Group 4 metallocenes bearing η5-2-(iv-azolyl)indenyl ligands: synthesis, structure characterization, and olefin polymerization catalysis

1800

Organometallics 2009, 28, 1800–1816

Group 4 Metallocenes Bearing η⁵-2-(N-Azolyl)indenyl Ligands:

Synthesis, Structure Characterization, and Oleﬁn Polymerization

Catalysis

Artem Y. Lebedev,^†Vyatcheslav V. Izmer,^†Andrey F. Asachenko,^†Alexey A. Tzarev,^†

Dmitry V. Uborsky,^†Yuliya A. Homutova,^†Elizar R. Shperber,^†Jo Ann M. Canich,^‡and

Alexander Z. Voskoboynikov*^,†

Department of Chemistry, Moscow State UniVersity, Leninskie Gory, 1/3, Moscow, GSP-1, 119991,

Russian Federation, and ExxonMobil Chemical Company, 5200 Bayway DriVe, Baytown, Texas 77520

ReceiVed October 24, 2008

The Pd-catalyzed cross-coupling reactions of readily available 2-bromo-1H-indene with 1H-pyrrole,

1H-indole, 9H-carbazole, and their derivatives were shown to be convenient methods to obtain novel

ligands containing azole fragments bonded with cyclopentadienyl via nitrogen. An alternative protocol

using enol triﬂates of 1-indanone or 2-indanone is also useful, particularly for synthesizing indenes bearing

the N-azolyl fragment in position 1. On the other hand, the synthesis of 2-(1H-benzimidazol-1-yl)-1H-

indene can be achieved via the Cu-catalyzed reactions only. The substituted indenes with the N-azolyl

fragment in position 2 were further used for obtaining several semisandwich complexes of zirconium,

[η⁵-2-(N-azolyl)indenyl]zirconium tribromides, as well as symmetrical and unsymmetrical Waymouth-

type zirconium and hafnium complexes containing indenyl ligands bearing planar N-azolyl or aryl fragments

in position 2. These metallocenes were unambiguously characterized, including by X-ray crystal structure

analysis, and a study of the ﬂuxional behavior of several Waymouth-type complexes in solution was

carried out by NMR spectroscopy. Finally, novel Waymouth-type complexes, after being activated by

MAO, were found to form active catalysts of ethylene homopolymerization and ethylene/1-octene

copolymerization.

developed an effective process leading to ePP using a metal-

locene catalyst involving an unbridged complex of type A (M

) Zr, Hf; X ) halogen, hydrocarbyl) activated by MAO.^4a-c

In the latter case, the detailed analysis of the ePP structure

performed by Busico et al.^4dusing high-ﬁeld ¹³C NMR

spectroscopy gave some insight into the polymerization mech-

anism and reveled a particular role of the conformationally

“locked” rac-like species. Thus, the bulkiness of the aryl

substituents, propene concentration, reaction temperature, sol-

vent polarity, and nature of the cocatalyst (the counterion effect)

were found to play a crucial roles in the polymer stereoblock

structure.

Introduction

Since the 1950s, a tremendous advance in the stereoselective

polymerization of prochiral oleﬁns, particularly propylene, using

homogeneous and supported catalysts based on the group 4

metallocenes¹has been made. Such catalysts can be used to

produce an unprecedented variety of polyoleﬁn materials. The

most successful efforts in stereoselective oleﬁn polymerization

were directed toward synthesis of isotactic polypropylenes (iPP)

having many industrial applications.²Another promising polypro-

pylene material is a highly stretchable atactic-isotactic stere-

oblock polymer having elastomeric properties: i.e., the so-called

elastomeric polypropylene (ePP). This polymer was ﬁrst de-

scribed by Natta et al. as early as 1957,³with the most

remarkable contribution made by Waymouth et al., who

* To whom correspondence should be addressed. E-mail: voskoboy@

org.chem.msu.ru. Tel.: +7 (495) 939 4764. Fax: +7 (495) 932 8846.

^†Moscow State University.

^‡ExxonMobil Chemical Company.

(1) Metallocenes: Synthesis, ReactiVity, Applications, Togni, A., Hal-

terman, R. L., Eds.; Wiley-VCH: Weinheim, Germany, 1998, and references

therein.

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100, 1253.

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(Milan) 1957, 39, 275. (b) Natta, G. J. Polym. Sci. 1959, 34, 531.

(4) (a) Coates, G. W.; Waymouth, R. M. Science 1995, 267, 217. (b)

Hauptman, E.; Waymouth, R. M.; Ziller, J. W. J. Am. Chem. Soc. 1995,

117, 11586. (c) Lin, S.; Waymouth, R. M. Acc. Chem. Res. 2002, 35, 765,

and references therein. (d) Busico, V. In StereoselectiVe Polymerization

with Single-Site Catalysts; Baugh, L. S., Canich, J. A. M., Eds.; CRC Press:

Boca Raton, FL, 2008; p 203,and references therein. (e) Dreier, T.;

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Wibbeling, B. Organometallics 2000, 19, 4095.

Since the publication of the ﬁrst work of Waymouth et al.,

researchers have obtained a large number of complexes of type

A, including compounds bearing bulky a aryl group in position

2 of the indenyl ligands. An interesting variation, namely the

replacement of aryl by heteroaryl substituents in metallocenes

of type B, was reported by Erker et al.^4e,f5-Methylthien-2-yl-

substituted complexes activated by MAO were used to carry

out propylene polymerization, giving ePP with slightly improved

mechanical properties. However, the respective 1-methylpyrrol-

2-yl-substituted catalyst system was found to behave substan-

tially differently, leading only to the formation of an atactic

propene oligomer, even at -20 °C. Taking into account these

10.1021/om8010257 CCC: $40.75

2009 American Chemical Society

Publication on Web 02/12/2009

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1801

data, one can assume that a catalyst bearing the electron donor

pyrrol-1-yl fragment in position 2 of the indenyl ligands can

show a better performance in ePP synthesis. However, until

recently, it was not clear how to obtain 2-(N-azolyl)indenes for

synthesizing the respective group 4 metal complexes.

In this work, we aimed to study the unbridged metallocenes

of type C (M ) Zr, Hf; X ) Cl, Br) bearing 2-(N-azolyl)indenyl

ligands instead of the geometrically similar 2-arylindenyls as

in the traditional Waymouth-type metallocenes (type A) or

Erker’s heterosubstituted complexes (type B). The difference

2,2′-bis(1H-pyrrol-2-yl)propanes.⁷Other products, including

indolizine, indoles,⁸and pyrroles substituted with R,ꢀ-unsatur-

ated fragments,⁹can be formed in such reactions. Next, 2,5-

dimethyl-1H-pyrrole, as its lithium salt or 1-Me₃Sn derivative,

was found not to react with 2-indanone. However, 2,4-dimethyl-

1H-pyrrole with one free R-site reacts with 2-indanone to form

2-(1H-inden-2-yl)-3,5-dimethyl-1H-pyrrole (3) in almost quan-

titative yield (eq 3). In order to use this product for further

metallocene synthesis, the acidic NH site needed to be methy-

lated. However, methylation of the lithiated derivative lead

instead to a mixture of isomeric 1(3)-Me-substituted indenes

(4) rather than the desired 2-(1H-inden-2-yl)-1,3,5-trimethyl-

1H-pyrrole, probably because the acidities of NH and CH sites

in this compound are comparable while the nucleophilicity of

the carbanion is undoubtedly much higher than that of the

pyrrolyl anion. The well-known pathways to N-vinylazoles, such

of electronic effects and geometry of N-azolyl and similarly

substituted aryl fragments is apparently a major factor inﬂuenc-

ing the activity and stereochemistry of the respective catalysts.

However, it should be noted that a detailed study of oleﬁn

polymerization is outside the scope of this paper. Herein, we

describe the synthesis of metallocenes of type C and their

analogues, as well as a structural study of these complexes in

the solid state and solution. Additionally, different approaches

to the desired N-azolyl-substituted indenes, particularly pal-

ladium-catalyzed protocols, are considered in detail.

Results and Discussion

Synthesis of 2-(1H-Pyrrol-1-yl)-, 2-(1H-Indol-1-yl)-, and

2-(9H-Carbazol-9-yl)-1H-indenes via the Pd-Catalyzed

Amination of 2-Bromo-1H-indene. 2-Indanone is known to

react readily with the nucleophilic secondary amines to form

2-R₂N-substituted indenes (eq 1).⁵This approach has been

recently applied for synthesizing metallocene ligands.⁶However,

similar condensation with 1 equiv of the less nucleophilic 1H-

pyrrole gave on reﬂux in toluene a mixture of 2-(1H-inden-2-

yl)-1H-pyrrole (1) and 2,5-bis(1H-inden-2-yl)-1H-pyrrole (2) (eq

2), but not the desired 1-(1H-inden-2-yl)-1H-pyrrole. This result

as addition of azoles to acetylenes¹⁰and the Troﬁmov reaction,¹¹

cannot be used to obtain 2-(N-azolyl)-1H-indenes, since the

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is unremarkable, as the condensation of pyrrole with aldehydes

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bonds. For instance, pyrrole and substituted pyrroles with at

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1802 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

respective acetylenes do not exist. An alternative approach, the

acid-catalyzed dehydration of 2-(N-azolyl)indan-1-ols, can

hardly be expected to be useful. In fact, a few examples of such

elimination were described in the literature¹²because vinylazoles

are apparently not stable under acidic conditions of elimination.

Therefore, the catalytic amination of 2-bromo-1H-indene seems

to be the only appropriate alternative for synthesizing the desired

ligands from azoles. Recently, we have shown that lithium salts

of azoles are the best substrates for Pd-catalyzed vinylation of

azoles.^13-15For instance, indolylpotassium or -sodium and

trans-ꢀ-bromostyrene gave 1-[(E)-2-phenylethenyl]-1H-indole

in very low yield, while indolyllithium gave an almost quantita-

tive yield of this product. However, we have found that a similar

reaction of 1H-indole with 2-bromo-1H-indene in the presence

of Pd(dba)₂/2 o-PhC₆H₄P^tBu₂cannot be performed using in-

dolyllithium as a source of the indolyl fragment, probably

because of transmetalation with 2-bromo-1H-indene. Alternative

coupling reactions between 2-bromo-1H-indene and 1-(trim-

ethylsilyl)-1H-pyrrole (5 mol % Pd(PPh₃)₄, toluene, 10 h, 20

°C) or 1-(trimethylstannyl)-1H-indole (4 mol % of Pd(dba)₂/2

o-PhC₆H₄P^tBu₂, toluene, 10 h, 50 °C) were altogether unsuc-

cessful. Finally, we found that the desired indenylindole can

be obtained under less basic conditions, i.e. using K₃PO₄as base,

and nonmetalated azoles such as pyrrole, indole, carbazole, and

their derivatives (eq 4; the isolated yields or HPLC yields are

given in parentheses).

reactions were performed in toluene at elevated temperatures

(70-110 °C), though 2-bromo-1H-indene was recovered in high

yield. Surprisingly, a similar reaction with 2-bromo-4,7-dimeth-

yl-1H-indene in the presence of 1 mol % of Pd(dba)₂/2

o-PhC₆H₄P^tBu₂proceeded readily at 75 °C and gave the

substituted indene 15 in as high as 52% yield for 24 h (eq 5).

Further on, using 2 mol % of Pd(OAc)₂/2 P^tBu₃as a catalyst,

other substituted indenes 6-14 bearing substituted pyrrole

fragments were synthesized in moderate yields in toluene at 80

°C (eq 4). 2,5-Dimethyl-1H-pyrrole failed to react with 2-bromo-

1H-indene under the conditions employed, probably because

of steric reasons. It is of interest that the Pd-catalyzed vinylation

of this azole with trans-ꢀ-bromostyrene was shown to proceed

readily at elevated temperatures,¹³though 2,5-dimethyl-1H-

pyrrole failed to react with more sterically crowded substrates,

such as cis-ꢀ-bromostyrene, 2-bromopropene, and obviously

2-bromo-1H-indene.

Additionally, the only weakly nucleophilic amine studied by

us was diphenylamine, which reacted with 2-bromo-1H-indene

in the presence of 4 mol % of Pd(OAc)₂/2 P^tBu₃in toluene to

form N-(1H-inden-2-yl)-N,N-diphenylamine (16) in 35% yield

after 9 h at 70 °C (eq 6).

An optimization of this procedure for 1H-pyrrole showed that

2 mol % of Pd(OAc)₂/2 o-PhC₆H₄P^tBu₂is the best catalyst,

giving 1-(1H-inden-2-yl)-1H-pyrrole (5) in 24% yield (HPLC)

after 46 h in toluene at room temperature, and this compound

was isolated in 20% yield. Alternatively, a catalyst such as

Pd(OAc)₂/2 P^tBu₃(2 mol %) gave 5 in as low as 7% yield after

24 h at ambient temperature. No product was formed if these

Actually, the synthesis of the indenes bearing an azole

substituent on the cyclopentadienyl ring can be achieved in an

alternative manner: i.e., via the Pd-catalyzed coupling of the

triﬂate of 2-indanone enol in the presence of K₃PO₄as a

base.^14a,c,n,pOn the evidence of HPLC, this reaction with 1H-

indole gave indene 7 in 57% yield in the presence of 4 mol %

of Pd(dba)₂and 8 mol % of 2-dimethylamino-2′-(di-tert-

butylphosphino)biphenyl (17) after 9 h at 85 °C (eq 7).

(12) (a) Pichler, H.; Folkers, G.; Roth, H. J.; Eger, K. Liebigs Ann. Chem.

1986, 1485. (b) Gross, H.; Beisert, S.; Costisella, B. J. Prakt. Chem. 1981,

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Voskoboynikov, A. Z. Org. Lett. 2002, 4, 623.

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azoles with vinyl halides and triﬂates, see: (a) Old, D. W.; Harris, M. C.;

Buchwald, S. L. Org. Lett. 2000, 2, 1403. (b) Barluenga, J.; Fernandez,

M. A.; Aznar, F.; Valdes, C. Chem. Commun. 2002, 2362. (c) Huang, X.;

Anderson, K. W.; Zim, D.; Jiang, L.; Klapars, A.; Buchwald, S. L. J. Am.

Chem. Soc. 2003, 125, 6653. (d) Barluenga, J.; Fernandez, M. A.; Aznar,

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Fernandez, M. A.; Aznar, F.; Valdes, C. Chem. Eur. J. 2004, 10, 494. (f)

Barluenga, J.; Fernandez, M. A.; Aznar, F.; Valdes, C. Chem. Commun.

2004, 1400. (g) Barluenga, J.; Fernandez, M. A.; Aznar, F.; Valdes, C.

Chem. Eur. J. 2005, 11, 2276. (h) Willis, M. C.; Brace, G. N.; Holmes,

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Urgaonkar, S.; Verkade, J. G. Org. Lett. 2005, 7, 4427. (j) Dalili, S.; Yudin,

A. K. Org. Lett. 2005, 7, 1161. (k) Barluenga, J.; Valdes, C. Chem. Commun.

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Movassaghi, M.; Ondrus, A. E. J. Org. Chem. 2005, 70, 8638. (n)

Movassaghi, M.; Ondrus, A. E. Org. Lett. 2005, 7, 4423. (o) Dehli, J. R.;

Legros, J.; Bolm, C. Chem. Commun. 2005, 973. (p) Ondrus, A. E.;

Movassaghi, M. Tetrahedron 2006, 62, 5287.

Synthesis of 3-(1H-Pyrrol-1-yl)- and 3-(1H-Indol-1-yl)-1H-

indenes. The scope of this protocol is wider than that of the

protocol using vinyl halides as the starting substrates, since many

different vinyl triﬂates obtained from cyclopentenones and

indanones are potentially available. For instance, 1H-inden-3-

yl triﬂate (18) can be readily obtained from 1-indanone,¹⁶while

the respective 3-halo-1H-indenes are known to be less thermally

(15) For the Cu-catalyzed reaction of azoles with vinyl halides, see:

Taillefer, M.; Ouali, A.; Renard, B.; Spindler, J.-F. Chem. Eur. J. 2006,

12, 5301.

(16) (a) Rossi, R.; Bellina, F.; Ciucci, D.; Carpita, A.; Fanelli, C.

Tetrahedron 1998, 54, 7595. (b) Schumann, H.; Stenzel, O.; Girgsdies, F.;

Halterman, R. L. Organometallics 2001, 20, 1743.

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1803

stable and, therefore, less useful.¹⁷Vinyl triﬂate 18 was found

to react readily with 1H-pyrrole and 1H-indole, forming the

3-substituted indenes 19 (NR₂) 1H-pyrrol-1-yl) and 20 (1H-

indol-1-yl) in 31 and 45% yields, respectively, after 24 h in

toluene at reﬂux (eq 8). Alternatively, several attempts to obtain

20 from 3-halo-1H-indene failed, probably because of a low

thermal stability of the latter substrate.

This approach was recently applied for the arylation of azoles,²²

as well as for the vinylation of 1H-benzimidazole.^22dIn this

manner, 2 equiv of (1H-inden-2-yl)boronic acid have been found

to react in air with 1 equiv of 1H-benzimidazole to form 21 in

a

moderate yield in the presence of 30 mol % of

[(TMEDA)CuOH]₂Cl₂in dichloromethane for 15 h at room

temperature (eq 10). Indene 21 was isolated by ﬂash chroma-

tography on silica gel and unambiguously characterized by NMR

spectroscopy and other means.

Synthesis of 2-(1H-Benzimidazol-1-yl)-1H-indene. In order

to obtain zirconium complexes bearing 1H-benzimidazol-1-yl-

substituted indenyl ligands, we ﬁrst aimed to synthesize the

respective substituted indenes. The unactivated aryl halides are

known to react with 1H-benzimidazole to form 1-aryl-1H-

benzimidazoles in the presence of copper catalysts.¹⁸The only

described example of the Cu-catalyzed vinylation of 1H-

benzimidazole required an ionic liquid as a solvent¹⁹or use of

a polydentate iminopyridine ligand.¹⁵An attempt to apply this

protocol developed for the copper-catalyzed arylation/vinylation

of other N-H substrates with aryl/vinyl halides²⁰failed. Thus,

the reaction between 2-bromo-1H-indene and 1H-benzimidazole

gave 1-(1H-inden-2-yl)-1H-benzimidazole (21) and a byproduct

of the halogen exchange,²¹i.e. 2-iodo-1H-indene, in 3 and 5%

yields, respectively, in the presence of 10 mol % of CuI, 40

mol % of MeNHCH₂CH₂NHMe, 1 equiv of KI, and 3 equiv of

K₂CO₃in toluene for 48 h at reﬂux. In the presence of 20 mol

% of CuI, 1 equiv of KI, 1 equiv of phenanthroline, 40 mol %

of dibenzylideneacetone (dba), and 2 equiv of Cs₂CO₃(eq 9)

the yield of indene 21 was higher but still did not exceed a

meager 15%.

Synthesis of Bis[η⁵-2-(N-azolyl)indenyl]zirconium and

-hafnium Dichlorides. Transmetalation reactions using orga-

notin reagents²³were applied for synthesizing Waymouth-type

zirconocenes from the 2-N-substituted indenes described above.

In this way, the ligands 5-8 and 11-14 were deprotonated by

ⁿBuLi (eq 11) and then treated with Et₃SnCl to obtain the

respective tin-substituted indenes. Finally, a reaction of the

toluene solution of the organotin reagent with 0.5 equiv of ZrCl₄

gave 22-29, which were isolated in analytically pure form by

crystallization from toluene. The metallocenes 22, 26, and 28

were characterized by X-ray crystal structure analyses (see

below).

Alternatively, the vinylation can be achieved by the use of

respective boronic acids in the oxidative cross-coupling reaction.

(17) (a) Sakai, M.; Childs, R. F.; Winstein, S. J. Org. Chem. 1972, 37,

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41, 1707. (c) Boyd, D. R.; Sharma, N. D.; Bowers, N. I.; Boyle, R.; Harrison,

J. S.; Lee, K.; Bugg, T. D. H.; Gibson, D. T. Org. Biomol. Chem. 2003, 1,

1298.

These complexes can be also obtained via direct transmeta-

lation using the lithium salt of the respective ligand and 0.5

equiv of ZrCl₄.¹For instance, in this way, complex 29 was

obtained in as high as 66% yield. Analogously, zirconium

(18) (a) Lo, Y. S.; Nolan, J. C.; Maren, T. H.; Welstead, W. J.;

Gripshover, D. F.; Shamblee, D. A. J. Med. Chem. 1992, 35, 4790. (b)

Cozzi, P.; Carganico, G.; Fusar, D.; Grossoni, M.; Menichincheri, M.;

Pinciroli, V.; Tonani, R.; Vaghi, F.; Salvati, P. J. Med. Chem. 1993, 36,

2964. (c) Kiyomori, A.; Marcoux, J.-F.; Buchwald, S. L. Tetrahedron Lett.

1999, 40, 2657. (d) Collman, J. P.; Wang, Z.; Zhong, M.; Zeng, L. J. Chem.

Soc., Perkin Trans. 1 2000, 1217. (e) Perry, M. C.; Cui, X.; Powell, M. T.;

Hou, D.-R.; Reibenspies, J. H.; Burgess, K. J. Am. Chem. Soc. 2003, 125,

113. (f) Wu, Y.-J.; He, H.; l′Heureux, A. Tetrahedron Lett. 2003, 44, 4217.

(g) Antilla, J. C.; Baskin, J. M.; Barder, T. E.; Buchwald, S. L. J. Org.

Chem. 2004, 69, 5578. (h) Liu, L.; Frohn, M.; Xi, N.; Dominguez, C.;

Hungate, R.; Reider, P. J. J. Org. Chem. 2005, 70, 10135. (i) Kuil, M.;

Bekedam, E. K.; Visser, G. M.; van den Hoogenband, A.; Terpstra, J. W.;

Kamer, P. C. J.; van Leuween, P. W. N. M.; van Strijdonck, G. P. F.

Tetrahedron Lett. 2005, 46, 2405. (j) Hosseinzadeh, R.; Tajbakhsh, M.;

Alikarami, M. Tetrahedron Lett. 2006, 47, 5203. (k) Xie, Y.-X.; Pi, S.-F.;

Wang, J.; Yin, D.-L.; Li, J.-H. J. Org. Chem. 2006, 71, 8324. (l) Zhang,

G.; Mao, J.; Zhu, D.; Wu, F.; Chen, H.; Wan, B. Tetrahedron 2006, 62,

4435. (m) Lv, X.; Wang, Z.; Bao, W. Tetrahedron 2006, 62, 4756.

(19) Wang, Z.; Bao, W.; Jiang, Y. Chem. Commun. 2005, 2849.

(20) (a) Klapars, A.; Antilla, J. C.; Huang, X.; Buchwald, S. L. J. Am.

Chem. Soc. 2001, 123, 7727. (b) Antilla, J. C.; Klapars, A.; Buchwald,

S. L. J. Am. Chem. Soc. 2002, 124, 11684. (c) Kwong, F. Y.; Buchwald,

S. L. Org. Lett. 2003, 5, 793. (d) Antilla, J. C.; Baskin, J. M.; Barder, T. E.;

Buchwald, S. L. J. Org. Chem. 2004, 69, 5578.

(22) (a) Collman, J. P.; Zhong, M. Org. Lett. 2000, 2, 1233. (b) Collman,

J. P.; Zhong, M.; Zeng, L.; Costanzo, S. J. Org. Chem. 2001, 66, 2001. (c)

Collman, J. P.; Zhong, M.; Zhang, C.; Costanzo, S. J. Org. Chem. 2001,

66, 7892. (d) Lam, P. Y. S.; Vincent, G.; Clark, C. G.; Deudon, S.; Jadhav,

P. K. Tetrahedron Lett. 2001, 42, 3415. (e) Nakamura, T.; Sato, M.;

Kakinuma, H.; Miyata, N.; Taniguchi, K.; Bando, K.; Koda, A.; Kameo,

K. J. Med. Chem. 2003, 46, 5416. (f) Kantam, M. L.; Venkanna, G. T.;

Sridhar, C.; Sreedhar, B.; Choudary, B. M. J. Org. Chem. 2006, 71, 9522.

(23) (a) Huttenhofer, M.; Prosenc, M.-H.; Rief, U.; Schaper, F.;

Brintzinger, H.-H. Organometallics 1996, 15, 4816. (b) Nifant′ev, I. E.;

Ivchenko, P. V. Organometallics 1997, 16, 713. (c) Voskoboynikov, A. Z.;

Agarkov, A. Y.; Chernishev, E. A.; Beletskaya, I. P.; Churakov, A. V.;

Kuz′mina, L. G. J. Organomet. Chem. 1997, 530, 75. (d) Agarkov, A. Y.;

Izmer, V. V.; Riabov, A. N.; Kuz′mina, L. G.; Howard, J. A. K.; Beletskaya,

I. P.; Voskoboynikov, A. Z. J. Organomet. Chem. 2001, 619, 280. (e) Izmer,

V. V.; Agarkov, A. Y.; Nosova, V. M.; Kuz′mina, L. G.; Howard, J. A. K.;

Beletskaya, I. P.; Voskoboynikov, A. Z. J. Chem. Soc., Dalton Trans. 2001,

1131. (f) Hu¨ttenhofer, M.; Schaper, F.; Brintzinger, H.-H. J. Organomet.

Chem. 2002, 660, 85. (g) Hu¨ttenhofer, M.; Weeber, A.; Brintzinger, H.-H.

J. Organomet. Chem. 2002, 663, 58. (h) Izmer, V. V.; Lebedev, A. Y.;

Nikulin, M. V.; Ryabov, A. N.; Asachenko, A. F.; Lygin, A. V.; Sorokin,

D. A.; Voskoboynikov, A. Z. Organometallics 2006, 25, 1217.

(21) Klapars, A.; Buchwald, S. L. J. Am. Chem. Soc. 2002, 124, 14844.

1804 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

complexes 30 and 31, including 7-methylindol-1-yl and 2-phe-

nylindol-1-yl fragments, respectively, as well as the hafnium

complex 32, bearing N-substituted tetrahydrocarbazole frag-

ments, and Zr and Hf complexes 33 and 34, involving pyrrole-

substituted 4,7-dimethylindenyl ligands, were successfully

obtained using direct transmetalation from the lithium salts of

indenes 9 (eq 12), 10 (eq 13), 13 (eq 14), and 15 (eq 15). Thus,

the complexes 30-34 were isolated in analytically pure form

in 25, 49, 49, 37, and 45% yields, respectively.

1-yl), and 38 (9H-carbazol-1-yl) and Me₃SiNMe₂in toluene at

room temperature (eq 16).^24b,c,e,f,iAnalytically pure 35-38 were

isolated in 37, 63, 76, and 53% yields, respectively, by

crystallization of the crude products from toluene. Complex 36,

as characterized by an X-ray crystal structure analysis (for a

full description of the structure, see below), has a dimeric

structure with two bridging Br ligands: i.e., [Cp′ZrBr₂]₂(µ-Br)₂.

Also, as conﬁrmed by crystal structure analysis, NMR spec-

troscopy, and element analysis, the “semi-sandwich” complexes

include one solvate molecule of toluene per two Zr units. As

the only singlet attributed to the 1,3-protons of indenyl was

observed in the ¹H NMR spectrum of 35 (as well as 36-38) in

C₆D₆, the symmetrical structure of the dimers is retained in

hydrocarbon solutions. The dissociation of a bridged complex

involving the Zr(µ-Br)₂Zr fragment into monomeric species

cannot be realized under the conditions studied. An attempt to

obtain 35 using as little as 3 equiv of Me₃SiBr at the last stage

failed, since an incomplete substitution of NMe₂with bromide

ligands in the Zr coordination sphere was observed. On the

evidence of NMR spectroscopy, a ca. 1:1 mixture of 35 and a

new compound was formed. The latter complex includes one

NMe₂per one indenyl ligand and seems to have a symmetrical

dimeric structure: e.g., [Cp′ZrBr₂]₂(µ-NMe₂)₂or most likely

[Cp′ZrBr(NMe₂)]₂(µ-Br)₂.

Synthesis of Unsymmetrical Complexes Bearing η⁵-2-(N-

Azolyl)indenyl Ligands. The four unsymmetrical zirconocenes

39-42, bearing 1H-pyrrol-1-yl and 9H-carbazol-9-yl, 1H-pyrrol-

1-yl and 1H-indol-1-yl, 1H-indol-yl and 9H-carbazol-9-yl, and

7-methyl-1H-indol-yl and 9H-carbazol-9-yl fragments, respec-

tively, were synthesized from “semi-sandwich” complexes

35-38 and the lithium salts of the respective indenes²⁴ⁱas shown

in eqs 17-20, respectively. Complex 39 was isolated in

analytically pure form after crystallization of the crude product

from a mixture of toluene and hexanes (1:1, vol.), while 40-42

were crystallized from toluene.

Synthesis of [η⁵-2-(N-Azolyl)indenyl]zirconium Tribro-

mides. The second aim of this work was to develop synthetic

pathways to unsymmetrical Waymouth-type zirconocenes bear-

ing two different 2-(N-azolyl)indenyl ligands or 2-arylindenyl

and 2-(N-azolyl)indenyl ligands. In order to obtain the former

compounds, ﬁrst, the synthesis of [2-(N-azolyl)indenyl]zirco-

nium tribromides (Cp′ZrBr₃) was developed. In this way,

indenes 5, 7, 9, and 14 reacted with Zr(NMe₂)₄, forming the

respective tris(dimethylamido)[2-(N-azolyl)indenyl]zirconium

complexes in ether at room temperature.²⁴The following

treatment of the crude tris-amide complexes thus formed with

4 equiv of Me₃SiBr resulted in the target complexes 35 (NR₂

) 1H-pyrrol-1-yl), 36 (1H-indol-1-yl), 37 (7-methyl-1H-indol-

(24) (a) Chandra, G.; Lappert, M. F. J. Chem. Soc. A 1968, 1940. (b)

Hughes, A. K.; Meetsma, A.; Teuben, J. H. Organometallics 1993, 12, 1936.

(c) Herrmann, W. A.; Morawietz, M. J. A. J. Organomet. Chem. 1994,

482, 169. (d) Diamond, G. M.; Rodewald, S.; Jordan, R. F. Organometallics

1995, 14, 5. (e) Diamond, G. M.; Jordan, R. F.; Petersen, J. L. J. Am. Chem.

Soc. 1996, 118, 8024. (f) Carpenetti, D. W.; Kloppenburg, L.; Kupec, J. T.;

Petersen, J. L. Organometallics 1996, 15, 1572. (g) Diamond, G. M.; Jordan,

R. F.; Petersen, J. L. Organometallics 1996, 15, 4030. (h) Christopher, J. N.;

Diamond, G. M.; Jordan, R. F.; Petersen, J. L. Organometallics 1996, 15,

4038. (i) Diamond, G. M.; Jordan, R. F.; Petersen, J. L. Organometallics

1996, 15, 4045. (j) Vogel, A.; Priermeier, T.; Herrmann, W. A. J.

Organomet. Chem. 1997, 527, 297. (k) Tagge, C. D.; Kravchenko, R. L.;

Lal, T. K.; Waymouth, R. M. Organometallics 1999, 18, 380. (l) Ryabov,

A. N.; Izmer, V. V.; Borisenko, A. A.; Canich, J. A. M.; Kuz′mina, L. G.;

Howard, J. A. K.; Voskoboynikov, A. Z. J. Chem. Soc., Dalton. Trans.

2002, 2995.

Furthermore, unsymmetrical complexes 44-46 and 48-50,

bearing 2-phenylndenyl and 2-mesitylindenyl as well as 2-(N-

azolyl)indenyl ligands, were obtained from the respective (2-

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1805

resonance. Stepwise lowering of the temperature from 303 to

203 K by 10 K increments reveals the dynamic process on a

1

400 MHz H NMR time scale. At 203 K, 1-H (3-H) indenyl

protons appear as two narrow singlets at δ 6.77 and 4.82 ppm

in the ratio 7:4. By analogy with the previously studied

conformation behavior of bis[2-(2-furyl)indenyl]zirconium

derivatives,^4ewe can suggest that these signals belong to two

diastereomeric rotamers of 25. They arise as a result of

“freezing” of the hindered rotation around the indenyl C2-N

vector on the NMR time scale. The Gibbs activation energy of

this process evaluated according to the described procedure²⁵

is 50 kJ/mol. A similar picture is observed in the case of

metallocene 26. At 203 K (in CD₂Cl₂), 1-H (3-H) indenyl

protons appear as two narrow singlets at δ 5.00 and 6.84 ppm.

The ratio of isomers at 203 K is ca. 53:47. Warming results in

the broadening and further coalescence of these signals (T_coal

) 275 K). Rotation barriers for 26 have been evaluated to be

similar to those for 25. It should be noted that for 22 (in CD₂Cl₂)

arylindenyl)zirconium tribromides 43 and 47 and lithium salts

of indenes 5, 7, and 14 (eqs 21 and 22). Complex 49 was isolated

in 58% yield by crystallization of the crude product from a

mixture of hexanes and toluene (7:4 v:v), while other complexes

were isolated in 22-43% yields after crystallization of the crude

products from toluene. the unsymmetrical metallocenes 44-46

and 48-50 were unambiguously characterized by NMR spec-

troscopy. Additionally, the structure of 50 was studied by X-ray

crystallography (see below for the crystallographic details).

1

the discussed temperature dependence of the H NMR spectra

was not observed at temperatures between 303 and 173 K.

The only unsymmetrical zirconocene studied by ¹H NMR at

different temperatures between 303 and 203 K was complex

50, bearing mesityl and 9H-carbazol-9-yl fragments. In this case,

the resonances attributed to 1,3-H of both indenyl fragments

are broadened at room temperature (Figure 1). The resonance

attributed to 4-Me of mesityl fragment appears as a narrow

singlet at low temperatures. However, cooling results in the

broadening of the resonance attributed to 2,6-Me₂of mesityl.

The observed dynamic behavior is likely to originate from the

hindered rotation around indenyl-aryl bond rather than around

indenyl-Zr bond.^4e

Finally, in order to illustrate a possible application of the

aforementioned indenes 19 and 21 for metallocene synthesis,

the unsymmetrical complexes 51 and 52 bearing C₅Me₅ligands

as well as 1-(1H-pyrrol-1-yl)- and 2-(1H-benzimidazol-1-

yl)indenyl ligands were synthesized from Cp*ZrCl₃and lithium

salts 19 and 21, as shown in eqs 23 and 24. These complexes

were isolated in analytically pure form in 61 and 46% yields,

respectively. It should be noted that, in the reaction of

ZrCl₄(THF)₂with 2 equiv of the lithium salt of 21 in THF at

ambient temperature, the corresponding symmetrical Waymouth-

type complex was not formed. This is probably due to an

undesirable coordination of the imidazole fragment with the Zr

atom of ZrCl₄(THF)₂or, more likely, the respective monoin-

denylzirconium intermediate giving some oligomeric or poly-

meric complexes.

Study of the Solid-State Structures of 22, 26, 32, 38,

and 50. The solid-state structures of 22, 26, 32, 38, and 50

were determined by X-ray diffraction analysis. The resulting

crystallographic data for 22, 26, 32, and 50 are summarized in

Table 1. The structures are depicted in Figures 2-5, and

schematic views of 22, 26, 32, and 50 are shown in Figure 6.

Complex 22 adopts a racemic-like metallocene conformation

with a crystallographically imposed C₂-axial symmetry. The

zirconium atom has a typical pseudotetrahedral coordination

with two substituted η⁵-indenyl and two σ-Cl ligands (see Table

1 for the corresponding angles). The two pyrrolyl residues are

arranged toward the forward upper right and lower left quadrants

(relative to each other) at the front side of the bent metallocene

wedge. The angle between the indenyl planes of opposite ligands

is 44.33(11)°. To characterize the orientation of the indenyl

ligands, we chose the torsion angle C(2)-Cp(c)-Cp(c′)-C(2′)

(Cp(c) stands for Cp centroid), presented in Table 1. These

ligands occupy the respective positions almost above and below

the Zr-Cl vectors. Consequently, the annelated phenylene rings

are found oriented toward the respective opposite positions at

the bent metallocene sectors (Figure 6). The bonding of the

indenyl ﬁve-membered ring to zirconium is rather unsymmetric:

the Zr(1)-C(1)/C(3) distances are somewhat shorter than the

Zr(1)-C(8)/C(9) distances. It should be also noted that

Zr(1)-C(1) is signiﬁcantly shorter than Zr(1)-C(3). The C(2)

carbon atom bearing the pyrrolyl substituent is placed markedly

outside the plane of the other atoms of the indenyl moiety (0.180

Å). The pyrrolyl substituent shows a ﬂat conformation with a

trigonal-planar nitrogen atom (the sum of angles at N(1) is

359.3°). The N(1)-C(1) bond length is less than the standard

X-ray value for the unconjugated C-N bond (1.426 Å).²⁶The

1

Temperature-Dependent Dynamic H NMR Spectra of

25, 26, and 50. Complex 25 shows temperature-dependent

1

dynamic H NMR spectra. At high temperature (303 K in

CD₂Cl₂, 400 MHz), this complex exhibits a spectrum featuring

1-H and 3-H indenyl protons at δ 5.96 ppm as a broad

(25) Sack, R. A. Mol. Phys. 1958, 1, 163.

1806 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

1

Figure 1. Dynamic H NMR spectra (400 MHz) of 50 in CD₂Cl₂.

Table 1. Selected Bond Distances (Å) and Angles (deg) for 22, 26, 32, and 50

bond or angle

22 (M ) Zr, Hal ) Cl)

26 (M ) Zr, Hal ) Cl)

32 (M ) Hf, Hal ) Cl)

50 (M ) Zr, Hal ) Br)

M-Hal(1)

M-Hal(1′)

2.4852(14)

2.4116(9)

2.3956(13)

2.5842(11)

2.5837(10)

M-C(1)

M-C(2)

M-C(3)

M-C(9)

M-C(8)

M-C(1′)

M-C(2′)

M-C(3′)

M-C(9′)

M-C(8′)

2.490(6)

2.594(6)

2.521(6)

2.535(6)

2.552(6)

2.476(3)

2.590(3)

2.556(3)

2.577(3)

2.579(3)

2.508(5)

2.556(4)

2.486(4)

2.563(5)

2.554(5)

2.483(6)

2.550(6)

2.579(5)

2.578(5)

2.586(6)

2.478(5)

2.576(5)

2.527(5)

2.581(5)

2.586(6)

M-Cp(c)

M-Cp(c′)

2.227(6)

1.374(8)

2.252(3)

1.410(4)

2.227(5)

1.407(6)

2.252(5)

2.242(5)

N(1)-C(2)

C(22)-C(2′)

1.394(7)

1.490(8)

Hal(1)-M-Hal(1′)

Hal(1)-M-Cp(c)

Hal(1)-M-Cp(c′)

Hal(1′)-M-Cp(c)

Hal(1′)-M-Cp(c′)

Cp(c)-M-Cp(c′)

96.77(7)

105.8(2)

105.7(2)

95.80(5)

105.42(8)

108.19(8)

95.78(6)

107.81(12)

105.26(12)

93.72(4)

110.11(13)

106.04(13)

103.98(13)

108.27(13)

129.14(19)

131.9(2)

130.2(7)

44.33(11)

16.1(5)

129.04(12)

79.0(3)

129.72(17)

73.5(6)

C(2)-Cp(c)-Cp(c′)-C(2′)

72.4(6)

angle between mean planes of

indenyl and indenyl′ ligands

angle between mean planes of

indenyl and its substituent, θ

θ′

55.61(7)

32.75(18)

55.36(12)

36.91(16)

58.20(14)

37.21(17)

37.09(16)

angle between the mean planes of the indenyl ligand and its

substituent is 16.1° (Table 1). This might imply weak conjuga-

tion between those π-systems.

The Zr-C distances as well as Cp(centroid)-Zr-Cp(centroid)

and Cl-Zr-Cl angles in 22 are comparable with those observed

in the previously investigated 2-substituted bis(indenyl)zirco-

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1807

Figure 2. ORTEP view (50% probability) of 22.

Figure 5. ORTEP view (50% probability) of 50.

Figure 3. ORTEP view (50% probability) of 26.

Figure 6. Overhead views of the metallocene conformations of

complexes 22 (left top), 26 (right top), 32 (left bottom), and 50

(right bottom).

The X-ray diffraction study of 26 shows that this metal-

locene complex has a conformational arrangement different

from that of 22, in spite of the fact that it also represents the

rac conformer with a crystallographically imposed C₂-axial

symmetry (Figures 2, 3, and 6). In the crystal, complex 26

favors an arrangement in which both the annelated phenylene

groups point toward the Zr-Cl vectors while both the indolyl

substituents are oriented on opposite sides of the metallocene

framework. The zirconium atom in 26 has also pseudotet-

rahedral coordination with two substituted η⁵-indenyl and two

(26) Allen, F. H.; Kennard, O.; Watson, D.; Brammer, L.; Orpen, A. G.;

Taylor, R. J. Chem. Soc., Perkin Trans. 1987, S1.

Figure 4. ORTEP view (50% probability) of 32.

(27) (a) Bruce, M. D.; Coates, G. W.; Hauptman, E.; Waymouth, R. M.;

Ziller, J. W. J. Am. Chem. Soc. 1997, 119, 11174. (b) Halterman, R. L.;

Fahey, D. R.; Bailly, E. F.; Dockter, D. W.; Stenzel, O.; Shipman, J. L.;

Khan, M. A.; Dechert, S.; Schumann, H. Organometallics 2000, 19, 5464.

(c) Dreier, T.; Unger, G.; Erker, G.; Wibbeling, B.; Frohlich, R. J.

Organomet. Chem. 2001, 622, 143.

nium dichloride complexes, while the Zr-Cl bonds are sub-

stantially longer.^{4b,e,f,6f,i,27}However, the analysis of the data from

the Cambridge Structural Database²⁸has revealed that Zr-Cl

bonds vary in the wide range 2.405-2.465 Å.

1808 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

σ-Cl ligands (Table 1). However, the distribution of the

Zr-C(Cp) bonds in 26 is somewhat different from that in

22, featuring one short Zr(1)-C(1) bond in comparison with

the other Zr-C distances. However, the Zr(1)-C(3) bond

length is shorter than the Zr(1)-C(8)/C(9) lengths. As for

22, the C(2) carbon atom bearing the indolyl substituent is

placed markedly outside the plane of the rest of the atoms

of the indenyl moiety (0.149 Å). The indolyl substituent

shows a ﬂat conformation with a trigonal-planar nitrogen

atom (sum of angles at N(1) 359.9°). The C(1)-N(1) bond

length is longer than in 22 and the interplanar angle is also

larger, apparently due to the sterics, thereby implying no

conjugation between the indenyl ligand and its substituents.

Zirconium and hafnium are similar group 4 metals separated

by only one row on the periodic table of the elements.

Complexes of zirconium and hafnium with the same ligand

environments are closely isostructural and possess similar

chemical properties.²⁹In fact, the solid-state structures of

zirconium and hafnium metallocenes derived from analogous

2-substituted indene ligands are nearly identical. Comparison

of the crystal structures of the zirconium and hafnium complexes

26 and 32 reveals close structural similarity (Table 1 and Figures

3, 4, and 6). As for 26, complex 32 adopts the racemic-like

metallocene conformation. The geometry around the hafnium

atom in 32 is pseudotetrahedral with a crystallographically

imposed C₂-axial symmetry. The bond lengths of the corre-

sponding metal-cyclopentadienyl bonds in 26 and 32 are not

the same (Table 1); the difference between M-C(1)/C(3) and

M-C(8)/C(9) pairs is more pronounced in the case of 32. The

C(2) atom also deviates from the plane of the indenyl ligand

(0.160 Å). The mutual orientation of the ligands as well as of

the ligands and their substituents in 32 is similar to that in 26

(Table 1).

In complex 50 the two opposite indenyl ligands have different

substituents and cannot be described as having any symmetry.

Complex 50 is characterized by a racemic-like metallocene

conformation. The zirconium atom adopts pseudotetrahedral

coordination, with two substituted η⁵-indenyl and two σ-Br

ligands (see Table 1 for the corresponding angles). The mutual

orientation of the ligands as well as the interplanar angles of

the ligands and their substituents (θ, θ′) are nearly identical

with those of complexes 26 and 32. The distribution of Zr-C

bonds is different for two ligands. For the unprimed indenyl, it

is similar to the case of complex 26, while the bonding pattern

of the Zr atom to the carbons of the primed ligand is similar to

the case of complex 22. Deviations of the C(2) and C(2′) atoms

from the mean plane of the indenyl ligands are also signiﬁcant,

being 0.199 and 0.185 Å, respectively.

Figure 7. ORTEP view (50% probability) of 38.

Table 2. Selected Bond Distances (Å) and Angles (deg) for 38

Zr(1)-C(1)

Zr(1)-C(2)

Zr(1)-C(3)

Zr(1)-C(9)

Zr(1)-C(8)

Zr(1)-Br(1)

Zr(1)-Br(1′)

Zr(1)-Br2)

Zr(1)-Br(3)

N(1)-C(2)

2.456(4)

2.584(4)

2.462(4)

2.485(4)

2.501(4)

2.7561(5)

2.7152(5)

2.5446(6)

2.5698(6)

1.387(5)

Zr(1′)-C(1′)

Zr(1′)-C(2′)

Zr(1′)-C(3′)

Zr(1′)-C(9′)

Zr(1′)-C(8′)

Zr(1′)-Br(1′)

Zr(1′)-Br(1)

Zr(1′)-Br(2′)

Zr(1′)-Br(3′)

N(1′)-C(2′)

2.460(4)

2.570(3)

2.450(4)

2.481(4)

2.512(4)

2.7535(6)

2.7354(5)

2.5461(6)

2.5663(6)

1.395(5)

angle between mean planes of indenyl and its substituent, θ 22.41(13)

angle between mean planes of indenyl and its substituent, θ′ 19.30(14)

from the Zr atom to bridged bromines are signiﬁcantly longer.

The lengths of N(1,1′)-C(2,2′) bonds are slightly shorter than

the standard X-ray value for the unconjugated C-N bond,

and the angles (θ, θ′) between mean planes of the substituents

at C(2,2′) atoms and indenyl ligands are ∼20° (Table 2). This

might imply weak conjugation between those π-systems.

Oleﬁn Polymerization Catalyzed by 22, 23, and 33

Activated by MAO. A preliminary study of zirconocenes

bearing 2-(N-azolyl)indenyl ligands showed that 22, 23, and 33/

MAO are active catalysts of ethylene (PE) and propylene (PP)

polymerization as well as ethylene/1-octene (EO) and ethylene/

propylene (EP) copolymerization (Table 3). Under the conditions

of ethylene polymerization (PE) studied, the insertion of methyls

in the indenyl fragment resulted in a ca. 2.3-fold increase of

the catalytic activity (cf. entries 1 and 3), though the substitution

of pyrrol-1-yl with 2,4-dimethylpyrrol-1-yl gave a less active

catalyst (cf. entries 1 and 2). On the other hand, polyethylene

with a higher molecular weight was formed in the case of the

Me-substituted complexes 23 and 33. Interestingly, both Me-

substituted complexes activated by MAO gave a molecular

weight distribution (PDI) of the polymer narrower than that

obtained for 22/MAO. Next, surprisingly, 22/MAO showed

close activity in ethylene polymerization and ethylene/1-octene

copolymerization (entries 1 and 4). This was also the case of

the catalyst based on the 4,7-dimethylindenyl complex 23. In

contrast, 33/MAO showed a considerably lower activity in the

copolymerization reaction (cf. entries 3 and 6). Additionally,

each catalyst studied gave ethylene/1-octene copolymer with a

lower molecular weight than the respective ethylene homopoly-

mer. Interestingly, as in the ethylene homopolymerization, both

catalysts based on the Me-substituted zirconocenes gave co-

polymer with a narrower molecular weight distribution (cf.

entries 4 and 5/6). The catalysts based on the more sterically

crowded metallocenes 23 and 33 showed a lower level of the

The structure of the dimeric complex 38 is depicted in Figure

7. Both Zr atoms adopt a four-legged piano-stool conformation

being coordinated by η⁵-indenyl ligand, two terminal, and two

bridged Cl atoms. Selected characteristics of the geometry are

presented in Table 2.

The distribution of the Zr-C bond lengths in 38 is similar to

that for previously described complexes. The Zr-C(1,1′)/C(3,3′)

distances are shorter in comparison to Zr-C(8,8′)/C(9,9′), and

Zr-C(2,2′) are the longest bonds because of signiﬁcant deviation

of the C(2) and C(2′) atoms from the plane of the corresponding

indenyl ligand (0.178 and 0.193 Å). As expected, the distances

(28) (a) Allen, F. N.; Kennard, O. Chem. Des. Auto. News 1993, 8, 31.

(b) Cambridge Structural Database, 2005.

(29) Cardin, D. J.; Lappert, M. F.; Raston, C. L. Chemistry of Organo-

Zirconium and -Hafnium Compounds, Ellis Horwood: New York, 1986,

pp 1-451.

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1809

Table 3. Results of Ethylene (PE) and Propylene (PP)

Polymerization and Ethylene/1-Octene (EO) and Ethylene/Propylene

(EP) Copolymerization Catalyzed by 22, 23, and 33 Activated by

MAO

Waymouth-type zirconium and hafnium complexes involving

two indenyl ligands bearing planar N-azolyl fragments in

position 2 were obtained and, after being activated by MAO,

form active catalysts for ethylene homopolymerization and

ethylene/1-octene copolymerization. The activity in propylene

polymerization is, however, rather modest. Catalytic properties

will be considered in detail elsewhere.

run activity, kg of P

comonomer

entry complex type (mol of Zr)^-1h^-1M_w, kDa PDI content, wt %

1

2

3

4

5

6

7

8

22

23

33

22

23

33

22

23

33

22

33

PE^a

EO^b

EP^c

PP^d

5370

1870

12200

5150

1700

6940

5530

650

790

1560

2020

403

1310

330

26.2

160

6.3

10.0

3.0

2.3

1.6

2.6

1.6

2.0

2.9

3.1

1.8

1.9

1.3

6.8

3.3

4.6

27.3

32.6

30.3

Experimental Section

General Procedure. All manipulations with air- and moisture-

sensitive compounds were performed either under an atmosphere

of thoroughly puriﬁed argon using standard Schlenk techniques or

in a controlled-atmosphere glovebox (VAC). Tetrahydrofuran,

dimethoxyethane (DME), and ether for synthesis were puriﬁed by

distillation over LiAlH₄and kept over sodium benzophenone ketyl.

Hydrocarbon solvents (including benzene-d₈for NMR measure-

ments) were distilled and stored over CaH₂or Na/K alloy.

Methylene chloride (and CD₂Cl₂for NMR measurements) was

distilled and stored over CaH₂. Chloroform-d was distilled over

P₄O₁₀andstoredovermolecularsieves(3Å).2-Bromo-1H-indene,^27b,30

1H-inden-2-yl triﬂuoromethanesulfonate (18),³¹2-bromo-4,7-

dimethyl-1H-indene,^27b,322-phenyl-1H-indene,³³(µ-bromo)dibro-

mo[η⁵-2-phenylindenyl]zirconium dimer (43),²⁴ⁱ1,2,3,4-tetrahy-

drocyclopenta[b]indole,³⁴Pd(dba)₂,³⁵[(TMEDA)Cu(OH)]₂Cl₂,^22c

9

10

11

1420

890

600

^aConditions: 0.02 µmol of the zirconium complex, 10 µmol of MAO

([Zr]/[Al] ) 1/500), 75 psig of ethylene, 3.80 mL of toluene, 80 °C.

^bConditions: 0.02 µmol of the zirconium complex, 10 µmol of MAO

([Zr]/[Al] ) 1/500), 75 psig of ethylene, 0.64 mL of 1-octene, 3.80 mL

of toluene, 80 °C. ^cConditions: 0.08 µmol of the zirconium complex, 40

µmol of MAO ([Zr]/[Al] ) 1/500), 10 psig of ethylene, 1.066 mL of

propylene, 3.77 mL of hexane, 70 °C. ^dConditions: 0.08 µmol of the

zirconium complex, 40 µmol of MAO ([Zr]/[Al] ) 1/500), 1.066 mL of

propylene, 0.40 mL of toluene, 3.73 mL of hexane, 70 °C.

comonomer insertion, i.e. 3.3 and 4.6 wt % of 1-octene,

respectively, compared with 6.8 wt % of the comonomer

obtained for 22/MAO.

37

ZrCl₄(THF)₂,³⁶and Cp*ZrCl₃were prepared according to the

published methods. Analytical and semipreparative liquid chroma-

tography was performed using a Waters Delta 600 HPLC system

including a 996 Photodiode Array Detector, Symmetry C18 (Waters,

60 Å, 5 µm, 4.6 × 250 mm) or Chromolith RP-18 (Merck, 4.6 ×

100 mm) columns, and a Nova-Pack C18 column (Waters, 60 Å,

6 µm, 3.9 and 19 × 300 mm), respectively, in a methanol-water

mobile phase. For analytical runs, calculations of yields of the

products were performed under the assumption that extinction

coefﬁcients of isomeric indenes and diastereomeric methoxyindanes

are equal. ¹H and ¹³C spectra were recorded with Bruker DPX-300

or Avance-400 spectrometers for 1-10% solutions in deuterated

solvents. Chemical shifts for ¹H and ¹³C were measured relative to

TMS. In ¹H NMR spectra, the assignment was made on the evidence

of double-resonance, NOE, NOEdif, APT, and DEPT experiments.

C, H microanalyses were done using a Carlo Erba 1106 analyzer.

1-(1H-Inden-2-yl)-1H-pyrrole (5). In a three-necked round-

bottom ﬂask (1 L), equipped with an Allihn condenser and magnetic

stirrer bar, under an argon atmosphere 4.59 g (15.4 mmol) of 2-(di-

tert-butylphosphino)-1,1′-biphenyl and 1.73 g (7.70 mmol) of

Pd(OAc)₂were added to a mixture of 49.0 g (231 mmol) of

anhydrous K₃PO₄, 30.0 g (154 mmol) of 2-bromo-1H-indene, and

11.5 mL (11.1 g, 165 mmol) of pyrrole in 500 mL of toluene and 50

mL of DME, at ambient temperature. This mixture was stirred at

room temperature for 72 h. The reaction mixture was ﬁltered

through a layer (d ) 100 mm, l ) 40 mm) of silica gel 60 (40-63

µm) on a fritted-glass funnel. The silica gel layer was additionally

washed with 200 mL of methyl tert-butyl ether (MTBE). The

combined extract was evaporated to dryness. The crude product

was puriﬁed using ﬂash chromatography (silica gel 60, 40-63 µm,

In ethylene/propylene copolymerization the activity of 22/

MAO was very close to the activity of this system for ethylene

homopolymerization (cf. entries 1 and 7). This was not the case

for 23/MAO and 33/MAO, where the activities for the copo-

lymerization were considerably lower than for the ethylene

homopolymerization (cf. entries 2 and 8 as well as 3 and 9,

respectively). However, in all cases studied, ethylene-propylene

copolymer had a considerably lower molecular weight than the

respective ethylene homopolymer. The dramatic effect was

particularly observed for 33/MAO, which gave ethylene ho-

mopolymer and ethylene/1-octene copolymer with M_wvalues

equal to 2020 and 330 kDa, respectively, though ethylene/

propylene copolymer had a M_wvalue as low as 6.3 kDa.

Surprisingly, in contrast to the ethylene/1-octene copolymeri-

zation, in the case of the ethylene/propylene copolymerization,

the level of comonomer insertion was slightly higher for the

catalysts involving more sterically crowded complexes 23 and

33 (cf. entries 8/9 and 7). Interestingly, both 22/MAO and 33/

MAO formed low-molecular-weight propylene homopolymer,

as shown in Table 3 (entries 10 and 11). Additionally, these

catalysts were found to have considerably lower activities in

propylene polymerization compared with ethylene homopolym-

erization, which is known to be a common phenomenon for

the Waymouth-type catalysts.^4cTaking into account the po-

lymerization conditions used, one can conclude that the substitu-

tion of phenyl with pyrrol-1-yl in position 2 of the indenyls of

the Waymouth-type zirconocene results in increasing catalytic

activity of the respective catalyst in propylene polymerization.^4c

Detailed results of the propylene homopolymerization catalyzed

by the zirconium complexes bearing 2-(N-azolyl)indenyl ligands

activated by MAO will be published and discussed elsewhere.

(30) (a) MacDowell, D. W. H.; Lindley, W. A. J. Org. Chem. 1982,

47, 705. (b) McEwen, I.; Ro¨nnqvist, M.; Ahlberg, P. J. Am. Chem. Soc.

1993, 115, 3989.

(31) Radivoy, G.; Yus, M.; Alonso, F. Tetrahedron 1999, 55, 14479.

(32) Schumann, H.; Karasiak, D. F.; Muhle, S. H.; Halterman, R. L.;

Kaminsky, W.; Weingarten, U. J. Organomet. Chem. 1999, 579, 356.

(33) Lee, D.-W.; Yun, J. Bull. Korean Chem. Soc. 2004, 25, 29.

(34) Rodriguez, J. G.; Temprano, F.; Esteban-Calderon, C.; Martinez-

Ripoll, M.; Garcia-Blanco, S. Tetrahedron 1985, 41, 3813.

(35) Ukai, T.; Kawazawa, H.; Ishii, Y.; Bonnett, J. J.; Ibers, J. A. J.

Organomet. Chem. 1974, 65, 253.

Conclusion

The Pd-catalyzed cross-coupling reactions of readily available

2-bromo-1H-indene and triﬂate of 2-indanone with azoles, such

as pyrrole and its analogues, were shown to be convenient and

useful methods to obtain novel ligands containing azole frag-

ments bonded with cyclopentadienyl via nitrogen. The respective

(36) Manzer, L. E. Inorg. Synth. 1982, 22, 135.

(37) Ryabov, A. N.; Gribkov, D. V.; Izmer, V. V.; Voskoboynikov, A. Z.

Organometallics 2002, 21, 2842.

1810 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

d ) 40 mm, l ) 500 mm; eluent 10/1 hexanes/MTBE). This

procedure gave 5.62 g (20%) of white crystalline product. Anal.

Calcd for C₁₃H₁₁N: C, 86.15; H, 6.12; N, 7.73. Found: C, 86.24;

H, 6.19; N, 7.55. ¹H NMR (CDCl₃): δ 8.08 (m, 1H, 7-H of indenyl),

7.92-8.01 (m, 3H, 3,4,6-H of indenyl), 7.83 (dt, J ) 7.2 Hz, J )

1.5 Hz, 1H, 5-H of indenyl), 7.77 (t, J ) 7.4 Hz, 2H, 2,5-H of

N-pyrrolyl), 7.00 (t, J ) 2.19 Hz, 2H, 3,4-H of N-pyrrolyl), 4.51

(s, 2H, CH₂). ¹³C{¹H} NMR (CDCl₃): δ 144.7, 144.1, 138.0, 126.9,

123.8, 123.4, 120.2, 118.7, 111.2, 110.6, 37.4.

was ﬁltered through a glass frit (G3). The precipitate was addition-

ally washed with 3 × 75 mL of dichloromethane. The combined

extract was evaporated to dryness. The product was isolated by

passing through a short column with silica gel 60 (40-63 um, d )

100 mm, l ) 100 mm; eluent 100/1 hexanes/Et₂O). This procedure

gave 6.18 g (42%) of 9. Anal. Calcd for C₁₈H₁₅N: C, 88.13; H,

6.16; N, 5.71. Found: C, 88.09; H, 6.19; N, 5.75. ¹H NMR (DMSO-

d₆): δ 7.53 (d, J ) 3.2 Hz, 1H, 2-H in indol-1-yl), 7.44-7.51 (m,

3H, 4-H in indol-1-yl and 4,7-H in inden-2-yl), 7.32 (m 1H, 6-H

in inden-2-yl), 7.24 (m, 1H, 5-H in inden-2-yl), 7.03 (m, 1H, 5-H

in indol-1-yl), 6.96 (m, 1H, 6-H in indol-1-yl), 6.81 (s, 1H, 3-H in

inden-2-yl), 6.64 (d, J ) 3.2 Hz, 1H, 2-H in indol-1-yl), 3.92 (s,

2H, CH₂), 2.32 (s, 3H, Me). ¹³C{¹H} NMR (DMSO-d₆): δ 145.1,

142.8, 140.3, 135.1, 130.2, 129.3, 126.7, 125.7, 124.92, 124.90,

123.8, 121.4, 121.3, 120.4, 118.7, 103.4, 41.3, 19.5.

1-(1H-Inden-2-yl)-2-phenyl-1H-indole (10). A mixture of 7.80 g

(40 mmol) of 2-bromo-1H-indene, 7.73 g (40 mmol) of 2-phenyl-

1H-indole, 25.47 g (120 mmol) of anhydrous K₃PO₄, and 817 mg

(1.6 mmol) of Pd(P^tBu₃)₂in a mixture of 120 mL of toluene and

20 mL of DME was stirred for 20 h at 95 °C. The resulting mixture

was ﬁltered through a glass frit (G3). The precipitate was addition-

ally washed with 3 × 75 mL of dichloromethane. The combined

extract was evaporated to dryness. The product was isolated by

passing through short column with silica gel 60 (40-63 um, d )

100 mm, l ) 100 mm; eluent 100/1 hexanes/Et₂O). This procedure

gave 5.63 g (46%) of 10. Anal. Calcd for C₂₃H₁₇N: C, 89.87; H,

5.57; N, 4.56. Found: C, 89.81; H, 5.61; N, 4.45. ¹H NMR (CDCl₃):

δ 7.70 (m, 1H, 7-H in indenyl), 7.55-7.61 (m, 3H, 4-H in indolyl

and 2,6-H in Ph), 7.50 (m, 1H, 4-H in indenyl), 7.19-7.41 (m,

8H, 5,6,7-H in indolyl, 5,6-H in indenyl and 3,4,5-H in Ph), 7.07

(s, 1H, 3-H in indolyl), 6.79 (s, 1H, 3-H in indenyl), 3.32 (s, 2H,

CH₂). ¹³C{¹H} NMR (CDCl₃): δ 147.7, 146.5, 143.5, 143.0, 140.7,

138.4, 132.8, 128.6, 128.5, 127.8, 126.7, 126.1, 124.9, 123.6, 122.6,

121.3, 121.0, 120.6, 111.1, 104.4, 40.4.

1-(1H-Inden-2-yl)-2,4-dimethyl-1H-pyrrole (6). The reaction

was carried out similarly to the preparation of compound 5, star-

ting from 7.40 mL (6.84 g, 72 mmol) of 2,4-dimethylpyrrole, 13.7 g

(70 mmol) of 2-bromoindene, 44.5 g (210 mmol) of K₃PO₄, 1.13 g

(13.0 mL of 0.2 M solution in toluene, 5.60 mmol) of ^tBu₃P, 1.61 g

(2.80 mmol) of Pd(dba)₂, 170 mL of toluene, and 35 mL of DME.

The reaction mixture was stirred at 80 °C for 14 h. Yield: 7.81 g

(53%) of 6. Anal. Calcd for C₁₅H₁₅N: C, 86.08; H, 7.22; N, 6.69.

1

Found: C, 85.99; H, 7.27; N, 6.62. H NMR (CDCl₃): δ 7.43 (m,

1H, 7-H of indenyl), 7.28-7.37 (m, 3H, 3,4,6-H of indenyl), 7.19

(dt, J ) 7.3 Hz, J ) 1.6 Hz, 1H, 5-H of indenyl), 6.71 (s, 1H, 5-H

of N-pyrrolyl), 6.56 (s, 1H, 3-H of indenyl), 5.94 (s, 1H, 3-H of

N-pyrrolyl), 3.82 (s, 2H, CH₂), 2.47 (s, 3H, 2-Me of N-pyrrolyl),

2.15 (s, 3H, 4-Me of N-pyrrolyl). ¹³C{¹H} NMR (CDCl₃): δ 144.6,

144.4, 138.3, 129.5, 126.8, 123.9, 123.2, 120.3, 119.5, 117.6, 114.8,

112.1, 39.6, 14.8, 11.7.

1-(1H-Inden-2-yl)-1H-indole (7). Method A. The reaction was

carried out similarly to the preparation of compound 5, starting

from 4.80 g (41 mmol) of indole, 8.00 g (41 mmol) of 2-bromoin-

dene, 52.2 g (246 mmol) of K₃PO₄, 0.331 g (3.80 mL of 0.2 M

t

solution in toluene, 1.64 mmol) of Bu₃P, 0.184 g (0.82 mmol) of

Pd(OAc)₂, 110 mL of toluene, and 20 mL of DME. The reaction

mixture was stirred at 70 °C for 8.5 h. Yield: 5.64 g (60%) of 7.

Anal. Calcd for C₁₇H₁₃N: C, 88.28; H, 5.67; N, 6.06. Found: C,

88.10; H, 5.60; N, 6.19. ¹H NMR (CDCl₃): δ 7.79 (m, 1H, 7-H of

N-indolyl), 7.63 (m, 1H, 4-H of N-indolyl), 7.36 (m, 1H, 7-H

of indenyl), 7.09-7.33 (m, 6H, 4,5,6-H of indenyl and 2,5,6-H of

N-indolyl), 6.79 (s, 1H, 3-H of indenyl), 6.61 (dd, J ) 3.4 Hz, J )

0.8 Hz, 1H, 3-H of N-indolyl), 3.84 (s, 2H, CH₂). ¹³C{¹H} NMR

(CDCl₃): δ 144.3, 143.9, 137.7, 135.4, 130.0, 127.0, 126.3, 123.9,

123.3, 123.0, 121.3, 121.0, 120.3, 113.9, 112.2, 104.8, 39.2.

Method B. A mixture of 100 mg (0.38 mmol) of 1H-inden-2-yl

triﬂuoromethanesulfonate, 44.5 mg (0.38 mmol) of 1H-indole, 11.5

mg (0.02 mmol) of Pd(dba)₂, 13.7 mg (0.04 mmol) of 17, and 212

mg (1.0 mmol) of K₃PO₄in 3 mL of toluene was stirred for 9 h at

85 °C. The product was isolated by semipreparative HPLC. Yield:

50 mg (57%). Anal. Calcd for C₁₇H₁₃N: C, 88.28; H, 5.67; N, 6.06.

Found: C, 88.43; H, 5.79; N, 5.85.

1-(1H-Inden-2-yl)-2,3-dimethyl-1H-indole (11). The reaction

was carried out similarly to the preparation of compound 5, starting

from 7.41 g (51 mmol) of 2,3-dimethylindole, 9.95 g (51 mmol)

of 2-bromoindene, 32.4 g (153 mmol) of K₃PO₄, 1.03 g (11.9 mL

t

of 0.2 M solution in toluene, 5.10 mmol) of Bu₃P, 0.572 g (2.55

mmol) of Pd(OAc)₂, 140 mL of toluene, and 30 mL of DME. The

reaction mixture was stirred at 85 °C for 11 h. Yield: 6.37 g (48%)

of 11. Anal. Calcd for C₁₉H₁₇N: C, 87.99; H, 6.61; N, 5.40. Found:

1

C, 88.13; H, 6.68; N, 5.58. H NMR (CDCl₃): δ 7.09-7.53 (m,

8H, 4,5,6,7-H of indenyl and 4,5,6,7-H of N-indolyl), 6.82 (s, 1H,

3-H of indenyl), 3.76 (s, 2H, CH₂), 2.35 (s, 3H, 2-Me of N-indolyl),

2.28 (s, 3H, 3-Me of N-indolyl). ¹³C{¹H} NMR (CDCl₃): δ 143.2,

143.0, 140.6, 136.9, 132.6, 129.2, 126.8, 126.5, 125.0, 123.7, 121.4,

121.2, 119.7, 117.9, 110.2, 108.9, 40.2, 11.4, 8.8.

1-(1H-Inden-2-yl)-2-methyl-1H-indole (8). The reaction was

carried out similarly to the preparation of compound 5, starting

from 4.45 g (34 mmol) of 2-methylindole, 6.63 g (34 mmol) of

2-bromoindene, 21.6 g (102 mmol) of K₃PO₄, 0.404 g (4.65 mL of

0.2 M solution in toluene, 2.00 mmol) of ^tBu₃P, 0.224 g (1.00 mmol)

of Pd(OAc)₂, 80 mL of toluene, and 15 mL of DME. The reaction

mixture was stirred at 75 °C for 9 h. Yield: 4.00 g (48%) of 8.

Anal. Calcd for C₁₈H₁₅N: C, 88.13; H, 6.16; N, 5.71. Found: C,

4-(1H-Inden-2-yl)-1,2,3,4-tetrahydrocyclopenta[b]indole (12).

The reaction was carried out similarly to the preparation of

compound 5, starting from 6.28 g (40 mmol) of 1,2,3,4-tetrahy-

drocyclopenta[b]indole, 7.80 g (40 mmol) of 2-bromoindene, 25.4 g

(120 mmol) of K₃PO₄, 0.808 g (9.30 mL of 0.2 M solution in

t

toluene, 4.00 mmol) of Bu₃P, 0.449 g (2.00 mmol) of Pd(OAc)₂,

120 mL of toluene, and 20 mL of DME. The reaction mixture was

stirred at 85 °C for 11 h. Yield: 3.53 g (33%) of 12. Anal. Calcd

for C₂₀H₁₇N: C, 88.52; H, 6.31; N, 5.16. Found: C, 88.60; H, 6.34;

N, 5.33. ¹H NMR (CDCl₃): δ 7.68 (m, 1H, 7-H of indenyl),

7.07-7.46 (m, 7H, 4,5,6-H of indenyl and 4,5,6,7-H of N-azolyl),

6.72 (s, 1H, 3-H of indenyl), 3.81 (s, 2H, CH₂of indenyl), 2.97

(m, 2H, 2-CH₂of N-azolyl), 2.80 (m, 2H, 4-CH₂of N-azolyl), 2.49

(m, 2H, 3-CH₂of N-azolyl). ¹³C{¹H} NMR (CDCl₃): δ 144.6, 144.1,

143.8, 140.6, 138.3, 126.8, 125.7, 123.8, 123.2, 122.0, 121.5, 120.6,

120.2, 118.7, 115.5, 112.4, 39.5, 28.1, 28.0, 24.0.

1

88.22; H, 6.09; N, 5.84. H NMR (CDCl₃): δ 7.06-7.54 (m, 8H,

4,5,6,7-H of indenyl and 4,5,6,7-H of N-indolyl), 6.83 (s, 1H, 3-H

of indenyl), 6.36 (s, 1H, 3-H of N-indolyl), 3.75 (s, 2H, CH₂), 2.41

(s, 3H, Me). ¹³C{¹H} NMR (CDCl₃): δ 143.0, 142.5, 140.6, 137.8,

136.8, 128.5, 127.0, 126.8, 125.1, 123.7, 121.3*, 120.2, 119.6,

110.5, 102.3, 40.0, 13.9 (the asteisk denotes two chemically

nonequivalent carbon nuclei).

1-(1H-Inden-2-yl)-7-methyl-1H-indole (9). A mixture of 11.7 g

(60 mmol) of 2-bromo-1H-indene, 7.86 g (60 mmol) of 7-methyl-

1H-indole, 38.2 g (180 mmol) of anhydrous K₃PO₄, and 817 mg

(1.6 mmol) of Pd(P^tBu₃)₂in a mixture of 180 mL of toluene and

30 mL of DME was stirred for 20 h at 95 °C. The resulting mixture

9-(1H-Inden-2-yl)-2,3,4,9-tetrahydro-1H-carbazole (13). The

reaction was carried out similarly to the preparation of compound

5, starting from 8.73 g (51 mmol) of 2,3,4,9-tetrahydro-1H-

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1811

carbazole, 10.0 g (51 mmol) of 2-bromoindene, 32.4 g (153 mmol)

of K₃PO₄, 1.01 g (11.6 mL of 0.2 M solution in toluene, 5.00 mmol)

of Bu₃P, 0.561 g (2.50 mmol) of Pd(OAc)₂, 150 mL of toluene,

at 120 °C. The resulting mixture was ﬁltered through a glass frit

(G3). The precipitate was additionally washed with 3 × 50 mL of

methyl tert-butyl ether. The combined extract was evaporated to

dryness. The product was isolated by ﬂash chromatography (silica

gel 60, 40-63 µm, d ) 50 mm, l ) 500 mm; eluent 20/1 hexanes/

MTBE). This procedure gave 0.96 g (15%) of the title product.

Anal. Calcd for C₁₃H₁₁N: C, 86.15; H, 6.12; N, 7.73. Found: C,

86.34; H, 6.21; N, 7.86. ¹H NMR (CDCl₃): δ 7.58 (m, 1H, 7-H of

indenyl), 7.45 (m, 1H, 4-H of indenyl), 7.21-7.34 (m, 2H, 5,6-H

of indenyl), 7.08 (t, J ) 2.1 Hz, 2H, 2,5-H of pyrrolyl), 6.33 (t, J

) 2.1 Hz, 2H, 3,4-H of pyrrolyl), 6.23 (t, J ) 2.3 Hz, 1H, 2-H of

indenyl), 3.41 (d, J ) 2.3 Hz, 2H, CH₂). ¹³C{¹H} NMR (CDCl₃):

δ 143.8, 142.2, 139.8, 126.4, 125.7, 124.3, 120.2, 119.7, 119.5,

109.4, 35.8.

t

and 30 mL of DME. The reaction mixture was stirred at 80 °C for

8.5 h. Yield: 8.92 g (61%) of 13. Anal. Calcd for C₂₁H₁₉N: C, 88.38;

1

H, 6.71; N, 4.91. Found: C, 88.29; H, 6.80; N, 4.94. H NMR

(CDCl₃): δ 6.96-7.38 (m, 8H, 4,5,6,7-H of indenyl and 6,7,8,9-H

of N-azolyl), 6.65 (m, 1H, 3-H of indenyl), 3.68 (s, 2H, CH₂of

indenyl), 2.62 (m, 4H, 3-CH₂and 4-CH₂of N-azolyl), 1.75 (m,

4H, 2-CH₂and 5-CH₂of N-azolyl). ¹³C{¹H} NMR (CDCl₃): δ

143.4, 142.7, 140.1, 136.8, 135.5, 128.2, 126.8, 124.6, 123.7, 123.5,

121.6, 120.9, 119.9, 117.8, 112.1, 110.7, 40.0, 24.0, 23.5, 22.8,

21.1.

9-(1H-Inden-2-yl)-9H-carbazole (14). The reaction was carried

out similarly to the preparation of compound 5, starting from 6.69 g

(40 mmol) of carbazole, 7.80 g (40 mmol) of 2-bromoindene, 25.5 g

(120 mmol) of K₃PO₄, 817 mg (1.6 mmol) of Pd(^tBu₃P)₂, 120 mL

of toluene, and 20 mL of DME. The reaction mixture was stirred

at 95 °C for 20 h. Yield: 9.80 g (87%) of 14. Anal. Calcd for

C₂₁H₁₅N: C, 89.65; H, 5.37; N, 4.98. Found: C, 89.71; H, 5.31; N,

1-(1H-Inden-3-yl)-1H-indole (20). In a 100 mL pressure glass

vessel, a mixture of 10.0 g (38 mmol) of 1H-inden-3-yl triﬂuo-

romethanesulfonate, 4.45 g (38 mmol) of 1H-indole, 21 g of K₃PO₄,

862 mg (1.5 mmol) of Pd(dba)₂, 869 mg (3.0 mmol) of (biphenyl-

2-yl)di-tert-butylphosphine, and 100 mL of toluene was stirred for

15 h at 120 °C. The resulting mixture was ﬁltered through a short

layer of silica gel 60 (40-63 µm), and this layer was additionally

washed by 200 mL of methyl tert-butyl ether. The product was

isolated from the combined elute using ﬂash chromatography on

silica gel 60 (40-63 µm, d ) 40 mm, l ) 500 mm, 10/1 hexanes/

methyl tert-butyl ether). Yield: 3.95 g (45%) of dark red oil. Anal.

Calcd for C₁₇H₁₃N: C, 88.28; H, 5.67; N, 6.06. Found: C, 88.40;

1

5.11. H NMR (CDCl₃): δ 8.08 (d, J ) 7.8 Hz, 2H, 4,5-H of

N-carbazolyl), 7.57 (d, J ) 8.0 Hz, 2H, 1,8-H of N-carbazolyl),

7.20-7.48 (m, 8H, 4,5,6,7-H of indenyl and 2,3,6,7-H of N-

carbazolyl), 7.02 (s, 1H, 3-H of indenyl), 3.92 (s, 2H, CH₂). ¹³C{¹H}

NMR (CDCl₃): δ 143.2, 142.2, 140.6, 140.2, 126.9, 126.1, 125.7,

125.1, 123.7*, 121.2, 120.2*, 110.5, 39.0 (asterisks denote two

chemically nonequivalent carbon nuclei).

1

H, 5.70; N, 6.31. H{¹³C} NMR (CDCl₃): δ 7.72-7.67 (m, 1H),

7.58-7.53 (m, 1H), 7.52-7.47 (m, 1H), 7.42 (d, 3.12 Hz, 1H),

7.41-7.35 (m, 1H), 7.34-7.26 (m, 2H), 7.25-7.14 (m, 2H), 6.69

(dt, J ) 0.6 Hz, J ) 3.1 Hz, 1H), 6.55 (t, J ) 2.2 Hz, 1H), 3.61 (d,

J ) 2.2 Hz, 2H). ¹³C{¹H} NMR (CDCl₃): δ 143.5, 140.9, 140.7,

136.2, 128.9, 127.5, 126.4, 125.8, 124.4, 123.9, 122.1, 120.9, 120.3,

119.8, 111.4, 103.2, 36.4.

1-(4,7-Dimethyl-1H-inden-2-yl)-1H-pyrrole (15). In a round-

bottom ﬂask (0.1 L) in the glovebox, a mixture of 6.69 g (30 mmol)

of 2-bromo-4,7-dimethyl-1H-indene, 2.80 mL (2.68 g, 40.0 mmol)

of pyrrole, 19.1 g (90 mmol) of anhydrous K₃PO₄, 575 mg (1.0

mmol) of Pd(dba)₂, and 596 mg (2.0 mmol) of 2-(di-tert-

butylphosphino)-1,1′-biphenyl in 100 mL of toluene was stirred

for 24 h at 75 °C. The resulting mixture was ﬁltered through a

glass frit (G3). The precipitate was additionally washed with 3 ×

50 mL of methyl tert-butyl ether. The combined extract was

evaporated to dryness. The product was isolated by ﬂash chroma-

tography (silica gel 60, 40-63 µm, d ) 50 mm, l ) 500 mm;

eluent 50/1 hexanes/MTBE). This procedure gave 3.25 g (52%) of

a white solid. Anal. Calcd for C₁₅H₁₅N: C, 86.08; H, 7.22; N, 6.69.

Found: C, 86.31; H, 7.04; N, 6.90. ¹H NMR (CDCl₃): δ 7.07 (t, J

) 2.1 Hz, 2H, 2,5-H of pyrrolyl), 6.98 (d, J ) 7.7 Hz, 1H, 5-H of

indenyl), 6.85 (d, J ) 7.7 Hz, 1H, 6-H of indenyl), 6.59 (t, J ) 1.2

Hz, 1H, 3-H of indenyl), 6.29 (t, J ) 2.1 Hz, 2H, 3,4-H of pyrrolyl),

3.62 (br.s, 2H, CH₂), 2.36 (s, 3H, 4-Me of indenyl), 2.29 (s, 3H,

7-Me of indenyl). ¹³C{¹H} NMR (CDCl₃): δ 144.1, 142.5, 136.4,

129.8, 128.3, 126.9, 125.4, 118.8, 110.4, 109.9, 36.7, 18.3, 18.2.

N-(1H-Inden-2-yl)-N,N-diphenylamine (16). A mixture of 177

mg (1.05 mmol) of diphenylamine, 195 mg (1.00 mmol) of

2-bromo-1H-indene, 640 mg of K₃PO₄, 4.5 mg (0.02 mmol) of

Pd(OAc)₂, and 2.0 mL of 0.02 M (0.04 mmol) of P^tBu₃in toluene

was stirred for 9 h at 70 °C. The resulting mixture was passed

through a short column with silica gel 60 (40-63 µm, l ) 30 mm,

d ) 50 mm). The product was isolated from the eluate using

semipreparative HPLC. Yield: 99 mg (35%). Anal. Calcd for

C₂₁H₁₇N: C, 89.01; H, 6.05; N, 4.94. Found: C, 89.19; H, 6.10; N,

5.01. ¹H NMR (CDCl₃): δ 7.31-7.24 (m, 4H), 7.21-7.16 (m, 4H),

7.15-7.10 (m, 2H), 7.10-7.06 (m, 2H), 7.04 (d, J ) 7.3 Hz, 1H),

6.95 (dt, J ) 1.0 Hz, J ) 7.3 Hz, 1H), 6.04 (s, 1H), 3.45 (s, 2H).

¹³C{¹H} NMR (CDCl₃): δ 152.9, 146.9, 145.7, 137.8, 129.2, 126.6,

125.5, 124.1, 122.9, 122.1, 118.5, 110.5, 39.1.

1-(1H-Inden-2-yl)-1H-benzimidazole (21). In a 100 mL Erlen-

meyer ﬂask, a mixture of 3.20 g (20.0 mmol) of 1H-inden-2-

ylboronic acid, 1.18 g (10.0 mmol) of benzimidazole, 0.93 g (2.00

mmol) of [(TMEDA)CuOH]₂Cl₂, and 40 mL of dichloromethane

was stirred for 20 h (in air). The resulted mixture was passed

through a short column with silica gel 60 (40-63 µm, d ) 40 mm,

l ) 20 mm). This column was additionally washed with 500 mL

of dichloromethane. The combined eluate was evaporated to

dryness. The crude product was puriﬁed using medium-pressure

chromatography on silica gel 60 (40-63 µm, d ) 40 mm, l ) 350

mm; eluent 1/1 v/v hexanes/dichloromethane). Yield: 530 mg (23%)

of white solid. Anal. Calcd for C₁₆H₁₂N₂: C, 82.73; H, 5.21; N,

12.06. Found: C, 82.65; H, 5.20; N, 11.81. ¹H{¹³C} NMR (CDCl₃):

δ 8.19 (br s, 1H, 2-H in 1H-benzimidazol-1-yl), 7.87 (m, 1H, 7-H

in 1H-benzimidazol-1-yl), 7.80 (m, 1H, 4-H in 1H-benzimidazol-

1-yl), 7.30-7.50 (m, 7H, 4,5,7-H in indenyl and 4,5,6,7-H in 1H-

benzimidazol-1-yl), 7.23 (dt, J ) 7.5 Hz, J ) 1.3 Hz, 1H, 6-H in

indenyl), 7.00 (m, 1H, 3-H in indenyl), 3.99 (m, 2H, CH₂). ¹³C

NMR (CDCl₃): δ 144.5 (br), 143.1, 141.3 (br), 140.3, 137.9, 127.3,

125.1, 124.2, 123.6 (br), 123.2, 121.1, 120.9, 117.0, 111.9, 38.7.

Bis[η⁵-2-(1H-pyrrol-1-yl)indenyl]zirconium dichloride (22).

In a round-bottom ﬂask (0.1 L) in the glovebox, to a solution of

4.22 g (23.3 mmol) of 5 in a mixture of 60 mL of toluene and 6

n

mL of ether was added 9.6 mL of a 2.5 M solution of BuLi (24

mmol) in hexanes at room temperature. This mixture was stirred

overnight. Then, 4.19 mL (6.04 g, 25 mmol) of Et₃SnCl was added

dropwise, and the reaction mixture was stirred for 3 h at room

temperature and then was ﬁltered through Celite 503 (on a fritted-

glass funnel). The Celite layer was additionally washed with 50

mL of toluene. The combined extract was evaporated under vacuum

to ca. two-thirds of its former volume. To the resulting mixture

was added 2.70 g (11.6 mmol) of ZrCl₄at room temperature. This

mixture was stirred for 2 days and then ﬁltered through a glass frit

(G4). The crystals that precipitated at -30 °C from the ﬁltrate were

1-(1H-Inden-3-yl)-1H-pyrrole (19). In a round-bottom ﬂask (0.1

L) in the glovebox, a mixture of 9.10 g (35 mmol) of 1H-inden-

3-yl triﬂuoromethanesulfonate, 2.45 mL (2.35 g, 35 mmol) of

pyrrole, 21.2 g (100 mmol) of anhydrous K₃PO₄, 805 mg (1.4

mmol) of Pd(dba)₂, and 821 mg (2.8 mmol) of 2-(di-tert-

butylphosphino)biphenyl in 100 mL of toluene was stirred for 24 h

1812 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

separated, washed with 5 mL of cold toluene, and dried under

vacuum. Yield: 1.03 g (17%) of yellowish crystals of 22. Anal.

Calcd for C₂₆H₂₀Cl₂N₂Zr: C, 59.76; H, 3.86; N, 5.36. Found: C,

59.52; H, 3.77; N, 5.34. ¹H NMR (CD₂Cl₂): δ 7.56 (m, 4H,

4,4′,7,7′-H in indenyl), 7.27 (m, 4H, 5,5′,6,6′-H in indenyl), 6.87

(t, J ) 2.3 Hz, 4H, 2,2′,5,5′-H in N-pyrrolyl), 6.25 (t, J ) 2.3 Hz,

4H, 3,3′,4,4′-H in N-pyrrolyl), 5.83 (s, 4H, 1,1′,3,3′-H of indenyl).

¹³C{¹H} NMR (CD₂Cl₂): δ 142.2, 141.9, 127.6, 127.0, 120.9, 112.9,

93.9.

Bis[η⁵-2-(2,3-dihydrocyclopenta[b]indol-4(1H)-yl)indenyl]zir-

conium Dichloride (27). The reaction was carried out similarly to

the preparation of compound 22, starting from 3.52 g (13.0 mmol)

of 12 in a mixture of 60 mL of toluene and 6 mL of ether, 5.6 mL

n

of a 2.5 M solution of BuLi (14.0 mmol) in hexanes, 2.50 mL

(3.60 g, 15.0 mmol) of Et₃SnCl, and 1.51 g (6.50 mmol) of ZrCl₄.

The crude product was recrystallized from a toluene/hexanes

mixture at -30 °C. Yield: 0.69 g (15%) of yellowish crystals of

27. Anal. Calcd for C₄₀H₃₂Cl₂N₂Zr: C, 68.36; H, 4.59; N, 3.99.

Found: C, 68.64; H, 4.73; N, 3.75. ¹H NMR (CD₂Cl₂): δ 7.84-7.91

(m, 2H, 5,5′-H of N-azolyl), 7.46-7.52 (m, 6H, 6,6′,7,7′,8,8′-H of

N-azolyl), 7.27 (dd, J ) 6.3 Hz, J ) 3.1 Hz, 4H, 4,4′,7,7′-H

of indenyl), 7.04 (dd, J ) 6.3 Hz, J ) 3.1 Hz, 4H, 5,5′,6,6′-H of

indenyl), 6.36 (m, 4H, 1,1′,3,3′-H of indenyl), 3.08 (m, 4H, 4,4′-

CH₂of N-azolyl), 2.86 (m, 4H, 2,2′-CH₂of N-azolyl), 2.54 (m,

4H, 3,3′-CH₂of N-azolyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 145.4, 144.9,

140.8, 128.0, 127.0, 126.8, 126.3, 125.2, 122.4, 121.9, 119.3, 113.9,

96.0, 29.2, 28.5, 24.2.

Bis[η⁵-2-(2,4-dimethyl-1H-pyrrol-1-yl)indenyl]zirconium Dichlo-

ride (23). The reaction was carried out similarly to the preparation

of compound 22, starting from 5.90 g (28.2 mmol) of 6 in a mixture

of 85 mL of toluene and 17 mL of ether, 11.8 mL of a 2.5 M

n

solution of BuLi (29.6 mmol) in hexanes, 5.03 mL (7.24 g, 30

mmol) of Et₃SnCl, and 3.26 g (14.0 mmol) of ZrCl₄. Yield: 3.01 g

(37%) of yellowish crystals of 23. Anal. Calcd for C₃₀H₂₈Cl₂N₂Zr:

1

C, 62.27; H, 4.88; N, 4.84. Found: C, 62.06; H, 4.70; N, 5.17. H

NMR (CD₂Cl₂): δ 7.51 (m, 4H, 4,4′,7,7′-H of indenyl), 7.25 (m,

4H, 5,5′,6,6′-H of indenyl), 6.53 (s, 2H, 5,5′-H of N-pyrrolyl), 5.84

(s, 2H, 3,3′-H of N-pyrrolyl), 5.77 (s, 4H, 1,1′,3,3′-H of indenyl),

2.25 (s, 6H, 2,2′-Me of N-pyrrolyl), 2.05 (s, 6H, 4,4′-Me of

N-pyrrolyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 142.7, 131.7, 127.6, 127.0,

125.0, 122.2, 119.5, 115.0, 95.8, 16.6, 13.1.

Bis[η⁵-2-(1,2,3,4-tetrahydro-9H-carbazol-9-yl)indenyl]zirco-

nium Dichloride (28). The reaction was carried out similarly to

the preparation of compound 22, starting from 4.91 g (17.2 mmol)

of 13 in a mixture of 70 mL of toluene and 7 mL of ether, 7.2 mL

n

of 2.5 M solution of BuLi (18 mmol) in hexanes, 3.19 mL (4.59

Bis[η⁵-2-(1H-indol-1-yl)indenyl]zirconium Dichloride (24).

The reaction was carried out similarly to the preparation of

compound 22, starting from 5.59 g (24.2 mmol) of 7 in a mixture

of 50 mL of toluene and 10 mL of ether, 10.0 mL of a 2.5 M

solution of ⁿBuLi (25 mmol) in hexanes, 5.02 mL (7.23 g, 30 mmol)

of Et₃SnCl, and 2.82 g (12.1 mmol) of ZrCl₄. Yield: 1.89 g (25%)

of yellowish crystals of 24. Anal. Calcd for C₃₄H₂₄Cl₂N₂Zr: C,

g, 19 mmol) of Et₃SnCl, and 2.00 g (8.6 mmol) of ZrCl₄. Yield:

1.15 g (18%) of yellowish crystals of 28. Anal. Calcd for

C₄₂H₃₆Cl₂N₂Zr: C, 69.02; H, 4.96; N, 3.83. Found: C, 68.86; H,

5.11; N, 3.92. ¹H NMR (CD₂Cl₂): δ 7.70 (m, 2H, 6,6′-H of

N-azolyl), 7.55 (m, 2H, 9,9′-H of N-azolyl), 7.22-7.40 (m, 12H,

4,4′,5,5′,6,6′,7,7′-H of indenyl and 7,7′,8,8′-H of N-azolyl), 5.95

(br.s, 4H, 1,1′,3,3′-H of indenyl), 2.76, 2.28, 2.08, and 1.84 (four

multiplets, 4 × 4H, 2,2′-CH_2,3,3′-CH₂, 4,4′-CH₂, and 5,5′-CH₂of

N-azolyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 137.2, 134.9, 133.7, 128.0,

125.4, 123.8, 123.1, 121.2, 120.0, 117.0, 113.2, 111.1, 95.3 (br.),

23.8, 22.1, 20.9, 19.6.

1

65.58; H, 3.88; N, 4.50. Found: C, 65.77; H, 3.98; N, 4.39. H

NMR (CD₂Cl₂): δ 7.17-7.63 (m, 16H, 4,4′,5,5′,6,6′,7,7′-H of

indenyl and 4,4′,5,5′,6,6′,7,7′-H of N-indolyl), 7.13 (d, J ) 3.6 Hz,

2H, 2,2′-H of N-indolyl), 6.64 (m, 2H, 3,3′-H of N-indolyl), 5.98

(s, 4H, 1,1′,3,3′-H of indenyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 143.2,

136.7, 131.8, 128.7, 127.6, 127.3, 124.9, 123.1, 123.0, 114.0, 107.6,

107.3, 95.1.

Bis[η⁵-2-(9H-carbazol-9-yl)indenyl]zirconium Dichloride (29).

Method A. The reaction was carried out similarly to the preparation

of compound 22,starting from 4.75 g (16.9 mmol) of 14 in a mixture

of 50 mL of toluene and 6 mL of ether, 7.1 mL of 2.5 M solution

Bis[η⁵-2-(2-methyl-1H-indol-1-yl)indenyl]zirconium Dichlo-

ride (25). The reaction was carried out similarly to the preparation

of compound 22, starting from 4.07 g (16.6 mmol) of 8 in a mixture

of 70 mL of toluene and 15 mL of ether, 7.2 mL of a 2.5 M solution

n

of BuLi (17.5 mmol) in hexanes, 3.02 mL (4.34 g, 18 mmol) of

Et₃SnCl, and 1.96 g (11.6 mmol) of ZrCl₄. This compound was

found to be practically insoluble in all common solvents. Therefore,

the resulting mixture was ﬁltered through a glass frit (G4), and the

solid obtained was washed with 2 × 15 mL of hot toluene, 2 × 30

mL of hot DME, and 2 × 30 mL of dichloromethane and then

dried under vacuum. Yield: 3.29 g (54%) of yellow powder of 29.

Anal. Calcd for C₄₂H₂₈Cl₂N₂Zr: C, 69.79; H, 3.90; N, 3.88. Found:

n

of BuLi (18 mmol) in hexanes, 3.19 mL (4.59 g, 19 mmol) of

Et₃SnCl, and 1.93 g (8.3 mmol) of ZrCl₄. Yield: 0.98 g (18%) of

yellowish crystals of 25. Anal. Calcd for C₃₆H₂₈Cl₂N₂Zr: C, 66.44;

1

H, 4.34; N, 4.30. Found: C, 66.65; H, 4.47; N, 4.50. H NMR

(CD₂Cl₂): δ 7.61 (m, 2H, 4,4′-H of N-indolyl), 7.82 (m, 2H, 7,7′-H

of N-indolyl), 7.23-7.36 (m, 12H, 4,4′,5,5′,6,6′,7,7′-H of indenyl

and 5,5′,6,6′-H of N-indolyl), 6.48 (s, 2H, 3,3′-H of N-indolyl),

5.96 (br s, 4H, 1,1′,3,3′-H of indenyl), 2.10 (s, 6H, 2,2′-Me of

indolyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 135.7, 135.6, 130.9, 128.6,

126.9, 126.1, 124.2, 123.5, 121.9, 114.3, 112.1 (br.), 107.7, 99.3

(br), 17.2.

1

C, 69.54; H, 3.78; N, 3.61. H NMR (CD₂Cl₂): δ 8.11 (m, 4H,

4,4′,5,5′-H of N-carbazolyl), 7.56 (m, 4H, 1,1′,8,8′-H of N-

carbazolyl), 7.80 (m, 16H, 4,4′,5,5′,6,6′,7,7′-H of indenyl and

2,2′,3,3′,6,6′,7,7′-H of N-carbazolyl), 6.17 (s, 4H, 1,1′,3,3′-H of

indenyl).

Method B. To a solution of 5.21 g (18.5 mmol) of 22 in 400

n

Bis[η⁵-2-(2,3-dimethyl-1H-indol-1-yl)indenyl]zirconium Dichlo-

ride (26). The reaction was carried out similarly to the preparation

of compound 22, starting from 6.30 g (24.3 mmol) of 11 in a

mixture of 105 mL of toluene and 10 mL of ether, 10.0 mL of 2.5

M solution of ⁿBuLi (25 mmol) in hexanes, 5.03 mL (7.24 g, 30.0

mmol) of Et₃SnCl, and 2.82 g (12.1 mmol) of ZrCl₄. Yield: 2.18 g

(27%) of yellowish crystals of 26. Anal. Calcd for C₃₈H₃₂Cl₂N₂Zr:

mL of ether was added 7.40 mL (18.5 mmol) of 2.5 M BuLi in

hexanes at room temperature. This mixture was stirred overnight,

and then 3.49 g (9.26 mmol) of ZrCl₄(THF)₂was added at room

temperature. The resulting mixture was stirred for 24 h and than

evaporated to dryness. The residue was washed with 2 × 50 mL

of hot toluene, 2 × 50 mL of dichloromethane, and 2 × 50 mL of

THF and then dried under vacuum. Yield: 4.40 g (66%) of yellow

powder of 29. Anal. Calcd for C₄₂H₂₈Cl₂N₂Zr: C, 69.79; H, 3.90;

N, 3.88. Found: C, 69.99; H, 4.04; N, 4.04.

1

C, 67.24; H, 4.75; N, 4.13. Found: C, 67.11; H, 4.73; N, 3.99. H

NMR (CD₂Cl₂): δ 7.78 (m, 2H, 4,4′-H of N-indolyl), 7.61 (m, 2H,

7,7′-H of N-indolyl), 7.20-7.37 (m, 12H, 4,4′,5,5′,6,6′,7,7′-H of

indenyl and 5,5′,6,6′-H of N-indolyl), 5.90 (br s, 4H, 1,1′,3,3′-H of

indenyl), 2.29 (s, 6H, 2,2′-Me of N-indolyl), 1.94 (s, 6H, 3,3′-Me

of N-indolyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 139.7, 135.5, 135.0, 131.8,

128.5, 126.8, 126.2 (br), 124.4, 123.1, 120.3, 120.1, 114.1, 113.8,

99.1 (br), 14.1, 13.9, 10.4, 10.2.

Bis[η⁵-2-(7-methyl-1H-indol-1-yl)indenyl]zirconium Dichlo-

ride (30). To a solution of 2.45 g (10.0 mmol) of 9 in 100 mL of

n

Et₂O was added 4.00 mL (10.0 mmol) of 2.5 M BuLi in hexanes

at room temperature. This mixture was stirred overnight, and then

1.89 g (5.0 mmol) of ZrCl₄(THF)₂was added at room temperature.

This mixture was stirred for 1 day and then evaporated to dryness.

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1813

To the residue was added 150 mL of toluene. The mixture was

heated to reﬂux and then ﬁltered through Celite 503 (on a fritted-

glass funnel). Crystals precipitating at -30 °C from the ﬁltrate were

separated, washed with 20 mL of cold toluene, and dried under

vacuum. Yield: 0.80 g (25%) of 30. Anal. Calcd for C₃₆H₂₈Cl₂N₂Zr:

Bis[η⁵-4,7-dimethyl-2-(1H-pyrrol-1-yl)indenyl]hafnium Dichlo-

ride (34). The reaction was carried out similarly to the preparation

of compound 33, starting from 0.70 g (3.35 mmol) of 15 in 35 mL

n

of toluene, 1.34 mL of a 2.5 M solution of BuLi (3.35 mmol) in

hexanes, and 0.54 g (1.57 mmol) of HfCl₄. The reaction mixture

was stirred for 20 h at 110 °C, and the product was isolated as

described for 33. Yield: 0.53 g (45%) of white powder of 34. Anal.

Calcd for C₃₀H₂₈Cl₂N₂Hf: C, 54.11; H, 4.24; N, 4.21. Found: C,

54.19; H, 4.28; N, 4.13. ¹H NMR (CD₂Cl₂): δ 7.17 (t, J ) 2.2 Hz,

4H), 6.88 (s, 4H), 6.49 (t, J ) 2.2 Hz, 4H), 5.86 (s, 4H), 2.36 (s,

12H). ¹³C{¹H} NMR (CD₂Cl₂): δ 137.0, 132.3, 126.8, 120.4, 111.9,

89.9, 19.2.

1

C, 66.44; H, 4.34; N, 4.30. Found: C, 66.48; H, 4.32; N, 4.45. H

NMR (CD₂Cl₂): δ 7.55 (m, 2H, 4-H in indolyl), 7.44 (d, J ) 3.3

Hz, 2H, 3-H in indolyl), 7.88 (m, 4H, 4,7-H in indenyl), 7.24 (m,

4H, 5,6-H in indenyl), 7.17 (m, 2H, 5-H in indolyl), 6.86 (m, 2H,

5-H in indolyl), 6.84 (d, J ) 3.3 Hz, 2H, 2-H in indolyl), 5.70 (s,

4H, 1,3-H in indenyl), 1.83 (s, 6H, Me).

Bis[η⁵-2-(2-phenyl-1H-indol-1-yl)indenyl]zirconium Dichlo-

ride (31). To a solution of 5.63 g (18.3 mmol) of 10 in 200 mL of

(µ-Bromo)dibromo[η⁵-2-(1H-pyrrol-1-yl)indenyl]zirconium

Dimer (35). In a round-bottom ﬂask (0.5 L) in the glovebox, to a

solution of 7.74 g (29 mmol) of Zr(NMe₂)₄in 400 mL of ether

was added 5.43 g (30 mmol) of 5. This mixture was stirred

overnight at room temperature and then evaporated to dryness. The

obtained oil was dissolved in 400 mL of toluene, and 17.8 g (116

mmol) of Me₃SiBr was added. The resulting mixture was stirred

overnight, and then the obtained yellow solution was evaporated

to a volume equal to ca. 100 mL. Crystals precipitating at -30 °C

were separated, washed with 40 mL of cold toluene, and dried under

vacuum. Yield: 13.4 g (40%) of yellow crystalline solid of 35 · C₇H₈.

Anal. Calcd for C₃₃H₂₈Br₆N₂Zr₂: C, 35.56; H, 2.53; N, 2.51. Found:

n

Et₂O was added 7.32 mL (18.3 mmol) of 2.5 M BuLi in hexanes

at room temperature. This mixture was stirred overnight, and then

3.46 g (9.16 mmol) of ZrCl₄(THF)₂was added at room temperature.

This mixture was stirred for 1 day and then evaporated to dryness.

To the residue was added 150 mL of toluene. The mixture was

heated to reﬂux and then ﬁltered through Celite 503 (on a fritted-

glass funnel). The Celite layer was washed with 300 mL of

dichloromethane. The combined extract was evaporated to dryness

to give 3.50 g (49%) of 31. Anal. Calcd for C₄₆H₃₂Cl₂N₂Zr: C,

1

71.30; H, 4.16; N, 3.62. Found: C, 71.28; H, 4.17; N, 3.77. H

1

NMR (CD₂Cl₂): δ 7.77 (br.s, 4H), 7.65 (m, 4H), 7.80 (m, 4H),

7.25 (m, 4H), 7.10-7.22 (m, 8H), 7.01 (br.s, 4H), 6.77 (s, 4H).

C, 35.73; H, 2.70; N, 2.68. H NMR (CD₂Cl₂): δ 7.81-7.73 (m,

4H), 7.45-7.39 (m, 4H), 7.26 (t, J ) 2.1 Hz, 4H), 7.14-7.24 (s,

5H), 6.88 (s, 4H), 6.40 (t, J ) 2.1 Hz, 4H), 2.34 (s, 3H). ¹³C{¹H}

NMR (CD₂Cl₂): δ 140.4, 133.8 (C₇H₈), 129.0 (C₇H₈), 128.3 (C₇H₈),

128.1, 126.5, 125.7, 125.0 (C₇H₈), 119.6, 112.2, 94.4, 38.3 (C₇H₈).

Bis[η⁵-2-(1,2,3,4-tetrahydro-9H-carbazol-9-yl)indenyl]hafni-

um Dichloride (32). In a round-bottom ﬂask (0.15 L) in the

glovebox, to a solution of 2.41 g (8.44 mmol) of 13 in 100 mL of

(µ-Bromo)dibromo[η⁵-2-(1H-indol-1-yl)indenyl]zirconium

Dimer (36). The reaction was carried out similarly to the preparation

of compound 35, starting from 1.92 g (8.3 mmol) of 7, 2.22 g (8.3

mmol) of Zr(NMe₂)₄, 5.41 g (33 mmol) of Me₃SiBr, and 70 mL of

ether. Yield: 3.17 g (63%) of yellow solid of 36 · C₇H₈. Anal. Calcd

for C₄₁H₃₂Br₆N₂Zr₂: C, 40.54; H, 2.66; N, 2.31. Found: C, 40.78;

n

toluene was added 3.38 mL of a 2.5 M solution of BuLi (8.44

mmol) in hexanes at room temperature. This mixture was stirred

overnight. Then, 1.35 g (4.22 mmol) of HfCl₄was added at room

temperature. This mixture was reﬂuxed for 10 h; then, this hot

mixture was ﬁltered through Celite 503. The Celite layer was

additionally washed with 2 × 50 mL of hot toluene. The combined

extract was evaporated to ca. 40 mL. Yellowish crystals precipitat-

ing at room temperature were separated, washed with 10 mL of

cold toluene and 10 mL of hexanes, and dried under vacuum. Yield:

1.70 g (49%) of 32. Anal. Calcd for C₄₂H₃₆Cl₂N₂Hf: C, 61.66; H,

4.44; N, 3.42. Found: C, 61.83; H, 4.52; N, 3.64. ¹H NMR (CD₂Cl₂):

δ 7.70 (m, 2H, 6,6′-H of N-azolyl), 7.60 (m, 2H, 9,9′-H of N-azolyl),

7.22-7.43 (m, 12H, 4,4′,5,5′,6,6′,7,7′-H of indenyl and 7,7′,8,8′-H

of N-azolyl), 5.88 (br.s, 4H, 1,1′,3,3′-H of indenyl), 2.80, 2.30, 1.87,

and 1.76 (four multiplets, 4 × 4H, 2,2′-CH_2,3,3′-CH₂, 4,4′-CH₂,

and 5,5′-CH₂of N-azolyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 136.8, 135.1,

133.8, 128.0, 125.2, 123.8, 122.4 (br.), 121.2, 120.0, 116.9, 113.1,

111.2, 92.6 (br), 23.9, 22.2, 20.9, 19.7.

1

H, 2.81; N, 2.49. H NMR (CD₂Cl₂): δ 8.06 (d, J ) 8.5 Hz, 2H),

7.87 (dd, J ) 3.0 Hz, J ) 6.3 Hz, 4H), 7.72 (d, J ) 8.0 Hz, 2H),

7.69 (d, J ) 3.4 Hz, 2H), 7.49 (dd, J ) 3.0 Hz, J ) 6.3 Hz, 4H),

7.47-7.42 (m, 2H), 7.42-7.35 (m, 4H), 7.34-7.25 (m, 4H),

7.14-7.24 (s, 5H), 6.85 (d, J ) 3.4 Hz, 2H), 2.37 (s, 3H).

(µ-Bromo)dibromo[η⁵-2-(7-methyl-1H-indol-1-yl)indenyl]zir-

conium Dimer (37). To a solution of 5.30 g (21.6 mmol) of 9 in

220 mL of Et₂O was added 5.49 g (20.5 mmol) of Zr(NMe₂)₄at

room temperature. This mixture was stirred for 2 days and then

evaporated to dryness. To a solution of the residue in 220 mL of

toluene was added 10.26 g (67 mmol) of Me₃SiBr. The resulting

mixture was stirred for 1 day and then evaporated to dryness. The

residue was washed with 3 × 10 mL of toluene and 3 × 10 mL of

hexanes and dried under vacuum. Yield: 9.00 g (76%) of 37. Anal.

Calcd for C₃₆H₂₈Br₆N₂Zr₂: C, 37.58; H, 2.45; N, 2.43. Found: C,

37.60; H, 2.44; N, 2.35. ¹H NMR (CD₂Cl₂): δ 7.87 (m, 8H, 4,7-H

in indenyl), 7.55 (d, J ) 3.5 Hz, 4H, 3-H in indolyl), 7.51 (m, 4H,

4-H in indolyl), 7.49 (m, 8H, 5,6-H in indenyl), 7.20 (m, 4H, 5-H

in indolyl), 7.13 (m, 4H, 6-H in indolyl), 6.98 (s, 8H, 1,3-H in

indenyl), 6.73 (d, J ) 3.5 Hz, 4H, 2-H in indolyl), 2.38 (s, 12H,

Me).

(µ-Bromo)dibromo[η⁵-2-(9H-carbazol-1-yl)indenyl]zirconi-

um Dimer (38). The reaction was carried out similarly to the

preparation of compound 35, starting from 2.83 g (10 mmol) of

14, 2.67 g (10 mmol) of Zr(NMe₂)₄, 6.52 g (33 mmol) of Me₃SiBr,

and 100 mL of ether. Yield: 2.56 g (39%) of yellow solid of

38 · C₇H₈. Anal. Calcd for C₄₉H₃₆Br₆N₂Zr₂: C, 44.77; H, 2.76; N,

2.13. Found: C, 44.91; H, 2.79; N, 2.22. ¹H NMR (CD₂Cl₂): δ 8.27

(d, J ) 8.4 Hz, 4H), 8.14 (dq, J ) 0.7 Hz, J ) 7.7 Hz, 4H), 7.79

(dd, J ) 3.0 Hz, J ) 6.3 Hz, 4H), 7.79 (ddd, J ) 1.3 Hz, J ) 7.3

Hz, J ) 8.4 Hz, 4H), 7.44-7.37 (m, 8H), 7.35 (s, 4H), 7.14-7.24

(s, 5H), 2.37 (s, 3H). ¹³C{¹H} NMR (CD₂Cl₂): δ 139.6, 133.2

Bis[η⁵-4,7-dimethyl-2-(1H-pyrrol-1-yl)indenyl]zirconium Dichlo-

ride (33). In a round-bottom ﬂask (0.1 L) in the glovebox, to a

solution of 1.25 g (6.00 mmol) of 15 in 70 mL of toluene was

added 2.40 mL of 2.5 M ⁿBuLi (6.00 mmol) in hexanes at ambient

temperature. The suspension formed was additionally stirred

overnight, and then 0.70 g (3.00 mmol) of ZrCl₄was added. This

mixture was stirred for 3 h at 110 °C and 1 day at ambient

temperature. The hot mixture was ﬁltered through Celite 503. The

Celite layer was washed with 2 × 50 mL of hot toluene. The

combined extract was evaporated to ca. 50 mL. The precipitate

that formed was ﬁltered off, washed with 2 × 10 mL of hexanes,

and dried under vacuum. Yield: 0.65 g (37%) of yellowish

crystalline solid. Anal. Calcd for C₃₀H₂₈Cl₂N₂Zr: C, 62.27; H, 4.88;

1

N, 4.84. Found: C, 62.39; H, 4.78; N, 4.90. H NMR (CD₂Cl₂): δ

7.10 (t, J ) 3.1 Hz, 4H, 2,2′,5,5′-H of pyrrolyl), 6.84 (s, 4H,

5,5′,6,6′-H of indenyl), 6.41 (t, J ) 3.1 Hz, 4H, 3,3′,4,4′-H of

pyrrolyl), 5.92 (s, 4H, 1,1′,3,3′-H of indenyl), 2.28 (s, 12H, 4,4′,7,7′-

Me of indenyl). ¹³C{¹H} NMR (CD₂Cl₂): δ 138.9, 133.6, 128.2,

127.1, 121.5, 113.2, 93.5, 20.4.

1814 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

1

(C₇H₈), 129.3 (C₇H₈), 128.7 (C₇H₈), 128.0, 126.8, 126.5, 125.9

(C₇H₈), 125.1, 124.4, 123.3, 121.9, 120.2, 113.1, 99.1, 38.5 (C₇H₈).

3.61; N, 3.69. H NMR (CD₂Cl₂): δ 8.17 (m, 2H), 7.53-7.63 (m,

5H), 7.27-7.42 (m, 7H), 7.12-7.20 (3H), 6.98 (m, 2H), 6.91 (m,

1H), 6.74 (m, 1H), 6.20 (s, 2H), 5.94 (s, 2H), 1.78 (s, 3H, Me).

[η⁵-2-(1H-Pyrrol-1-yl)indenyl][η⁵-2-(9H-carbazol-1-yl)inde-

nyl]zirconium Dibromide (39). To a solution of 562 mg (2.0

mmol) of 14 in 20 mL of ether was added 0.8 mL of 2.5 M (2.0

mmol) of ⁿBuLi in hexanes at room temperature. This mixture was

stirred overnight and then added to a solution of 1.12 g (2.0 mmol)

of 35 in 20 mL of toluene at -35 °C. The resulting mixture was

stirred for 0.5 h at this temperature and overnight at ambient

temperature and then evaporated to a volume equal to ca. 25 mL.

A mixture of this solution with 20 mL of toluene was ﬁltered

through a glass frit at 100-110 °C. The residue was additionally

washed with 10 mL of hot toluene. The combined toluene extract

was evaporated to a volume equal to 15 mL. Crystals precipitating

from this solution at -30 °C were collected, washed with 5 mL of

cold toluene, and dried under vacuum. Yield: 470 mg (33%) of

yellowish solid of 39. Anal. Calcd for C₃₄H₂₄Br₂N₂Zr: C, 57.39;

[η⁵-2-Phenylindenyl][η⁵-2-(1H-pyrrol-1-yl)indenyl]zirconi-

um Dibromide (44). To a solution of 0.36 g (2.0 mmol) of 5 in 20

mL of ether was added 0.80 mL (2.0 mmol) of 2.5 M BuLi in

hexanes at room temperature. This mixture was stirred for 1.5 h

and then added to a suspension of 1.14 g (2.0 mmol) of 43 · C₇H₈

in 20 mL of toluene at -35 °C. The resulting mixture was stirred

for 30 min at this temperature and 30 min at room temperature

and then evaporated to dryness. The product was recrystallized from

toluene. The crystals precipitating at -30 °C were collected, washed

with hexanes, and dried under vacuum. Yield: 0.48 g (37%). Anal.

Calcd for C₂₈H₂₁Br₂NZr: C, 54.02; H, 3.40; N, 2.25. Found: C,

n

1

54.35; H, 3.44; N, 2.02. H NMR (CD₂Cl₂): δ 7.68 (m, 2H), 7.54

(m, 2H), 7.48 (m, 2H), 7.45 (m, 1H), 7.39 (m, 2H), 7.24 (m, 2H),

7.19 (m, 2H), 6.80 (m, 2H), 6.64 (m, 2H), 6.28 (m, 2H), 6.00 (m,

2H). ¹³C{¹H} NMR (CD₂Cl₂): δ 141.4, 134.9, 134.3, 130.62,

130.55, 128.55, 128.53, 128.47, 127.7, 127.3, 127.1, 124.4, 120.9,

112.9, 105.5, 96.0, 94.6.

[η⁵-2-Phenylindenyl][η⁵-2-(1H-indol-1-yl)indenyl]zirconium

Dibromide (45). The reaction was carried out similarly to the

preparation of compound 44, starting from 0.46 g (2.0 mmol) of 7,

1

H, 3.40; N, 3.94. Found: C, 57.47; H, 3.45; N, 4.08. H NMR

(CD₂Cl₂): δ 8.22 (d, J ) 7.7 Hz, 2H), 7.85 (d, J ) 8.3 Hz, 2H),

7.70-7.63 (m, 2H), 7.59 (ddd, J ) 1.1 Hz, J ) 7.5 Hz, J ) 8.2

Hz, 2H), 7.50-7.45 (m, 2H), 7.40-7.39 (m, 2H), 7.34-7.26 (m,

4H), 7.24-7.15 (m, 2H), 6.84 (t, J ) 2.2 Hz, 2H), 6.32 (t, J ) 2.2

Hz, 2H), 6.30 (s, 2H), 5.86 (s, 2H). ¹³C{¹H} NMR (CD₂Cl₂): δ

141.6, 139.6, 139.0, 126.8, 126.5, 126.4, 126.3, 126.1, 124.8, 123.9,

123.4, 121.9, 120.4, 119.3, 112.9, 111.5, 97.0, 92.8.

n

0.80 mL (2.0 mmol) of 2.5 M BuLi in hexanes, and 1.14 g (2.0

mmol) of 43 · C₇H₈. Yield: 0.77 g (66%). Anal. Calcd for

[η⁵-2-(1H-Pyrrol-1-yl)indenyl][η⁵-2-(1H-indol-1-yl)indenyl]zir-

conium Dibromide (40). The reaction was carried out similarly to

the preparation of compound 39, starting from 362 mg (2.0 mmol)

C₃₂H₂₃Br₂NZr: C, 57.15; H, 3.45; N, 2.08. Found: C, 57.31; H,

1

3.68; N, 2.19. H NMR (CD₂Cl₂): δ 7.67 (m, 1H), 7.43-7.61 (m,

7H), 7.19-7.37 (m, 10H), 7.16 (m, 2H), 6.71 (m, 1H), 6.48 (s,

n

of 5, 0.8 mL of 2.5 M (2.0 mmol) BuLi in hexanes, and 1.22 g

2H), 6.26 (s, 2H).

[η⁵-2-Phenylindenyl][η⁵-2-(9H-carbazol-1-yl)indenyl]zirconi-

um Dibromide (46). The reaction was carried out similarly to the

preparation of compound 44, starting from 0.56 g (2.0 mmol) of

(2.0 mmol) of 36. Yield: 470 mg (37%) of yellow solid of 40.

Anal. Calcd for C₃₀H₂₂Br₂N₂Zr: C, 54.47; H, 3.35; N, 4.23. Found:

C, 54.59; H, 3.40; N, 4.10. ¹H NMR (CD₂Cl₂): δ 7.72 (d, J ) 7.8

Hz, 1H), 7.70-7.66 (m, 2H), 7.60 (d, J ) 8.4 Hz, 1H), 7.57-7.50

(m, 2H), 7.41-7.37 (m, 2H), 7.36-7.33 (m, 2H), 7.32-7.27 (m,

2H), 7.25-7.19 (m, 1H), 6.92 (t, J ) 2.2 Hz, 2H), 6.77 (dd, J )

0.7 Hz, J ) 3.5 Hz, 1H), 6.36 (t, J ) 2.2 Hz, 2H), 6.18 (s, 2H),

5.85 (s, 2H). ¹³C{¹H} NMR (CD₂Cl₂): δ 140.9, 140.4, 135.2, 130.3,

127.3, 126.4, 126.3, 126.13, 126.12, 123.5, 123.21, 123.20, 121.8,

121.6, 119.4, 112.7, 111.5, 106.2, 94.2, 93.0.

[η⁵-2-(1H-Indol-1-yl)indenyl][η⁵-2-(9H-carbazol-1-yl)inde-

nyl]zirconium Dibromide (41). The reaction was carried out

similarly to the preparation of compound 39, starting from 462 mg

(2.0 mmol) of 7, 0.8 mL of 2.5 M (2.0 mmol) of ⁿBuLi in hexanes,

and 1.32 g (2.0 mmol) of 38. Yield: 213 mg (14%) of yellow solid

of 41. Anal. Calcd for C₃₈H₂₆Br₂N₂Zr: C, 59.92; H, 3.44; N, 3.68.

Found: C, 59.97; H, 3.47; N, 3.66. ¹H NMR (CD₂Cl₂): δ 8.22 (dd,

J ) 0.6 Hz, J ) 7.4 Hz, 2H), 7.72-7.67 (m, 3H), 7.60-7.55 (m,

3H), 7.52 (ddd, J ) 1.3 Hz, J ) 7.3 Hz, J ) 8.0 Hz, 2H), 7.48-7.43

(m, 2H), 7.42-7.38 (m, 2H), 7.37-7.31 (m, 4H), 7.30-7.26 (m,

2H), 7.02 (d, J ) 3.5 Hz, 1H), 6.63 (d, J ) 3.5 Hz, 1H), 6.22 (s,

2H), 6.13 (s, 2H). ¹³C{¹H} NMR (CD₂Cl₂): δ 141.0, 139.4, 139.2,

135.0, 130.3, 126.8, 126.7, 126.6, 126.5, 126.4, 126.1, 124.7, 124.0,

123.6, 123.5, 121.9, 121.7, 121.4, 120.3, 112.7, 112.5, 106.3, 97.1,

94.2.

n

14, 0.80 mL (2.0 mmol) of 2.5 M BuLi in hexanes, and 1.14 g

(2.0 mmol) of 43 · C₇H₈. Yield: 0.45 g (29%). Anal. Calcd for

C₃₆H₂₅Br₂NZr: C, 59.84; H, 3.49; N, 1.94. Found: C, 59.71; H,

1

3.69; N, 2.05. H NMR (CD₂Cl₂): δ 8.21 (m, 2H), 7.80 (m, 2H),

7.51-7.55 (m, 4H), 7.45 (m, 2H), 7.37-7.41 (m, 3H), 7.31-7.36

(m, 4H), 7.22 (m, 4H), 6.37 (m, 2H), 6.30 (s, 2H).

2-Mesityl-1H-indene. A mixture of mesitylmagnesium bromide

(obtained from 535 mg of magnesium turnings and 3.98 g of mesityl

bromide in 60 mL of THF), 3.90 g (20 mmol) of 2-bromo-1H-

indene, 230 mg (0.4 mmol) of Pd(dba)₂, and 2.0 mL of 0.2 M (0.4

mmol) P^tBu₃in toluene was stirred for 48 h at room temperature.

To the resulting mixture was added 100 mL of brine, and the organic

layer was separated. The aqueous layer was washed with 2 × 50

mL of ether. The combined extract was dried over Na₂SO₄and

evaporated to dryness. The product was isolated using ﬂash

chromatography on silica gel 60 (40-63 um; d ) 40 mm, l ) 200

mm; 10/1 v/v hexanes/methyl tert-butyl ether). Yield: 3.04 g (65%)

1

of yellowish oil. H NMR (CDCl₃): δ 7.56 (dq, J ) 0.8 Hz, J )

7.4 Hz, 1H), 7.49 (dt, J ) 1.0 Hz, J ) 7.4 Hz, 2H), 7.38 (tt, J )

0.5 Hz, J ) 7.5 Hz, 1H), 7.27 (dt, J ) 1.1 Hz, J ) 7.4 Hz, 1H),

7.00 (s, 2H), 6.72-6.70 (m, 1H), 3.63 (s, 2H), 2.39 (s, 3H), 2.25

(s, 6H).

[η⁵-2-(7-Methyl-1H-indol-1-yl)indenyl][η⁵-2-(9H-carbazol-1-

yl)indenyl]zirconium Dibromide (42). To a solution of 1.97 g

(6.99 mmol) of 14 in a mixture of 80 mL of Et₂O and 80 mL of

toluene was added 2.80 mL (7.0 mmol) of 2.5 M ⁿBuLi in hexanes

at room temperature. This mixture was stirred overnight, and then

4.03 g (7.00 mmol) of 37 was added at -30 °C. This mixture was

stirred for 1 day at room temperature and than evaporated to

dryness. To the residue was added 150 mL of toluene. The resulting

mixture was reﬂuxed for 1 day and then ﬁltered through Celite

503 (on a fritted-glass funnel). The ﬁltrate was evaporated to

dryness. The residue was washed with 3 × 20 mL of toluene and

dried under vacuum. Yield: 4.03 g (74%) of 42. Anal. Calcd for

C₃₉H₂₈Br₂N₂Zr: C, 60.39; H, 3.64; N, 3.61. Found: C, 60.41; H,

(µ-Bromo)dibromo[η⁵-2-mesitylindenyl]zirconium Dimer (47).

A mixture of 5.37 g (22.9 mmol) of 2-mesityl-1H-indene and 5.89 g

(22.0 mmol) of Zr(NMe₂)₄in 300 mL of ether was stirred for 12 h

at room temperature. The resulting mixture was evaporated to

dryness, and 200 mL of toluene was added. To the solution obtained

was added 11.4 g (74.5 mmol) of Me₃SiBr at room temperature.

This mixture was stirred for 12 h and then evaporated to dryness.

To the residue were added 30 mL of toluene and 50 mL of hexanes.

The precipitate that formed was ﬁltered off, washed with 3 × 50

mL of hexanes, and dried under vacuum. Yield: 8.98 g (72%) of

yellowish solid of 47. Anal. Calcd for C₁₈H₁₇Br₃Zr: C, 38.31; H,

1

3.04. Found: C, 38.57; H, 3.29. H NMR (CD₂Cl₂): δ 7.89 (dd, J

) 6.6 Hz, J ) 3.1 Hz, 4H), 7.41 (dd, J ) 6.6 Hz, J ) 3.1 Hz, 4H),

Metallocenes with η⁵-2(N-Azolyl)indenyl Ligands

Organometallics, Vol. 28, No. 6, 2009 1815

1

7.15 (s, 4H), 7.00 (s, 4H), 2.51 (s, 12H), 2.33 (s, 6H). ¹³C{¹H}

NMR (CD₂Cl₂): δ 144.4, 140.6, 138.2, 131.9, 131.6, 130.3, 129.2,

128.1, 111.0, 25.9, 22.2.

N, 2.93. Found: C, 58.11; H, 5.40; N, 2.76. H NMR (CD₂Cl₂): δ

7.66 (m, 2H, 7-H in indenyl), 7.54 (m, 1H, 4-H in indenyl), 7.31

(ddd, J ) 8.7 Hz, J ) 6.7 Hz, J ) 1.2 Hz, 1H, 6-H in indenyl),

7.22 (ddd, J ) 8.4 Hz, J ) 6.7 Hz, J ) 1.3 Hz, 1H, 5-H in indenyl),

7.12 (t, J ) 2.2 Hz, 2H, 2,5-H in pyrrolyl), 6.35 (d, J ) 3.3 Hz,

1H, 2-H in indenyl), 6.30 (t, J ) 2.2 Hz, 2H, 3,4-H in pyrrolyl),

5.79 (dd, J ) 3.3 Hz, J ) 0.9 Hz, 1H, 3-H in indenyl), 1.90 (s,

15H, Cp*). ¹³C{¹H} NMR (CD₂Cl₂): δ 136.4, 128.2, 127.9, 127.1,

126.9, 126.4, 123.9, 123.5, 123.3, 111.4, 111.2, 95.6, 13.5.

[η⁵-Pentamethylcyclopentadienyl][η⁵-2-(1H-benzimidazol-1-

yl)-1H-indenyl]zirconium Dichloride (52). In a round-bottom ﬂask

(0.1 L) in the glovebox, to a suspension of 0.53 g (2.30 mmol) of

21 in 10 mL of toluene was added 0.38 g (2.30 mmol) of

LiN(TMS)₂with vigorous stirring. This mixture was additionally

stirred for 10 h at ambient temperature, and then 0.77 g (2.30 mmol)

of Cp*ZrCl₃was added. The resulting mixture was stirred for 10 h

at 95 °C and then ﬁltered through Celite 503. The Celite layer was

washed with 2 × 40 mL of hot toluene. The combined extract was

evaporated to ca. 25 mL. Crystals precipitating from this solution

at -30 °C were collected, washed with 5 mL of cold toluene, and

dried under vacuum. Yield: 0.40 g (44%) of white solid. Anal. Calcd

for C₂₆H₂₆Cl₂N₂Zr: C, 59.07; H, 4.96; N, 5.30. Found: C, 59.22;

H, 5.05; N, 5.38. ¹H{¹³C} NMR (CD₂Cl₂): δ 8.79 (br.s, 1H, 2-H in

1H-benzimidazol-1-yl), 8.29 (m, 1H, 7-H in 1H-benzimidazol-1-

yl), 7.73 (m, 1H, 4-H in 1H-benzimidazol-1-yl), 6.87-7.58 (m,

6-H, 4,5,6,7-H in indenyl and 5,6-H in 1H-benzimidazol-1-yl), 6.25

(br.s, 2H, 1,3-H in indenyl), 2.06 (s, 15H, Cp*).

X-ray Structural Determinations of 22, 26, 32, 38, and 50.

The resulting crystallographic data are summarized in the Support-

ing Information. For complex 50, data were collected on a CAD4

Enraf-Nonius instrument (λ(Mo KR) ) 0.710 73 Å, graphite

monochromator, θ-⁵/₃θ scans) at room temperature. All other X-ray

experiments were carried out using a SMART 1000 CCD diffrac-

tometer (λ(Mo KR) ) 0.710 73 Å, graphite monochromator, ω

scans) at 120 K. All structures were solved by direct methods and

reﬁned by the full-matrix least-squares procedure in anisotropic

approximation for non-hydrogen atoms. All the hydrogen atoms

were placed in geometrically calculated positions (except for

hydrogens of the water molecule in 50, for which hydrogens were

localized from the difference Fourier map) and included in the

reﬁnement using riding approximation. The complexes 22, 26, and

32 occupy a special position on the 2-fold axis. The crystal 22

contains a solvate toluene molecule which is disordered over two

sites related by an inversion center. The details of data collection

and crystal structure reﬁnement, for which we used the SAINT

Plus,³⁸SADABS,³⁹SHELXTL-97,⁴⁰and PLATON⁴¹program

packages, are summarized in the Supporting Information.

[η⁵-2-Mesitylindenyl][η⁵-2-(1H-pyrrol-1-yl)indenyl]zirconi-

um Dibromide (48). The reaction was carried out similarly to the

preparation of compound 39, starting from 362 mg (2.0 mmol) of

5, 0.8 mL of 2.5 M (2.0 mmol) ⁿBuLi in hexanes, and 1.12 g (2.0

mmol) of 47. The reaction mixture was evaporated to dryness. The

crude product was extracted with 2 × 20 mL of toluene. The

combined extract was ﬁltered through a PTFE membrane ﬁlter (0.45

um) and evaporated to a volume equal to ca. 10 mL. The precipitate

that formed was ﬁltered off, washed with 10 mL of toluene, and 3

× 10 mL of hexanes, and dried under vacuum. Yield: 575 mg (43%)

of yellow solid of 48. Anal. Calcd for C₃₁H₂₇Br₂NZr: C, 56.02; H,

4.09; N, 2.11. Found: C, 56.20; H, 4.25; N, 2.00. ¹H NMR (CD₂Cl₂):

δ 7.54-7.47 (m, 2H), 7.43-7.38 (m, 2H), 7.35-7.24 (m, 2H), 7.15

(s, 2H), 6.92 (t, J ) 2.5 Hz, 2H), 6.38 (t, J ) 2.5 Hz, 2H), 5.96 (s,

2H), 5.94 (s, 2H), 2.45 (s, 9H). ¹³C{¹H} NMR (CD₂Cl₂): δ 140.5,

138.4, 137.4, 136.5, 131.0, 129.5, 127.4, 126.7, 126.5, 126.4, 125.8,

123.4, 118.9, 111.7, 108.8, 93.0, 24.7, 20.7.

[η⁵-2-Mesitylindenyl][η⁵-2-(1H-indol-1-yl)indenyl]zirconi-

um Dibromide (49). The reaction was carried out similarly to the

preparation of compound 39, starting from 462 mg (2.0 mmol) of

7, 0.8 mL of 2.5 M (2.0 mmol) ⁿBuLi in hexanes, and 1.12 g (2.0

mmol) of 47. The reaction mixture was evaporated to dryness. The

crude product was extracted with 2 × 20 mL of toluene. The

combined extract was ﬁltered through a PTFE membrane ﬁlter (0.45

um) and evaporated to a volume equal to ca. 10 mL. A mixture of

this solution and 17 mL of hexanes was heated to reﬂux and

carefully placed in the refrigerator. Crystals precipitating at -30

°C were collected, washed with 20 mL of hexanes, and dried under

vacuum. Yield: 840 mg (58%) of yellow solid of 49. Anal. Calcd

for C₃₅H₂₉Br₂NZr: C, 58.82; H, 4.09; N, 1.96. Found: C, 58.75; H,

4.01; N, 2.12. ¹H NMR (CD₂Cl₂): δ 7.79-7.74 (m, 2H), 7.51-7.46

(m, 2H), 7.45-7.40 (m, 2H), 7.37-7.72 (m, 3H), 7.29-7.34 (m,

2H), 7.11 (d, J ) 3.1 Hz), 7.10 (s, 2H), 6.76 (dd, J ) 0.7 Hz, J )

3.5 Hz, 1H), 6.28 (s, 2H), 5.90 (s, 2H), 2.45 (s, 3H), 2.27 (s, 6H).

¹³C{¹H} NMR (CD₂Cl₂): δ 139.1, 138.3, 137.2, 136.4, 134.8, 131.1,

130.4, 129.5, 127.3, 126.91, 126.86, 126.8, 126.3, 125.8, 123.8,

123.7, 121.9, 121.5, 112.4, 108.9, 106.1, 94.8, 24.5, 20.6.

[η⁵-2-Mesitylindenyl][η⁵-2-(9H-carbazol-9-yl)indenyl]zirco-

nium Dibromide (50). The reaction was carried out similarly to

the preparation of compound 48, starting from 562 mg (2.0 mmol)

n

of 14, 0.8 mL of 2.5 M (2.0 mmol) BuLi in hexanes, and 1.12 g

(2.0 mmol) of 47. Yield: 340 mg (22%) of yellow solid of 50.

Anal. Calcd for C₃₉H₃₁Br₂NZr: C, 61.25; H, 4.09; N, 1.83. Found:

1

C, 61.07; H, 4.22; N, 1.70. H NMR (C₆D₆, 70 °C): δ 8.05 (dq, J

Oleﬁn Polymerization Studies. Polymerizations were conducted

in an inert-atmosphere (N₂) drybox using autoclaves equipped with

an external heater for temperature control, glass inserts (internal

volume of reactor 23.5 mL for PE and EO runs and 22.5 mL for

PP and EP runs), septum inlets, a regulated supply of nitrogen,

ethylene and propylene, and disposable PEEK mechanical stirrers

(800 rpm). The autoclaves were prepared by purging with dry

nitrogen at 110 or 115 °C for 5 h and then at 25 °C for 5 h. Solvents

and polymerization grade toluene and hexanes were supplied by

ExxonMobil Chemical Co. and thoroughly dried and degassed prior

to use. 1-Octene, 98% (Aldrich), was dried by stirring over Na/K

) 0.7 Hz, J ) 7.7 Hz, 2H), 7.89 (d, J ) 8.4 Hz, 2H), 7.61-7.54

(m, 2H), 7.51-7.44 (m, 2H), 7.38 (ddd, J ) 1.5 Hz, J ) 7.3 Hz,

J ) 8.1 Hz, 2H), 7.35-7.30 (m, 2H), 7.24-7.21 (m, 2H),

7.17-7.13 (m, 2H), 6.65 (s, 2H), 6.48 (s, 2H), 6.14 (s, 2H), 2.24

(s, 3H), 2.10 (s, 6H). ¹³C{¹H} NMR (C₆D₆, 70 °C): δ 139.6, 137.3,

136.9, 136.7, 131.1, 129.9, 129.0, 128.2, 127.6, 127.2, 127.1, 126.4,

126.3, 125.9, 124.9, 124.7, 121.7, 120.1, 112.7, 97.4, 24.0, 20.37.

[η⁵-Pentamethylcyclopentadienyl][η⁵-1-(1H-pyrrol-1-yl)-1H-

indenyl]zirconium Dichloride (51). In a round-bottom ﬂask (0.1

L) in the glovebox, to a solution of 0.65 g (3.60 mmol) of 19 in 35

mL of toluene was added 1.44 mL of 2.5 M ⁿBuLi (3.60 mmol) in

hexanes with vigorous stirring at ambient temperature. This mixture

was additionally stirred overnight, and then 1.20 g (3.60 mmol) of

Cp*ZrCl₃was added. The resulting mixture was stirred for 2 days

at ambient temperature and then for 10 h at 80 °C. The resulting

hot mixture was ﬁltered through Celite 503. The Celite layer was

washed with 2 × 20 mL of hot toluene. The combined extract was

evaporated to dryness. The residue was washed with 3 × 30 mL

of hexanes and dried under vacuum. Yield: 1.05 g (61%) of

yellowish solid. Anal. Calcd for C₂₃H₂₅Cl₂NZr: C, 57.84; H, 5.28;

(38) SMART and SAINT, Release 5.0, Area Detector Control and

Integration Software; Bruker AXS, Analytical X-Ray Instruments, Madison,

WI, 1998.

(39) Sheldrick, G. M. SADABS: A Program for Exploiting the

Redundancy of Area-Detector X-Ray Data; University of Go¨ttingen,

Go¨ttingen, Germany, 1999.

(40) Sheldrick, G. M. SHELXTL-97 Program for Solution and Reﬁne-

ment of Crystal Structure; Bruker AXS Inc., Madison, WI, 1997.

(41) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool;

Utrecht University, Utrecht, The Netherlands, 2002.

1816 Organometallics, Vol. 28, No. 6, 2009

LebedeV et al.

alloy overnight followed by ﬁltration through basic alumina

(Aldrich, Brockman Basic 1). Polymerization grade ethylene was

used and further puriﬁed by passing it through a series of columns:

500 cm³Oxyclear cylinder (Labclear, Oakland, CA) followed by a

500 cm³column packed with dried 3 Å molecular sieves (Aldrich),

and a 500 cm³column packed with dried 5 Å molecular sieves

(Aldrich). Polymerization grade propylene was used without further

puriﬁcation. MAO (methylalumoxane, 10 wt % in toluene) was

purchased from Albemarle Corp. and used as a 1 or 2 wt % in

toluene solution. Micromoles of MAO reported in the paper are

based on the micromoles of aluminum in MAO. The formula weight

of MAO is 58.0.

Ethylene Polymerization (PE) or Ethylene/1-Octene Copo-

lymerization (EO). The reactor was prepared as described above

and then purged with ethylene. Toluene (3.80 mL), 1-octene (0.64

mL) when used, and MAO (10 µmol) were added via syringe at

room temperature and atmospheric pressure. The reactor was then

brought to process temperature (80 °C) and charged with ethylene

to process pressure (75 psig) with stirring at 800 rpm. The transition-

metal compound (0.02 µmol as 0.2 mmol/L solution in toluene)

was added via syringe with the reactor at process conditions.

Ethylene was allowed to enter (through the use of computer-

controlled solenoid valves) the autoclaves during polymerization

to maintain reactor gauge pressure. Polymerizations were halted

by addition of approximately a 50 psig of O₂/Ar (5 mol % O₂) gas

mixture to the autoclaves for approximately 30 s. The polymer was

isolated after the solvent was removed under vacuum.

mL with a BHT concentration of 1.25 mg BHT/mL of TCB.

Samples were cooled to 135 °C for testing. Molecular weights (M_w

and M_n) and molecular weight distributions (PDI ) M_w/M_n) of the

polymer were measured by gel permeation chromatography using

a Symyx Technology GPC equipped with evaporative light scat-

tering detector and calibrated using polystyrene standards (Polymer

Laboratories: Polystyrene Calibration Kit S-M-10: mp (peak M_w)

between 5000 and 3 390 000). Samples were run in TCB (135 °C

sample temperature, 160 °C oven/columns) using three Polymer

Laboratories: PLgel 10 µm Mixed-B 300 × 7.5 mm columns in

series. No column spreading corrections were employed. Numerical

analyses were performed using Epoch software available from

Symyx Technologies. Samples for infrared analysis were prepared

by depositing the stabilized polymer solution onto a silanized wafer

(Part number S10860, Symyx). By this method, between ap-

proximately 0.12 and 0.24 mg of polymer was deposited on the

wafer cell. The samples were subsequently analyzed on a Bruker

Equinox 55 FTIR spectrometer equipped with Pikes’ MappIR

specular reﬂectance sample accessory. Spectra, covering a spectral

range of 5000-500 cm^-1, were collected at a 2 cm^-1resolution

with 32 scans. For ethylene-1-octene copolymers, the weight

percent of the comonomer was determined via measurement of the

methyl deformation band at ca. 1375 cm^-1. The peak height of

this band was normalized by the combination and overtone band

at ca. 4321 cm^-1, which corrects for path length differences. The

normalized peak height is correlated to individual calibration curves

1

from H NMR data to predict the weight percent of comonomer

Propylene Polymerization (PP). The reactor was prepared as

described above and then heated to 40 °C and purged with

propylene gas at atmospheric pressure. Hexanes (3.73 mL), MAO

(40 µmol), and liquid propylene (1.066 mL) were added via syringe.

The reactor was then heated to process temperature (70 °C) with

stirring at 800 rpm. The transition-metal complex (0.08 µmol as a

0.6 mmol/L solution in toluene) was added via syringe with the

reactor under process conditions. Polymerizations were halted by

addition of an approximately 50 psig of O₂/Ar (5 mol % O₂) gas

mixture to the autoclaves for approximately 30 s. The polymer was

isolated after the solvent was removed under vacuum.

Ethylene/Propylene Copolymerization (EP). The reactor was

prepared as described above and then purged with ethylene. The

reactor was heated to 40 °C, and ethylene was then added to a

target pressure of 10 psig (single addition), followed by the addition

of hexanes (3.77 mL), MAO (40 µmol), and then liquid propylene

(1.066 mL). All additions were made via syringe. The reactor was

then heated to process temperature (70 °C) with stirring at 800 rpm.

The transition-metal complex (0.08 µmol as a 0.6 mmol/L solution

in toluene) was added via syringe with the reactor under process

conditions. Polymerizations were halted by addition of an ap-

proximately 50 psig of O₂/Ar (5 mol % O₂) gas mixture to the

autoclaves for approximately 30 s. The polymer was isolated after

the solvent was removed under vacuum.

content within a concentration range of ca. 2-35 wt % for 1-octene.

Typically, R²correlations of 0.98 or greater are achieved. For

ethylene-propylene copolymers, the weight percent of ethylene is

determined via measurement of the methylene rocking band (ca.

770-700 cm^-1). The peak area of this band is normalized by sum

of the band areas of the combination and overtone bands in the

4500-4000 cm^-1range. The normalized band area is then

correlated to a calibration curved from ¹³C NMR data to predict

the weight percent of ethylene within a concentration range of ca.

5-40 wt %. Typically, R²correlations of 0.98 or greater are

achieved.

Acknowledgment. Financial support from ExxonMobil

Chemical Co. is gratefully acknowledged. We thank the

research and technical personnel of this company for the

catalyst and polymer properties tests performed. We also

appreciate the Crystallography Center of the Institute of

Organoelement Compounds of the Russian Academy of

Sciences for help with the X-ray measurements and reﬁne-

ments. Finally, we thank Prof. I. P. Beletskaya.

Supporting Information Available: CIF ﬁles and a table giving

crystallographic data and details of the data collection and crystal

structure reﬁnement for 20, 24, 28, 33, and 44 and text, ﬁgures,

and tables regarding the NMR dynamic study of 25 and 26. This

materialisavailablefreeofchargeviatheInternetathttp://pubs.acs.org.

Polymer Characterization. For analytical testing, polymer

sample solutions were prepared by dissolving polymer in 1,2,4-

trichlorobenzene (TCB) containing 2,6-di-tert-butyl-4-methylphenol

(BHT) at 160 °C in a shaker oven for approximately 3 h. The typical

concentration of polymer in solution is between 0.4 and 0.9 mg/

OM8010257

Article Doi

Group 4 metallocenes bearing η5-2-(iv-azolyl)indenyl ligands: synthesis, structure characterization, and olefin polymerization catalysis

DOI: 10.1021/om8010257

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Article abstract of DOI:10.1021/om8010257

Full text of DOI:10.1021/om8010257

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