Pyrrolide-imine benzyl complexes of zirconium and hafnium: Synthesis, structures, and efficient ethylene polymerization catalysis

Article abstract of DOI:10.1016/j.jorganchem.2003.11.041

A series of pyrrolyl-imines HL^1-6 was prepared by the condensation of pyrrole-2-carboxyaldehyde with different amines. The reaction of 2 equiv of pyrrolyl-imine with tetrabenzyl complexes of hafnium and zirconium M(CH₂Ph)₄ (M=Hf or Zr) gave dibenzyl complexes (L^3-6)₂M(CH₂Ph) ₂, which were characterized by NMR spectroscopy and crystal structure analysis. NMR spectra of the complexes with secondary alkyl substituents at the imine nitrogen (isopropyl: 3a, 4- tert -butylcyclohexyl: 4a and 4b) suggest that rapid racemization between Δ and Λ configurations occurs in solution on the NMR time scale. The complexes with pyrrolide-imine ligands with a tertiary alkyl group such as tert -butyl (5a and 5b) or 1-adamantyl (6a and 6b) at the imine nitrogen possess cis -configured benzyl groups. Hafnium complexes 5a and 6a react with B(C₆F₅)₃ in bromobenzene-d₅ to give the corresponding cationic benzyl complexes, which exhibit high activity for ethylene polymerization (5a: 2242 kg-polymer/ mol-Hf h bar, 6a: 2096 kg-polymer/ mol-Hf h bar). Zirconium complexes 5b and 6b display a remarkably high ethylene polymerization activity when activated with methylaluminoxane (5b: 17,952 kg-polymer/mol-Zr h bar, 6b: 22,944 kg-polymer/mol-Zr h bar).

Full text of DOI:10.1016/j.jorganchem.2003.11.041

Journal of Organometallic Chemistry 689 (2004) 1155–1164
www.elsevier.com/locate/jorganchem
Pyrrolide-imine benzyl complexes of zirconium and
hafnium: synthesis, structures, and efficient ethylene
polymerization catalysis
a,b,
b
b
a,1
Shigekazu Matsui
*, Yasunori Yoshida , Yukihiro Takagi , Thomas P. Spaniol
,
a, ,1
*
Jun Okuda
a
Institut fu€r Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universit€at Mainz, Duesbergweg 10-14, D-55099 Mainz, Germany
Catalysis Science Laboratory, Mitsui Chemicals, Inc., 580-32 Nagaura, Sodegaura, Chiba 299-0265, Japan
b
Received 26 September 2003; accepted 13 November 2003
Abstract
A series of pyrrolyl-imines HL1–6 was prepared by the condensation of pyrrole-2-carboxyaldehyde with different amines. The
reaction of 2 equiv of pyrrolyl-imine with tetrabenzyl complexes of hafnium and zirconium M(CH2Ph)4 (M ¼ Hf or Zr) gave
dibenzyl complexes (L3–6)2M(CH2Ph)2, which were characterized by NMR spectroscopy and crystal structure analysis. NMR
spectra of the complexes with secondary alkyl substituents at the imine nitrogen (isopropyl: 3a, 4-tert-butylcyclohexyl: 4a and 4b)
suggest that rapid racemization between D and K configurations occurs in solution on the NMR time scale. The complexes with
pyrrolide-imine ligands with a tertiary alkyl group such as tert-butyl (5a and 5b) or 1-adamantyl (6a and 6b) at the imine nitrogen
possess cis-configured benzyl groups. Hafnium complexes 5a and 6a react with B(C6F5)3 in bromobenzene-d5 to give the corre-
sponding cationic benzyl complexes, which exhibit high activity for ethylene polymerization (5a: 2242 kg-polymer/ mol-Hf h bar, 6a:
2096 kg-polymer/ mol-Hf h bar). Zirconium complexes 5b and 6b display a remarkably high ethylene polymerization activity when
activated with methylaluminoxane (5b: 17,952 kg-polymer/mol-Zr h bar, 6b: 22,944 kg-polymer/mol-Zr h bar).
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Pyrrolide-imine; Zirconium; Hafnium; Benzyl complex; Ethylene polymerization
1. Introduction
tivity, and stability [1]. Chelating non-cyclopentadienyl
ligands which include diamido [2–6], diphenoxy [7–9],
phenoxy-imine [10–15], pyrrolide-imine [16–21], indo-
lido-imine [25], phosphine-imido [22], tris(pyrazolyl)bo-
rate ligands [23] are currently being explored for the
design of olefin polymerization catalysts based on group
4 transition metal complexes. Some of these systems
have proved to be more active, allowing high flexibility
in the design of polymerization processes. For instance,
methylaluminoxane-activated pyrrolide-imine dichloro
titanium complexes allow the synthesis of conventional
polyolefins with high activity [16] and promote a living
copolymerization of ethylene with norbornene [16d].
Recently, we have reported the synthesis of dibenzyl
hafnium complexes containing pyrrolide-imine ligands
as highly active catalyst precursors for ethylene poly-
merization. In this article we describe the full details for
the synthesis and structure of a series of dibenzyl
In the last two decades, remarkable advances have
been made in the design and synthesis of well-defined
olefin polymerization catalysts which allowed the syn-
thesis of polyolefins with novel properties and applica-
tions. The vast majority of homogeneous catalysts are
based on metallocene derivatives. Recently, transition
metal complexes which do not contain cyclopentadienyl
ligands have received considerable attention as new
generations of polymerization catalyst precursors with
improved catalytic performance, such as activity, selec-
* Corresponding authors. Tel.: +0241-894-645; fax: +0241-892-644.
E-mail address: jun.okuda@ac.rwth-aachen.de (J. Okuda).
1
New address: Institute of Inorganic Chemistry, Aachen University
of Technology (RWTH), Prof.-Pirlet-Strasse 1, D-52056 Aachen,
Germany.
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.11.041

1156
S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
hafnium and zirconium pyrrolide-imine complexes. The
reactions of these complexes with B(C6F5)3 are exam-
ined along with the results of ethylene polymerization
studies [24].
then investigated. The introduction of an isopropyl
group in the ligand L3 gave the hafnium complex
(L3)2Hf(CH2Ph)2 (3a). However, complex 3a gradually
decomposed at room temperature even in the solid state.
Attachment of a 4-tert-butylcyclohexyl group which is
sterically larger than an isopropyl group enhanced the
thermal stability leading to (L4)2Hf(CH2Ph)2 (4a),
which is stable at room temperature in the solid state as
well as in benzene or bromobenzene solution. In a
similar manner, the dibenzyl zirconium complex
(L4)2Zr(CH2Ph)2 (4b) was isolated from the reaction of
2 equiv of HL4 with Zr(CH2Ph)4 in toluene. 4b is ther-
mally less stable than the corresponding hafnium com-
plex 4a.
2. Results and discussion
Pyrrole-imines (HL1–5) used as ligand precursors in
this study were prepared from the reaction of pyrrole-2-
carboxyaldehyde with a corresponding primary amine
(or aniline) derivatives using a standard condensation
method [16c]. All pyrrole-imines were characterized by
1H and 13C NMR spectroscopy and elemental analysis.
According to crystal structure analyses, the pyrrole-
imines HL1 and HL4 exist as hydrogen-bridged dimers
in the solid state (see Section 5).
1
In the H NMR spectra of the complexes 3a, 4a, and
4b, a singlet assigned to the benzyl methylene group was
observed at 2.83, 2.64, and 2.73 ppm, respectively. The
13C NMR spectra of these complexes show one reso-
nance for the methylene groups (3a, 82.15; 4a, 81.98; 4b,
The synthesis of bis(pyrrolide-imine) dibenzyl com-
plexes is summarized in Scheme 1. Pyrrole-imine HL1
with a 4-isopropylphenyl group as the imine substituent
R reacted with 0.5 equiv. of Hf(CH2Ph)4 at )30 °C in
toluene to give an orange solid as a complex mixture. In
1
76.46 ppm). 2D H NMR (COSY) analysis of complex
4a confirmed C2-symmetry on the NMR time scale.
Nuclear Overhauser experiments by irradiating the
methylene protons led to the disappearance of the peak
for the 5-proton in the pyrrole ring, suggesting a cis-
configuration for the pyrrole groups in 4a. The typical
AB quartet pattern due to cis-benzyl groups was not
found in the 1H NMR spectra. These results suggest that
epimerization between the K and D configuration oc-
curs, probably caused by a rapid site exchange of the
benzyl and pyrrole-imine groups in solution on the
NMR time scale (Scheme 2).
1
the complicated H NMR spectra of the reaction mix-
ture, a singlet at 2.73 ppm could be assigned to the
equivalent protons of the benzylic methylene groups
(13C NMR: 82.70 ppm). Isolation of the complex failed
because of its low stability; it decomposed during the
purification step. Likewise, when HL2 with a primary
alkyl substituent was used, the corresponding complex
could not be obtained under similar conditions; only an
insoluble precipitate was obtained from toluene.
The preparation of bis(pyrrolide-imine) complexes
with a secondary alkyl group at the imine position was
In contrast, thermally robust dibenzyl hafnium or
zirconium complexes, cis-(L5;6)2M(CH2Ph)2 (5a, R: t-
Bu, M: Hf; 5b, R: t-Bu, M: Zr; 6a, R: 1-adamantyl, M:
Hf; 6b, R: 1-adamantyl, M: Zr), were successfully ob-
tained from the reaction of 2 equiv of HL5;6 with
R
O
N
N
1
H
Hf(CH2Ph)4 or Zr(CH2Ph)4 in toluene. The H NMR
RNH2
spectra of the hafnium (5a and 6a) and zirconium
complexes (5b and 6b) with a tertiary alkyl group show
mainly one isomer in solution (benzene-d6 and bromo-
benzene-d5). Within the temperature range of )30 and
75 °C, the spectra of these complexes in bromobenzene-
H
2
NH
N
R
N
R
HL1: 4-iPrPh
HL2: Et
HL3: iPr
M(CH2Ph)4
1
d5 solution practically show no change. The H NMR
resonances of the benzyl methylene moieties attached to
the central metal are recorded as an AB quartet, indi-
cating that no enantiomerization of the complex occurs
HL4: 4-tBu-cyclohexyl
HL5: tBu
HL6: 1-adamantyl
R
N
CH2Ph
CH2Ph
M
N
2
N
N
M
N
N
M
N
Bn
N
Bn
Bn
N
N
N
Bn
Bn
R
1a: R= 4-iPrPh, M = Hf
3a: R=iPr, M = Hf
4a: R=4-tBu-cyclohexyl, M = Hf, 4b: R=4-tBu-cyclohexyl, M = Zr
5a: R=tBu, M = Hf, 5b: R= tBu, M = Zr
R
R
R
R
M
R
N
Bn
N
N
∆
6a: R= 1-adamantyl, M = Hf, 6b: R= 1-adamantyl, M = Zr
∆
Scheme 1.
Scheme 2.

S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
1157
Table 1
Selected bond distances and bond angles of 6a and 6b as compared to
those of 5a [24]
in solution, probably due to the bulkiness of the R
groups. Apparently, pyrrolide-imine complexes with a
tertiary alkyl group adopt C2-symmetric configurations
with cis-benzyl groups.
Complex
5a
6a
6b
ꢀ
We have previously reported that complex 5a shows
C2-symmetry in solution, but not in the solid state [24].
In this work, we have crystallographically characterized
the adamantyl substituted complexes of hafnium (6a) as
well as of zirconium (6b). Both compounds crystallize
isotypically and show crystallographic C2-symmetry. In
all of these compounds, the pyrrolide moieties are
bound to the central metal in an g1-fashion with r-
character of the M–N bond. The structures are similar
to those of related dichloro titanium(IV) complexes with
two pyrrolide-imine ligands [16b,16c], where the metal
center is also octahedrally coordinated with trans-con-
figuration of the anionic pyrrolide donors and cis-con-
figuration of the neutral imine donors. The cis
configuration of the two benzyl groups is evident from
the C–M–C bond angles in 5a: C(19)–Hf–C(26) ¼
96.4(4)°, 6a: C(16)–Hf–Cð16Þ0 ¼ 91.4(2)°, and 6b: C(16)–
Zr–Cð16Þ0 ¼ 91.9(1)°. Both benzyl groups are bound in
an g1-fashion to the metal. Fig. 1 shows the ORTEP
diagram of the hafnium complex 6a. Table 1 summa-
rizes the pertinent bond parameters of 6a and 6b as
compared to those of 5a [24].
Bond distances (A)
M–NðaÞ
2.201(6)
2.196(6)
2.354(6)
2.363(6)
2.25(1)
2.197(4)
2.386(3)
2.264(4)
2.220(2)
2.403(2)
2.287(2)
M–NðnÞ
M–CðbenzylÞ
2.270(9)
Bond angles (°)
N
ðaÞ–M–NðaÞ
178.7(3)
90.4(2)
96.4(4)
73.1(3)
73.3(2)
106.4(2)
107.8(2)
83.8(3)
82.8(3)
96.9(3)
96.0(3)
93.6(3)
89.5(3)
155.6(3)
156.0(3)
116.3(7)
114.6(6)
170.1(2)
92.9(2)
91.4(2)
72.5(1)
100.5(1)
169.94(9)
92.07(8)
91.9(1)
NðnÞ–M–NðnÞ
C–M–C
NðaÞ–M–NðnÞ
72.37(6)
99.73(6)
NðaÞ–M–C
NðnÞ–M–C
M–C–C
87.4(2)
99.6(2)
85.24(7)
102.53(8)
91.4(2)
159.8(2)
92.32(7)
157.61(7)
112.0(3)
107.8(2)
Subsequently, the catalytic performances of the haf-
nium complexes 4a–6a and of the zirconium complexes
4b–6b were investigated. As for the hafnium complexes,
complex 4a with its secondary alkyl R substitutent dis-
played very low ethylene polymerization activities when
the cocatalysts B(C6F5)3/triisobutylaluminium (iBu3Al)
or methylalumoxane (MAO) were used (Table 2, entries
1 and 2). In contrast, cationic complexes derived from in
situ reaction of B(C6F5)3 with complexes 5a or 6a which
have tertiary alkyl substitutents polymerized ethylene
with high activities of more than 2000 kg-polymer/mol-
i
Hf h bar in the presence of Bu3Al (entries 3 and 5).
When MAO was used, the activities of 5a and 6a were
1273 and 616 kg-polymer/mol-Hf h bar (entries 4 and 6),
which are comparable to those found for titanium
complexes with pyrrolide-imine ligands under the same
polymerization conditions [16]. The hafnium catalysts
produced multimodal polyethylenes with broad molec-
ular weight distributions, possibly caused by the gradual
generation of the active species and/or isomerization of
the active species in the polymerization conditions [10p].
For the zirconium complexes, the ethylene polymer-
ization follows similar trends as the hafnium complexes.
Complex 4b with its secondary alkyl substituent practi-
cally displayed no activity. Although the zirconium
complexes 5b and 6b have the same ligands as the haf-
nium complexes 5a and 6a, they produced polyethylenes
with activities of 746 and 1760 kg-polymer/mol-Zr h,
respectively. The molecular weight distribution ðMw=MnÞ
values of the polymer obtained are 2.25 (5b) and 2.05
(6b), as expected for a polymer produced by a single-site
catalyst, with values for Mw of 2.4 ꢀ 104 and 6.3 ꢀ 104,
respectively. It is noteworthy that the complexes 5b and
6b exhibited activties that are one order of magnitude
larger (5b, 17,952 kg-polymer/mol-Zr h bar; 6b, 22,944
kg-polymer/mol-Zr h bar) and gave polymers with nar-
row molecular weight distribution values ðMw=Mn ca. 2),
when MAO was used as a cocatalyst.
Fig. 1. Molecular structure of complex 6a in the K configuration.
Thermal ellipsoids are given with 30% probability. Hydrogen atoms
are omitted for clarity.

1158
S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
Table 2
Ethylene polymerization results with Hf complexes 4a–6a or Zr complexes 4b–6b
iBu3Al
(mmol)
MAO
(mmol)
Yield (g)
Activitya
Mw (104)
Mw=Mn
Tm (°C)
b
b
Entry
Complex
(lmol)
B(C6F5)
(lmol)
1
2
4a
4a
5a
5a
6a
6a
4b
4b
5b
5b
5b
6b
6b
6b
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
0.5
5.0
5.0
0.5
10.0
–
0.25
–
–
Trace
Trace
0.934
0.530
0.874
0.257
Trace
Trace
0.311
3.368
1.496
0.733
3.671
1.912
–
–
–
–
1.25
–
–
–
–
–
3
10.0
–
0.25
–
2242
1273
2096
616
8.8
8.7
9.6
3.6
–
9.19
6.05
12.15
6.66
–
132
132
132
130
–
4
1.25
–
5
10.0
–
0.25
–
6
1.25
–
7
10.0
–
0.25
–
–
8
1.25
–
–
–
–
–
9
10.0
–
0.25
–
746
2.4
2.9
2.6
6.3
8.7
7.1
2.25
2.25
2.09
2.05
2.08
2.17
130
130
131
134
134
133
10
11
12
13
14
1.25
1.25
–
(8083)c
17,952
1760
(8810)c
22,944
–
–
10.0
–
0.25
–
1.25
1.25
–
–
Conditions: 25 °C, 0.1 MPa ethylene pressure, solvent: toluene (250 ml), polymerization time: 5 min.
a kg-polymer/mol-M h bar.
b Determined by GPC using polystyrene standard.
c Stirring difficulty was encountered because of excessive polymer production.
For the detailed investigation of the polymerization
catalysis using the above complexes, the structures of
the cationic species were studied by 1H NMR spec-
troscopy. With the hafnium complexes, homogeneous
red-brown solutions containing the ion pair [(L5)2Hf-
(CH2Ph)][B(C6F5)3(CH2P h)] (5a*) and [(L6)2Hf-
(CH2Ph)][B(C6F5)3(CH2P h)] (6a*) were successfully
obtained by the reaction 5a and 6a with 1 equiv of
B(C6F5)3 in bromobenzene-d5. The cationic hafnium
complexes 5a* or 6a* are stable in bromobenzene-d5
even at room temperature. The 1H NMR spectra ()25 °C,
bromobenzene-d5) for the hafnium cationic complexes
show the resonances for the methylene groups attached
to the hafnium atom (5a*: 3.66 ppm, 6a*: 3.67 ppm) and
the boron atom (5a*: 2.54 ppm, 6a*: 2.61 ppm). The
anion shows Dd(m; p-F) values (5a*: 2.78 ppm, 6a*:
2.85 ppm) indicative of a solvent-separated ion pair [25].
were slightly larger than those of the corresponding
hafnium complexes 5a* and 6a*. This suggests that the
hafnium complexes have a higher ion pair character
than the zirconium analogues.
3. Conclusion
We could show that thermally robust dibenzyl haf-
nium and zirconium complexes with two pyrrolide-imine
ligands are accessible by the proper choice of the imine
substituent. The dibenzyl hafnium complexes can be
converted into the benzyl cations by the reaction of
B(C6F5)3 which polymerize ethylene with very high ac-
tivity. Similar to titanium pyrrolide-imine complexes
[16], hafnium and zirconium complexes containing spe-
cifically substituted pyrrolide-imine ligands promise to
be highly efficient olefin polymerization catalysts.
1
In contrast, the H NMR spectra of the corresponding
cationic zirconium complexes 5b* and 6b* showed one
singlet (5b*: 3.55 ppm, 6b*: 3.56 ppm) assigned to the
methylene protons of the equivalent benzyl groups
(Scheme 3). Values for Dd(m; p-F) of the anion of the
zirconium complexes (5b*: 2.96 ppm, 6b*: 2.97 ppm)
4. Experimental
4.1. General procedures
All manipulations were performed under exclusion of
oxygen and moisture in an argon or nitrogen atmo-
sphere using standard Schlenk techniques in oven-dried
glassware. Toluene and n-pentane used for complex
syntheses were distilled from sodium/benzophenone
ketyl. Toluene used for polymerizations was dried over
Al2O3 and degassed by bubbling nitrogen gas. Starting
materials for the synthesis of ligand precursors HL1–6, 2-
carboxypyrolaldehyde (98%), 4-isopropylaniline (99%),
Ph
Ph
N
C F
6 5
N
N
N
R
R
B
B(C6F5)3
M
N
R
R
C F
6
5
M
N
C F
6
N
5
N
Ph
Ph
M: Hf, Zr
Scheme 3.

S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
1159
ethylamine (70% aq.), isopropylamine (99.5%), tert-bu-
tylamine (97%), 4-tert-butylcyclohexylamine (97%), and
1-adamantylamine (97%) were purchased from com-
mercial sources and used without further purification.
M(CH2Ph)4 (M ¼ Zr, Hf) [26] and B(C6F5)3 [27] were
prepared according to literature procedures. Ethylene
was obtained from Sumitomo Seika Co. Methylalu-
moxane (MAO) was purchased from Albemarle as a 1.2
M of a toluene solution, and remaining trimethylalu-
minum was evaporated in vacuo prior to use. 1H,
13C{1H}, and 19F NMR spectra were recorded on a
Bruker DRX-400 spectrometer at 25 °C (unless stated
otherwise). Chemical shifts were measured relative to
Calc. for C14H16N2: C, 79.21; H, 7.60; N, 13.20. Found:
C, 79.19; H, 7.67; N, 13.26%.
4.3. Preparation of HL2
Pyrrole-2-carboxyaldehyde (1.01 g, 10.30 mmol) was
dissolved in ethanol (5 ml). To this solution, ethylamine
(70% aqueous, 1.29 g, 20.00 mmol) was added. The re-
action mixture was stirred for 12 h at room temperature.
After the evaporation of the ethanol, the resulting
mixture was distilled under reduced pressure to give N-
(2-pyrrolidene)-ethylamine (HL2) as a colorless liquid in
48.4% yield (0.61 g, 4.99 mmol), b.p. 65 °C/2.0 mbar. 1H
NMR (C6D6) d:1.18 (t, J ¼ 7:2 Hz, 3H, CH3), 3.38 (q,
J ¼ 7:2 Hz, 2H, CH2), 6.33 (dd, J ¼ 3:2 and 2.4 Hz, 1H,
pyrrole-4-H), 6.48 (br s, 1H, pyrrole-3-H), 6.53 (d,
J ¼ 3:2 Hz, 1H, pyrrole-5-H), 7.83 (s, 1H, CH@N),
10.48 (br s, 1H, NH). 13C NMR (C6D6) d: 16.30, 54.67,
109.34, 114.21, 121.73, 130.37, 151.37. Anal. Calc. for
C8H12N2: C, 68.82; H, 8.25; N, 22.93. Found: C, 68.66;
H, 7.88; N, 22.87%.
1
residual H and 13C resonances in the deuterated sol-
vents. NMR solvents (benzene-d6 and bromobenzene-
d5) were distilled from sodium and stored under argon.
NOESY experiments were performed at 25 °C. Ele-
mental analyses were carried out in this department. Mw
values and molecular weight distribution ðMw=MnÞ val-
ues of the polymers were determined using a Waters
150-C gel permeation chromatograph at 145 °C using
polyethylene calibration and equipped with three TSK-
gel columns (two sets of TSKgelGMHHR-H(S)HT and
TSKgelGMH6-HTL). ortho-Dichlorobenzene was em-
ployed as solvent at a flow rate of 1.0 ml/min. Transition
melting temperatures ðTmÞ of the polymers were deter-
mined by DSC with a Perkin Elmer DSC-7 differential-
scanning calorimeter in the following manner: First, the
sample was heated to 200 °C at 20 °C/min, maintained
at 200 °C for 10 min, and then cooled to 30 °C at 10 °C/
min for crystallization followed by reheating at 10 °C/
min. The thermogram of the sample was recorded in the
second heating run to remove the thermal history. The
instrument was calibrated by the melting points of in-
dium and lead.
4.4. Preparation of HL3
Pyrrole-2-carboxyaldehyde (1.06 g, 10.81 mmol) was
dissolved in ethanol (5 ml). To this solution, isopropyl-
amine (1.18 g, 19.90 mmol) was added. The reaction
mixture was stirred for 17 h at room temperature. After
the evaporation of the ethanol, the resulting mixture was
distilled under reduced pressure to give N-(2-pyrrolid-
ene)-isopropylamine (HL3) as a colorless liquid in 73.6%
yield (1.08 g, 7.96 mmol), b.p. 67 °C/2.3 mbar. 1H NMR
(C6D6) d: 1.21 (d, J ¼ 6:4 Hz, 6H, CH3), 3.29 (q, J ¼ 6:4
Hz, 1H, CH), 6.29 (dd, J ¼ 3:2 and 2.8 Hz, 1H, pyrrole-4-
H), 6.51 (d, J ¼ 3:6 Hz, 1H, pyrrole-3-H), 6.55 (br s, 1H,
pyrrole-5-H), 7.90 (s, 1H, CH@N), 10.42 (br s, 1H, NH).
13C NMR (C6D6) d: 24.13, 60.62, 109.29, 113.73, 121.39,
130.43, 149.22. Anal. Calc. for C8H12N2: C, 70.55; H,
8.88; N, 20.57. Found: C, 70.43; H, 8.74; N, 20.67%.
4.2. Preparation of HL1
To a solution of pyrrole-2-carboxyaldehyde (4.83 g,
49.78 mmol) in ethanol (100 ml) were added 4-isopro-
pylaniline (7.44 g, 54.73 mmol) and catalytic amount of
p-toluenesulfonic acid. The reaction mixture was stirred
for 12 h at 50 °C. After the evaporation of the ethanol,
the resulting mixture was purified by column chroma-
tography on silica gel using n-hexane/ethyl acetate (19/1)
as eluent, and recrystallization was attempted from
ethanol to give N-(2-pyrrolidene)-4-isopropylaniline
(HL1) as white crystals in 58.2% yield (7.32 g, 28.99
4.5. Preparation of HL4
Pyrrole-2-carboxyaldehyde (1.15 g, 11.86 mmol) was
dissolved in ethanol (5 ml). To this solution, 4-tert-bu-
tylcyclohexylamine (2.25 g, 14.05 mmol) was added. The
reaction mixture was stirred for 15 h at room tempera-
ture. After the evaporation of the ethanol, the resulting
mixture was recrystallized in ethanol to give N-(2-pyr-
rolidene)-40-t-butylcyclohexylamine (HL4) as colorless
1
1
mmol). H NMR (C6D6) d: 1.26 (d, J ¼ 6:8 Hz, 6H,
crystals in 50.8% yield (1.40 g, 6.02 mmol). H NMR
CH3), 2.83 (q, J ¼ 6:8 Hz, 1H, CH), 6.24 (dd, J ¼ 3:2
and 2.8 Hz, 1H, pyrrole-4-H), 6.43 (br s, 1H, pyrrole-3-
H), 6.58 (d, J ¼ 3:2 Hz, 1H, pyrrole-5-H), 7.17–7.26 (m,
2H, Ar–H), 8.15 (s, 1H, CH@N), 10.09 (br s, 1H, NH).
13C NMR (C6D6) d: 23.81, 33.60, 109.99, 116.45, 121.00,
123.08, 127.01, 130.92, 145.79, 149.28, 149.93. Anal
(C6D6) d: 0.93 (s, 9H, t-Bu), 1.03–1.18 (m, 3H,
CH + CH2), 1.67–1.96 (m, 6H, CH2), 2.91–2.99 (m, 1H,
N–CH), 6.30 (dd, J ¼ 3:2 and 2.8 Hz, 1H, pyrrole-4-H),
6.42 (d, J ¼ 1:2 Hz, 1H, pyrrole-3-H), 6.51–6.52 (m, 1H,
pyrrole-5-H), 8.01 (s, 1H, CH@N). 13C NMR (C6D6) d:
25.75, 27.30, 31.95, 35.08, 46.99, 69.42, 109.30, 113.47,

1160
S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
121.15, 128.87, 149.32. Anal. Calc. for C14H16N2: C,
77.53; H, 10.41; N, 12.06. Found: C, 77.48; H, 10.48; N,
11.99%.
128.11, 128.23, 128.87, 138.84, 139.87, 141.30, 146.05,
146.43, 158.43, 158.92.
4.9. Preparation of (L3)2Hf(CH2Ph)2 (3a)
4.6. Preparation of HL5
To a stirred solution of Hf(CH2Ph)4 (203 mg, 0.374
mmol) in toluene (10 ml) at )78 °C with shielded light, a
solution of HL3 (102 mg, 0.748 mmol) in toluene (5 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 3 h. The reaction mixture
was allowed to warm to )30 °C and stored overnight.
The resulting mixture was evaporated at 0 °C. The solid
was washed with toluene (0.5 ml)/n-pentane (5 ml) at
)30 °C to give an orange solid (38 mg, 0.061 mmol) in
Pyrrole-2-carboxyaldehyde (3.12 g, 32.10 mmol) was
dissolved in ethanol (50 ml). To this solution, tert-bu-
tylamine (3.66 g, 48.50 mmol) was added. The reaction
mixture was stirred for 24 h at room temperature. After
the evaporation of the ethanol, the resulting mixture was
distilled under reduced pressure to give N-(2-pyrrolid-
ene)-tert-butylamine (HL5) as yellow crystals in 72.1%
1
yield (3.97 g, 23.17 mmol), b.p. 66–68 °C/1.8 mbar. H
1
NMR (C6D6) d: 1.26 (s, 9H, t-Bu), 6.31 (dd, 3.2 and 2.8
Hz, 1H, pyrrole-4-H), 6.49 (br s, 1H, pyrrole-3-H), 6.52
(d, J ¼ 3:6 Hz, 1H, pyrrole-5-H), 8.05 (s, 1H, CH ¼ N),
9.71 (br s, 1H, NH). 13C NMR (C6D6) d: 29.49, 56.06,
109.30, 113.16, 120.80, 131.20, 145.77. Anal. Calc. for
C9H14N2: C, 71.96; H, 9.39; N, 18.65. Found: C, 71.83;
H, 9.19; N, 18.62%.
16.3% yield. H NMR (C6D6) d: 0.64 (d, J ¼ 6:8 Hz,
12H, CH3), 2.83 (s, 4H, CH2Ph), 3.17 (q, J ¼ 6:8 Hz,
2H, CH), 6.47 (dd, J ¼ 3:6 and 2.0 Hz, 2H, pyrrole-4-
H), 6.69 (m, 2H, pyrrole-3-H), 6.80–7.24 (m, 20H, Ar-
H), 7.51 (s, 2H, pyrrole-5-H), 7.57 (s, 2H, CH@N). 13C
NMR (C6D6) d: 22.47, 54.50, 82.15, 113.48, 119.48,
121.43, 125.23, 128.87, 138.99, 140.01, 146.28, 158.30.
4.7. Preparation of HL6
4.10. Preparation of (L4)2Hf(CH2Ph)2 (4a)
Pyrrole-2-carboxyaldehyde (2.365 g, 24.37 mmol) was
dissolved in ethanol (50 ml). To this solution, 1-ada-
mantylamine (4.51 g, 28.92 mmol) was added. The re-
action mixture was stirred for 24 h at 50 °C. After
evaporating the ethanol, the resulting mixture was re-
crystallized from ethyl acetate to give N-(2-pyrrolidene)-
1-adamantylamine (HL6) as a white powder in 92.9%
To a stirred solution of Hf(CH2Ph)4 (310 mg, 0.571
mmol) in toluene (10 ml) at )78 °C with shielded light, a
solution of HL4 (266 mg, 1.145 mmol) in toluene (10 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 3 h. The reaction mixture
was allowed to warm to )30 °C and stored for 4 days.
The resulting mixture was evaporated at 0 °C. The solid
was recrystallized with a mixture of toluene (0.5 ml) and
n-pentane (5 ml) at )30 °C to give a red-orange powder
1
yield (5.17 g, 22.64 mmol). H NMR (C6D6) d: 1.66–
1.71 (m, 6H, CH2), 1.86 (d, 6H, J ¼ 2:4 Hz, N–CH2),
2.12 (br s, 3H, CH), 6.22 (dd, J ¼ 3:2 and 2.8 Hz, 1H,
pyrrole-4-H), 6.44 (d, J ¼ 1:6 Hz, 1H, pyrrole-3-H),
6.55 (d, J ¼ 3:2 Hz, 1H, pyrrole-5-H), 8.07 (s, 1H,
CH@N), 9.10 (brs, 1H, NH). 13C NMR (C6D6) d: 29.62,
36.46, 43.27, 56.39, 109.31, 112.88, 120.49, 131.50,
145.09. Anal. Calc. for C15H20N2: C, 78.90; H, 8.83; N,
12.27. Found: C, 78.73; H, 8.78; N, 12.36%.
1
(285 mg, 0.346 mmol) in 60.7% yield. H NMR (C6D6)
d: 0.69–1.09 (m, 28H, CH3 + CH2 + CH (0.85: s (CH3)),
1.48–1.51 (m, 4H, CH2), 1.61–1.64 (m, 4H, CH2), 2.64
(s, 4H, CH2-Ph), 2.69–2.76 (m, 2H, N–CH), 6.45 (dd,
J ¼ 2:0 and 1.0 Hz, 2H, pyrrole-4-H), 6.72 (d, J ¼ 2:4
Hz, 2H, pyrrole-3-H), 6.87 (t, 2H, J ¼ 7:2 Hz, Ar-HðpÞ),
7.05-7.25 (m, 8H, Ar–H(o) + Ar–HðmÞ), 7.51 (br s, 2H,
pyrrole-3-H), 7.66 (s, 2H, CH@N). 13C NMR (C6D6) d:
26.38, 27.18, 31.72, 33.53, 47.12, 63.22, 81.98 (t,
JC–H ¼ 118 Hz), 113.37, 119.24, 121.56, 125.23, 128.87,
139.01,140.22, 146.09, 158.60. Anal. Calc. for
C44H60N24Hf: C, 64.15; H, 7.34; N, 6.80. Found: C,
63.02; H, 7.29; N, 6.94%.
4.8. Preparation of (L1)2Hf(CH2Ph)2 (1a) (mixture)
To a stirred solution of Hf(CH2Ph)4 (127 mg, 0.234
mmol) in toluene (8 ml) at )78 °C with shielded light, a
solution of HL1 (99 mg, 0.468 mmol) in toluene (4 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 3h. The reaction mixture was
allowed to warm to )30 °C and stored overnight. The
resulting mixture was evaporated at 0 °C to obtain 150
4.11. Preparation of (L4)2Zr(CH2Ph)2 (4b)
To a stirred solution of Zr(CH2Ph)4 (234 mg, 0.513
mmol) in toluene (8 ml) at )78 °C with shielded light, a
solution of HL4 (239 mg, 1.028 mmol) in toluene (7 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 3 h. The reaction mixture
was allowed to warm to )30 °C and stored overnight.
The resulting mixture was evaporated at 0 °C to obtain a
1
mg of an orange solid as a crude mixture. H NMR
(C6D6) d: 1.05–1.28 (m, CH3), 2.61–2.80 (m, CH), 2.73
(s, CH2), 6.35–7.49 (m, Ar–H + pyrrole-H), 7.72–7.73
(m, CH@N). 13C NMR (C6D6) d: 23.51, 23.60, 23.73,
33.44, 33.63, 82.70, 113.69, 114.64, 121.68, 121.85,
121.94, 122.33, 122.39, 125.81, 126.12, 126.24, 126.36,

S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
1161
1
crude orange solid. H NMR (C6D6) d: 0.71–1.03, (m,
was allowed to warm to )30 °C and stored overnight.
The resulting mixture was evaporated at 0 °C. The solid
was recrystallized from toluene (0.5 ml)/n-pentane (5 ml)
at )78 °C to give a red powder (265 mg, 0.463 mmol) in
28H, CH3 + CH2 + CH (0.87: s (CH3)), 1.54–1.70 (m,
8H, CH2), 2.73 (s, 4H, CH2–Ph), 2.69–2.76 (m, 2H, N–
CH), 6.45 (d, J ¼ 1:2 Hz, 2H, pyrrole-4-H), 6.76 (d,
J ¼ 1:2 Hz, 2H, pyrrole-3-H), 6.83 (t, 2H, J ¼ 7:2 Hz,
Ar–HðpÞ), 7.04–7.25 (m, 8H, Ar–H(o) + Ar-HðmÞ), 7.38
(d, J ¼ 8:0 Hz, 2H, pyrrole-3-H), 7.59 (s, 2H, CH@N).
13C NMR (C6D6) d: 26.46, 27.21, 31.75, 33.88, 47.17,
62.68, 76.46 (t, JC–H ¼ 121 Hz), 112.83, 118.21, 123.43,
125.23, 126.06, 137.43, 138.56, 139.73, 142.73, 157.22.
1
46.3% yield. H NMR (C6D6) d: 0.85 (s, 18H, t-Bu),
2.92, 3.10 (AB q, J ¼ 11:6 Hz, 4H, CH2Ph), 6.51 (dd,
J ¼ 2:0 and 1.2 Hz, 2H, pyrrole-4-H), 6.77 (dd, J ¼ 3:2
and 1.6 Hz, 2H, pyrrole-3-H), 6.86–7.20 (m, 10H, Ar–
H), 7.73 (br s, 2H, pyrrole-5-H), 7.76 (s, 2H, CH@N).
(Additional complicated multiplets were observed at
0.87–1.30 ppm.) 13C NMR (C6D6) d: 29.97, 57.82, 81.98
(t, JC–H ¼ 121 Hz), 113.42, 121.32, 125.23, 126.88,
128.87, 138.73, 139.64, 147.83, 157.89. Anal. Calc. for
C32H40N4Zr: C, 67.20; H, 7.05; N, 9.80. Found: C,
65.75; H, 6.90; N, 9.91%.
4.12. Preparation of (L5)2Hf(CH2Ph)2 (5a)
To a stirred solution of Hf(CH2Ph)4 (0.545 g, 1.00
mmol) in toluene (15 ml) at )78 °C with shielded light, a
solution of HL5 (0.300 g, 2.00 mmol) in toluene (5 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 3 h. The reaction mixture
was allowed to warm to )30 °C and stored overnight.
The resulting mixture was evaporated at 0 °C. The solid
was recrystallized from toluene (0.5 ml)/n-pentane (5 ml)
at )78 °C to give orange crystals (0.458 g, 0.694 mmol)
in 69.4% yield. Single crystals of 5a, suitable for an X-
ray structure determination were obtained by cooling a
toluene/pentane (1/10) solution of 5a to )78 °C. 1H
NMR (C6D6) d: 0.83 (s, 18H, t-Bu), 2.59, 2.80 (AB q,
J ¼ 12:0 Hz, 4H, CH2Ph), 6.49 (dd, J ¼ 3:3 and 1.2 Hz,
2H, pyrrole-4-H), 6.72 (dd, J ¼ 3:3 and 1.0 Hz, 2H,
pyrrole-3-H), 6.85 (t, 2H, J ¼ 7:6 Hz, Ar-HðpÞ), 6.94 (d,
4H, J ¼ 7:2 Hz, Ar–HðoÞ), 7.22 (t, 4H, J ¼ 7:6 Hz, Ar–
HðmÞ), 7.71 (br s, 2H, pyrrole-3-H), 7.84 (s, 2H,
CH@N). 13C NMR (C6D6) d: 29.90, 58.38, 84.23,
113.91, 120.92, 121.46, 126.48, 127.84, 138.66, 139.98,
149.98, 158.44. Anal. Calc. for C32H40N4Hf: C, 58.27;
H, 6.11; N, 8.49. Found: C, 57.75; H, 6.20; N, 8.22%.
4.15. Preparation of cationic complex 5b*
One equivalent of B(C6F5)3 was added to 5b in
bromobenzene-d5 at )30 °C under an atmosphere of
1
argon. H NMR (C6D5Br, )25 °C) d: 0.82–1.42 (m),
3.55 (br s), 6.27–7.48 (m), 7.99–8.31 (m). 13C NMR
(C6D5Br, )25 °C, selected peaks) d: 29.84, 61.85, 65.05,
116.32, 135.44, 137.83, 141.87, 147.28, 148.86, 149.76,
158.07. 19F NMR (C6D5Br, )25 °C) d: )130.41 (o-F),
)162.59 (p-F), )165.55 (m-F).
4.16. Preparation of (L6)2Hf(CH2Ph)2 (6a)
To a stirred solution of Hf(CH2Ph)4 (1.082 g, 1.99
mmol) in toluene (20 ml) at )78 °C with shielded light, a
solution of HL6 (0.910 g, 3.99 mmol) in toluene (20 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 2 h. The reaction mixture
was allowed to warm to )30 °C and stored for 2 days.
The resulting mixture was evaporated at 0 °C. The solid
was recrystallized from toluene (0.5 ml)/n-pentane (5 ml)
at )30 °C to give orange crystals (0.884 g, 1.08 mmol) in
54.2% yield. Single crystals of 6a, suitable for a crystal
structure determination were obtained from a toluene
4.13. Preparation of the cationic complex 5a*
One equivalent of B(C6F5)3 was added to 5a in
bromobenzene-d5 at )30 °C under an argon atmo-
sphere. H NMR (C6D5Br, )25 °C) d: 0.90 (s, 18H, t-
1
1
solution of 6a. H NMR (C6D6) d: 1.34–1.97 (m, 30H,
Bu), 2.54 (s, 2H, BCH2), 3.66 (s, 2H, HfCH2), 6.45–6.48
(d, J ¼ 7.2 Hz, 2H, pyrrole-4-H), 6.58 (br s, 2H, pyrrole-
3-H), 6.97–7.46 (m, 10H), 7.50 (br s, 2H, pyrrole-5-H),
8.27 (s, 2H, CH@N). 13C NMR (C6D5Br, )25 °C) d:
29.86, 61.11, 83.12, 117.48, 134.86, 141.87, 143.55,
147.53, 149.70, 159.42. 19F NMR (C6D5Br, )25 °C) d:
)130.25 (o-F), )162.93 (p-F), )165.71 (m-F).
adamantyl), 2.65, 2.89 (AB q, J ¼ 12:0 Hz, 4H, CH2Ph),
6.49 (dd, J ¼ 3:2 and 2.4 Hz, 2H, pyrrole-4-H), 6.78 (d,
J ¼ 2:4 Hz, 2H, pyrrole-3-H), 6.88 (t, J ¼ 7:2 Hz, 2H,
Ar–HðpÞ), 7.03, 7.09 (d, J ¼ 7:2 Hz, 4H, Ar–H(o)), 7.10-
7.18 (m, 4H, Ar–HðmÞ), 7.70 (br s, 2H, pyrrole-3-H),
7.92 (s, 2H, CH@N). 13C NMR (C6D6) d: 20.96, 29.57,
35.59, 42.70, 59.26, 84.67 (t, JC–H ¼ 116 Hz), 113.78,
120.82, 125.23, 126.59, 128.87, 139.09, 139.62, 149.28,
157.26. Anal. Calc. for C44H52N4Hf: C, 64.78; H, 6.42;
N, 6.87. Found: C, 64.21; H, 6.78; N, 6.91%.
4.14. Preparation of (L5)2Zr(CH2Ph)2)2 (5b)
To a stirred solution of Zr(CH2Ph)4 (456 mg, 1.00
mmol) in toluene (15 ml) at )78 °C with shielded light, a
solution of HL5 (0.300 g, 2.00 mmol) in toluene (5 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 3 h. The reaction mixture
4.17. Preparation of cationic complex 6a*
One equivalent of B(C6F5)3 was added to 6a in bro-
mobenzene-d5 at )30 °C under an argon atmosphere.

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S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
1
1H NMR (C6D5Br, )25 °C) d: 1.27–2.10 (m, 30H,
adamantyl), 2.61 (s, 2H, BCH2), 3.67 (s, 2H, HfCH2),
6.41–7.78 (m, 16H, Ar–H), 8.27 (br s, 2H, CH@N). 13C
NMR (C6D5Br, )25 °C) d: 21.69, 29.49, 35.13, 42.67,
61.04, 83.84, 116.82, 135.51, 137.69, 138.89, 147.38,
148.95, 149.81, 159.37. 19F NMR (C6D5Br, )25 °C) d:
)130.27 (o-F), )163.00 (p-F), )165.85 (m-F).
benzene solution of 6b. H NMR (C6D6) d: 1.39–1.70
(m, 30H, adamantyl), 2.99, 3.20 (AB q, J ¼ 11:2 Hz, 4H,
CH2Ph), 6.51 (dd, J ¼ 2:8 and 2.0 Hz, 2H, pyrrole-4-H),
6.78 (d, J ¼ 2:8 Hz, 2H, pyrrole-3-H), 6.89-6.91 (m, 2H,
Ar–HðpÞ), 7.09-7.37 (m, 8H, Ar–H(o) and Ar–HðmÞ),
7.76 (br s, 2H, pyrrole-3-H), 7.83 (s, 2H, CH@N). 13C
NMR (C6D6) d: 20.96, 29.60, 35.63, 42.85, 58.76, 82.93
(t, JC–H ¼ 116 Hz), 113.33, 120.81, 121.34, 125.23,
128.87, 139.05, 139.31, 147.96, 156.66. Anal. Calc. for
C44H52N4Zr: C, 72.58; H, 7.20; N, 7.69. Found: C,
72.73; H, 7.05; N, 7.98%.
4.18. Preparation of (L6)2Zr(CH2Ph)2 (6b)
To a stirred solution of Zr(CH2Ph)4 (460 mg, 1.01
mmol) in toluene (10 ml) at )78 °C with shielded light, a
solution of HL6 (461 mg, 2.02 mmol) in toluene (10 ml)
was added dropwise over a 5 min period under an argon
atmosphere and stirred for 2 h. The reaction mixture
was allowed to warm to )30 °C and stored overnight.
The resulting mixture was evaporated at 0 °C. The solid
was recrystallized from toluene (0.5 ml)/n-pentane (5 ml)
at )30 °C to give a red-orange powder (0.531 g, 0.729
mmol) in 72.2% yield. Single crystals of 6b, suitable for a
crystal structure determination were obtained from a
4.19. Preparation of cationic complex 6b*
One equivalent of B(C6F5)3 was added to 6b in
bromobenzene-d5 at )30 °C under an argon atmo-
1
sphere. H NMR (C6D5Br, )25 °C) d: 1.00–2.30 (m),
3.56 (br s), 6.15–7.80 (m), 7.90–8.55 (m). 13C NMR
(C6D5Br, )25 °C, selected peaks) d: 21.69, 28.97, 29.51,
35.17, 42.14, 61.58, 115.94, 137.70, 137.83, 138.91,
147.33, 148.86, 149.70. 19F NMR (C6D5Br, )25 °C) d:
)130.51 (o-F), )162.54 (p-F), )165.54 (m-F).
Table 3
Summary of crystallographic data for complexes 6a and 6b
Complex
6a
6b
Crystal data
Empirical formula
Formula weight
C44H52N4Hf ꢁ 2C6H6
971.60
C44H52N4Zr ꢁ 2C6H6
884.33
Crystal color, habit
Crystal dimensions (mm)
Crystal system
Orange, plate
0.1 ꢀ 0.3 ꢀ 0.3
Monoclinic
13.307(1)
9.5690(7)
19.271(1)
99.905(1)
2417.3(3)
P2=c (no. 13)
4/2
Red, prism
0.9 ꢀ 0.9 ꢀ 0.9
Monoclinic
13.070(1)
9.6256(5)
19.255(1)
101.742(8)
2371.8(3)
P2=c (no. 13)
4/2
ꢀ
a (A)
ꢀ
b (A)
ꢀ
c (A)
b (°)
U (A )
Space group
3
ꢀ
Z
Dcalc (mg/m3)
F ð000Þ
1.335
1000
2.198
1.238
936
0.273
l (Mo KaÞ (mmꢂ1
Data collection
)
ꢀ
k (Mo Ka radiation) (A)
Temperature (K)
0.71073
203(2)
0.71073
293(2)
2hmax
Number of total reflections
Number of unique reflections
56.7
14,236
56.0
9456
5492 ðRint ¼ 0:0862Þ
5712 ðRint ¼ 0:0172Þ
Structure solution and refinement
Number of observations ðI > 2rðIÞÞ
Number of variables
4766
271
4519
270
Reflection/parameter ratio
Final R indices ðI > 2rðIÞÞ; R1, wR2
Final R indices (all data) R1, wR2
Goodness-of-fit
20
21
0.0419, 0.1024
0.0528, 0.1140
1.101
0.0409, 0.1068
0.0599, 0.1158
1.061
3
ꢀ
Maximum peak in final difference map (e/A )
ꢀ
Minimum peak in final difference map (e/A )
2.129
–0.969
0.425
–0.625
3

S. Matsui et al. / Journal of Organometallic Chemistry 689 (2004) 1155–1164
1163
4.20. Polymerization procedure
Cambridge CB2 1EZ, UK (Fax: (internat.) + 44-1223/
336-033; E-mail: deposit@ccdc.cam.ac.uk).
The ethylene polymerization was carried out at 25 °C
under atmospheric pressure in a 500-ml glass reactor
equipped with a propeller-like stirrer. The solvent (250
ml: toluene or n-heptane) was introduced into the ni-
trogen-purged reactor and stirred (600 rpm). The sol-
vent was thermostated to a prescribed polymerization
temperature, and then the monomer gas feed (100 l/h)
was started. After 15 min, polymerization was initiated
by adding a toluene solution of the cocatalyst followed
by catalyst solution in toluene into the reactor with
vigorous stirring (600 rpm). After 5 min, isobutanol (10
ml) was added to terminate the polymerization and the
ethylene gas feed was stopped. To the resulting mixture,
methanol (1000 ml) and conc. HCl (2 ml) were added.
The polymer was collected by filtration, washed with
methanol (200 ml) and dried in vacuo at 80 °C for 10 h.
Acknowledgements
We thank Drs. B. Mathiasch, C. Capacchione, H.
Makio, and T. Fujita for useful discussions.
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