(pS)-5c diastereomer as a yellow powder. ¹H

NMR (600 MHz, CDCl₃, 25 °C): δ = 7.67 (m, 4 H, arom. CH in

six-membered ring), 7.25 (m, 4 H, arom. CH in six-membered ring),

1

methane at –20 °C yielded 0.037 g (31%) of a pale green solid. H

NMR (400 MHz, CDCl₃, 25 °C): δ = 6.51 (m, 2 H, arom. CH in

five-membered ring), 5.58 (m, 2 H, arom. CH in five-membered

ring), 3.00 (m, 4 H, aliph. CH in six-membered ring), 2.50 (m, 4

H, aliph. CH in six-membered ring), 1.96 (m, 4 H, aliph. CH in

six-membered ring and in pinenyl ring), 1.80 (m, 6 H, aliph. CH

in six-membered ring and in pinenyl ring), 1.62 (m, 12 H, aliph. CH

in six-membered ring and in pinenyl ring), 1.31 (d, J = 10.15 Hz, 1

H, aliph. CH in pinenyl ring), 1.30 (d, J = 10.15 Hz, aliph. CH in

pinenyl ring), 1.20 (m, 2 H, aliph. CH in pinenyl ring), 1.14 (s, 3

6.41 (m, 2 H, arom. CH in five-membered ring), 6.34 (m, 2 H, H, CH₃in pinenyl ring), 1.01 (s, 3 H, CH₃in pinenyl ring), 0.75 (s,

arom. CH in five-membered ring), 1.94 (m, 4 H, aliph. CH in pi-

nenyl ring), 1.78 (m, 2 H, aliph. CH in pinenyl ring), 1.59 (m, 6 H,

aliph. CH in pinenyl ring), 1.44 (m, 2 H, aliph. CH in pinenyl ring),

3 H, CH₃in pinenyl ring), 0.73 (s, 3 H, CH₃in pinenyl ring), 0.67

(m, 4 H, CH₂between Si and pinenyl ring), 0.26 (s, 3 H, CH₃

attached to Si), 0.25 (s, 3 H, CH₃attached to Si), 0.17 (s, 6 H, CH₃

Eur. J. Inorg. Chem. 2005, 1514–1529

www.eurjic.org

1523

S. Silver, A. Puranen, R. Sjöholm, T. Repo, R. Leino

FULL PAPER

attached to Si) ppm. ¹³C NMR (100.6 MHz, CDCl₃, 25 °C): δ =

CH in five-membered ring), 49.32 (aliph. CH in five-membered

140.48 (C_q), 140.42 (C_q), 136.24 (C_q), 136.18 (C_q), 118.86 (C_q), ring), 40.79 (CH in pinenyl ring), 40.77 (CH in pinenyl ring), 39.69

118.68 (C_q), 116.42 (arom. CH), 116.38 (arom. CH), 111.96 (arom. (2 C_qin pinenyl ring), 31.39 (CH in pinenyl ring), 31.38 (CH in

CH), 111.85 (arom. CH), 49.02 (aliph. C in six-membered ring or

in pinenyl ring), 48.82 (aliph. C in six-membered ring or in pinenyl

ring), 40.60 (aliph. C in six-membered ring or in pinenyl ring),

40.59 (aliph. C in six-membered ring or in pinenyl ring), 39.53 (C_q

in pinenyl ring), 39.44 (C_qin pinenyl ring), 31.11 (aliph. C in six-

membered ring or in pinenyl ring), 31.01 (aliph. C in six-membered

ring or in pinenyl ring), 26.91 (aliph. C in six-membered ring or in

pinenyl ring), 26.86 (aliph. C in six-membered ring or in pinenyl

ring), 26.10 (aliph. C in six-membered ring or in pinenyl ring),

26.06 (aliph. C in six-membered ring or in pinenyl ring), 25.68 (al-

iph. C in six-membered ring or in pinenyl ring), 25.61 (aliph. C in

six-membered ring or in pinenyl ring), 25.18 (aliph. C in six-mem-

bered ring or in pinenyl ring), 25.16 (aliph. C in six-membered ring

or in pinenyl ring), 24.76 (aliph. C in six-membered ring or in pi-

nenyl ring), 24.73 (aliph. C in six-membered ring or in pinenyl

ring), 24.56 (aliph. C in six-membered ring or in pinenyl ring),

24.54 (aliph. C in six-membered ring or in pinenyl ring), 22.93 (al-

iph. C in six-membered ring or in pinenyl ring), 22.91 (aliph. C in

six-membered ring or in pinenyl ring), 22.64 (2 aliph. C in six-

membered ring or in pinenyl ring), 22.26 (aliph. C in six-membered

ring or in pinenyl ring), 22.24 (aliph. C in six-membered ring or in

pinenyl ring), 19.97 (2 aliph. C in six-membered ring or in pinenyl

ring), –0.52 (CH₃–Si), –0.74 (CH₃–Si), –0.99 (CH₃–Si), –1.34

(CH₃–Si) ppm. ²⁹Si NMR (79.5 MHz, CDCl₃, 25 °C): δ = –6.37,

–6.47 ppm. In the EIMS mass spectrum parent ions of composition

C₄₂H₆₆Cl₂Si₂Zr⁺were observed in the appropriate ratios at m/z =

786–794.

pinenyl ring), 27.07 (2 CH₃in pinenyl ring), 25.81 (CH₂in pinenyl

ring), 25.69 (CH₂in pinenyl ring), 24.92 (2 CH₂in pinenyl ring),

24.35 (bridging CH₂between Si and pinenyl ring), 24.22 (bridging

CH₂between Si and pinenyl ring), 23.13 (2 CH₂in pinenyl ring),

20.18 (2 CH₃in pinenyl ring), 17.24 (CH₃attached to five-mem-

bered ring), 17.20 (CH₃attached to five-membered ring), –0.78

(CH₃attached to Si), –1.02 (CH₃attached to Si), –1.17 (CH₃at-

tached to Si), –1.38 (CH₃attached to Si) ppm. ²⁹Si NMR

(119.3 MHz, CDCl₃, 25 °C): δ = –8.30, –8.43 ppm. EIMS (70 eV)

calcd. for C₂₂H₃₂Si 324.2273, found 324.2273.

Bis{2-[(7,7-dimethylnorpinanylmethyl)dimethylsilyl](1-methyl)-

indenyl}zirconium Dichlorides [(pR)(pR)-8a, (pS)(pS)-8b, (pR)(pS)-

8c]: To a mixture of 7a/7b (1.2887 g, 4.0 mmol) in diethyl ether

(30 mL) at 0 °C was added nBuLi (2.5 m in n-hexane, 1.6 mL,

4.0 mmol). The yellow solution was stirred at room temperature for

4 h. The reaction mixture was cooled to 0 °C and ZrCl₄(0.4626 g,

2.0 mmol) was added. After stirring the suspension at room tem-

perature for 18 h, the solvents were removed under vacuum. The

residue was dissolved in dichloromethane, filtered and the filtrate

was concentrated. The crude product was purified with silanized

silica gel column chromatography under argon using pentane as

eluent providing 0.8499 g (53%) of a mixture of 8a–c as a yellow

oil. Combination of fractions containing only the racemic-like dia-

stereomers (pR)(pR)-8a and (pS)(pS)-8b yielded 0.2938 g (18%) of

a such mixture. When to this mixture was added cold pentane at

–60 °C a small sample (0.054 g, 3%) of 8a/8b was obtained as yellow

crystals enriched in one of the racemic-like diastereomers in a 57:43

ratio. ¹H NMR (600 MHz, CDCl₃, 25 °C): δ = 7.97 (m, 4 H, arom.

CH in 8a and 8b), 7.59 (m, 4 H, arom. CH in 8a and 8b), 7.33 (m,

4 H, arom. CH in 8a and 8b), 7.20 (m, 4 H, arom. CH in 8a and

8b), 5.14 (m, 2 H, olefinic CH in five-membered ring in 8a and 8b),

5.13 (m, 2 H, olefinic CH in five-membered ring in 8a and 8b), 2.46

(s, 6 H, CH₃attached to five-membered ring in 8a and 8b), 2.45 (s,

6 H, CH₃attached to five-membered ring in 8a and 8b), 1.87 (m,

4 H, CH in pinenyl ring in 8a and 8b), 1.77 (m, 8 H, CH in pinenyl

ring in 8a and 8b), 1.60 (m, 8 H, CH in pinenyl ring in 8a and 8b),

1.49 (m, 4 H, CH in pinenyl ring in 8a and 8b), 1.23 (m, 8 H, CH

in pinenyl ring in 8a and 8b), 1.06 (m, 4 H, CH in pinenyl ring in

8a and 8b), 1.01 (s, 6 H, CH₃attached to pinenyl ring in 8a or 8b),

0.99 (s, 6 H, CH₃attached to pinenyl ring in 8a or 8b), 0.64 (s, 6

H, CH₃attached to pinenyl ring in 8a or 8b), 0.63 (s, 6 H, CH₃

A Diastereomeric Mixture of (6,6-dimethylbicyclo[3.1.1]hept-2-yl-

methyl)dimethyl(1-methyl-1H-inden-2-yl)silanes (7a/7b): To 1^[28]

(3.4065 g, 11.0 mmol) in tetrahydrofuran (50 mL) at 0 °C was

added nBuLi (2.5 m in n-hexane, 4.5 mL, 11.1 mmol). The orange

solution was stirred at room temperature for 3.5 h and to this solu-

tion was added dropwise methyl iodide (1.4 mL, 21.9 mmol) at

0 °C. The resulting red reaction mixture was stirred at room tem-

perature for 1.5 h before saturated aqueous NH₄Cl solution

(50 mL) was added. The layers formed were separated and the

aqueous layer was further extracted with diethyl ether (30 mL). The

combined organic layers were dried with Na₂SO₄, filtered and the

solvents evaporated to dryness. The crude product was purified

with silica gel column chromatography using hexane as eluent pro-

viding 2.6259 g (74%) of 7a/7b (a mixture of two diastereomers) as

a colorless oil. ¹H NMR (600 MHz, CDCl₃, 25 °C): δ = 7.45 (m, attached to pinenyl ring in 8a or 8b), 0.43 (m, 4 H, bridging CH₂

1+1 H, arom. CH), 7.39 (m, 1+1 H, arom. CH), 7.28 (m, 1+1 H, between pinenyl ring and Si in 8a or 8b), 0.35 (m, 4 H, bridging

arom. CH), 7.22 (m, 1+1 H, arom. CH), 7.06 (m, 1+1 H, olefinic

CH₂between pinenyl ring and Si in 8a or 8b), 0.19 (s, 12 H, CH₃

CH in five-membered ring), 3.59 (m, 1+1 H, aliph. CH in five- attached to Si in 8a or 8b), –0.08 (s, 6 H, CH₃attached to Si in 8a

membered ring), 2.21 (m, 1+1 H, CH in pinenyl ring), 2.05 (m, 1+1

H, CH in pinenyl ring), 1.88 (m, 1+1 H, CH in pinenyl ring), 1.74

(m, 3+3 H, CH in pinenyl ring), 1.68 (m, 1+1 H, CH in pinenyl

or 8b), –0.10 (s, 6 H, CH₃attached to Si in 8a or 8b) ppm. ¹³C

NMR (150.9 MHz, CDCl₃, 25 °C): δ = 139.13 (2 C_q), 139.08 (2

C_q), 131.65 (2 C_q), 131.64 (2 C_q), 126.15 (4 arom. CH in 8a and

ring), 1.42 (m, 1+1 H, CH in pinenyl ring), 1.39 (m, 3+3 H, CH₃8b), 125.74 (2 C_q), 125.72 (2 C_q), 125.04 (4 arom. CH in 8a and

attached to five-membered ring), 1.30 (m, 1+1 H, CH in pinenyl

ring), 1.21 (s, 3 H, CH₃in pinenyl ring), 1.20 (s, 3 H, CH₃in pinenyl

ring), 0.85 (m, 1+1 H, bridging CH between Si and pinenyl ring),

0.84 (s, 3 H, CH₃in pinenyl ring), 0.83 (s, 3 H, CH₃in pinenyl

ring), 0.75 (m, 1+1 H, bridging CH between Si and pinenyl ring),

0.28 (m, 6+6 H, CH₃attached to Si) ppm. ¹³C NMR (150.9 MHz,

8b), 124.79 (4 arom. CH in 8a and 8b), 124.52 (4 C_q), 123.96 (2

arom. CH in 8a and 8b), 123.93 (2 arom. CH in 8a and 8b), 106.70

(4 olefinic CH in five-membered ring in 8a and 8b), 48.82 (2 CH

in pinenyl ring in 8a and 8b), 48.79 (2 CH in pinenyl ring in 8a

and 8b), 40.71 (2 CH in pinenyl ring in 8a and 8b), 40.67 (2 CH in

pinenyl ring in 8a and 8b), 39.45 (4 C_qin pinenyl ring in 8a and

CDCl₃, 25 °C): δ = 155.20 (C_q), 155.14 (C_q), 152.51 (C_q), 152.48 8b), 30.96 (2 CH in pinenyl ring in 8a and 8b), 30.87 (2 CH in

(C_q), 144.36 (2 C_q), 140.01 (olefinic CH in five-membered ring), pinenyl ring in 8a and 8b), 26.89 (2 CH₃attached to pinenyl ring

140.00 (olefinic CH in five-membered ring), 126.48 (2 arom. CH),

124.98 (2 arom. CH), 122.58 (2 arom. CH), 120.84 (2 arom. CH), 25.86 (2 CH in pinenyl ring in 8a and 8b), 25.80 (2 CH in pinenyl

49.51 (CH in pinenyl ring), 49.37 (CH in pinenyl ring), 49.33 (aliph. ring in 8a and 8b), 25.05 (2 bridging CH₂between pinenyl ring and

in 8a or 8b), 26.83 (2 CH₃attached to pinenyl ring in 8a or 8b),

1524

www.eurjic.org

Eur. J. Inorg. Chem. 2005, 1514–1529

Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

FULL PAPER

Si in 8a or 8b), 24.96 (2 bridging CH₂between pinenyl ring and Si

in 8a or 8b), 24.86 (4 CH in pinenyl ring in 8a and 8b), 22.95 (2

CH in pinenyl ring in 8a and 8b), 22.92 (2 CH in pinenyl ring in

8a and 8b), 20.00 (2 CH₃attached to pinenyl ring in 8a or 8b),

19.95 (2 CH₃attached to pinenyl ring in 8a or 8b), 13.83 (2 CH₃

attached to five-membered ring in 8a or 8b), 13.80 (2 CH₃attached

to five-membered ring in 8a or 8b), –0.52 (2 CH₃attached to Si in

8a or 8b), –0.86 (2 CH₃attached to Si in 8a or 8b), –1.03 (2 CH₃

attached to Si in 8a or 8b), –1.45 (2 CH₃attached to Si in 8a or

8b) ppm. ²⁹Si NMR (119.3 MHz, CDCl₃, 25 °C): δ = –4.29 (2 Si

in 8a or 8b), –4.31 (2 Si in 8a or 8b) ppm. In the EIMS mass

spectrum parent ions of composition C₄₄H₆₂Cl₂Si₂Zr⁺were ob-

served in the appropriate ratios at m/z = 806–814.

ether (10 mL) at 0 °C was added nBuLi (2.5 m in n-hexane, 660 μL,

1.7 mmol). The pale orange solution was stirred at room tempera-

ture for 4 h. The reaction mixture was cooled to 0 °C and ZrCl₄

(0.2011 g, 0.9 mmol) was added. After stirring the suspension at

room temperature for 20 h, the solvent was removed under vacuum.

The residue was dissolved in dichloromethane, filtered and the fil-

trate was evaporated. The residue was dried in vacuo and the crude

product was analyzed with 600 MHz ¹H NMR spectroscopy. ¹H

NMR (600 MHz, CDCl₃, 25 °C): δ = 7.71 (m, 4 H, arom. CH in

10a and/or 10b and/or 10c), 7.54 (m, 4 H, arom. CH in 10a and/

or 10b and/or 10c), 7.47 (m, 4 H, arom. CH in 10a and/or 10b and/

or 10c), 7.38 (m, 2 H, arom. CH in 10a and/or 10b and/or 10c),

7.29 (m, 2 H, arom. CH in 10a and/or 10b and/or 10c), 7.22 (m, 8

H, arom. CH in 10a and/or 10b and/or 10c), 6.41 (m, 2 H, olefinic

CH in five-membered ring in 10a and/or 10b and/or 10c), 5.92 (m,

4 H, olefinic CH in five-membered ring in 10a and/or 10b and/or

10c), 2.51 (m, 6 H, CH₃attached to five-membered ring in 10a and/

or 10b and/or 10c), 2.31 (m, 12 H, CH₃attached to five-membered

ring in 10a and/or 10b and/or 10c), 1.10 (m, 18 H, CH₃in pinenyl

ring in 10a and/or 10b and/or 10c), 0.72 (m, 12 H, bridging CH

between Si and pinenyl ring in 10a and/or 10b and/or 10c), 0.64

(m, 18 H, CH₃in pinenyl ring in 10a and/or 10b and/or 10c), 0.38

(m, 36 H, CH₃attached to Si in 10a and/or 10b and/or 10c), 1.95–

1.12 (m, 54 H, aliph. CH in pinenyl ring in 10a and/or 10b and/or

10c), signals from the aliph. protons in pinenyl ring in 10a, 10b and

10c are overlapping with each other and other signals in the region

1.95–1.12 ppm. From the Cp-H (5.92, 6.28 and 6.41 ppm) and Cp-

CH₃signals (2.21, 2.31 and 2.51 ppm) it could be calculated that

the amount of the mixture of formed metallocenes was approxi-

mately 70%.

A Diastereomeric Mixture of (6,6-Dimethylbicyclo[3.1.1]hept-2-yl-

methyl)dimethyl(3-methyl-1H-inden-1-yl)silanes (9a/9b): To meth-

ylindene^[55](2.1064 g, 16.2 mmol) in tetrahydrofuran (20 mL) at

0 °C was added nBuLi (2.5 m in n-hexane, 6.6 mL, 16.3 mmol). The

brownish green solution was stirred at room temperature for 4 h.

The lithium salt was the added dropwise at 0 °C to a solution of

the chiral chlorosilane (3.9218 g, 17.0 mmol) in tetrahydrofuran

(10 mL). The resulting orange reaction mixture was stirred at room

temperature for 2 h before saturated aqueous NH₄Cl solution

(50 mL) was added. The layers formed were separated and the

aqueous layer was further extracted with diethyl ether (30 mL). The

combined organic layers were dried with Na₂SO₄, filtered and the

solvents evaporated. The crude product was purified with silica gel

column chromatography using hexane as eluent providing 2.7974 g

(53%) of 9a/9b (a mixture of two diastereomers) as a pale yellow

oil. ¹H NMR (600 MHz, CDCl₃, 25 °C): δ = 7.43 (m, 1+1 H, arom.

CH), 7.40 (m, 1+1 H, arom. CH), 7.28 (m, 1+1 H, arom. CH),

7.19 (m, 1+1 H, arom. CH), 6.30 (m, 1+1 H, olefinic CH in five-

membered ring), 3.38 (m, 1+1 H, aliph. CH in five-membered ring),

2.23 (s, 3+3 H, CH₃attached to five-membered ring), 2.01 (m, 2+2

H, 2 CH in pinenyl ring), 1.01 (m, 1+1 H, CH in pinenyl ring),

1.73 (m, 2+2 H, 2 CH in pinenyl ring), 1.67 (m, 1+1 H, CH in

pinenyl ring), 1.55 (m, 1+1 H, CH in pinenyl ring), 1.32 (m, 2+2

H, 2 CH in pinenyl ring), 1.22 (m, 1+1 H, CH in pinenyl ring),

1.18 (s, 3 H, CH₃in pinenyl ring), 1.17 (s, 3 H, CH₃in pinenyl

ring), 0.79 (s, 3 H, CH₃in pinenyl ring), 0.78 (s, 3 H, CH₃in pinenyl

ring), 0.53 (m, 1+1 H, bridging CH between Si and pinenyl ring),

0.45 (m, 1+1 H, bridging CH between Si and pinenyl ring), –0.00

(s, 3 H, CH₃attached to Si), –0.04 (s, 3 H, CH₃attached to Si),

–0.07 (s, 3 H, CH₃attached to Si), –0.11 (s, 3 H, CH₃attached to

Si) ppm. ¹³C NMR (150.9 MHz, CDCl₃, 25 °C): δ = 146.23 (2 C_q),

145.38 (2 C_q), 137.03 (2 C_q), 130.97 (2 olefinic CH in five-mem-

bered ring), 124.75 (2 arom. CH), 123.66 (2 arom. CH), 122.91 (2

arom. CH), 118.98 (2 arom. CH), 49.45 (CH in pinenyl ring), 49.33

(CH in pinenyl ring), 44.38 (aliph. CH in five-membered ring),

44.36 (aliph. CH in five-membered ring), 40.74 (2 CH in pinenyl

ring), 39.66 (2 C_qin pinenyl ring), 31.76 (CH in pinenyl ring), 31.16

(CH in pinenyl ring), 27.06 (2 CH₃in pinenyl ring), 25.74 (CH₂in

pinenyl ring), 25.62 (CH₂in pinenyl ring), 24.90 (CH₂in pinenyl

ring), 24.88 (CH₂in pinenyl ring), 23.08 (2 CH₂in pinenyl ring),

22.77 (bridging CH₂between Si and pinenyl ring), 22.70 (bridging

CH₂between Si and pinenyl ring), 20.16 (2 CH₃in pinenyl ring),

13.09 (2 CH₃attached to five-membered ring), –2.54 (CH₃attached

to Si), –2.74 (CH₃attached to Si), –2.80 (CH₃attached to Si),

–3.03 (CH₃attached to Si) ppm. ²⁹Si NMR (119.3 MHz, CDCl₃,

25 °C): δ = –4.13 (2 Si) ppm. EIMS (70 eV) calcd. for C₂₂H₃₂Si

324.2273, found 324.2275.

Mixture of a Diastereomeric Mixture of 2-[6,6-(Dimethylbicy-

clo[3.1.1]hept-2-ylmethyl)dimethylsilyl]-1-trimethylsilyl-1H-indenes

(11a/11b) and 2-[(6,6-dimethylbicyclo[3.1.1]hept-2-ylmethyl)dimeth-

ylsilyl]-3-trimethylsilyl-1H-indene (12): To 1 (3.3786 g, 10.9 mmol)

in tetrahydrofuran (40 mL) at 0 °C was added nBuLi (2.5 m in n-

hexane, 4.4 mL, 11.0 mmol). The orange solution was stirred at

room temperature for 3 h and to this solution was added dropwise

chlorodimethylsilane (1.4 mL, 10.9 mmol) in tetrahydrofuran

(10 mL) at 0 °C. The resulting brownish-orange reaction mixture

was stirred at room temperature for 1.5 h before saturated aqueous

NH₄Cl solution (50 mL) was added. The layers formed were sepa-

rated and the aqueous layer was further extracted with diethyl ether

(30 mL). The combined organic layers were dried with Na₂SO₄,

filtered and the solvents evaporated to dryness. The crude product

was purified with silica gel column chromatography using hexane

as eluent providing 2.9362 g (71%) of a mixture of 11a/11b (a mix-

ture of two diastereomers) and 12 as an orange oil. The chemical

1

shifts are largely overlapping both in the H NMR and in the ¹³C

NMR spectrum. ¹H NMR (600 MHz, CDCl₃, 25 °C): δ = 7.53–

6.70 (m, 14 H, arom. CH in six-membered ring and olefinic CH in

five-membered ring in 11a, 11b and 12), 3.77–3.49 (m, 4 H, aliph.

CH in five-membered ring in 11a, 11b and 12), 2.06–1.30 (m, 27

H, aliph. CH in pinenyl ring in 11a, 11b and 12), 1.20 (m, 9 H,

CH₃in pinenyl ring in 11a, 11b and 12), 0.95–0.77 (m, 15 H, CH₃

in pinenyl ring in 11a, 11b and 12 and bridging CH between Si and

pinenyl ring in 11a, 11b and 12), 0.32 (m, 18 H, CH₃attached to

Si in 11a, 11b and 12), 0.05 (m, 27 H, CH₃attached to Si in 11a,

11b and 12) ppm. ¹³C NMR (150.9 MHz, CDCl₃, 25 °C): δ =

151.09, 150.95, 149.14, 148.99, 144.83 (10 overlapping C_qin 11a,

11b and 12), 140.26–140.07 and 124.77–120.78 (12 arom. CH in

six-membered ring and 2 olefinic CH in five-membered ring in 11a,

Bis{3-[(7,7-Dimethylnorpinanylmethyl)dimethylsilyl]-1-methyl-

indenyl}zirconium Dichlorides [(pR)(pR)-10a, (pS)(pS)-10b, (pR) 11b and 12), 51.21–48.71 (aliph. CH in pinenyl ring in 11a, 11b

(pS)-10c]: To a mixture of 9a/9b (0.5294 g, 1.6 mmol) in diethyl and 12), 40.77–40.64 (aliph. CH in pinenyl ring in 11a, 11b and

Eur. J. Inorg. Chem. 2005, 1514–1529

www.eurjic.org

1525

S. Silver, A. Puranen, R. Sjöholm, T. Repo, R. Leino

12), 39.68–39.58 (C_qin 11a, 11b and 12), 31.39–30.65 (aliph. CH pinenyl ring in 15a, 15b, 16a and 16b), 27.07 (4 CH₃in pinenyl ring

FULL PAPER

in pinenyl ring in 11a, 11b and 12), 27.04 (CH₃in pinenyl ring in

11a, 11b and 12), 24.93–22.79 (aliphtic CH in pinenyl ring in 11a,

11b and 12), 20.17–20.08 (CH₃in pinenyl ring in 11a, 11b and 12),

0.74 – (–2. 42) (CH₃attached to Si in 11a, 11b and 12) ppm. EIMS

(70 eV) calcd. for C₂₄H₃₈Si₂382.2512, found 382.2510.

in 15a, 15b, 16a and 16b), 25.89–22.56 (12 overlapping CH₂in pi-

nenyl ring in 15a, 15b, 16a and 16b), 20.18 (4 CH₃in pinenyl ring

in 15a, 15b, 16a and 16b), –0.66 – (–3.09) (20 overlapping CH₃

attached to Si in 15a, 15b, 16a and 16b). EIMS (70 eV) calcd. for

C₂₄H₃₈Si₂382.2512, found 382.2518.

Mixture of [2-({[(1S,2S5S)-6,6-Dimethylbicyclo[3.1.1]hept-2-yl]-

methyl}dimethylsilyl)indenyl]titanium Trichloride (13) and [1-(Tri-

methylsilyl)indenyl]titanium Trichlorides (14a and 14b): To a solu-

tion of a mixture of 11a, 11b and 12 (0.6153 g, 1.6 mmol) in dichlo-

romethane (4 mL) at –78 °C was added TiCl₄·DCM (1.6 mL,

1.6 mmol) in drops. The resulting dark red reaction mixture was

gradually warmed to room temperature and after stirring the reac-

tion mixture at room temperature for 19 h the solvent was removed.

The reaction product was crystallized from n-pentane at –78 °C

yielding a 1:1:1 mixture of 13, 14a and 14b as a black solid. ¹H

NMR (250 MHz, CDCl₃, 25 °C): δ = 7.79 (m, 6 H, arom. CH in

13 and/or 14a and/or 14b), 7.51 (m, 6 H, arom. CH in 13 and/or

14a and/or 14b), 7.37 (6 H, olefinic CH in five-membered ring in

13, 14a and 14b), 2.12 (m, 1 H, aliph. CH in pinenyl ring in 13),

1.99 (m, 1 H, aliph. CH in pinenyl ring in 13), 1.84 (m, 1 H, aliph.

CH in pinenyl ring in 13), 1.75 (m, 2 H, aliph. CH in pinenyl ring

in 13), 1.87 (m, 3 H, aliph. CH in pinenyl ring in 13), 1.33 (m, 1

H, aliph. CH in pinenyl ring in 13), 1.12 (s, 3 H, CH₃in pinenyl

ring in 13), 0.85 (m, 2 H, bridging CH₂between Si and pinenyl

ring in 13), 0.76 (s, 3 H, CH₃in pinenyl ring in 13), 0.46 (m, 24 H,

CH₃attached to Si in 13, 14a and 14b).

Mixture of {1-{{[(1S,2S5S)-6,6-Dimethylbicyclo[3.1.1]hept-2-yl]-

methyl}dimethylsilyl}indenyl}titanium Trichloride (17a and 17b) and

[1-(Trimethylsilyl)indenyl]titanium Trichlorides (14a and 14b): To a

solution of a mixture of 15a, 15b, 16a and 16b (0.6045 g, 1.6 mmol)

in dichloromethane (4 mL) at –78 °C was added TiCl₄·DCM

(1.6 mL, 1.6 mmol) in drops. The resulting dark red reaction mix-

ture was gradually warmed into room temperature and after stir-

ring the reaction mixture at room temperature for 19 h the solvent

was removed. The crude product was analyzed with ¹H NMR

(600 MHz, CDCl₃, 25 °C): δ = 7.90, 7.82, 7.57, 7.46, 7.38, 7.22 (m,

12 H, overlapping signals from aromatic CH in 17a and 17b and

olefinic CH in five-membered ring in 17a and 17b), 7.82 (m, 4 H,

arom. CH in 14a and 14b), 7.53 (m, 4 H, arom. CH in 14a and

14b), 7.38 (m, 4 H, olefinic CH in five-membered ring in 14a and

14b), 2.21–1.24 (m, 18 H, overlapping signals from aliph. CH in

pinenyl ring in 17a and 17b), 1.18 (s, 3 H, CH₃in pinenyl ring in

17a or 17b), 1.12 (m, 3 H, CH₃in pinenyl ring in 17a or 17b), 0.88

(m, 4 H, bridging CH₂between Si and pinenyl ring in 17a or 17b),

0.82 (s, 3 H, CH₃in pinenyl ring in 17a or 17b), 0.73 (m, 3 H, CH₃

in pinenyl ring in 17a or 17b), 0.52 (m, 24 H, CH₃attached to Si

in 17a, 17b, 14a and 14b), 0.40 (m, 6 H, CH₃attached to Si in 17a

and 17b) ppm.

Mixture of Diastereomeric Mixtures of 3-[(6,6-Dimethylbicy-

clo[3.1.1]hept-2-ylmethyl)dimethylsilyl]-1-trimethylsilyl-1H-indenes

(15a/15b) and 1-[(6,6-Dimethylbicyclo[3.1.1]hept-2-ylmethyl)dimeth-

ylsilyl]-3-trimethylsilyl-1H-indenes (16a/16b): To a diastereomeric

mixture of 1-[dimethyl(7,7-dimethylnorpinanylmethyl)silyl]indene

(4a/4b) (2.9742 g, 9.6 mmol) in tetrahydrofuran (30 mL) at 0 °C was

added nBuLi (2.5 m in n-hexane, 3.9 mL, 9.7 mmol). The orange

solution was stirred at room temperature for 3 h and to this solu-

tion was added dropwise chlorodimethylsilane (1.3 mL, 9.6 mmol)

in tetrahydrofuran (8 mL) at 0 °C. The resulting yellowish-brown

(6,6-Dimethylbicyclo[3.1.1]hept-2-en-2-ylmethyl)-(1H-inden-2-yl)di-

methylsilane (22): To α-pinene potassium salt (4.4 mmol) in α-pi-

nene (2.1 mL, 13.1 mmol) were added THF (2 mL) and 2-(chloro-

dimethylsilyl)indene (21) (0.9141g, 4.4 mmol) in THF (2 mL) at

–72 °C. The resulting brown reaction mixture was taken into room

temperature and stirred for 1 h before saturated aqueous NH₄Cl

solution (50 mL) was added. The layers formed were separated and

the aqueous layer was further extracted with diethyl ether (30 mL).

reaction mixture was stirred at room temperature for 1.5 h before The combined organic layers were dried with Na₂SO₄, filtered and

saturated aqueous NH₄Cl solution (50 mL) was added. The layers

formed were separated and the aqueous layer was further extracted

with diethyl ether (30 mL). The combined organic layers were dried

with Na₂SO₄, filtered and the solvents evaporated to dryness. The

crude product was purified with silica gel column chromatography

using hexane as eluent providing 2.3547g (76%) of a mixture of the

diastereomeric mixtures 15a/15b and 16a/16b as an orange oil. The

chemical shifts are largely overlapping both in the ¹H NMR and

the solvents evaporated. The excess α-pinene was separated from

the crude product by distillation under reduced pressure. The resi-

due was further purified with silica gel column chromatography

using hexane as eluent providing 0.0378 g (3%) of 22 as a colorless

1

oil. H NMR (600 MHz, CDCl₃, 25 °C): δ = 7.49 (m, 1 H, arom.

CH), 7.41 (m, 1 H, arom. CH), 7.28 (m, 1 H, arom. CH), 7.19 (m,

1 H, arom. CH), 7.12 (m, 1 H, olefinic CH in five-membered ring),

5.06 (m, 1 H, olefinic CH in pinenyl ring), 3.46 (m, 2 H, aliph. CH₂

in pinenyl ring), 2.35 (m, 1 H, aliph. CH in pinenyl ring), 2.22 (m,

2 H, 2 aliph. CH in pinenyl ring), 2.06 (m, 1 H, aliph. CH in

pinenyl ring), 1.93 (m, 1 H, aliph. CH in pinenyl ring), 1.77 (d, J

= 14.9 Hz, 1 H, aliph. CH between Si and pinenyl ring), 1.61 (d, J

= 14.9 Hz, 1 H, aliph. CH between Si and pinenyl ring), 1.25 (s, 3

H, CH₃in pinenyl ring), 1.18 (d, J = 9.1 Hz, 1 H, aliph. CH in

pinenyl ring), 0.88 (s, 3 H, CH₃in pinenyl ring), 0.24 (s, 3 H, CH₃

attached to Si), 0.23 (s, 3 H, CH₃attached to Si) ppm. ¹³C NMR

(150.9 MHz, CDCl₃, 25 °C): δ = 148.60 (C_q), 146.92 (C_q), 145.76

1

in the ¹³C NMR spectrum. H NMR (600 MHz, CDCl₃, 25 °C): δ

= 7.56–7.18 (m, 16 H, arom. CH in 15a, 15b, 16a and 16b), 6.93–

6.67 (m, 4 H, olefinic CH in five-membered ring in 15a, 15b, 16a

and 16b), 3.62–3.43 (m, aliph. CH in five-membered ring in 15a,

15b, 16a and 16b), 2.23–1.30 (m, 36 H, aliph. CH in pinenyl ring

in 15a, 15b, 16a and 16b), 1.16 (m, 12 H, CH₃in pinenyl ring in

15a, 15b, 16a and 16b), 0.83 (m, 8 H, CH₂bridging between Si and

pinenyl ring in 15a, 15b, 16a and 16b), 0.78 (m, 12 H, CH₃in

pinenyl ring in 15a, 15b, 16a and 16b), 0.33 (m, 24 H, CH₃attached

to Si in 15a, 15b, 16a and 16b), –0.04 (m, 36 H, CH₃attached to (C_q), 145.22 (C_q), 141.16 (olefinic CH in five-membered ring),

Si in 15a, 15b, 16a and 16b) ppm. ¹³C NMR (150.9 MHz, CDCl₃,

25 °C): δ = 147.65, 146.58, 141.57 (12 overlapping C_qin 15a, 15b,

16a and 16b), 145.73–145.58 (4 overlapping olefinic CH in five-

membered ring in 15a, 15b, 16a and 16b), 124.88–121.13 (16 over-

lapping aromatic CH in 15a, 15b, 16a and 16b), 49.48–46.44, 40.81–

40.74, 31.50–31.14 (16 overlapping aliph. CH in five-membered

ring and in pinenyl ring in 15a, 15b, 16a and 16b), 39.69 (4 C_qin

126.37 (arom. CH), 124.83 (arom. CH), 123.77 (arom. CH), 120.95

(arom. CH), 114.69 (olefinic CH in pinenyl ring), 48.27 (aliph. CH

in pinenyl ring), 42.67 (aliph. CH₂in five-membered ring), 40.68

(aliph. CH in pinenyl ring), 38.07 (C_q), 31.96 (aliph. CH₂in pinenyl

ring), 31.52 (aliph. CH₂in pinenyl ring), 27.33 (aliph. CH₂between

Si and pinenyl ring), 26.63 (CH₃in pinenyl), 21.42 (CH₃in pi-

nenyl), –2.06 (CH₃attached to Si), –2.23 (CH₃attached to Si) ppm.

1526

www.eurjic.org

Eur. J. Inorg. Chem. 2005, 1514–1529

Chiral Bis(indenyl)zirconium Dichlorides Containing β-Pinenyl-Derived Ligand Substituents

FULL PAPER

²⁹Si NMR (119.3 MHz, CDCl₃, 25 °C): δ = –9.39 ppm. EIMS nenyl ring in 24a or 24b), 48.20 (aliph. CH in pinenyl ring in 24a

(70 eV) calcd. for C₂₁H₂₈Si 308.1960, found 308.1965.

or 24b), 45.73 (aliph. CH in five-membered ring in 24a or 24b),

45.72 (aliph. CH in five-membered ring in 24a or 24b), 40.86 (aliph.

CH₂in five-membered ring in 25), 40.65 (aliph. CH in pinenyl ring

in 24a or 24b), 40.63 (aliph. CH in pinenyl ring in 24a or 24b),

38.00 (C_qin 24a and 24b), 37.97 (C_qin 25), 31.97 (aliph. CH₂in

pinenyl ring in 24a or 24b), 31.94 (aliph. CH₂in pinenyl ring in

24a or 24b), 31.56 (aliph. CH₂in pinenyl ring in 24a and 24b),

26.85 (aliph. CH₂between Si and pinenyl ring in 25), 26.61 (CH₃

in pinenyl ring in 24a, 24b and 25), 25.85 (aliph. CH₂between Si

and pinenyl ring in 24a or 24b), 25.79 (aliph. CH₂between Si and

pinenyl ring in 24a or 24b), 21.41 (CH₃in pinenyl ring in 24a, 24b

and 25), –2.10 (CH₃attached to Si in 25), –2.45 (CH₃attached to

Si in 25), –3.56 (CH₃attached to Si in 24a or 24b), –3.65 (CH₃

attached to Si in 24a or 24b), –3.88 (CH₃attached to Si in 24a or

24b), –3.97 (CH₃attached to Si in 24a or 24b). Almost all signals

from the aliph. carbons in pinenyl ring (except signal from quater-

nary carbon) in 25 are overlapping with signals from 24a/24b and

the chemical shifts of these overlapping signals are not listed here

ppm. ²⁹Si NMR (119.3 MHz, CDCl₃, 25 °C): δ = 3.13 (Si in 24a

or 24b), 3.09 (Si in 24a or 24b), –10.08 (Si in 25) ppm. EIMS

(70 eV) calcd. for C₂₁H₂₈Si 308.1960, found 308.1965.

Mixture of

a Diastereomeric Mixture of (6,6-Dimethylbicy-

clo[3.1.1]hept-2-en-2-ylmethyl)-(1H-inden-1-yl)dimethylsilanes (24a/

24b) and (6,6-Dimethylbicyclo[3.1.1]hept-2-en-2-ylmethyl)-(3H-in-

den-1-yl)dimethylsilane (25): To α-pinene potassium salt

(20.6 mmol) in α-pinene (9.8 mL, 62.0 mmol) were added THF

(20 mL) and a diastereomeric mixture of 1-(chlorodimethylsilyl)in-

denes (23a/23b) (0.9141g, 4.4 mmol) in THF (40 mL) at –72 °C.

The resulting dark brown reaction mixture was taken into room

temperature and stirred there for 2 h before saturated aqueous

NH₄Cl solution (70 mL) was added. The layers formed were sepa-

rated and the aqueous layer was further extracted with diethyl ether

(50 mL). The combined organic layers were dried with Na₂SO₄,

filtered and the solvents evaporated. The residue was purified with

silica gel column chromatography using hexane as eluent. The ob-

tained yellow oil still contained some α-pinene, which was sepa-

rated by distillation under reduced pressure. The yellow residue

provided 1.3523 g (21%) of a mixture of diastereomers 24a/24b and

25. The amount of the minor product 25 was 15 %. ¹H NMR

(600 MHz, CDCl₃, 25 °C): δ = 7.67 (m, 1 H, arom CH in 25), 7.62

(m, 5 H, arom. CH in 24a, 24b and 25), 7.43 (m, 1 H, arom. CH

in 25), 7.39 (m, 2 H, arom. CH in 24a and 24b or 2 arom. CH in

24a or 24b), 7.32 (m, 3 H, arom. CH in 24a and 24b or 2 arom.

CH in 24a or 24b and arom. CH in 25), 7.07 (m, 2 H, olefinic CH

in five-membered ring in 24a and 24b), 6.90 (m, 1 H, olefinic CH

in five-membered ring in 25), 6.81 (m, 2 H, olefinic CH in five-

membered ring in 24a and 24b), 5.22 (m, 3 H, olefinic CH in pi-

nenyl ring in 24a, 24b and 25), 3.71 (m, 2 H, aliph. CH in five-

membered ring in 24a and 24b), 3.54 (m, 2 H, aliph. CH₂in five-

membered ring in 25), 2.51 (m, 2 H, aliph. CH in pinenyl in 24a

and 24b), 2.46 (m, 1 H, aliph. CH in pinenyl in 25), 2.39 (m, 4 H,

aliph. CH₂in pinenyl in 24a and 24b), 2.23 (m, 2 H, aliph. CH in

pinenyl in 24a and 24b), 2.05 (m, 3 H, aliph. CH in pinenyl in 24a

and 24b and aliph. CH between Si and pinenyl ring in 25), 1.86

(m, 1 H, aliph. CH between Si and pinenyl ring in 25), 1.76 (d, J

= 13.5 Hz, 1 H, aliph. CH between Si and pinenyl ring in 24a or

24b), 1.71 (d, J = 13.5 Hz, 1 H, aliph. CH between Si and pinenyl

ring in 24a or 24b), 1.59 (d, J = 13.5 Hz, 1 H, aliph. CH between

Si and pinenyl ring in 24a or 24b), 1.53 (d, J = 13.5 Hz, 1 H, aliph.

CH between Si and pinenyl ring in 24a or 24b), 1.42 (s, 9 H, CH₃

in pinenyl ring 24a, 24b and 25), 1.35 (m, 4 H, 2 aliph. CH in

pinenyl ring in 24a and 24b), 1.06 (s, 9 H, CH₃in pinenyl ring 24a,

24b and 25), 0.49 (s, 6 H, CH₃attached to Si in 25), 0.13 (s, 3 H,

CH₃attached to Si in 24a or 24b), 0.10 (s, 3 H, CH₃attached to

Si in 24a or 24b), 0.04 (s, 3 H, CH₃attached to Si in 24a or 24b),

0.01 (s, 3 H, CH₃attached to Si in 24a or 24b). Almost all signals

from the aliph. protons in pinenyl ring (except signal from one CH)

in 25 are overlapping with signals from 24a/24b and the chemical

shifts of these overlapping signals are not listed here ppm. ¹³C

NMR (150.9 MHz, CDCl₃, 25 °C): δ = 148.11 (C_qin 25), 145.34

(C_qin 24a or 24b), 145.30 (C_qin 24a or 24b), 145.11 (C_qin 25),

144.73 (C_qin 24a or 24b), 144.67 (C_qin 24a or 24b and olefinic

CH in five-membered ring in 25), 144.60 (C_qin 25), 144.53 (C_qin

25), 144.33 (C_qin 24a or 24b), 144.27 (C_qin 24a or 24b), 135.60

(olefinic CH in five-membered ring in 24a and 24b), 129.12 (olefinic

CH in five-membered ring in 24a or 24b), 129.09 (olefinic CH in

five-membered ring in 24a or 24b), 126.16 (arom. CH in 25), 124.92

(arom. CH in 24a and 24b), 124.36 (arom. CH in 25), 123.83 (arom.

Dehydropolymerization of Phenylsilane. General Procedure: A tube

was charged with 1 mol-% of the metallocene catalyst, evacuated

and backfilled with argon. Phenylsilane was added by syringe and

the reaction mixture was degassed three times. The catalyst was

activated at room temperature by addition of 2 mol-% of nBuLi.

The reaction mixture was stirred at room temperature for 24 h.

The formed viscous solution was dissolved in tetrahydrofuran and

filtered through kiselguhr. The filtrate was concentrated in vacuo

to leave the polysilane. The polymer obtained was analyzed by GC-

1

MS, H NMR, ²⁹Si{¹H} NMR and GPC.

Polymerization of Phenylsilane with [Cp₂ZrCl₂]: By applying the ge-

neral procedure, [Cp₂ZrCl₂] (0.0111 g, 0.04 mmol), nBuLi (31 μL,

0.08 mmol) and phenylsilane (480 μL, 3.86 mmol) gave 0.41 g

(98%) of polysilane as a yellow, highly viscous oil.

Polymerization of Phenylsilane with 2: By applying the general pro-

cedure, 2 (0.0943 g, 0.12 mmol), nBuLi (97 μL, 0.24 mmol) and

phenylsilane (1.5 mL, 12.1 mmol) gave 1.26 g (97%) of polysilane

as a yellow oil.

Polymerization of Phenylsilane with 3: By applying the general pro-

cedure, 3 (0.060 g, 0.08 mmol), nBuLi (62 μL; 0,16 mmol) and

phenylsilane (950 μL, 7.64 mmol) gave 0.38 g (46%) of polysilane

as a pale yellow oil.

Polymerization of Phenylsilane with (pR)(pS)-5c: By applying the

general procedure, (pR)(pS)-5c (0.0261 g, 0.03 mmol), nBuLi

(27 μL, 0.07 mmol) and phenylsilane (420 μL, 3.34 mmol) gave

0.33 g (90%) of polysilane as a yellow oil.

Polymerization of Phenylsilane with (pR)(pS)-6c: By applying the

general procedure, (pR)(pS)-6c (0.0125 g, 0.02 mmol), nBuLi

(13 μL, 0.03 mmol) and phenylsilane (198 μL, 1.59 mmol) gave

0.04 g (25%) of polysilane as a yellow oil.

Polymerization of Ethylene and Propylene: The olefin polymeriza-

tion reactions were performed in a steel reactor rinsed with 200 mL

of a 0.3% methylaluminoxane (MAO) solution in toluene prior to

use. After evacuation of the steel reactor, 200 mL of dry toluene

was cannulated in. MAO was added to the reactor by syringe. The

CH in 25), 123.77 (arom. CH in 24a and 24b), 122.87 (arom. CH system was saturated with the gas (monomer) and after complete

in 24a and 24b), 122.16 (arom. CH in 25), 121.17 (arom. CH in

24a and 24b), 115.13 (olefinic CH in pinenyl ring in 24a and 24b),

saturation and thermal equilibrium of the system (50 °C) the poly-

merization was started by adding the prepared catalyst solution (in

114.72 (olefinic CH in pinenyl ring in 25), 48.25 (aliph. CH in pi- toluene) to the reactor. Gas (monomer) was continuously added

Eur. J. Inorg. Chem. 2005, 1514–1529

S. Silver, A. Puranen, R. Sjöholm, T. Repo, R. Leino

FULL PAPER

and the pressure was kept constant during the polymerization reac-

tion and the gas consumption was monitored. The polymerization

was quenched by adding the reaction mixture to a dilute hydrochlo-

ric acid/methanol mixture. The produced polyethylene, which was

insoluble in toluene, was washed with a dilute hydrochloric acid/

methanol mixture, filtered, washed further with methanol, filtered

and dried at 60 °C overnight. The polypropylene produced was

mixed with a dilute hydrochloric acid/methanol mixture and the

formed layers were separated and the polypropylene was further

washed two times with methanol. The oily polypropylene obtained

was dried under vacuum.

Acknowledgments

Financial support from the Neste Research Foundation is grate-

fully acknowledged. We also thank Mr. Markku Reunanen, Mrs.

Päivi Pennanen, Mr. Mattias Roslund, Mr. Esa Kokko and Mr.

Mikko Lankinen for their assistance with the ESIMS, EIMS, NMR

and GPC-analyses.

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6270–6271.

Methyl- and Ethyl- Carboalumination of 1-Octene. General Pro-

cedure: In a glove box, trimethylaluminum or triethylaluminum was

placed in a reaction vessel followed by addition of a catalyst solu-

tion in dichloromethane (3 mL) under argon atmosphere. To this

mixture was then added 1-octene and the reaction mixture was

stirred at room temperature for 19 h. After cooling to 0 °C, oxygen

was bubbled through the solution until all volatiles were evapo-

rated. The resulting yellow oil was treated with 15% aqueous

NaOH solution and extracted with diethyl ether (40 mL). The or-

ganic layer was dried with NaSO₄, filtered and the solvents evapo-

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Synthesis of 2-Methyl-1-octanol Using 2 or (pR)(pS)-5c: By apply-

ing the general procedure, 1-octene (157 μL, 1 mmol), trimethylalu-

minum (96 μL, 1 mmol) and 2 (0.0623 g, 0.08 mmol) or (pR)(pS)-

5c (0.0623 g, 0.08 mmol) gave after purification by column

chromatography 2-methyl-1-octanol as a colorless oil in 8%

(11.7 mg) and 18% (26.2 mg) yields, respectively. ¹H NMR

(600 MHz, CDCl₃, 25 °C): δ = 3.49 (m, 1 H, CH next to OH), 3.40

(m, 1 H, CH next to OH), 2.03 (br. s, 1 H, OH), 1.60 (m, 1 H,

CH), 1.38 (m, 2 H, 2 CH), 1.25 (m, 7 H, 3 CH₂and CH), 1.08 (m,

1 H, CH), 0.90 (d, J = 6.7 Hz, 3 H, CH₃), 0.86 (t, J = 6.9 Hz, 3 H,

CH₃) ppm. ¹³C NMR (150.9 MHz, CDCl₃, 25 °C): δ = 68.64 (CH₂–

OH), 35.98 (CH), 33.23 (CH₂), 31.96 (CH₂), 29.71 (CH₂), 27.04

(CH₂), 22.88 (CH₂), 16.69 (CH₃), 14.29 (CH₃). EIMS (30eV) calcd.

for C₁₉H₂₀O 144.1514, found 144.1499 (reaction using 2), found

144.1487 (reaction using (pR)(pS)-5c). Enantiomeric excesses were

determined from the ¹H NMR spectra of the esters formed with

(S)-(+)-MTPA-Cl using a literature procedure.^[54]For the reaction

catalyzed by complex 2: ee = 0.5%, [α]²_D⁴= +0.09 (c = 0.0117 g/mL

CHCl₃). For the reaction catalyzed by (pR)(pS)-5c: ee = 3%, [α]²_D⁴

= –0.6 (c = 0.0120 g/mL CHCl₃).

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1529

Article Doi

Chiral indenes and group-4 metallocene dichlorides containing α- And β-pinenyl-derived ligand substituants: Synthesis and catalytic applications in polymerization and carboalumination reactions

DOI: 10.1002/ejic.200400882

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