The reaction of [η5:C5H4-(CH 2)n-C6H5]2MCl 2 complexes (n=1-5; M=Zr, Hf) with EtLi

Article abstract of DOI:10.1016/j.ica.2003.12.040

The reaction of metallocene complexes of the type [η⁵:C ₅H₄-(CH₂)_n-C₆H ₅]₂MCl₂ (n=1-5; M=Zr, Hf) with EtLi gives the mono nuclear ethyl derivatives [η⁵:C₅H ₄-(CH₂)_n-C₆H₅] ₂M(Et)Cl and the metallacycles [η⁵:C₅H ₄-(CH₂)_n-C₆H₅] [η⁵:C₅H₄-(CH₂) _n-η¹:C₆H₄]MEt. A large excess of EtLi affords the dinuclear species [η⁵:C₅H ₄-(CH₂)_n-η⁶:C₆H ₅]₂M₂Cl₂ (n=2-5). All types of complexes can be activated with methylalumoxane (MAO) and then be used for catalytic polymerization of ethylene.

Full text of DOI:10.1016/j.ica.2003.12.040

Inorganica Chimica Acta 357 (2004) 1682–1694
www.elsevier.com/locate/ica
The reaction of [g5:C5H4–(CH2)n–C6H5]2MCl2 complexes
(n ¼ 1–5; M ¼ Zr, Hf) with EtLi
*
Helmut G. Alt , Christine E. Denner, Wolfgang Milius
Laboratorium fu€r Anorganische Chemie, Universit€at Bayreuth, Postfach 101251, Universit€atsstrasse 30, NW I, D-95440 Bayreuth, Germany
Received 11 September 2003; accepted 3 December 2003
Dedicated to Professor Helmut Werner on the occasion of his 70th birthday (19.4.2004)
Abstract
The reaction of metallocene complexes of the type [g5:C5H4–(CH2)n–C6H5]2MCl2 (n ¼ 1–5; M ¼ Zr, Hf) with EtLi gives the
mono nuclear ethyl derivatives [g5:C5H4–(CH2)n–C6H5]2M(Et)Cl and the metallacycles [g5:C5H4–(CH2)n–C6H5][g5:C5H4–(CH2)n–
g1:C6H4]MEt. A large excess of EtLi affords the dinuclear species [g5:C5H4–(CH2)n–g6:C6H5]2M2Cl2 (n ¼ 2–5). All types of
complexes can be activated with methylalumoxane (MAO) and then be used for catalytic polymerization of ethylene.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Metallocene complexes; Metallacycles; Dinuclear complexes; Ethylene polymerization
1. Introduction
The reaction of x-phenylalkyl substituted metallo-
Cl
+ 2 n-BuLi
cene complexes of the type [g5:C5H4–(CH2)n–
C6H5]2MCl2 (n ¼ 1–3; M ¼ Zr, Hf) with BuLi gives a
variety of reaction products depending on n [1–4].
Zr
Zr
- 2 LiCl
Cl
The first step is the formation of
a dibutyl
complex and lithium chloride. The dibutyl complex
can undergo reductive b-H elimination to give bu-
tane and the butene complex [g5:C5H4–(CH2)n–
H
- n-BuH
Zr
Zr
C6H5]2ZrC4H8. This olefin complex can form
a
metallacyclic butyl complex via ortho-metallation and
oxidative addition.
In order to investigate this reaction further, we varied
the parameters n and the lithium alkyl. Depending on
the various parameters, different reaction products
could be identified and characterized.
2. Results and discussion
2.1. Synthesis and characterization of the x-phenylalkyl
substituted zirconocene and hafnocene dichloride com-
plexes 1–10
Metallocene dichloride complexes with substituted
cyclopentadienyl ligands have been synthesized in large
numbers in recent years [1,5–8].
* Corresponding author. Tel.: +49-921-55-2555; fax: +49-921-55-
2157.
E-mail address: helmut.alt@uni-bayreuth.de (H.G. Alt).
0020-1693/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.12.040

H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
1683
The synthesized x-phenylalkyl substituted hafnocene
complexes 7–10 are new. They were characterized by 1H
and 13C NMR spectroscopy (Table 1, Figs. 1 and 2).
The symmetric complexes 7–10 show two multiplet
signals between d ¼ 5:89 and 5.56 ppm for the eight
protons of the cyclopentadienyl ligands.The protons of
the phenyl ligands are found at d ¼ 7:18–7:00 ppm. The
aliphatic CH2 bridges give proton signals at d ¼
2:98–0:95 ppm.
In the 13C NMR spectrum the signals for the phenyl
carbon atoms appear at d ¼ 128:8–125:9 ppm, while the
carbon atoms of the cyclopentadienyl ligands are found
in the region of d ¼ 116:3–109:0 ppm.
2.2. X-ray structure of the x-phenylalkyl substituted
hafnocene dichloride complex [g5:C5H4–(CH2)3–C6H5]2
HfCl2 (8)
Scheme 1. Synthesis of complexes 1–10.
The reaction of a substituted cyclopentadienyl alkali
metal salt [9] with zirconium and hafnium tetrachloride
in diethyl ether gave the corresponding zirconocene and
hafnocene complexes 1–10 (Scheme 1).
The X-ray structural analysis of a single crystal of 8
reveals important bond lengths (pm) and angles (°)
(Table 2).
Table 1
1H and 13C NMR data for the metallocene complexes 1–10
Compound 1H NMRa d (ppm)
13C NMRbd (ppm)
1
7.46–7.12 (m, 10H), 6.39–6.32 (m, 4H), 6.28–6.16 (m, 4H), 3.98 (s, 4H)
(Cq): 141.1, 134.2
(CH): 128.6, 128.2, 128.3, 116.8, 112.4
(CH2): 35.7
2
7.47–7.14 (m, 10H), 6.39–6.29 (m, 4H), 6.26–6.16 (m, 4H), 3.14–2.90 (m, 8H)
7.36–7.18 (m, 10H), 6.30–6.21 (m, 8H), 2.75–2.64 (m, 8H), 1.95–1.89 (m, 4H)
7.39–7.17 (m, 10H), 6.29 (m, 4H), 6.21 (m, 4H), 2.68 (m, 8H), 1.67 (m, 8H)
7.39–7.24 (m, 10H), 6.34 (m, 4H), 6.25 (m, 4H), 2.71 (m, 4H), 1.78–1.42 (m, 16H)
7.15–7.03 (m, 10H), 5.78–5.75 (m, 4H), 5.62–5.59 (m, 4H), 3.92 (s, 4H)
(Cq): 141.0, 133.9
(CH): 128.5, 128.3, 128.2, 116.6, 112.1
(CH2): 36.6, 32.0
3
(Cq): 141.8, 134.5
(CH): 128.5, 128.2, 128.1, 116.6, 112.0
(CH2): 35.4, 32.0, 30.0
4
(Cq): 142.3, 134.6
(CH): 128.3, 128.2, 125.6, 116.6, 112.1
(CH2): 35.5, 30.9, 30.1, 29.9
5
(Cq): 142.5, 134.8
(CH): 128.3, 128.1, 128.0, 116.6, 112.1
(CH2): 35.7, 31.1, 30.4, 29.9, 28.8
6
(Cq): 141.5, 132.3
(CH): 128.7, 128.4, 128.1, 115.5, 111.1
(CH2): 35.1
7
7.13–7.00 (m, 10H), 5.70–5.68 (m, 4H), 5.58–5.56 (m, 4H), 2.98–2.67 (m, 8H)
7.18–7.03 (m, 10H), 5.89–5.87 (m, 4H), 5.64–5.62 (m, 4H), 2.76–1.72 (m,8H),
7.15–7.01 (m, 10H), 5.75–5.72 (m, 4H), 5.63 – 5.61 (m, 4H), 2.49 (m, 8H), 1.15 (m, 8H)
(Cq): 141.3, 131.6
(CH): 128.6, 128.4, 126.0, 115.0, 110.3
(CH2): 36.8, 31.9
8
(Cq): 141.9, 130.9
(CH): 128.5, 128.4, 125.9, 116.3, 110.1
(CH2): 35.6, 32.7, 30.4
9
(Cq):141.5, 131.1
(CH):128.7, 128.4, 126.2, 115.7, 110.5
(CH2): 35.3, 30.5, 29.8, 29.0
10
7.14–7.00 (m, 10H), 5.78–5.73 (m, 4H), 5.64 – 5.60 (m, 4H), 2.56 (m, 4H), 1.26–0.95 (m, 16H) (Cq): 141.8, 131.5
(CH): 128.8, 128.6, 127.0, 115.9, 109.9
(CH2): 35.7, 31.0, 30.8, 29.3, 28.7
a 25 °C, in chloroform-d1, rel. chloroform (7.24).
b 25 °C, in chloroform-d1, rel. chloroform-d1 (77.0).

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Fig. 1. 1H NMR spectrum of 8.
Fig. 2. 13C NMR spectrum of 8.
Table 2
Important bond distances (pm) and angles (°) of complex 8
Hf–C(1)#1
Hf–C(1)
Hf–Cl
255.1
255.1
257.3
257.3
C(9)–C(10)
C(9)–C(14)
C(10)–C(11)
C(11)–C(12)
139.0
140.0
142.0
132.0
C(12)–C(13)
C(13)–C(14)
C(6)–C(7)
146.0
136.0
157.0
153.0
Hf–Cl#1
C(7)–C(8)
Cl–Hf–Cl#1
C(1)–C(6)–C(7)
C(9)–C(8)–C(7)
93.31
109.9
116.0
C(8)–C(7)–C(6)
C(1)–C(5)–C(4)
C(3)–C(4)–C(5)
113.0
93.0
119.0
C(3)–C(2)–C(1)
C(5)–C(1)–C(2)
121.0
111.0
Both substituted cyclopentadienyl ligands are tilted
and the bond lengths between the central metal and the
cyclopentadienyl carbon atoms vary from 242 to
255.1 pm.
The carbon–carbon distances in the phenyl groups
are in the range from 139.0 to 146.0 pm. The carbon–
carbon distances between the bridging CH2 groups differ
from 150.0 to 157.0 pm.

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1685
Fig. 3. Molecular structure of 8; hydrogen atoms omitted for clarity.
Slight differences can be found for the Hf–Cl bond
length and Cl–Hf–Cl bond angles observed in the
structures of [g5:C5H4–(CH2)3–g5:C5H4]HfCl2 (242.3
pm, 95.87°) [10], [g5:C5(CH3)5]2HfCl2 (241.5 pm,
96.04°) [11] and [g5:C5H4–(CH2)3–C6H5]2HfCl2 (257.3
pm, 93.91°) (8).
ligands give four resonance signals in the region of
1
d ¼ 5:23–6:00 ppm. In the H NMR spectrum of 17 the
ethyl group shows a triplet signal for the methyl group
at d ¼ 1:5 ppm [3J(H,H) ¼ 7.7 Hz] and a quadruplet
signal for the methylene group at d ¼ 0:9 ppm
[3J(H,H) ¼ 7.7 Hz].
The structure of the molecule is given in Fig. 3.
The signals for the aliphatic CH2 groups of the x-
alkenyl substituent are found as multiplets between
d ¼ 2:3–3:6 ppm. The signals for the two phenyl groups
appear as multiplets at d ¼ 7:00–7:20 ppm.
2.3. Synthesis and characterization of x-phenylalkyl
substituted zirconocene and hafnocene ethyl chloride
complexes
In the 13C NMR spectrum of 17 the quarternary car-
bon atom of the phenyl group is observed at d ¼ 141:8
ppm, while the quarternary carbon atom of the cyclo-
pentadienyl substituent appears at d ¼ 131:5 ppm.
Further data are listed in Table 3.
The dichloride complexes 1–10 were dissolved in
toluene and treated with one equivalent of EtLi in ether.
After stirring over night at 0 °C, the ethyl chloride
complexes 11–20 could be isolated (Scheme 2).
The ethyl chloro zirconocene complexes 11–15 are
stable at 0 °C, the corresponding hafnocene complexes
16–20 could be handled at room temperature without
decomposition.
2.4. Synthesis and characterization of metallacyclic
zirconocene ethyl complexes
The reaction between [g5:C5H4–(CH2)n–C6H5]2MCl2
(n ¼ 1–5; M ¼ Zr, Hf) and 2EtLi in toluene results in the
formation of the metallacyclic complexes 21–22
(M ¼ Zr, n ¼ 1; 2) and the formation of the diethyl
complexes 23–27 (M ¼ Hf, n ¼ 1–5) (Scheme 3).
Under CH bond activation the x-phenyl substituted
cyclopentadienyl substituent reacts with 2EtLi.
In the first step a zirconocene diethyl complex is the
intermediate that is stable for a few minutes in solution
at low temperatures ()60 °C). Under ethane elimination
via b-H-transfer a further intermediate, a reactive eth-
ylene complex, is formed that gives the corresponding
metallacycles 21 and 22 (Scheme 3).
1
Complexes 11–20 were characterized by H and 13C
NMR spectroscopy (see Table 3, Figs. 4 and 5).
Due to the asymmetry of complexes 11–20, the 8
protons of the x-phenyl substituted cyclopentadienyl
With two equivalents of EtLi the x-phenyl substi-
tuted hafnocene dichloride complexes 6–10 form the
corresponding hafnocene diethyl complexes 23–27
(Scheme 4).
Metallocene dichloride complexes with C3, C4 or
C5ꢀ spacers also react with 2EtLi to give product
mixtures that have not yet been completely identi-
fied.
Complexes 23–27 were isolated and characterized by
1H and 13C NMR spectroscopy (see Table 4).
1H NMR and 13C NMR of the complexes 21–27 are
listed in Table 4.
Scheme 2. Synthesis of the x-phenylalkyl substituted zirconocene and
hafnocene complexes 11–20.

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Table 3
1H and 13C NMR data for the metallocene complexes 11–20
Compound
1H NMRa d (ppm)
13C NMRbd (ppm)
11
7.18–7.05 (m, 10H), 6.00 (m, 2H), 5.73 (m, 2H),
5.46 (m, 2H), 5.31 (m, 2H), 3.58 (s, 4H)
(Cq): 141.7, 131.0
(CH): 128.7, 128.4, 126.2, 115.7, 112.2,
110.5, 108.0
(CH2): 45.3, 34.9
(CH3): 18.9
12
13
14
15
16
17
18
19
20
7.17–7.05 (m, 10H), 5.98 (m, 2H), 5.69 (m, 2H), 5.43 (m, 2H),
5.27 (m, 2H), 2.87–2.69 (m, 8H), 1.42 (t, 3H), 1.10 (q, 4H)
(Cq): 141.5, 130.6
(CH): 128.6, 128.4, 126.1, 115.5, 111.9,
110.3, 107.3
(CH2): 45.1, 37.7, 33.1
(CH3): 18.7
7.15–7.05 (m, 10H), 6.04 (m, 2H), 5.75 (m, 2H), 5.52 (m, 2H),
5.35 (m, 2H), 2.68–1.77 (m, 12H), 1.46 (t, 3H), 1.11 (q, 4H)
(Cq): 142.1, 131.1
(CH): 128.6, 128.5, 125.9, 115.3, 112.1,
109.5, 107.5
(CH2): 45.1, 35.6, 32.9, 29.8
(CH3): 18.2
7.15–7.04 (m, 10H), 6.00 (m, 2H), 5.71 (m, 2H), 5.49 (m, 2H),
5.37 (m, 2H), 2.51 (m, 8H), 1.62 (m, 8H), 1.43 (t, 3H), 1.14 (q, 4H)
(Cq): 141.8, 131.5
(CH): 128.4, 128.2, 125.7, 115.4, 112.4,
109.2, 107.9
(CH2): 44.8, 35.1, 33.2, 30.2
(CH3): 18.2
7.14–7.03 (m, 10H), 5.99 (m, 2H), 5.71 (m, 2H), 5.43 (m, 2H),
5.34 (m, 2H), 2.57 (m, 8H), 1.52 (m, 8H), 1.42 (t, 3H), 1.07 (q, 4H)
(Cq): 141.9, 131.2
(CH): 128.7, 128.5, 126.2, 115.5, 112.2,
109.6, 108.3
(CH2): 45.5, 35.4, 31.3, 30.5, 29.6, 28.5
(CH3): 18.5
7.15–7.05 (m, 10H), 6.04 (m, 2H), 5.75 (m, 2H), 5.52 (m, 2H),
5.35 (m, 2H), 2.68–1.77 (m, 12H), 1.46 (t, 3H), 1.11 (q, 4H)
(Cq): 142.1, 131.1
(CH): 128.6, 128.5, 125.9, 115.3, 112.1,
109.5, 107.5
(CH2): 45.1, 35.6, 32.9, 29.8
(CH3): 18.2
7.15–7.04 (m, 10H), 6.00 (m, 2H), 5.71 (m, 2H), 5.49 (m, 2H),
5.37 (m, 2H), 2.51 (m, 8H), 1.62 (m, 8H), 1.43 (t, 3H), 1.14 (q, 4H)
(Cq): 141.8, 131.5
(CH): 128.4, 128.2, 125.7, 115.4, 112.4,
109.2, 107.9
(CH2): 44.8, 35.1, 33.2, 30.2
(CH3): 18.2
7.14–7.03 (m, 10H), 5.99 (m, 2H), 5.71 (m, 2H), 5.43 (m, 2H),
5.34 (m, 2H), 2.57 (m, 8H), 1.52 (m, 8H), 1.42 (t, 3H), 1.07 (q, 4H)
(Cq): 141.9, 131.2
(CH): 128.7, 128.5, 126.2, 115.5, 112.2,
109.6, 108.3
(CH2): 45.5, 35.4, 31.3, 30.5, 29.6, 28.5
(CH3): 18.5
7.18–7.03 (m, 10H), 5.92 (m, 2H), 5.66 (m, 2H), 5.42 (m, 2H),
5.28 (m, 2H), 3.21 (s, 4H), 1.67 (t, 3H), 0.0.95 (q, 4H)
(Cq): 141.7, 129.6
(CH): 128.6, 128.5, 125.9, 113.9, 110.8,
108.5, 107.2
(CH2): 46.7, 37.5
(CH3): 18.2
7.17–7.03 (m, 10H), 5.88 (m, 2H), 5.64 (m, 2H), 5.38 (m, 2H),
5.24 (m, 2H), 2.86–2.68 (m, 8H), 1.63 (t, 6H), 0.86 (q, 8H)
(Cq): 141.6, 129.7
(CH): 128.6, 128.4, 126.0, 114.1, 110.9,
108.8, 106.8
(CH2): 45.2, 37.3, 31.9
(CH3): 17.0
a 25 °C, in benzene-d6, rel. benzene (7.15).
b 25 °C, in benzene-d6, rel. benzene-d6 (128.0).
The metallacycles 21, 22 and the hafnocene diethyl
complexes 23–27 were characterized by 1H and 13C
NMR spectroscopy. NMR data is listed in Table 4.
The reaction of Cp2ZrCl2 and two equivalents of
EtMgCl as alkylating reagent leads to the formation of
the dinuclear complex [Cp2ZrEt]2(l-ethene) [12,13].

H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
1687
Fig. 4. (a) 1H NMR spectrum of complex 17. (b) 13C NMR spectrum of complex 17.
Fig. 5. (a) 1H NMR spectrum of complex 22. (b) 13C NMR spectrum of complex 22.

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H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
The 13C NMR spectrum of the metallacycle 22 shows
eight different tertiary carbon signals for both cyclo-
pentadienyl ligands in the region of d ¼ 115:0–103:2
ppm. The two differently shielded C2-spacers give four
different resonance signals at d ¼ 45:7, 43.6, 32.0 and
29.2 ppm.
Separated signals are observed for the carbon atoms
of the non-bonded and the bonded phenyl groups in the
region of d ¼ 130:9–129:5 ppm.
The shift for the zirconium bonded, quarternary
carbon atom of the phenyl group is observed at
d ¼ 189:0 ppm.
The resonance signals for the ethyl group are ob-
served at d ¼ 45:7 (CH2) and 16.5 ppm (CH3).
Scheme 3. Synthesis of the metallacyclic zirconocene ethyl complexes
21 and 22.
2.5. Synthesis and characterization of dinuclear zirconium
and hafnium chloride complexes
Surprisingly the reaction of the x-phenyl substituted
cyclopentadienyl zirconium or hafnium complexes 1–10
with an excess of lithium ethyl in diethyl ether (Scheme
5) gives dinuclear complexes with g5-cyclopentadienyl
ligands, g6-phenyl ligands and bridging chloro ligands.
Obviously the metal prefers the g6-coordination of an
arene ligand instead of a phenylalkyl substituted cyclo-
pentadienyl ligand.
The reducing agent EtLi leads to a change of the
oxidation number of zirconium and hafnium from IV to
II.The composition of the complexes has been estab-
lished by elemental analysis, mass spectroscopy and
NMR spectroscopy.
Similar mononuclear complexes containing g6-
bonded arene ligands have been described in the
literature [8,14–19]. Typical examples are complexes
like [(g5:C5H4–CMe2–g6:C6H5)MMe2]þ (M ¼ Ti, Zr)
and [(g5:C5H4–CMe2–CH2–g6:C6H5)MMe2]þ [8,16]
that are stabilized by perfluorated anions like
[B(C6F5)4]ꢀ.
Scheme 4. Synthesis of the hafnocene diethyl complexes 23–27.
1
In the H NMR spectrum of 22 (Fig. 5) the eight
cyclopentadienyl protons show six different signals in
the area of d ¼ 6:17–4:48 ppm.
Also dinuclear dications are known such as the
dimethyl bridged g6-toluene ligands containþing com-
plexes [(g5:C5H3R2)(g6:C6H5Me)Hf(l–Me)]2
SiMe3) [17].
(R¼
This indicates a dissymmetric metallocene complex
structure.
Neutral complexes with g6-bonded arene ligands like
(g6:C6H6)2Ti are also known from cocondensation re-
actions [18,19] and prove this type of bonding mode.
The apparently strong coordination of the phenyl
groups to the metal is an indication for the fact that the
solvent can play an important role in olefin polymeri-
zation when metallocene complexes are applied as
catalysts.
It is not possible to obtain these dinuclear com-
plexes 28–35 with an excess of BuLi instead of EtLi.
The products of this reaction are a mixture and not
yet identified. Different from this reaction, Cp2ZrCl2
and BuLi give butane, butene and Cp2ZrBu2 that
reacts immediately under decomposition [7,20–26].
The hydrogen atoms of the ethyl group are diaste-
reotopic and show two multiplets at d ¼ 1:06–0:52 ppm
(CH2) and a triplet at d ¼ 1:40 ppm (CH3).
The signals for the phenyl groups appear in the region
of d ¼ 7:17–6:90 ppm.
The protons of the C2 spacer of the metal bonded
phenyl groups are diastereotopic and form 4 multiplet
signals in the range of d ¼ 2:72–1:75 ppm, while the pro-
tons of the C2 spacer of the free phenyl group appear as
two multiplet signals between d ¼ 2:60–2:34 ppm.
1
In the H NMR spectrum of 21 the fixed C1 spacer
shows two doublet signals at d ¼ 3:95 and 3.82 ppm and
the ‘‘free’’ C1 spacer a singlet signal at d ¼ 3:49 ppm.

H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
1689
Table 4
1H and 13C NMR data for complexes 21–27
Compound
1H NMRad (ppm)
13C NMRbsd (ppm)
21
7.36–7.13 (m, 9H), 6.37 (m, 1H), 6.04 (m, 1H), 5.92 (m, 2H),
5.86 (m, 2H), 5.46 (m, 1H), 5.02 (m, 1H), 3.96 (d, 1H),
3.76 (d, 1H), 3.46 (s, 2H) 1.41 (t, 3H), 1.26–0.85 (m, 2H)
(Cq): 186.1, 162.5, 141.9, 138.5
(CH):138.4, 128.9, 128.5, 128.0, 127.0, 125.2, 123.3,
115.8, 113.9, 111.7, 110.3, 109.2, 107.5, 104.2, 103.9
(CH2): 56.2, 38.1, 37.7, 30.0
(CH3): 17.2
22
7.16–6.93 (m, 9H), 6.17 (m, 1H), 5.67 (m, 1H), 5.62 (m, 2H),
5.36 (m, 2H), 5.18 (m, 1H), 4.88 (m, 1H), 2.72–2.54 (m, 6H),
2.41–2.12 (m, 2H), 1.41 (t, 3H), 1.06–0.52 (m, 2H)
(Cq): 189.3, 147.5, 141.6, 130.9
(CH):130.0, 128.5, 128.3, 127,3 127.0, 125.9, 123.5,
115.0, 114.3, 111.7, 109.2, 108.7, 106.8, 103.6, 103.1
(CH2): 45.7, 43.6, 37.8, 32.0 29.2
(CH3): 16.6
23
24
25
26
27
7.19–7.00 (m, 10H), 5.58 (m, 8H), 3.19 (s, 4H), 1.49 (t, 6H),
0.14 (q, 8H)
(Cq): 141.8, 126.0
(CH): 128.8, 128.6, 126.1, 110.5, 108.7
(CH2): 50.0, 36.5
(CH3): 16.2
7.17–7.02 (m, 10H), 5.54 (m, 8H), 2.75–2.54 (m, 8H),
1.46 (t, 6H), 0.13 (q, 8H)
(Cq): 141.6, 125.7
(CH): 128.6, 128.4, 125.9, 110.0, 108.1
(CH2): 49.2, 38.5, 31.8
(CH3): 15.8
7.16–7.02 (m, 10H), 5.49 (m, 8H), 2.62–2.31 (m, 12H),
1.47 (t, 6H), 0.14 (q, 8H)
(Cq): 141.4, 125.1
(CH): 128.6, 128.3, 125.8, 109.8, 107.9
(CH2): 49.0, 38.3, 31.5, 30.1
(CH3): 15.3
7.17–7.01 (m, 10H), 5.50 (m, 8H), 2.21 (m, 8H), 1.46 (t, 6H),
1.00 (m, 8H) 0.13 (q, 8H)
(Cq): 141.6, 125.4
(CH): 128.8, 128.6, 126.0, 110.3, 107.9
(CH2): 48.9, 38.2, 34.8, 33.0, 31.9
(CH3): 15.8
7.17–7.02 (m, 10H), 5.48 (m, 8H), 2.69 (m, 4H), 1.46 (t, 6H),
1.10– 0.75 (m, 16H), 0.14 (q, 8H)
(Cq): 141.1, 126.2
(CH): 128.7, 128.4, 126.1, 110.2, 108.3
(CH2): 48.7, 37.5, 35.8, 33.3, 32.2, 29.9
(CH3): 15.9
a 25 °C, in benzene-d6, rel. benzene (7.15)
b 25 °C, in benzene-d6, rel. benzene-d6 (128.0).
(g5:C5H4–CH2–C6H5)2ZrCl2 cannot form a corre-
sponding dinuclear compound. The distance between
the Cp ligand and the Ph group is not long enough for a
dinuclear species.
In the zirconocene complexes 2–5 and hafnocene
complexes 7–10, with more than one CH2 spacer, the
steric conditions are sufficient for the formation of
complexes 28–35.
1
Complexes 28–35 were characterized by H and 13C
1
NMR spectroscopy (see Table 5). Fig. 6 shows the H
NMR spectrum of complex 29.
Four different resonance signals at d ¼ 6:19, 6.05,
5.81 and 5.74 ppm are assigned to the eight cyclopen-
tadienyl protons. This is in accordance with the asym-
metry of the complex. The resonance signals for the
three CH2 spacer groups are found as multiplets at
d ¼ 2:69, 2.57 and 1.85 ppm. The two phenyl groups
appear as a multiplet at d ¼ 7:19–7:08 ppm.
Scheme 5. Synthesis of the dinuclear complexes 28–35.
Dinuclear zirconium or hafnium complexes are often
synthesized as l-oxo [27–31], l-halo [32–37] or l-hydr-
ido bridged compounds [38–45].
For the formation of complexes 28–35, the length of
the CH2 spacers is the decisive factor. For steric reasons
Fig. 7 represents the 13C NMR spectrum of the dinu-
clear complex 29. The four different, tertiary carbon res-
onance signals for the cyclopentadienyl ligands appear at

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H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
Table 5
1H and 13C NMR data for the dinuclear complexes 28–43
Compound
1H NMRad (ppm)
13C NMRbd (ppm)
28
7.16–7.00 (m, 10H), 5.94 (vq, 2H), 5.88 (vq, 2H), 5.77 (vq, 2H),
5.73 (vq, 2H), 2.94 (m, 4H), 2.68 (m, 4H)
(Cq): 141.1, 133.0
(CH): 129.0, 128.6, 126.0, 116.5, 113.4, 112.9, 108.7
(CH2): 37.5, 32.7
29
30
31
32
33
34
35
36
7.19–7.08 (m, 10H), 6.20 (vq, 2H), 6.06 (vq, 2H), 5.80 (vq, 2H),
5.74 (vq, 2H), 2.72–2.55 (m,8H), 1.85 (vq, 4H)
(Cq): 142.1, 130.5
(CH): 128.6, 128.5, 125.9, 116.7, 113.4, 113.2, 108.9
(CH2): 35.6, 33.1, 30.1
7.19–7.03 (m, 10H), 6.21 (vq, 2H), 6.06 (vq, 2H), 5.81 (vq, 2H),
5.72 (vq, 2H), 2.69 (m, 4H), 2.53 (m, 4H), 1.58 (m, 8H)
(Cq): 142.4, 130.7
(CH): 128.5, 128.3, 125.7, 117.5, 113.2, 113.1, 108.7
(CH2): 35.8, 31.2, 31.0, 30.5
7.18–7.06 (m, 10H), 6.23 (vq, 2H), 6.08 (vq, 2H), 5.84 (vq, 2H),
5.73 (vq, 2H), 2.72 (m, 4H), 2.61 (m, 8H), 1.57–1.35 (m, 8H)
(Cq): 142.4, 130.7
(CH): 128.5, 128.3, 125.7, 116.8, 113.2, 113.1, 108.7
(CH2): 35.8, 31.2, 31.1, 30.5, 30.4
7.16–7.03 (m, 10H), 6.11 (vq, 2H), 5.83 (vq, 2H), 5.77 (vq, 2H),
5.55 (vq, 2H), 2.96 (m, 4H), 2.70 (m, 4H)
(Cq): 141.2, 131.0
(CH): 128.6, 128.4, 126.0, 116.4, 114.7, 110.4, 109.9
(CH2): 36.9, 32.3
7.19–7.08 (m, 10H), 6.14 (vq, 2H), 6.02 (vq, 2H), 5.75 (vq, 2H),
5.64 (vq, 2H), 2.75–2.51 (m, 8H), 1.82 (vq, 4H)
(Cq): 142.1, 128.7
(CH): 128.5, 128.3, 125.9, 115.5, 112.3, 107.4
(CH2): 35.6, 33.2, 30.0
7.19–7.03 (m, 10H), 6.18 (vq, 2H), 6.06 (vq, 2H), 5.87 (vq, 2H),
5.62 (vq, 2H), 2.71 (m, 4H), 2.57 (m, 4H), 1.61 (m, 8H)
(Cq): 142.2, 129.1
(CH): 128.5, 128.3, 125.7, 115.8, 112.5, 107.9
(CH2): 35.8, 32.9, 31.0, 30.2
7.17–7.02 (m, 10H), 6.19 (vq, 2H), 6.08 (vq, 2H), 5.92 (vq, 2H),
5.69 (vq, 2H), 2.70 (m, 4H), 2.59 (m, 8H), 1.60–1.41 (m, 8H)
(Cq): 142.4, 129.0
(CH): 128.6, 128.2, 126.1, 116.0, 112.8, 112.7, 108.0
(CH2): 36.2, 33.2, 31.1, 30.5, 30.2
7.19–7.09 (m, 10H), 5.70 (vq, 2H), 5.65 (vq, 2H), 5.58 (vq, 2H),
5.36 (vq, 2H), 2.78 (m, 4H), 2.62 (m, 4H), 0.20 (s, 6H)
(Cq): 141.8, 127.0
(CH): 128.6, 128.5, 126.0, 111.4, 110.5, 110.0, 106.9
(CH2): 38.1, 32.2
(CH3): 22.5
37
38
39
40
41
42
7.18–7.07 (m, 10H), 5.72 (m, 4H), 5.65 (vq, 2H), 5.46 (vq, 2H),
2.57 (m, 4H), 2.36 (m, 4H), 1.84 (m, 4H), 0.18 (s, 6H)
(Cq): 142.4, 126.9
(CH): 128.8, 128.7, 126.9, 111.8, 110.8, 110.3, 107.4
(CH2): 35.9, 33.6, 29.7
(CH3): 22.7
7.17–7.06 (m, 10H), 5.69 (vq, 2H), 5.67 (vq, 2H), 5.65 (vq, 2H),
5.41 (vq, 2H), 2.53 (m, 4H), 2.62 (m, 4H), 1.62 (m, 8H), 0.18 (s, 6H)
(Cq): 142.6, 127.1
(CH): 128.9, 128.8, 127.2, 112.5, 111.1, 110.9, 107.6
(CH2): 36.2, 32.6, 32.2, 29.7
(CH3): 22.9
7.18–7.06 (m, 10H), 5.63 (m, 4H), 5.59 (vq, 2H), 5.39 (vq, 2H),
2.42 (m, 4H), 2.29 (m, 8H), 1.50–1.32 (m, 8H)
(Cq): 142.7, 126.8
(CH): 128.7, 128.6, 126.7, 111.9, 111.8, 110.9, 108.5
(CH2): 36.1, 32.2, 31.5, 31.1, 29.9
(CH3): 23.1
7.17–7.06 (m, 10H), 5.96 (vq, 2H), 5.63 (vq, 2H), 5.58 (vq, 2H),
5.35 (vq, 2H), 2.76 (m, 4H), 2.51 (m, 4H), 0.20 (s, 6H)
(Cq): 141.3, 126.5
(CH): 128.6, 128.5, 126.1, 111.2, 110.3, 109.6, 107.9
(CH2): 37.5, 32.4
(CH3): 22.5
7.18–7.08 (m, 10H), 5.64 (m, 4H), 5.48 (vq, 2H), 5.36 (vq, 2H),
2.37–2.20 (m, 8H), 1.81 (m, 4H), 0.18 (s, 6H)
(Cq): 141.4, 126.9
(CH): 128.8, 128.7, 126.2, 111.8, 111.7, 110.5, 107.6
(CH2): 35.7, 33.6, 29.7
(CH3): 21.9
7.19–7.08 (m, 10H), 5.69 (vq, 2H), 5.67 (vq, 2H), 5.35 (vq, 2H),
5.21 (vq, 2H), 2.51 (m, 4H), 2.41 (m, 4H), 1.59 (m, 8H), 0.21 (s, 6H)
(Cq): 141.6, 127.1
(CH): 128.9, 128.8, 126.7, 112.1, 111.9, 110.7, 107.5
(CH2): 36.2, 33.2, 32.7, 29.9
(CH3): 22.9

H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
1691
Table 5 (continued)
Compound
43
1H NMRad (ppm)
13C NMRbd (ppm)
7.18–7.06 (m, 10H), 5.63 (m, 4H), 5.31 (vq, 2H), 5.22 (vq, 2H),
2.42 (m, 4H), 2.27 (m,8H), 1.49–1.30 (m, 8H), 0.20 (s, 6H)
(Cq): 141.5, 126.8
(CH): 128.7, 128.6, 126.5, 111.6, 111.4, 110.9, 107.6
(CH2): 36.1, 32.5, 31.9, 31.1, 29.9
(CH3): 22.5
a 25 °C, in benzene-d6, rel. benzene (7.15).
b 25 °C, in benzene-d6, rel. benzene-d6 (128.0).
Fig. 6. 1H NMR spectrum of complex 29.
Fig. 7. 13C NMR spectrum of complex 29.
d ¼ 116:8, 113.4, 113.2 and 108.8 ppm, the quarternary
carbon atom at d ¼ 130:5 ppm. The three CH2 spacer
groups give resonance signals at d ¼ 35:6, 33.1 and 30.1
ppm, the ten carbon atoms of the phenyl groups at
d ¼ 128:5, 128.4 and 125.9 ppm. The quarternary carbon
atom of the phenyl group is found at d ¼ 142:1 ppm.

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H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
3.3. Mass spectroscopy
Routine measurement were performed using a Varian
MAT CH7 instrument (direct inlet, electron impact
ionization 70 eV) in the Central Analytical Department
at the University of Bayreuth.
3.4. Elemental analysis
The micro analyses were conducted by the Mikro-
analytisches Labor Pascher, Remagen.
Scheme 6. Synthesis of complexes 36–43.
2.6. Synthesis and characterization of methyl bridged
dinuclear x-phenyl substituted cyclopentadienyl com-
plexes of zirconium(II) and hafnium(II)
3.5. X-ray data analysis
The crystal data and structure refinements were
conducted with a Siemens P4-diffractometer at the
University of Bayreuth.
The reaction of the dinuclear chloro bridged com-
plexes 28–35 and two equivalents of MeLi gives the di-
nuclear methyl bridged zirconium(II) and hafnium(II)
complexes 36–43 (Scheme 6).
Crystal data and structure refinements of complex 8:
Colourless crystals from toluene with a monoclinic
crystal system and a C2=c space group. The unique cell
dimension are a ¼ 2879:0 pm, b ¼ 714:4 pm and
c ¼ 1255:4 pm. V ¼ 250180:0 pm3, Z ¼ 4, dcalc ¼ 1:635
Like the corresponding chloro complexes 28–35, the
methyl substituted compounds 36–43 are characterized
1
by H and 13C NMR spectroscopy (Table 5).
Mg/m3,
absorption
coefficient:
4.396
mmꢀ1
,
F ð000Þ ¼ 1216, reflections collected: 2236, independent
reflections: 2236, Goodness-of-fit on F 2 ¼ 1:159, R in-
dices (all data): R1 ¼ 0:1020, wR2 ¼ 0:2893.
2.7. Polymerization reactions
2.7.1. Homogeneous ethylene polymerization
The crystal was measured at a temperature of 293 K.
Complexes 7–43 were dissolved in toluene solution,
activated with MAO (Al:Zr ¼ 2500:1) and used for ho-
mogeneous polymerization of ethylene at 60 °C, 10 bar
ethylene pressure in pentane solution, for 1 h. The re-
sults of the activity of the catalysts for the polymeriza-
tion of ethylene will be published later.
3.6. General synthesis procedure for the cyclopentadienyl
derivatives
Sodium cyclopentadienyl (160 mmol) was placed in a
reaction flask and 100 ml ammonia were condensed into
it at )78 °C. Within 1 h, 100.0 mmol of the corre-
sponding a-phenylalkylbromide, dissolved in 100 ml
n-pentane, were added dropwise to the dark brown so-
lution at )78 °C. The reaction mixture was stirred for 2
h at )78 °C and then slowly warmed up to room tem-
perature (r.t). Ammonia was allowed to evaporate. The
residue was mixed with 200 ml n-pentane, the suspen-
sion filtered over sodium sulfate and silica gel and the
solvent evaporated in vacuo. The products were ob-
tained as colourless to light yellow oils in 80–90% yields.
3. Experimental
3.1. NMR spectroscopy
The instrument Bruker ARX 250 was available for re-
cording NMR spectra. The organometallic samples were
transferred into NMR tubes under argon and measured at
1
25 °C. The chemical shifts in the H NMR spectra are
referenced to the residual proton signal of the solvent
(d ¼ 7:24 ppm for chloroform, d ¼ 7:15 ppm for benzene)
and in 13C NMR spectra to the solvent signal (d ¼ 77:0
ppm for chloroform-d1, d ¼ 128:0 ppm for benzene-d6).
3.7. General synthesis procedure for the metallocene
dichloride complexes [g5:C5H4–(CH2)n–C6H5]2MCl2
[M ¼ Zr, n ¼ 1–5 (1–5); M ¼ Hf, n ¼ 1–5 (6–10)]
3.2. Gas chromatography
The ligand precursor (10.0 mmol) was dissolved in
100 ml diethyl ether at )78 °C and reacted with 6.3 ml
(10.0 mmol) n-butyllithium (1.6 M in n-hexane). Then
zirconium tetrachloride or hafnium tetrachloride (5.0
mmol) were added at )78 °C and the reaction mixture
was stirred over night at r.t.
Organic compounds were analyzed with a Perkin–
Elmer Auto System Gas Chromatograph with flame
ionization detector. The gas chromatograph was equip-
ped with a 30 m J&W Fused Silica Column (DB 1, film
thickness 0.25 lm). Carrier gas was helium, flow through
the column was 4 ml minꢀ1 (split 1:15, 60 ml minꢀ1).
The suspension was filtered over sodium sulfate and
the solution evaporated. The residue was washed twice

H.G. Alt et al. / Inorganica Chimica Acta 357 (2004) 1682–1694
1693
with n-pentane and freed from solvent residues in vacuo.
The yields were 70–80%. The complexes are character-
ized in Table 1.
Elemental analysis of complex 29: Calc. C, 54.35; H,
4.85; Cl, 11.45. Found: C, 57.20; H, 5.21; Cl, 11.8%.
The mass spectrum of complex 29 shows the mole-
cular peak at Mþ 618.
3.8. General synthesis procedure for the metallocene ethyl
chloride complexes [g5:C5H4–(CH2)n–C6H5]2M(C2H5)
Cl [M ¼ Zr, n ¼ 1–5 (11–15); M ¼ Hf, n ¼ 1–5 (16–20)]
3.12. General synthesis procedure for the dinuclear com-
plexes [g5:C5H4–(CH2)n–g6:C6H5]2M2(CH3)2 [M ¼
Zr, n ¼ 2–5 (36–39); M ¼ Hf, n ¼ 2–5 (40–43)]
EtLi (5.0 mmol, 3.13 ml, 1.6 M in ether) was added to
5.0 mmol of the metallocene dichloride complexes in
toluene at 0 °C. The reaction mixture was stirred for 15
h at 0 °C. After filtration over sodium sulfate, the tol-
uene/ether solvent was removed in vacuo. The residue
was extracted twice with 50 ml pentane, the solution was
filtered over sodium sulfate and the solvent was evapo-
rated again in vacuo. The yields were 65–70%.
3.0 mmol (1.9 ml) of MeLi (1.6 M in ether) were
added to a solution of 3.0 mmol of the corresponding
dinuclear chloride complex in toluene at 0 °C. After
stirring over night, the reaction mixture was filtered over
sodium sulfate and the solvents were evaporated in va-
cuo. The residue was extracted twice with 50 ml pentane.
After filtration over sodium sulfate, the solvent was re-
moved in vacuo. The yields were 70–80%.
3.9. General synthesis procedure for the metallacyclic
complexes [g5:C5H4–(CH2)n–C6H5] [g5:C5H4–(CH2)n
–g1:C6H4]2MC2H5 [M ¼ Zr, n ¼ 1 (21); M ¼ Zr, n ¼ 2
(22)]
Acknowledgements
We thank Deutsche Forschungsgemeinschaft and
ConocoPhillips (Bartlesville, OK, USA) for the financial
support.
The corresponding metallocene complex (3.0 mmol)
was dissolved in toluene and 6.0 mmol (3.75 ml) of EtLi
(1.6 M in ether) were added at )78 °C. The reaction
mixture was warmed to r.t. and stirred over night. It was
filtered over sodium sulfate and the solvent was removed
in vacuo. The yields were 75–85%.
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