Indenyl nickel complexes: Synthesis, characterization and styrene polymerization catalysis

Article abstract of DOI:10.1016/j.jorganchem.2003.09.002

Neutral indenyl nickel complexes with the general formula (η-1-R-Ind) Ni(PPh₃)Cl (R=cyclopentyl (1), benzyl (2)) have been prepared and characterized by ¹H-NMR spectroscopy and single-crystal X-ray analysis. The results of X-ray crystal structural determination reveal that the hapticity of indenyl ligand in complex 1 or 2 is significantly distorted away from an idealized η⁵ mode to an unsymmetrical η³ mode. Furthermore, the structures of (R-Ind)Ni(PPh₃)Cl exhibit a progressively more distorted coordination of the indenyl ring from cyclopentyl to benzyl. Both of them are inert toward the insertion of styrene, however, they are able to catalyze the polymerization of styrene effectively in the presence of NaBPh₄ and PPh₃ to give syndio-rich atactic poly(styrene) with M_w values in the range of 10⁴. The NaBPh₄·1·PPh₃ system shows the higher catalytic activity than the NaBPh₄·2·PPh ₃ system.

Full text of DOI:10.1016/j.jorganchem.2003.09.002

Journal of Organometallic Chemistry 688 (2003) 132ꢀ137
/
www.elsevier.com/locate/jorganchem
Indenyl nickel complexes: synthesis, characterization and styrene
polymerization catalysis
Hongmei Sun, Wanfei Li, Xiaoyan Han, Qi Shen *, Yong Zhang
Department of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215006, China
Received 1 April 2003; received in revised form 31 August 2003; accepted 2 September 2003
Abstract
Neutral indenyl nickel complexes with the general formula (h-1-Rꢀ
/
Ind)Ni(PPh3)Cl (Rꢁcyclopentyl (1), benzyl (2)) have been
/
prepared and characterized by 1H-NMR spectroscopy and single-crystal X-ray analysis. The results of X-ray crystal structural
determination reveal that the hapticity of indenyl ligand in complex 1 or 2 is significantly distorted away from an idealized h5 mode
to an unsymmetrical h3 mode. Furthermore, the structures of (Rꢀ
coordination of the indenyl ring from cyclopentyl to benzyl. Both of them are inert toward the insertion of styrene, however, they
/Ind)Ni(PPh3)Cl exhibit a progressively more distorted
are able to catalyze the polymerization of styrene effectively in the presence of NaBPh4 and PPh3 to give syndio-rich atactic
poly(styrene) with Mw values in the range of 104. The NaBPh4×
2×PPh3 system.
# 2003 Elsevier B.V. All rights reserved.
/
1×
/
PPh3 system shows the higher catalytic activity than the NaBPh4×
/
/
Keywords: Nickel complex; Indenyl ligand; Polymerization; Styrene; Crystal structure
1. Introduction
generated cationic species [Ind(PPh3)Ni]ꢂ might be the
active centers for these reactions and the Ind substitu-
ents have a major influence on the course of the
catalysis, the later is in evidence by comparison the
analogous styrene reactions catalyzed by in situ gener-
The research of metallocene chemistry has showed
that the hapticity of a polyolefin ligand usually exerts a
dominant influence on the reactivity of its metal
complexes [1]. One such kind of ligand, namely indene
and its substituted derivatives, is of special interest in
Group IVB complexes owing to its easily coordination
modification by substitution [1,2]. However, their ap-
plications in group 10 metal complexes have received
less attention. Recently, Zargarian et al. have reported
ated cations from (1-Meꢀ
IndꢀCH2CH2NMe2)(PPh3)Niꢀ
knowledge about the structureꢀ
/
Ind)(PPh3)Niꢀ
/
Cl and (h3, h0-
/
/Cl [5]. However, the
/activity relationships
of indenyl nickel complexes seems still insufficient.
Recently, we have reported the development of Pd(II)
?
and Ni(II) acetylide complexes (PR3)2M(CÅ
/
CR)2 [Mꢁ
Ph, CH2OH,
CH2OOCCH3, CH2OOCPh, CH2OOCPhOH-o, CÅ
CC6H4CÅCH, etc.] as high active initiators for poly-
/
Pd, Ni; R?ꢁ
/
Ph3, n-Bu3; Rꢁ
/
that (Ind)(PR3)Ni-X (Indꢁ
derivatives; RꢁPh, Me, Cy, Bu, etc.; Xꢁ
alkynyl, imidate, thiolate, etc.) [3ꢀ6] can act as effective
precatalysts in a number of reactions, such as the
oligomerizations or polymerizations of ethylene [4],
styrene [5] and phenylacetylene [6], the dehydrogenative
oligomerization and polymerization of phenylsilane [7]
etc. Preliminary studies have implied that the in situ
/
indenyl and its substituted
/
/
/halide, alkyl,
/
/
merizations of a series of monomers, e.g. propargyl
alcohol [8], p-diethynylbenzene [9], methyl methacrylate
[10], styrene [11], and so on. To our some surprise, the
nickelocene
acetylides
(p-C5H5)(PPh3)Ni(CÅ
/
CR)2
showed no catalytic activity for styrene or methyl
methacrylate polymerization. Considering the so-called
‘indenyl effect’, also as an extension of our continuous
study in this area, we report herein the preparation and
structural characterization of new indenyl nickel com-
* Corresponding author. Tel.: ꢂ
5112-371.
E-mail address: qshen@suda.edu.cn (Q. Shen).
/
86-512-5112-513; fax: ꢂ86-512-
/
plexes (h-1-Rꢀ
/
Ind)(PPh3)Niꢀ
/
Cl (Rꢁcyclopentyl (1),
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.09.002

H. Sun et al. / Journal of Organometallic Chemistry 688 (2003) 132ꢀ
/137
133
benzyl (2)) and their catalytic activities in styrene
polymerization, which enlarge the list of analogous
complexes already described [3ꢀ7] to such an extend
that comparative studies of their structureꢀcatalytic
/
/
activity relationships may be possible.
2. Results and discussion
2.1. Synthesis and characterization of the indenylnickel
complexes
The indenyl nickel complexes 1 and 2 are synthesized
by the reactions of Ni(PPh3)2Cl2 with the corresponding
lithium R-indenyl as shown in Scheme 1. Because the
reaction of 1-cyclopentylindene or 1-benzylindene with
an equivmolar amount of n-BuLi in Et2O give a
quantitative yield of cyclopentyl or benzyl indenyl
lithium, so freshly prepared solution of indenyl lithium
is directly used in the following metathesis reactions.
Thus, 1-cyclopentylindene or 1-benzylindene reacted
with n-BuLi in Et2O for 40 min at 0 8C, the resulting
solution was slowly added into a stirring suspension of
Ni(PPh3)2Cl2 in Et2O in 1:1.8 molar ratio. After
Fig. 1. The crystal structure of complex 1.
workup, the expected complexes (Rꢀ/Ind)Ni(PPh3)Cl
(Rꢁcyclopentyl (1), benzyl (2)) were isolated as dark
/
red crystals in ca. 45% (1) or 65% (2) yield, supported by
1
elemental analysis and H-NMR spectroscopy. Suitable
crystals of 1 and 2 for X-ray diffraction studies are
grown from cold hexaneꢀDME solution.
/
Both of 1 and 2 have good thermal stability, they are
air- and moisture-sensitive, and soluble in toluene,
CH2Cl2, DME, THF and diethyl ether, but insoluble
in hexane.
Fig. 2. The crystal structure of complex 2.
The crystal structures of 1 and 2 were determined in
order to see the influence of substituted groups on
indenyl ring on the structures of these complexes. The
molecular structures of 1 and 2 are presented in Figs. 1
and 2, respectively. The crystallographic data and
selected bond lengths and angles for 1 and 2 are listed
in Tables 1 and 2, respectively. Molecular structures of 1
and 2 are analogues, and both are monomeric in the
solid state, but they crystallize in different space groups
(triclinic for 1 and orthorhombic for 2). Each Ni in the
two complexes is bound to P, Cl, C2, C3 and C4 based
on the bond distances of Ni to these atoms, while the
bond distances of the other two carbon atoms of the
five-membered ring, i.e. C1 and C5, to Ni are signifi-
cantly longer. The geometry of these complexes around
Ni can be described as a distorted square planar with
C2Ä
/
C3 occupying a single coordination site. In both
structures, the Ind hapticity of the Ind ligand is
significantly distorted away from an idealized h5 mode
toward a fairly unsymmetric h3 coordination, which is
common in this family of complexes [3b]. These distor-
tions can be mainly attributed to the tendency of Ni(II)
to avoid forming 18-electron complexes and the unequal
trans influences of the PPh3 and Cl groups [3b,d]. On
the other hand, the influence of substituted groups on
indenyl ring on the solid state structure of 1 and 2 is also
observed in the following manner. For instance, differ-
ent Niꢀ
NiꢀInd interaction can be compared quantitatively by
calculating the parameters such as the slip value (DMꢀ
C)ꢁ[MꢀCav(for C1, C5)]ꢀ[MꢀCav(for C2, C4)] [3a]. In
1, DMꢀCꢁ0.27, more close to the value found in 3
(0.25) [3b], meanwhile in 2, DMꢀCꢁ0.31 (Table 2),
/Ind interactions occurred in present case. The
/
/
/
/
/
/
/
/
/
/
indicating a less slip-fold distortion of Ind ligand in 1
compared to that in 2, as well as an increase of the Ind
hapticity from 3 to 1 to 2. Furthermore, as the observed
Scheme 1.

134
H. Sun et al. / Journal of Organometallic Chemistry 688 (2003) 132ꢀ137
/
Table 1
X-ray crystallographic data for 1 and 2
values of the C2ꢀ
/
C3, C3ꢀ
/
C4, Niꢀ
/
C2 and NiꢀC4 bond
/
lengths reflect the delocalization of the allyl moiety of
Ind ligand, so the local symmetry in the coordination of
the allyl moiety are also different in 1 and 2, and indicate
1
2
Empirical formula
Formular weight
C
539.72
32H30NiPCl
C38H38O2PClNi
651.84
193(2)
a more symmetric Niꢀ
the NiꢀP and NiꢀCl distance are apparently shorter in 1
(2.1810(10) and 2.187(10), respectively) than in 2
(2.1860(10) and 2.2390(10), respectively). Thus, Niꢀ
Ind interaction together with NiꢀCl and NiꢀP interac-
tions are stronger in 1 than those in 2, and seem closely
between 1 and 3. In the present case, we propose these
differences mainly arising from the different substitution
on the Ind ligand, and a ‘soft’, electron donating
substituent such as cyclopentyl may doing good to the
stronger coordination between the nickel atom vis a` vis
the ancillary ligands in these indenyl nickel complexes.
Alternatively, besides PPh3 and Clꢃ, the substitution of
the Ind ligand also be able to affect the relative ligand
trans effects, and then on the hapticity of the Ind ligand.
/
Ind interaction in 1. Additional,
/
/
Temperature(K)
˚
193(2)
0.71070
Triclinic
l (Moꢀ/Ka) (A)
0.71070
Orthorhombic
P212121
/
Crystal system
Space group
Unit cell dimensions
¯
P1
/
/
˚
a (A)
9.061(3)
10.351(4)
15.333(6)
80.137(13)
81.981(10)
66.410(10)
1294.5(8)
2
9.0898(5)
13.6106
26.450(2)
90.00
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
90.00
90.00
3
˚
V (A )
3272.3(4)
4
1.323
Z
Dcalc (g cmꢃ3
Absorption coefficent
)
1.385
0.934
0.756
(mmꢃ1
F(000)
)
564
1368
Since the nature of the NiꢀInd interaction in solution
/
Crystal size (mm3)
0.26ꢄ
55.0
10246
/
0.66ꢄ
/
0.13 0.45ꢄ
/
0.80ꢄ0.10
/
is believed to be able to influence substantially the
reactivity of Ind complexes, it is important to under-
stand Ind hapticity in solution. Zargarian’s group [3b]
have observed that, for 3 and its methyl derivative, the
direct correlation between structural and solution NMR
2umax (8)
Reflections collections
Independent reflections
55.0
32921
5650 [Rint
0.022]
ꢁ/
4159 [Rint
ꢁ/0.042]
Data/restraints/parameters
Goodness-of-fit on F2
4607/0/346
1.00
3644/0/426
1.00
1
spectra data and used the H-NMR resonances for the
Final R indices [I ꢀ
Rw
/
2s(I)]
0.033
0.097
0.0510
0.1510
symmetry-related pairs of protons (H2/H4, H6/H9, and
H7/H8) as a convenient indicator of Ind hapticity.
Accordingly, they concluded that the solid state struc-
tures of these complexes were maintained in the solu-
tion. Herein, the above conclusion can also be reached
from the paired comparisons of the 1H-NMR spectra of
these complexes (i.e. 1/3 and 2/3), as their 1H-NMR
spectra are very similar in pairs. For example, the H4
resonance in 1 (3.37 ppm) or in 2 (3.50 ppm) is very close
to the corresponding resonance for 3 (3.37 ppm).
Table 2
a
˚
Select bond lengths (A), bond angles (8) and structural parameters
˚
(A) for 1 and 2
a
1
2
3
Bond lengths
Niꢀ
Niꢀ
Niꢀ
Niꢀ
Niꢀ
Niꢀ
Niꢀ
C2ꢀ
C3ꢀ
C4ꢀ
C1ꢀ
C1ꢀ
/
P
2.1810(10)
2.187(10)
2.135(2)
2.053(2)
2.031(2)
2.336(2)
2.367(2)
1.418(3)
1.423(3)
1.457(3)
1.463(3)
1.423(3)
2.1860(10)
2.2390(10)
2.144(5)
2.053(5)
2.020(5)
2.377(5)
2.410(5)
1.393(8)
1.442(8)
1.466(8)
1.467(7)
1.427(7)
2.1782(11)
2.1865(10)
2.137(2)
2.072(2)
2.026(3)
2.308(2)
2.351(2)
1.403(4)
1.421(4)
1.451(4)
1.457(4)
1.4179(4)
2.2. The polymerization of styrene
/Cl
/
C2
C3
C4
C5
C1
To the best of our knowledge, the catalytic activity of
indenyl nickel complexes for styrene reactions has been
/
/
reported only by Zargarian’s group, a chelating aminoꢀ
indenyl cationic nickel complex in situ generated from
CH2CH2NMe2)Ni(PPh3)Cl and AgBPh4
/
/
/
(h3, h0-Indꢀ
/
/
C3
C4
C5
C2
C5
/
(or AgBF4) for styrene polymerization or a 3/AgBF4
system for oligomerization of styrene [5]. In the present
/
/
paper, the catalytic behavior of (Rꢀ
/
Ind)Ni(PPh3)Cl
/
(Rꢁcyclopentyl (1), benzyl (2)) for the polymerization
/
Bond angles
of styrene in toluene has been tested. The preliminary
results are listed in Table 3. The results show that
complex 1 or 2 without NaBPh4 is inert toward the
insertion of styrene, however, together with NaBPh4 and
PPh3, they show highly catalytic activity for the poly-
merization of styrene. The purpose of the reaction
between complex 1 or 2 with NaBPh4 is to abstract
the Clꢃ ligand from these complexes and facilitate the
Pꢀ
Pꢀ
Pꢀ
Clꢀ
C2ꢀ
/
Niꢀ
Niꢀ
Niꢀ
/
Cl
98.01(4)
165.98(6)
99.03(7)
96.01(6)
66.96(9)
102.80(5)
163.2(2)
96.5(2)
98.82(4)
165.62(7)
99.33(8)
95.48(8)
62.79(9)
/
/C2
/
/C4
/Niꢀ
/C2
93.9(2)
66.8(2)
/Niꢀ
/C4
Structural parameters
DMꢀ 0.27
/C
0.31
0.25
a
Taken from Ref. [3b].

H. Sun et al. / Journal of Organometallic Chemistry 688 (2003) 132ꢀ
/137
135
Table 3
a
Polymerization of styrene initiated by (Rꢀ
/Ind)Ni(PPh3)Cl/NaBh4/PPh3
b
Yield (%)
c
Run
R
Mn (ꢄ
/
10ꢃ3 10ꢃ3
)
Mw (ꢄ
/
)
Mw/Mn
Catalytic activity (kg PE/mol Ni h)
1
C5H9
C5H9
PhCH2
CH3
83
55
58
78
4.09
11.7
2.86
1.8
0.71
1.3
1.7
2 d
3
ꢀ/
8.68
5.96
ꢀ/
34.1
28.0
ꢀ/
3.93
4.70
4
a
b
c
General polymerization conditions: [Ni]ꢁ
Yieldꢁweight of polymer obtained/weight of monomer used.
Measured by GPC calibrated with standard polystyrene samples.
/
25 mM; [M]/[Ni]ꢁ
/
300; Tꢁ
/
80 8C; tꢁ
/
24 h; NaBPh4/(Rꢀ
/
Ind)Ni(PPh3)Cl/PPh3ꢁ7:1:1.
/
/
d
NaBPh4/(Rꢀ
/
Ind)Ni(PPh3)Cl/PPh3ꢁ7:1:4.
/
formation of cationic species [3d,4a,e], while the addi-
tion of moderate PPh3 is of benefit to suppress the
decomposition of the cationic species (as shown below).
For example, when the styrene polymerization was
obtained with 3. On the contrary, the polymer with the
most high molecular weight is obtained with 2, as well as
polymers with similar molecular weight are obtained
with 1or 3. Apparently, the differences between their
catalytic activities are in accord with those of between
their Ind hapticities as shown above, indicating a close
carried out in toluene at 80 8C with NaBPh4/1/PPh3ꢁ
/
7:1:4 (mole ratio), [styrene]/[1]ꢁ500 (mole ratio), the
/
polymer yield could reached 83% after 24 h (run 1, Table
3). The obtained polystyrene is soluble in THF with
relationship between structureꢀactivity of these indenyl
/
nickel complexes. In the present case, it is suggested that
a ‘soft’, electron donating substituent on the Ind ligang
is of benefit to increase the catalytic activity of the
indenyl nickel complex for styrene polymerization.
In addition, it is noteworthy that the proper quantity
of PPh3 is necessary to initiate a higher active polymer-
ization of styrene. In the present system, the optimal
Mwꢁ
/
11700 and Mw/Mnꢁ
2.86. Fig. 3 shows the 13C-
/
NMR spectrum (CDCl3) of the phenyl C-1 carbon of
the obtained polymer. According to reported results, the
phenyl C-1 carbon signal is the most important signal
for determining stereoregularity of polystyrene [15a].
The present spectrum shows characteristically broad
signals of atactic polystyrene in the range of ca. 145ꢀ147
/
Ni:PPh3 ratio seems to be about 1:1 for the NiꢀCl
/
ppm [15b]. Furthermore, the phenyl C-1 spectrum can
be analyzed in term of triads, the three main peaks from
precursor, and a large excess of PPh3 leads to a dramatic
decrease in polymer yield (runs 1 and 2, Table 3).
higher magnetic field (ca. dꢁ
/
145.8 ppm) to lower
However, a rapid decomposition of the NiꢀCl complex
/
magnetic field (ca. dꢁ146.7 ppm) are assigned to
/
is observed at the polymerization temperature in the
reaction system in the absence of PPh3. By the way,
PPh3 has no catalytic activity for the present polymer-
ization in blank experiment. On the other hand,
Zargarian et. al. have reported that a bis(phosphine)
syndiotactic triad (rr), heterotactic triad (mr) and
isotactic triad (mm), respectively. Thus, it is obviously
that the polystyrene obtained with NaBPh4/1/PPh3
system is a syndio-rich atactic polymer [15].
The influence of the substituents on Ind ligand on the
catalytic activity of the corresponding complexes are
also observed (runs 1, 3 and 4, Table 3), with (1-
(C5H9)Ind)Ni(PPh3)Cl being the most active one (ac-
cording to the polymer yield). Similar higher activity is
cationic species [(1-Meꢀ
Ind)Ni(PPh3)PPh3]ꢂ was ob-
/
tained in 90% yield when equimolar quantities of 3,
AgBF4 and PPh3 are stirred in CH2Cl2 [4a], similar
results were also observed when PPh3 was added to the
mixture of (h3, h0-Indꢀ
and NaBPh4 (ꢀ
philic ‘naked’ cation [(1-Meꢀ
/
CH2CH2Niꢀ
90%) [4e]. In fact, the highly electro-
Ind)Ni(PPh3)]ꢂ, which is
/
Pr2)Ni(PPh3)Cl
/
/
generated from the reaction between 3 and AgBF4 in
CH2Cl2 in the absence of any donor, is nonstabilized
and coordinates any residual PPh3 from 3. Thus,
combination with the reported results indicate that the
present styrene polymerization mainly be catalyzed by
the in situ generated cationic species [1-RꢀIn-
/
d(PPh3)Ni(PPh3)]ꢂ. An excess of PPh3 could suppress
the effective competition of styrene for coordination to
Ni, and leads to a dramatic decrease in polymer yield. It
is not clear, however, why the bis(phosphine) cationic
species [(1-Meꢀ
Ind)Ni(PPh3)PPh3]ꢂ is catalytically in-
sert toward ethylene polymerization [5], yet it shows
moderate activity for the polymerization of styrene. We
/
Fig. 3. 13C-NMR spectrum of polystyrene (CDCl3, 100 MHz).

136
H. Sun et al. / Journal of Organometallic Chemistry 688 (2003) 132ꢀ137
/
suggest it might be due to the fact that styrene is a more
electron-rich monomer than ethylene.
another 40 min at room temperature, filtered, and
evaporated to dryness. The residue was washed with
hexane (3ꢄ
byproducts and recrystallized from DMEꢀ
/
ca. 20 ml) to remove PPh3 and other
hexane solu-
/
3. Conclusion
tion at 0 8C yielded crystals (728 mg, 45%) suitable for
X-ray diffraction studies and elemental analysis. 1H-
NMR (C6D6, d): 7.72 (m, 5H, PPh3), 7.36 (m, 1H, H8),
7.02 (m, 11H, PPh3 and H9), 6.91 (t, 1H, H7), 6.45 (br s,
Indenyl nickel complexes (Rꢀ
cyclopentyl (1), benzyl (2)) can be easily prepared by
the reactions of RꢀIndLi (Rꢁcyclopentyl, benzyl) with
Ni(PPh3)2Cl2 in 1:1.8 molar ratio, respectively. More-
over, the NaBPh4/(RꢀInd)Ni(PPh3)Cl/PPh3 systems
/
Ind)Ni(PPh3)Cl (Rꢁ
/
/
/
1H, H3), 6.22 (d, 1H, H6), 3.37 (br s, 1H, H4), 0.89ꢀ
/
2.91 (m, 9H, C5H9). Anal. Calc. for C32H30ClNiP: C,
71.25; H, 5.56. Found: C, 71.28; H, 5.71%.
/
were found to be able to initiate the polymerization of
styrene with high activity to give moderate molecular
weight, syndio-rich atactic polystyrene. A close relation-
4.2. Synthesis of (1-C7H7C9H6)Ni(PPh3)Cl (2)
ship between the structureꢀactivity of these indenyl
/
nickel complexes is observed. Although the mechanistic
details of the styrene polymerization are not known with
certainty, the involvement of cationic species such as [(1-
Following the procedure similar to the synthesis of 1,
(1-C7H7C9H6)Li (5.2 ml, 3 mmol, 0.58 M in Et2O) was
added slowly to a stirring suspension of Ni(PPh3)2Cl2
(3.53 g, 5.4 mmol) in Et2O(60 ml) at room temperature
(r.t.). The color of the solution gradually changed to
dark red. The resulting solution was then stirred for
another 40 min, filtered, and evaporated to dryness. The
Rꢀ
gested. Further investigations focus on the detailed
structureꢀactivity relationships and mechanistic aspects
/
Ind)Ni(PPh3)PPh3]ꢂ in the reaction has been sug-
/
of the polymerization using these complexes are now in
progress.
residue was washed with hexane (3ꢄ
remove PPh3 and other byproducts and recrystalized
from Et2Oꢀhexane at ꢃ30 8C to give the product as
/ca. 20 ml) to
/
/
4. Experimental
dark red crystals (986 mg, 65%) for elemental analysis
1
and H-NMR. Recrystallization of a small portion of
All manipulations were performed under pure argon
with rigorous exclusion of air and moisture using
standard Schlenk techniques. Solvents were distilled
this solid from a cold DMEꢀhexane solution yielded
/
crystals suitable for X-ray diffraction studies. The result
of the X-ray diffraction analysis showed the crystal cell
contained a solvent molecular. 1H-NMR (C6D6, d): 7.68
(t, 1H, H8), 7.46 (m, 20H, Ar), 7.23 (m, 1H, H9), 6.93 (t,
1H, H7), 6.36 (br s, 1H, H3), 6.17 (br s 1H, H6), 3.50 (br
from Naꢀbenzophenone ketyl prior to use. Indene
/
˚
(Fluka) (dried over 4 A molecular sieves) and styrene
(dried over CaH2) were distilled before use. The
(PPh3)2NiCl2 [12] and the ligands 1-cyclopentylindene
[13], 1-benzylindene [14] and complex 3 [3b] were
prepared by published methods. Carbon and hydrogen
analyses were performed by direct combustion on a
Carlo-Erba EA-1110 instrument. Molecular weight and
molecular weight distributions were determined against
polystyrene standard by gel permeation chromatogra-
phy (GPC) on a Waters 1515 apparatus with three HR
columns (HR-1, HR-3 and HR-4); THF was used as an
eluent at 30 8C. 1H-NMR (C6D6) and 13C-NMR
(CDCl3) spectra were measured on a Unity Inova-400
spectrometer.
s, 1H, H4), 1.63 (br s, 2H, ꢀ
/
CH2ꢀph). Anal. Calc. for
/
C34H28ClNiP: C, 72.70; H, 5.02. Found: C, 72.93; H,
5.11%.
4.3. A typical procedure for polymerization of styrene
The procedures for the polymerization of styrene are
the same, and a typical polymerization reaction is given
as follows. Under dry argon, the solid initiator 1 (11.3
mg, 0.02 mmol), PPh3 (21 mg, 0.08 mmol), NaBPh4 (48
mg, 0.14 mmol), toluene (0.2 ml) and styrene (1.2 ml,
0.01 mol) were added into a dry glass ampule in turn.
Then, the sealed ampule was placed into a water bath
held at 80 8C. After a definite reaction time, the
polymerization was stopped by adding 1 ml of 5%
4.1. Synthesis of (1-C5H9C9H6)Ni(PPh3)Cl (1)
A Schlenk flask was charged with 1-cyclopentylindene
(0.55 g, 3 mmol), DME (50 ml) and a stir bar. n-BuLi
(2.3 mL, 3 mmol, 1.30 M in hexane) was added dropwise
to this solution via syringe at 0 8C. The solution was
stirred for 30 min and then added slowly to a stirring
suspension of Ni(PPh3)2Cl2 (3.53 g, 5.4 mmol) in DME
at 0 8C. The color of the solution gradually changed to
dark red. The resultant solution was then stirred for
HClꢀethanol. After evaporation of solvent and un-
/
reacted monomer, the resulted polymer was dissolved in
THF, followed by precipitation in 95% ethanol. After
filtration, the white polymer was dried in vacuum at
room temperature overnight. The polymer yield was
determined gravimetrically.

H. Sun et al. / Journal of Organometallic Chemistry 688 (2003) 132ꢀ
/137
137
Weingarten, J. Organomet. Chem. 636 (2001) 31 (and references
cited therein).
4.4. X-ray structural determination of 1 and 2
[3] (a) T.A. Huber, F. Be´langer-Garie´py, D. Zargarian, Organome-
tallics 14 (1995) 4997;
A suitable crystal was mounted in a thin-walled glass
capillary for X-ray structural analysis. Diffraction data
were collected on a Bruker SMART CCD area detector
using phi and omega scans. The structures were solved
by direct methods and refined by full-matrix least-
(b) T.A. Huber, M. Bayrakdarian, S. Dion, I. Dubuc, F.
Be´langer-Garie´py, D. Zargarian, Organometallics 16 (1997)
5811 (and references cited therein);
(c) I. Dubuc, M.-A. Dubois, F. Be´langer-Garie´py, D. Zargarian,
Organometallics 18 (1999) 30;
2
squares procedures based on jFj . All non-hydrogen
(d) L.F. Groux, F. Be´langer-Garie´py, D. Zargarian, R. Vollmer-
haus, Organometallics 19 (2000) 1507;
atoms were refined with anisotropic displacement coef-
ficients. Hydrogen atoms were treated as idealized
contributions. The structures were solved and refined
using SHELXS-97 and SHELXL-97 programs, respectively.
(e) F.-G. Fontaine, M.-A. Dubois, D. Zargarian, Organometallics
20 (2001) 5156.
[4] (a) R. Vollmerhaus, F. Be´langer-Garie´py, D. Zargarian, Organo-
metallics 16 (1997) 4762;
(b) M.-A. Dubois, R. Wang, D. Zargarian, J. Tian, R. Vollmer-
haus, Z. Li, S. Collins, Organometallics 20 (2001) 663;
(c) L.F. Groux, D. Zargarian, L.C. Simon, J.B.P. Soares, J. Mol.
Catal. A Chem. 3781 (2002) 1;
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 207234 and 207235 for
complexes 1 and 2, respectively. Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(d) R. Wang, L.F. Groux, D. Zargarian, Organometallics 21
(2002) 5531;
(e) L.F. Groux, D. Zargarian, Organometallics 22 (2003) 3124.
[5] L.F. Groux, D. Zargarian, Organometallics 20 (2001) 3811.
[6] R. Wang, F. Be´langer-Garie´py, D. Zargarian, Organometallics 18
(1999) 5548.
[7] (a) F.-G. Fontaine, T. Kadkhodazadeh, D. Zargarian, J. Chem.
Soc. Chem. Commun. (1998) 1253;
(Fax: ꢂ44-1223-336033; e-mail: deposit@ccdc.cam.a-
/
(b) F.-G. Fontaine, D. Zargarian, Organometallics 21 (2002) 401.
[8] (a) X.W. Zhan, M.J. Yang, H.M. Sun, Catal. Lett. 70 (2000) 79;
(b) M.J. Yang, H.M. Sun, G. Casalbore-Miceli, N. Camaioni, C.-
M. Mari, Synth. Met. 81 (1996) 65;
c.uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgements
(c) M.J. Yang, H.M. Sun, W.G. Chen, Polym. J. 27 (1995) 928.
[9] (a) X.W. Zhan, M.J. Yang, H.M. Sun, Macromol. Rapid
Commun. 22 (2001) 530;
We thank the Chinese National Natural Science
Foundation, the Department of Education of Jiangsu
Province and the Key Laboratory of Organic Chemistry
of Jiangsu Province for the financial support.
(b) X.W. Zhan, M.J. Yang, H.M. Sun, J. Mol. Catal. A Chem.
169 (2001) 63;
(c) X.W. Zhan, M.J. Yang, J. Mol. Catal. A Chem. 169 (2001) 27;
(d) X.W. Zhan, M.J. Yang, Macromol. Rapid Commun. 21
(2000) 1.
[10] H.M. Sun, Q. Shen, X.A. Peng, Catal. Lett. 80 (2002) 11.
[11] (a) H.M. Sun, M.J. Yang, Q. Shen, Eur. Polym. J. 38 (2002) 2045;
(b) H.M. Sun, M.J. Yang, Q. Shen, Chin. Chem. Lett. 12 (2001)
1033.
References
[1] M.E. Stoll, P. Belanzoni, M.J. Calhorda, M.G.B. Drew, V. Fe´lix.,
W.E. Geiger, C.A. Gamelas, I.S. Goncalves, C.C. Romao, L.F.
[12] L.M. Venanzi, J. Chem. Soc. (1958) 719.
[13] M.H. Qi, Q. Shen, Chin. J. Chem. 20 (2002) 564.
[14] N.E. Grimmer, N.J. Coville, C.B. Koning, J.M. Smith, L.M.
Cook, J. Organomet. Chem. 616 (2000) 112.
˜
Veiros, J. Am. Chem. Soc. 123 (2001) 10595 (and references cited
therein).
[2] (a) J.A. Ewen, J. Am. Chem. Soc. 106 (1984) 6355;
(b) W. Kaminsky, Makromol. Chem. Macromol. Symp. 47 (1991)
83;
[15] (a) H. Sato, Y. Tanaka, J. Polym. Sci. Polym. Phys. Ed. 21 (1983)
1667;
(b) N. Ishihara, T. Seimiya, M. Kuramoto, M. Uoi, Macro-
molecules 19 (1986) 2464.
(c) R.L. Halterman, Chem. Rev. 92 (1992) 965;
(d) H. Schumann, D.F. Karasiak, S.H. Muhle, W. Kaminsky, U.
¨