Synthesis, characterization and application of organolanthanide complexes [CH2=CHCH2CH2C5 H4)2Ln-Cl·2THF (Ln = Sm, Y, Dy, Er) as methacrylate (MMA) polymerization catalysts

Article abstract of DOI:10.1016/S0022-328X(01)01282-7

The title complexes (CH₂=CHCH₂CH₂ C₅H₄)₂Ln-C1·2THF (Ln = Sm, Y, Dy, Er) were synthesized as air and moisture sensitive free-flowing oils that have been fully characterized by MS, EA and IR.

Full text of DOI:10.1016/S0022-328X(01)01282-7

Journal of Organometallic Chemistry 647 (2002) 105–113
www.elsevier.com/locate/jorganchem
Synthesis, characterization and application of organolanthanide
complexes (CH2ꢀCHCH2CH2C5H4)2LnꢁCl·2THF (Ln=Sm, Y, Dy,
Er) as methyl methacrylate (MMA) polymerization catalysts
Muhammad D. Bala a, Jiling Huang a, Hao Zhang a, Yanlong Qian a,*, Junquan Sun b,
Chengfeng Liang b
a Laboratory of Organometallic Chemistry, East China Uni6ersity of Science and Technology, 130 Meilong Road, P.O. Box 310,
Shanghai 200237, People’s Republic of China
b Department of Chemical Engineering, Zhejiang Uni6ersity, Hangzhou 310027, People’s Republic of China
Received 11 July 2001; received in revised form 19 September 2001
Abstract
The title complexes (CH2ꢀCHCH2CH2C5H4)2LnꢁCl·2THF (Ln=Sm, Y, Dy, Er) were synthesized as air and moisture sensitive
free-flowing oils that have been fully characterized by MS, EA and IR. The EA and IR results indicate the presence of coordinated
THF molecules. No evidence of intra-molecular coordination of the butenyl side-chain was observed. In association with
Al(i-Bu)3, the complexes have shown high activity for the bulk polymerization of MMA. At a MMA/catalyst (MMA/cat) molar
ratio of 2000, temperature of 80 °C and polymerization time of 30 h, the catalyst system produced at a 70% conversion a
syndiorich polymer (rr=62%), Mp=1.65×106. Effects of temperature, time and molar ratios of MMA/catalyst and catalyst/co-
catalyst on the polymerization have been studied. The result showed that higher temperature, longer time and Al/catalyst molar
ratio=10 are conditions suitable for polymerization. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Lanthanides; 3-Butenylcyclopentadiene; MMA; Polymerization
1. Introduction
tacticity, degree of conversion and molecular weight.
Metallocene complexes bearing modifications at the
cyclopentadienyl (Cp) ring have been of great interest
to organometallic chemists, due to their capacity to act
as coordination polymerization catalysts or catalyst
precursors [2]. A variety of functional groups have been
used as side-chain modification to the Cp ring. These
among many include alkoxyalkyls (ROR%) [3]; alkyls
(Rꢁ) [4]; alkylsilyls (R3Siꢁ) [5]; amines (R2Nꢁ) [6]; and
v-alkenyls (CH2ꢀCHRꢁ) [7–9].
Reports have shown that the v-alkenyl (CH2ꢀCHRꢁ)
modified Cp ligands have been applied on Co [2], Ni
(II) [10], Ti [7,11], Zr [8,9,11,12], Hf [12]. Qian et al. [13]
have found its Ti-based complexes to exhibit high con-
version (100%) in the isomerization of 1,5-hexadiene.
The Zr-based complexes synthesized by Qian and
coworkers [9] exhibited a very high activity (106–107 g
PE mol Zr−1 h−1) for ethylene polymerization even at
low [Al]/[Zr] ratio (100ꢀ500). A very recent review [14]
outlined the importance of functionalized-Cp ligands
and their application in organometallic synthesis, but to
Metallocene compounds of the rare-earth metals
when treated with a Lewis acid cocatalyst such as
triiso-butyl aluminum Al(i-Bu)3 or methylaluminoxane
(MAO) generate active catalysts which are isoelectron
neutral analogs of the [Cp2MR]+ d0 Group 4 catalysts
(R=H, alkyl, growing polymer chain). These have
been accepted [1] as the active species responsible for
the CꢁC bond formation by insertion of an olefinic
substrate H2CꢀCHR into the metal–carbon bond.
Ligand modification has played a major role in the
development of new catalyst systems in which a great
level of control over the properties of the resulting
polymer is desired. Both the steric and electronic struc-
ture of the modified ligand has an impact on the
microstructure of the polymer produced, such as the
* Corresponding author. Tel.: +86-21-6470-2573; fax: +86-21-
6470-2573.
E-mail address: qianling@online.sh.cn (Y. Qian).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01282-7

106
M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
the best of our knowledge there is no report yet on the
application of v-alkenyl (CH2ꢀCHRꢁ) functionalized-
Cp ligands on rare-earth metals. In the chemistry of
v-alkenyl-substituted compounds, either the stabiliza-
tion of reactive species or further reactions (e.g. inser-
tion through coordination) of the double bond are
expected. Both situations and the corresponding impact
on reactivity have been reported in the literature [14].
In this report we discuss the synthesis of butenyl
(CH2ꢀCHCH2CH2ꢁ) functionalized-Cp lanthanide
complexes and their utilization in the activation of
syndiotactic polymerization of MMA.
ing oils were characterized by MS, EA and IR. 1H-
NMR spectroscopy was not attempted due to the
paramagnetic nature of the lanthanide metals. Spence
and Piers [8] prepared the corresponding Zr complexes
and reported obtaining oils and gummy solids that
defied purification and isolation by normal means.
However, their complexes were found to be 95% pure
1
by H-NMR spectroscopy.
By careful study of the MS dissociation peaks and
the IR spectra in addition to the C and H content from
the EA we proposed the empirical formula and struc-
ture shown in Scheme 1 (8a–d), in which the metal is a
nine-coordinate center solvated by two THF molecules.
Only complexes of relatively smaller radii lanthanide
metals were isolated. Attempts to isolate the corre-
sponding La and Nd complexes failed. This was antici-
pated as Schumann et al. [15] noted, large ionic radii
lanthanides mostly failed to give isolatable compounds
for simple bis(cyclopentadienyl) LnꢁCl complexes, pos-
sibly due to steric unsaturation.
The MS spectra of all the complexes show a similar
cleavage pattern. The highest M+ corresponds to the
[(CH2ꢀCHCH2CH2C5H4)2Ln·Cl]+ fragment, this indi-
cates that the two THF molecules are cleaved easily.
However, the elemental analysis clearly accounts for
their presence. The IR spectra show the presence of
ordinary uncoordinated CꢀC bonds of the 3-butenyl
substituents (1637 cm−1), and absorption bands at
1045 and 890 cm−1 verify the presence of the coordi-
nated THF molecule [16]. These facts coupled to the
concept of hard and soft acids and bases (HSAB) [17],
which classifies the rare-earth metals as hard Lewis
acids supports the structure of the complexes as con-
taining inter-molecular coordination to solvent
molecules rather than the intra-molecular coordination
of the CꢀC bonds of the 3-butenyl substituents. The
discussion on the intra-molecular coordination of v-
alkenyl (CH2ꢀCHRꢁ) side chains in general is still
unresolved [14]. Based on these results we conclude that
2. Results and discussion
2.1. Synthesis and characterization of catalyst
precursors
Synthesis of sandwich and half-sandwich Cp com-
plexes of the transition and rare-earth metals bearing
functionalities in the side-chain of the Cp fragment
have attracted tremendous attention during the last
decade. This is due to the fact that the side chain can be
used to modify the chemical and physical properties of
the classical Cp complex. The title complexes were
easily obtained using commonly employed metathetical
procedures as outlined in Scheme 1.
The methodology is the same for all the four com-
plexes. The complexes prepared are all free-flowing
clear oils exhibiting the characteristic color of the cen-
tral metal. All the new complexes are soluble in hydro-
carbon solvents such as toluene and n-hexane, although
they are still very sensitive to air and moisture. This has
made purification a rather difficult task. By washing the
crude product several times with hexane until no sticky
substance precipitates out followed each time by rotary
centrifugation, the clear analytically pure (by EA) oils
were obtained in moderate (ca. 55%) yields. The result-
Scheme 1. Synthetic route to title complexes.

M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
107
Table 1
2.2. Polymerization of MMA
Polymerization of MMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2-
LnꢁCl·2THF complexes
Polymerization of MMA using the title complexes as
catalysts was carried out using different cocatalysts.
The efficiency of the various catalyst/cocatalyst systems
is presented in Tables 1 and 2. To establish the role
Run
Ln
Conversion (%)
Mp (×10−3
)
B22
B4
B23
B24
Y
21.6
44.6
16.6
15.3
714.3
1462.5
745.1
Sm
Dy
Er
played
by
the
lanthanide
metal
Ln
in
(CH2ꢀCHCH2CH2C5H4)2LnꢁCl·2THF, Ln=Sm, Y,
Dy, Er), polymerization was carried out with the four
different complexes each having one of the lanthanide
metals as the central atom.
1037.8
Polymerization condition: MMA/cat=2000 (molar ratio); Al/cat=
10; 60 °C; 15 h.
Three different aluminum-based cocatalysts were
used: methyl aluminoxane (MAO), AlEt3 and Al(i-
Bu)3. The best catalytic efficiency of 45% with respect
to the conversion of monomer to PMMA and the
molecular weight of polymer was obtained with Al(i-
Bu)3 cocatalyst. Very low conversion of 1.2 and 10.3%
was observed for MAO and AlEt3, respectively, under
similar conditions. For the Al(i-Bu)3 cocatalyst the
efficiency increases as the Al/catalyst (Al/cat) molar
ratio increases up to a value of 10 and then declines
with a further increase in the Al ratio probably due to
over alkylation or decomposition of the catalyst. There-
fore, we realized that the Al/cat molar ratio of 10
utilizing Al(i-Bu)3 as the cocatalyst is the optimum
requirement for polymerization. The higher efficiency
of Al(i-Bu)3 as a cocatalyst in this system may be
attributed to steric factors, since the cocatalysts are
electronically similar. The large iso-butyl ligand may be
responsible for imparting the desired orientation and
stability to active species required for the initiation and
propagation of polymerization. A similar observation
was reported for a Ziegler–Natta three-component cat-
alyst system [19]. As the result in Table 3 (blank test)
indicates, aluminum enolates from the cocatalyst are
Table 2
Effect of cocatalysts on the polymerization of MMA catalyzed by
(CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF
Run Cocatalyst
Al/cat (molar Conversion
Mp (×10−3
)
ratio)
(%)
B9
MAO
10
10
2
1.2
10.3
2.6
248.8
4.0
B10 AlEt3
B5
B6
B4
B7
B8
Al(i-Bu)3
1651.5
1583.2
1462.5
1233.0
218.9
Al(i-Bu)3
Al(i-Bu)3
Al(i-Bu)3
Al(i-Bu)3
5
2.9
10
15
20
44.6
25.6
17.9
B27 None
Trace (ꢀ0.27)
Polymerization condition: MMA/cat=2000; 60 °C; 15 h; bulk.
the functional groups of the side-chains remain free and
uncoordinated. It is noteworthy that Okuda and Zim-
merman [18] succeeded under severe conditions (Na/
Hg) in inducing the intramolecular coordination of the
CꢀC double bond to the Co central metal yielding a
relatively stable chelate complex.
Table 3
Polymerization characterization of MMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF
Run
MMA/cat (molar ratio)
Temperature (°C)
Time (h)
Conversion (%)
Mp (×10−3
)
B1
B2
B3
B4
B26
B15
B16
B17
B4
B18
B19
B25
B4
500
60
60
60
60
60
0
20
40
60
80
60
60
60
60
60
60
15
15
15
15
15
15
15
15
15
15
5
10
15
20
30
20
63.3
57.4
46.4
44.6
14.2
1.7
22.9
240.7
937.9
1462.5
1257.4
13.8
1000
1500
2000
3000
2000
2000
2000
2000
2000
2000
2000
2000
2000
2000
Al(i-Bu)3
1.9
5.6
34.5
862.1
1462.5
1599.3
99.7
1102.7
1462.5
1571.3
1653.2
14.0
44.6
58.3
2.1
10.3
44.6
55.7
70.1
33.14
B20
B21
Blank a
Polymerization condition: Al(i-Bu)3/cat=10.
a Blank (no catalyst added).

108
M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
Fig. 1. Effect of MMA/catalyst molar ratio on the polymerization of MMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF.
recorded for living polymerizations using other rare-
earth catalyst systems [21,22].
involved as propagating species. However, the en-
hanced efficiency and syndiospecificity of the
polyMMA obtained accounts for the role of the Ln
complexes. We believe that the propagation stage in-
volves the Al enolate generated and coordinated by the
Ln complex.
Having established the most appropriate catalyst/co-
catalyst system for the polymerization, the effects of
varying the different experimental conditions was
studied.
The efficiency of each system is derived from the
percentage of monomer converted to PMMA and the
Mp of the polymer obtained. The observed order of
activity Sm\Y\Dy\Er is in line with the order of
ionic radii, as it has been noted that larger lanthanide
metals exhibit better catalytic properties [20]. On this
basis, we selected the samarium complex for further
studies.
Keeping the Al–Sm ratio constant, at 10:1, the
MMA/catalyst (MMA/cat) molar ratio was varied from
500 to 3000, the polymerization temperature was also
varied from 0 to 80 °C and the time of polymerization
was varied from 5 to 30 h. The general result is
presented in Table 3.
The high molecular weight polymer obtained (Mp\
106) even at low to moderate monomer conversion may
be attributed to the autoacceleration which has been
established to occur for bulk polymerization of MMA
arising from the high viscosity towards the end of the
polymerization [23].
Fig. 2 (runs B15, B16, B17, B4 and B18) presents the
effect of variation in polymerization temperature. Cata-
lyst efficiency increases directly with an increase in
temperature. As the temperature increases both the
percentage monomer conversion and the polymer
molecular weight increases. This indicates that even for
long hours, the high-temperature environment does not
hinder the catalyst efficiency. This is in contrast to our
observation on the polymerization of MMA activated
by pendant allyl–Cp lanthanide complexes [24]. This
observation is also rather different from the characteris-
tics of most rare-earth coordination polymerization,
where the activity and syndiospecificity of the catalyst
fall, as the temperature is raised [25]. In the allyl
system, we observed a sharp decrease in molecular
weight as the temperature rises, which may be due to
the deactivation of the (single component) catalyst,
arising from thermally activated side reactions. These
side reactions may be the intra-molecular coordination
of the allyl-functional groups to the central metal or
dimerization of the catalyst via the functional group or
both, leading to the inhibition of catalyst efficiency.
Neither seems to be happening in the present (dual
The effect of variation in MMA/cat molar ratio is
presented in Fig. 1 (runs B1, B2, B3, B4 and B26). The
clear trend from the plot is that as the amount of
monomer increases (i.e. decrease in initiator concentra-
tion) the molecular weight of the polymer obtained also
increase accordingly while the percentage of monomer
conversion decreases. A similar relationship has been

M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
109
component) system. It is, therefore, clear that the cocat-
alyst plays a stabilizing and important role of maintain-
ing the integrity of the catalyst and availability of active
species even under unfavorably drastic conditions.
The result of the investigation into the effect of
variation in time on the polymerization is presented in
Fig. 3 (runs B19, B25, B4, B20 and B21). Within the 30
h range used for the polymerization, the catalyst effi-
ciency increases with an increase in time. The slope of the
curve for percentage monomer conversion is much lower
than that for polymer molecular weight, which exhibits
a steep initial slope, later normalizing after about 15 h.
This shows a slow initiation rate system accompanied by
a long lifetime growing end and slow termination rate.
Fig. 2. Effect of temperature on the polymerization of MMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF.
Fig. 3. Effect of polymerization time on PMMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF.

110
M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
Table 4
Figs. 4 and 5. Fig. 4 representing polymerization at
80 °C is unimodal in nature indicating the presence of
only a single active propagation site in the system,
while Fig. 5 for polymerization at 60 °C is bimodal
indicating the production of heterogeneous products,
with the first peak comprising high molecular weight
fraction and the second peak comprising basically low
molecular weight fractions. The molecular weight distri-
bution (ca. 3.0) is much better than what has been
reported for similar multi-component lanthanide metal
coordinated MMA polymerization [19]. It is also clear
from Fig. 5 and from an earlier discussion, that poly-
merization at much lower temperatures will yield poly-
mers with improved molecular weight distribution
although this will give predominantly low molecular
weight fractions.
Effect of solvent on polymerization catalyzed by (CH2ꢀCHCH2CH2-
C5H4)2SmꢁCl·2THF
Run
Solvent
Conversion (%)
Mp (×10−3
)
B11
B12
B14
B13
Toluene
Petroleum ether
CH2Cl2
6.4
2.9
6.0
4.3
1154.4
824.4
671.0
786.6
THF
Polymerization condition: MMA/catalyst=2000; Al(i-Bu)/cat=10;
60 °C; 15 h; solvent–MMA=1:1 (volume).
The effect of different solvents on the polymerization
was studied and the result is presented in Table 4.
Generally a very low percentage of monomer was
converted, although high molecular weight polymers
were obtained. The possibility that the solvents em-
ployed introduced traces of impurities that served as
transfer agents cannot be ruled out. These will nega-
tively affect the efficiency of the catalyst. Coordination
of solvent molecules to the central metal may also
contribute to the observed differences in activity.
The molecular weight distribution Mw/Mn, of poly-
mers produced under different polymerization condi-
tions was recorded and the GPC plots are presented in
The tacticity of PMMA produced under different
1
reaction conditions have been determined by the H-
NMR spectroscopy of the polymers in CDCl3. The
result is presented in Fig. 6(a)–(c) and summarized in
Table 5.
In line with the established procedure, the tacticity of
PMMA prepared under different conditions was esti-
mated from these 500 MHz 1H-NMR spectra (Me
Fig. 4. GPC plot for the polymerization of MMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF. Mn=119 652; Mw=336 147; Mp=
229 016; Mz=670 537; Mz+1=994 794; Mw/Mn=2.81. Polymerization condition: MMA/cat=2000; Al(i-Bu)3/cat=10; 80 °C; 15 h.
Fig. 5. GPC plot for polymerization of MMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF. First peak: Mn=188 543; Mw=586 828;
Mp=699 191; Mz=970 089; Mz+1=1 290 058; Mw/Mn=3.11. Second peak: Mn=2523; Mw=3765; Mp=2524; Mz=5703; Mz+1=7852;
Mw/Mn=1.45. Polymerization condition: MMA/cat=2000; Al(i-Bu)3/cat=10; 60 °C; 15 h.

M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
111
Fig. 6. (a) 1H-NMR plot for PMMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF, run B18. (b) 1H-NMR plot for PMMA catalyzed by
(CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF, run B21. (c) 1H-NMR plot for PMMA catalyzed by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF, run B4.
Table 5
Tacticity of MMA polymerized by (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF
Run
Fig. 6
Temperature (°C)
Time (h)
Conversion (%)
Mp (×10−3
)
Tacticity (%)
rr
mr
mm
B18
B21
B4
a
b
c
80
60
60
15
30
15
58.3
70.1
63.3
1599.3
1653.2
22.9
58
62
62
37
34
34
5
4
4
Polymerization conditions: MMA/catalyst (molar ratio)=2000; Al(i-Bu)3/cat=10.

112
M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
peak; mm 1.17, mr 0.98, rr 0.78 ppm) [26–28]. The
results indicate that the present catalyst system gives
predominantly syndiotactic polymers.
The fact that syndiotacticity is not much affected by
temperature or time changes is noteworthy. Even at
80 °C after about 15 h of polymerization, the syndio-
tacticity is still 58%. Improvement in syndioselectivity
of the catalyst at lower temperature is in line with the
observed trend for lanthanide-catalyzed polymerization
of MMA [29].
3.2. Preparation of ligand: butenyl-cyclopentadienyl
potassium
The starting material 3-but-1-enol was first synthe-
sized via the Grignard process according to the litera-
ture procedure [31] (Scheme 1, steps 1–3). Into a dry
500 ml three-necked flask was transferred 300 ml of
ether, followed by 0.5 mol (95 g) of TsꢁCl and 0.5 mol
(28 g) 3-buten-1-ol in succession (step 4). The mixture
was stirred for 5 min giving a solution. An ice bath was
placed beneath the flask and 15 g of powdered KOH
were added slowly, and stirred continuously at r.t. for
another 3 h. The 3-butenyl tosylate was separated by
Buckner filtration as the filtrate in a 99% yield after
removing all the volatiles in vacuo.
3. Experimental
All operations involving the handling of air sensitive
materials were carried out under dry Ar using standard
Schlenk techniques. Tetrahydrofuran (THF), Et2O, tol-
uene and n-hexane were freshly distilled from sodium
benzophenone ketyl under Ar prior to use. MMA was
washed with dilute NaOH solution until colorless, dried
over anhydrous CaCl2, and vacuum distilled into ice-
cooled container containing CaH2.
Anhydrous lanthanide trichlorides were prepared ac-
cording to the procedure outlined in the literature [30].
Allyl chloride was dried over CaSO4 and distilled prior
to use collecting the middle fraction. a-Toluene sulfonyl
chloride(TsꢁCl, C6H5CH2SO2Cl) was recrystallized
from petroleum ether. Magnesium powder was washed
with ether to remove surface oxide coating and baked
in vacuo. Paraformaldehyde was dried over P2O5 in a
dessicator for 2 days in vacuo. NaCp was prepared by
the usual method. Into a dry ice–acetone cooled three-
necked flask, freshly cracked CpH was slowly dropped
on to a slightly excess molar quantity of Na wire in
THF, and stirred until no further sign of activity on the
surface of the Na.
NaCp (0.5 mol) was transferred to a pre-dried and
Ar-full 500 ml three-necked flask with one arm of the
flask fitted with an overpressure oil bubbler. On the
middle arm of the flask was a mechanical stirrer set at
a moderate speed. The flask was cooled using dry
ice–acetone at −30 °C and the allyl tosylate was
slowly dropped from the third arm. Stirring was contin-
ued for additional 3 h. The white cake-like solution was
hydrolyzed with 100 ml of ice cold water containing 5%
HCl. The aqueous layer was washed with two portions
of 30 ml ether. The combined organic portion was dried
over MgSO4 and distilled under reduced pressure, giv-
ing the product in 42% yield at 37–42 °C, 10 mmHg
(step 5). The colorless product was reacted with an
excess amount of potassium chips in THF at −20 °C
to give the reddish colored ligand 3-butenylcyclopenta-
dienyl potassium (step 6). The general synthetic route is
presented in Scheme 1.
3.3. Synthesis of complex: (CH2ꢀCHCH2CH2-
C5H4)2LnꢁCl·2THF. Ln=Sm, Y, Dy, Er
All the four complexes were synthesized via the same
route. Typical is the samarium complex. To pre-dried
100 ml Schlenk tube 0.95g (3.7 mmol) of SmCl3 was
transferred, followed by 30 ml of THF. After stirring
for 5 min, two molar equivalent of the ligand (7.4
mmol) 3-butenylcyclopentadienyl potassium in THF
was transferred by hypodermic syringe, degassed and
sealed. After stirring overnight at r.t., the reaction
mixture was centrifuged. The whitish KCl precipitate
was washed with THF and the combined orange solu-
tion was concentrated in vacuo. The crude oily product
was extracted once with Et2O and twice with n-hexane.
Removal of volatiles in vacuo gave clear mobile orange
oil in 57% yield. The complexes prepared were analyzed
by EA, MS and IR. Analytical data are presented
below.
3.1. Characterization
The 1H-NMR spectra were recorded in a Bruker
AVANCHE500 500 MHz NMR spectrometer at room
temperature (r.t.) in CDCl3. Inherent viscosity of
PMMA in CHCl3 was determined at 30 °C with an
Ubbelohde-type viscometer. Viscosity average molecu-
lar weight was calculated as [p]=5.5×10−3 M0p.79
(cm3 g−1) (where Mp=viscosity average molecular
weight). Molecular weight distribution (Mw/Mn) values
were obtained from Waters-208 LC/GPC chro-
matograms employing polystyrene standards for cali-
bration. Mass spectra were obtained on a HP5989A
mass spectrometer with EI (70 eV). Infrared spectra
were recorded on a Nicolet Magna-IR 550 spectrometer
as KBr pellets or Nujol mulls. Element analysis was
performed by the analytical laboratory at the Shanghai
Institute of Organic Chemistry.
3.3.1. (CH2ꢀCHCH2CH2C5H4)2SmꢁCl·2THF (3a)
Orange oil. Yield: 57%. Anal. Calc. for C26H38-
SmO2Cl: C, 54.93; H, 6.75. Found: C, 54.77; H, 6.23%.

M.D. Bala et al. / Journal of Organometallic Chemistry 647 (2002) 105–113
113
IR (cm−1): 3920w, 3420s, 3080s, 2950s, 2920s, 2850s,
1980w, 1820w, 1730m, 1660s, 1637s, 1600s, 1500m,
1430m, 1410m, 1370m, 1320m, 1300m, 1250m, 1200m,
1165m, 1150m, 1130m, 1060m, 1045m, 1030m,
1000s, 950m, 905s, 850m, 820m, 770s, 710m, 570s. MS;
m/z (fragment, relative intensity): 425 [M−2THF, 1],
390 [M−2THF−Cl, 16], 306 [CH2ꢀCHCH2CH2-
C5H4SmCl, 6], 120 [CH2ꢀCHCH2CH2C5H5, 31], 71
[THF−1, 1], 65 [Cp−, 6].
a water bath with occasional shaking for a certain
period. After polymerization, the ampoule was opened
and EtOH containing 5% HCl was introduced to termi-
nate the reaction and precipitate the polymer.
Acknowledgements
This project was supported by the special funds for
Major State Basic Research Projects (G1999064801),
National Natural Science Foundation of China
(20072004 and 29871010).
3.3.2. (CH2ꢀCHCH2CH2C5H4)2YꢁCl·2THF (3b)
Light brown oil. Yield: 58%. Anal. Calc. For
C26H38YO2Cl: C, 61.59; H, 7.57. Found: C, 61.70; H,
7.30%. IR (cm−1): 3920w, 3420s, 3080s, 2920s, 2850s,
2750w, 1820w, 1715m, 1660s, 1637s, 1600s, 1500w,
1440m, 1460m, 1410m, 1360m, 1330w 1300w, 1260m,
1200w, 1165w, 1060s, 1045s, 1000s, 905s, 850m, 770s,
680s, 520m. MS; m/z (fragment, relative intensity): 366
[M−2THF+4, 2], 243 [CH2ꢀCHCH2CH2C5H4YCl,
2], 120 [CH2ꢀCHCH2CH2C5H5, 22], 71 [THF−1, 7], 65
[Cp−, 18].
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