Highly syndioselective 3,4- trans polymerization of (E)-1-(4-Methylphenyl)-1,3-butadiene by fluorenyl N -heterocyclic carbene ligated lutetium bis(alkyl) Precursor

Article abstract of DOI:10.1021/acs.macromol.5b00226

(E)-1-(4-Methylphenyl)-1,3-butadiene (E-1-MPBD) synthesized via the Wittig-type reaction was polymerized with the ternary catalytic system (Flu-NHC)Lu(CH₂SiMe₃)₂/AlⁱBu₃/[Ph₃C][B(C₆F₅)₄] (Flu-NHC = C₁₃H₈CH₂CH₂(NCHCHN(C₆H₂Me₃-2,4,6)C) to afford a new product containing exclusively trans-3,4 (>99%) units with perfect syndiotacticity (rrrr > 99%). The regio-3,4 tacticity was proved by the IR and NMR (¹H and ¹³C) spectroscopic analyses, while the 3,4-stereotacticity was confirmed by a model polymer with lower regularity (3,4 = 90.9%, rrrr = 49.3%) prepared by the binary catalytic system (Am-NHC)Lu(CH₂SiMe₃)₂/[Ph₃C][B(C₆F₅)₄] (Am-NHC = 2,6-ⁱPrC₆H₃N→C(C₆H₅)NCH₂CH₂(NCHCHN(C₆H₂Me₃-2,4,6)C). The trans-planar conformation was uncovered through 2D-NOESY and ¹³C CPMAS NMR technologies. This represents the first stereo 3,4-syndioselective polymerization of 1,3-dienes achieved by a rare-earth metal based catalyst. Moreover, hydrogenating the resulting polymer gave the highly syndiotactic poly(4-methylphenyl-1-butene), which cannot be achieved by any other manner at the present stage.

Full text of DOI:10.1021/acs.macromol.5b00226

Article
pubs.acs.org/Macromolecules
Highly Syndioselective 3,4-Trans Polymerization of (E)‑1-(4-
Methylphenyl)-1,3-butadiene by Fluorenyl N‑Heterocyclic Carbene
Ligated Lutetium Bis(alkyl) Precursor
Changguang Yao,†,‡ Fei Lin,†,‡ Meiyan Wang,§ Dongtao Liu,† Bo Liu,† Na Liu,†,‡ Zichuan Wang,†,‡
Shiyu Long,†,‡ Chunji Wu,*,† and Dongmei Cui*,†
†State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun 130022, People’s Republic of China
‡University of the Chinese Academy of Sciences, Changchun Branch, Changchun 130022, People’s Republic of China
§Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun
130022, People’s Republic of China
S
* Supporting Information
ABSTRACT: (E)-1-(4-Methylphenyl)-1,3-butadiene (E-1-MPBD) synthe-
sized via the “Wittig-type” reaction was polymerized with the ternary
catalytic system (Flu-NHC)Lu(CH2SiMe3)2/AliBu3/[Ph3C][B(C6F5)4]
(Flu-NHC = C13H8CH2CH2(NCHCHN(C6H2Me3-2,4,6)C) to afford a
new product containing exclusively trans-3,4 (>99%) units with perfect
syndiotacticity (rrrr > 99%). The regio-3,4 tacticity was proved by the IR
and NMR (1H and 13C) spectroscopic analyses, while the 3,4-stereotacticity
was confirmed by a model polymer with lower regularity (3,4 = 90.9%, rrrr =
49.3%) prepared by the binary catalytic system (Am-NHC)Lu-
(CH2SiMe3)2/[Ph3C][B(C6F5)4] (Am-NHC = 2,6-iPrC6H3NC(C6H5)-
NCH2CH2(NCHCHN(C6H2Me3-2,4,6)C). The trans-planar conformation
was uncovered through 2D-NOESY and 13C CPMAS NMR technologies.
This represents the first stereo 3,4-syndioselective polymerization of 1,3-
dienes achieved by a rare-earth metal based catalyst. Moreover, hydrogenating the resulting polymer gave the highly syndiotactic
poly(4-methylphenyl-1-butene), which cannot be achieved by any other manner at the present stage.
monomers) are anticipated to generate more diverse micro-
structured polymers; for instance, 1-MPBD can be polymerized
theoretically into 10 kinds of stereoregular polymers (Chart 1)
that are easier to be postfunctionalized. To date, 1-PB has been
widely studied in cationic and anionic polymerization
mechanisms for the past 50 years.7 Masuda7a and Asami7b
demonstrated that 1-PB could be polymerized via cationic
catalysts such as stannic chloride, tungsten hexachloride, and
triphenylmethylstannic pentachloride to afford P(1-PB) with
more than 97% 3,4-units, whereas about half of the dangling
double bonds were intramolecularly cyclized during the
polymerization. Asami et al.7c reported that the anionic
polymerization of l-PB provided 95% trans-1,4 configuration.
The only coordination polymerization of 1-PB was achieved by
Longo et al.8 with the Ni(acac)2/MAO or CpTiCl3/MAO
system to give a 84% or 76% 3,4-selective polymer, respectively.
In contrast, the polymerization of 1-MPBD possessing the
similar reactivity to 1-PB has remained unexplored. Therefore,
investigation of efficient coordination catalytic systems
INTRODUCTION
■
Polymers are one of the most intriguing materials of our
modern world, able to assume a near-infinite variety of shapes
and properties, which have permeated almost every aspect of
our lives. The versatile properties and wide applications of
polymer materials are closely related to the variable micro-
structures, the composition, and its distribution along the
macromolecular chains, of which the tacticity is arguably the
most critical one,1 and how to control it has been a fascinating
and challenging subject of polymer chemistry for decades.
Polydienes as one subcategory of polyolefins exhibit more
isomeric structures than poly-α-olefins because they involve
more complicated regio- and stereotacticity,2 having striking
property discriminations. For example, cis-1,4-polyisoprene
(PIP) is one of the most important rubbers,3 trans-1,4-PIP is
a plastics possessing shape memory function,4 and 3,4-PIP is a
very important component of high-performance rubbers
because of its excellent wet-skid resistance and low rolling
resistance,5 and so on, while 1,2-polybutadienes with the
stereoisotacticity or syndiotacticity can be used to prepare high-
value-added fiber or long-life “green” tires.6 Therefore, the
substituted diene derivatives such as 1-phenyl-1,3-butadiene (1-
PB) and 1-(4-methylphenyl)-1,3-butadiene (1-MPBD, E and Z
Received: February 2, 2015
Revised: March 10, 2015
Published: March 26, 2015
© 2015 American Chemical Society
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methylphenyl-1-butene), a new type of polyolefin that cannot
be obtained in any other manner, is also provided. The details
of characterizing the microstructures and properties of these
new polymers are discussed.
Chart 1. Possible Stereoregular Polymers Obtainable from 1-
MPBD
RESULTS AND DISCUSSION
■
The Wittig reaction of phosphorus ylide and trans-4-
methylcinnamaldehyde afforded (E)-1-MPBD in a high yield
(89%) evidenced by giving the resonances at δ 5.18, 5.35, and
6.54 ppm assignable to the vinyl protons (the 1H NMR
spectrum, see Figure S1). (E)-1-MPBD was polymerized by the
ternary catalytic system Flu-NHC-Lu/[Ph3C][B(C6F5)4]/
AliBu3, and the representative polymerization data are
summarized in Table 1. The monomer conversion increased
when the polymerization temperature changed from 25 °C
(53.5%) to 50 °C (94.8%) but dropped slightly upon further
elevating the temperature to 80 °C, probably due to the catalyst
deactivation at high temperatures. Fixing the polymerization
temperature at 50 °C, increasing gradually the monomer
loading with the monomer-to-Lu ratio varying from 100:1 to
600:1 aroused the increase of the monomer conversion,
suggesting the catalytic activity proportional to the monomer
concentration. The activity of the present system was slightly
lower than that recorded for the 3,4-isoprene polymerization
with this or other catalyst systems,5,12 which is in agreement
with the steric bulkiness of the monomer 1-MPBD. Meanwhile
the molecular weight of the resulting polymers showed almost
linear correlation with the monomer-to-Lu ratio, and the
molecular weight distribution was nearly constant, indicative of
the single-sited catalytic system and the controllable polymer-
ization fashion.
As polymerization of conjugated dienes involves the issue of
regio- and stereoselectivities, thorough characterization of the
microstructure of the resultant new product poly(1-MPBD)
was mediated by IR and NMR spectroscopy measurements.
The resonances at δ 6.50 and 6.05 ppm are attributed to the
typical dangling olefinic protons CHCH arising from the 3,4-
units (Figure 1). The multiple signal at δ 2.70 and the triplet at
1.68 ppm (3JH−H = 6.0 Hz) are assigned to the methine and
methylene protons CH2−CH in polymer main chains,
respectively. No internal olefinic or aliphatic proton resonances
of 1,4-units at δ 5.11, 5.30 ppm and δ 3.05, 3.39 ppm are found,
indicating an over 99% 3,4-regioselectivity. In particular, the
integral intensity ratio of the resonances for the phenyl, olefinic,
and aliphatic protons is 4:2:3, meaning the absence of the
cyclization, etc., side reactions in the polymerization process.
The dangling double bonds can take trans- or cis- configuration.
The olefin proton H1 shows up as a doublet with a coupling
providing regio- and stereoselectivity for the polymerization of
1-PB or 1-MPBD to afford polymers with designated
microstructure, and absence of cyclization is an important
research topic because the resultant stereoregular polydiene
derivatives not only have different properties from their
polydiene congeners but also can be hydrogenated across the
double bonds to give various polyolefins such as poly(4-phenyl-
1-butene) and alternating styrene−ethylene (S−E) copolymer,
which cannot be obtained easily via other manners.9
Rare-earth metal complexes bearing cyclopentadienyl de-
rivatives or noncyclopentadienyl ligands have achieved an
upsurge in research interests, based on which the highly cis-
1,4,3,10 trans-1,4,4,11 and 3,4-/1,2-5,12 regio- and stereo-
isoselective polymerizations of butadiene/isoprene have been
realized; however, the highly stereo-syndioselective 3,4-/1,2-
polymerization has still remained an academic challenge for the
rare-earth metal catalysts because the syndioselectivity needs a
more sterically encumbered environment than the isoselectivity
for the active metal centers, which is obviously difficult for the
large rare-earth metal ions, and on the other hand, a steric bulky
metal center takes a risk of losing activity. To date, the known
catalysts for the highly 3,4-/1,2-syndioselective polymerizations
of 1,3-dienes are all based on the small central metals such as
Fe, Co, and Cr to meet the specific steric and electronic
demanding of the cis-η4-coordination mode/C3 insertion of the
monomers to the metal active species.13 Herein we report the
polymerization of (E)-1-MPBD with the cationic fluorenyl-
modified N-heterocyclic carbene supported lutetium alkyl
catalyst realizes for the first time the highly syndiotactic 3,4-
trans triple selectivities. In addition, the hydrogenation of the
isolated polymer to afford the highly syndiotactic poly(4-
a
Table 1. Polymerization of (E)-1-MPBD with Flu-NHC-Lu/[Ph3C][B(C6F5)4]/AliBu3
b
b
c
c
entry
[(E)-1-MPBD]/[Lu]
temp (°C)
yield (%)
3,4- (%)
rrrr (%)
Mn × 10−4
Mw/Mn
1
2
3
4
5
6
200
200
200
100
400
600
200
25
50
80
50
50
50
50
53.5
94.8
72.4
65.6
>99
>99
99.0
97.1
98.8
98.5
98.6
90.9
>99
>99
>99
>99
>99
96.0
49.3
2.1
3.5
2.4
1.3
7.6
9.7
3.9
1.6
1.8
2.1
1.7
1.9
1.9
1.5
>99
d
7
52.1
a
b
1
Conditions: Lu 10 μmol, [Ph3C][B(C6F5)4] 10 μmol, AliBu3 100 μmol, toluene 3 mL, time 12 h. Determined by H NMR and 13C NMR
c
d
spectroscopy in CDCl3. Determined by GPC in THF at 40 °C against polystyrene standard. (Am-NHC)Lu(CH2SiMe3)2/[Ph3C][B(C6F5)4] as
catalyst.
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1
Figure 1. H NMR (120 °C, o-C6D4Cl2) spectrum of poly(1-MPBD) (Table 1, entry 2).
Figure 2. 13C NMR (25 °C, CDCl3) spectra of poly(1-MPBD)s with Am-NHC-Lu (B) (Table 1, entry 7) and Flu-NHC-Lu (A) (Table 1, entry 2).
constant of JCHCH = 15.7 Hz6c,14 relating to the trans
configuration, in agreement with the strong absorption band at
965 cm−1 arising from the out-of-plane vibration of the trans-
olefinic C−H bond in the IR spectrum (Figure S6).7c,d Note
that the methylene protons display as a false triplet, meaning
that the two protons set in the similar magnetic environment;
thus, poly(1-MPBD) has the syndiotactic microstructure.15
Correspondingly, all the olefinic carbons C2 and C1 and the
methylene carbon C4 show strong and sharp singlets (13C
NMR spectrum, see Figure S7). These results were consistent
with the identification of the syndiotactic polystyrene,16
poly(methyl methacrylate),17 1,2-polybutadiene,18 and 1,2-
polypentadiene,2,14 and the syndiotactically enriched (rr =
50%) polyisoprene prepared by this catalytic system.12a
To obtain a solid proof, a model sample with high 3,4-
tacticity (90.9%) and low stereoregularity (rrrr = 49.3%) was
synthesized by the polymerization of (E)-1-MPBD using the
binary catalytic system (Am-NHC)Lu(CH2SiMe3)2/[Ph3C][B-
3
(C6F5)4] (Table 1, entry 7).12c For comparison the H NMR
1
spectra of two poly(1-MPBD)s obtained using the two different
catalytic systems were combined in Figure S8. All the peaks of
the stereoregular poly(1-MPBD) isolated from catalytic system
Flu-NHC-Lu (Figure S8A) are sharp and clear while those from
the less stereotactic poly(1-MPBD) obtained from the Am-
NHC-Lu system are broad and more complicated (Figure
S8B). In addition, the signals of the methylene protons from
the former appear upfield at δ 1.22 ppm than that in the latter,
in accordance with the racemo configuration.16 The 13C NMR
spectrum of the stereotactic poly(1-MPBD) gives three sharp
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Figure 3. 2D-NOESY (25 °C, CDCl3) spectrum of poly(1-MPBD).
Scheme 1. Probable Mechanistic Pathway for Polymerization of (E)-1-MPBD
singlets at δ 134.41, 130.20, and 41.79 ppm assignable to the
racemic pentad rrrr for C2, C1, and C4, respectively (Figure 2A).
For the less stereotactic poly(1-MPBD), besides the racemic
pentad rrrr resonances, there are also minor peaks at δ 134.50,
129.86, and 40.71 ppm attributed to the stereo errors of pentad
mmrr (about 34.5%) and δ 134.21, 130.26, and 42.39 ppm of
the pentad mrrr (about 16.2%) (Figure 2B).2,19 Nevertheless,
all of these peaks are not found at the same positions in Figure
2A, further attesting poly(1-MPBD) obtained with the catalytic
system Flu-NHC-Lu is highly syndiotactic (rrrr > 99%).
Conformation Analysis of Poly(1-MPBD). The con-
formation of poly(1-MPBD) was investigated by using 2D-
NOESY (two-dimensional nuclear Overhauser effect spectros-
copy) equipment to measure the distance-dependent NOE
effect between protons separated by less than 5 Å: the longer
the distance between the protons, the weaker the interaction.20
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Figure 4. 13C NMR (120 °C, o-C6D4Cl2) spectrum of poly(4-MPBT).
As shown in Figure 3, the cross-peaks at positions 1 and 2
derived from protons H1 and H2 are weak, indicating a large
spatial distance between them, alternatively, taking the trans-
configuration. Protons H2 and H5 exhibit a weak cross-peak at
position 3 probably owing to the rotation of the phenyl group
disturbing the conjugation between the vinyl group and the
phenyl ring. In particular, a strong cross-peak is observed at
position 5, suggesting the group H2−C2−C3−C4−H4 is
confined to the planar zigzag conformation. The similar two
strong cross-peaks at positions 4 and 6 means the C3−H3 bond
adopting a gauche conformation to both the C2−H2 bond and
the C1C2 double bond. Both methylene C4 and methine C3
show as singlets (δ 41.96 ppm vs 39.63 ppm) in the 13C
CPMAS (cross-polarization and magic-angle spinning, Figure
S9) NMR spectrum, meaning each represents a type of
chemically equivalent carbon. In particular, the one signal for
the methylene C4 carbons may be arising from the tttt
sequences, suggesting they are always trans to the methine C3
carbons in the γ-position.
The new polymer has a Tg of 90.6 °C close to that of
polystyrene (Figure S10), probably possessing similar insu-
lation and mechanical properties. Scanning the temperature
range from 25 to 300 °C, no melting point was found,
indicative of the amorphous morphology, which might be
attributed to the dangling double bonds and the bulky
substituents destroying the crystallinity of the macromolecular
chains as displayed by the X-ray diffraction analysis (Figure
S11).
species on the coordinating monomer forms the Lu−η3-allyl
intermediate. The following insertion of the coordinating
monomer into the Lu−η3-allyl moiety via C4 → C1 or C4 → C3
pathway gives correspondingly 1,4-unit or 3,4-unit, depending
on the electronics and sterics of the monomer. The presence of
a large substituent 4-MePh at C1 and its electron-donating
property to C3 facilitate the latter one, leading to the 3,4-
sequence. Nonetheless, if providing enough energy, the
monomer can also take the cis-η4 coordination, and the
reaction occurs partially via C4 → C1. This was proved by the
fact that performing the polymerization at elevated temperature
such as 80 °C, the cis-1,4 content increased to 2.9% (Table 1,
entry 3). Meanwhile, owing to the restriction of the bulky CGC
ligand, the monomer alternatively takes si-face and re-face with
respect to the active metal center; therefore, the newly
generated butenyl chain end adopts the opposite chirality to
the penultimate one (Scheme 1, intermediates A and B),
resulting in the 3,4-syndiotacticity. Changing the substituent at
C1 gradually to smaller groups from Ph, and Me to H, the cis-
1,4-unit in the products increases from 5.6% and 17.5% to
30.5% (Table S1), since the less encumbered monomer has
more chance of taking cis-η4 coordination mode, and the
reactivity at C1 also increases. Overall, both the sterics and
electronics of the ligand and the monomer are responsible for
determining the stereochemistry of the polymer formed.
Hydrogenation of Poly(1-MPBD). Hydrogenation was
carried out with p-toluenesulfonyl hydrazide (TSH) in refluxing
p-xylene according to the literature.9 The 1H NMR spectrum of
the hydrogenated polymer poly(4-MPBT) shows that the
signals arising from the olefinic protons at δ 6.50 and 6.05 ppm
disappear completely, and the resonances at δ 2.53 and 1.34
ppm are assignable to the newly generated saturate ethylene
group (Figure S12), suggesting the hydrogenation was
successful. The 13C NMR spectrum (Figure 4) displays sharp
singlets for all carbons, indicating the hydrogenated polymer
still has a high tacticity. Comparing with the 13C NMR
spectrum (Figure S13) of the isotactic enriched poly(4-PBT)
Probable Mechanism. The coordination of 1,3-conjugated
diene monomers to the transition metal (Mt) active species
adopts usually cis- and trans-η4 and cis- and trans-η2, etc., eight
modes. For the simple dienes such as butadiene, isoprene and
(E)-pentadiene, the cis-η4 coordination is the energetically most
favored. Monomer (E)-1-MPBD in this work adopts the trans-
η2 coordination because of the bulky para-methyl phenyl
substituent at C1.8 The probable mechanistic pathway is
depicted as Scheme 1. The anionic attack of the Lu−alkyl active
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prepared by rac-Me2Si(2-MeBenz[e]Ind)2ZrCl2/MAO,21 we
found that the resonances of C2 and C3 at δ 35.32 and 31.64
ppm in poly(1-MPBD) shift upfield than those in poly(4-PBT),
in correlation with the syndiotacticity.1 This result demon-
strated further poly(1-MPBD) had a high syndiotacticity that
was not changed by hydrogenation.9
instrument. Differential scanning calorimetry (DSC) analyses were
carried out on a Q 100 DSC from TA Instruments under a nitrogen
atmosphere. Wide-angle X-ray diffraction (WAXD) measurements
were performed using a Rigaku D/Max 2500 V PC X-ray
diffractometer (Cu Kα, λ = 1.5406 Å).
Synthesis of (E)-1-(4-Methypenyl)-1,3-butadiene. Under a
nitrogen atmosphere, 75 mL of n-butyllithium (1.6 M in hexane, 0.12
mol) was added dropwise to a suspension of methyltriphenylphos-
phonium bromide (42.87 g, 0.12 mol) in 500 mL of dry THF within
30 min at −20 °C. After the mixture was stirred for 30 min, 100 mL of
THF solution of 4-methylcinnamaldehyde (14.62 g, 0.10 mol) was
added dropwise to the solution within 60 min. The mixture was stirred
for another 2 h at −20 °C and then warmed to room temperature
slowly and kept stirring overnight. After the mixture was poured into
500 mL of water and the organic phase was separated, the aqueous
phase was extracted three times with diethyl ether (3 × 100 mL). The
combined organic phase were washed with brine, dried over MgSO4,
filtered, and concentrated in vacuo. Flash chromatography (20% Et2O/
CONCLUSIONS
■
We have demonstrated the highly syndiospecific 3,4-trans
selective polymerization of (E)-1-(4-methylphenyl)-1,3-buta-
diene ((E)-1-MPBD) has been achieved for the first time by
using the cationic NHC-ethylene fluorenyl lutetium alkyl
precursor to give a new type of amorphous polymer with a
high Tg close to polystyrene. The 3,4-regio- and stereo-
syndiotacticity are well-defined by the combined IR and NMR
spectroscopic analyses. Owing to this highly regio- and
stereoregularity, the P(1-MPBD) macromolecular main chains
take totally zigzag trans conformation in solution evidenced by
NOESY and 13C CPMAS spectra. Changing the substituent at
C1 of 1,3-butadiene from H, Me, Ph to 4-MePh, the resultant
polymers have different content of the 3,4-units that increases
with the volume of the substituent from 69.5, 82.5, 94.4 to 99%.
These results allow us to deduce a probable reaction pathway
for polymerization of (E)-1-MPBD:1-MPBD trans-η2 coor-
dinates to the cationic Lu3+ center to form the Lu−η3-allyl
intermediate, which attacks the monomer via C3 at the C4 of
the monomer, generating a 3,4-linkage owing to the electronics
of the para-methylphenyl electron-donating effect. The
combined influences of the CGC-ligand and the bulky
substituent of para-methylphenyl compel the alternating si-
face and re-face coordination of the incoming monomer, which
contributes to the highly syndiotacticity of the resultant
polymer. In contrast to their syndiotactic polybutadiene
analogue of crystalline plastic with a high melting point, this
syndiotactic 3,4-P(1-MPBD) is an amorphous plastic, revealing
that minimal changes in monomer structure arouses dramat-
ically different properties. This work suggests the specific
selective polymerization can be achieved by designing the
electronically and sterically proper monomer, which might not
be realized by the previously reported and widely employed
design of catalytic precursors.
1
hexane) afford the pure product in a yield of 89%. H NMR (400
MHz, CDCl3, 7.26 ppm, 25 °C): 7.32 (d, 2H, Ar−H), 7.16 (d, 2H,
Ar−H), 6.80−6.74 (m, 1H, olefin−H), 6.58−6.48 (m, 2H, olefin−H),
5.35 (d, 1H, olefin−H), 5.18 (d, 1H, olefin−H), 2.36 (s, 1H, −CH3).
13C NMR (100 MHz, CDCl3, 77.16 ppm, 25 °C): 137.66, 134.50,
129.47, 126.51, (m, 6C, Ar−C),137.47, 132.97, 128.85, 117.14, (m,
4C, olefin−C) 21.37 (s, 1C, −CH3).
Synthesis of Poly(1-MPBD). A typical polymerization procedure
(Table 1, entry 1) was described as follow. Under a nitrogen
atmosphere, (E)-1-MPBD (0.288 g, 2 mmol) was added into a 10 mL
flask. Then, 10 equiv of AliBu3 (0.20 mL, 0.5 mol/L), a toluene
solution (3.0 mL) of complex (Flu-NHC)Lu(CH2SiMe3)2 (7.3 mg, 10
μmol), and 1 equiv of [Ph3C][B(C6F5)4] (9.2 mg,10 μmol) were
added to the flask. The reaction apparatus was placed in a bath at 25
°C. After the reaction was stirred for 12 h, methanol was injected to
terminate the polymerization. The viscous mixture was poured into a
large quantity of methanol. The obtained white polymer was filtered
and then dried under vacuum at 40 °C to a constant weight.
Synthesis of Syndiotactic Poly(4-methyphenyl-1-butene).
Under a nitrogen atmosphere, poly(1-MPBD) (0.404 g, 2.8 mmol of
double bonds), p-toluenesulfonyl hydrazide (1.15 g, 6.2 mmol), and 50
mL of p-xylene were added to 100 mL flask and refluxed for 24 h. After
being cooled to room temperature, the clear solution was poured into
a large quantity of methanol. The obtained white polymer was filtered
and then dried under vacuum at 40 °C to a constant weight.
Synthesis of Isotactic Poly(4-phenyl-1-butene). Under a
nitrogen atmosphere, a toluene solution (4.0 mL) of complex rac-
Me2Si(2-MeBenz[e]Ind)2ZrCl2 (10 mg, 30 μmol) and 300 equiv
MAO were added into a 10 mL flask. The reaction apparatus was
placed in a bath at 50 °C and stirred 5 min. Then, a toluene solution of
4-phenyl-1-butene (0.793 g, 6 mmol) was added into the flask. After
the reaction was stirred for 4 h, methanol was carefully injected to
terminate the polymerization. The mixture was poured into a large
quantity of methanol. The obtained white polymer was filtered and
then dried under vacuum at 40 °C to a constant weight.
EXPERIMENTAL SECTION
■
General Methods and Materials. All manipulations were
performed under a dried and oxygen-free argon atmosphere using
standard high vacuum Schlenk techniques or in an Mbraun glovebox.
All solvents were purified from Mbraun SPS system. AliBu3 (1.0 M in
hexane), n-butyllithium (1.6 M in hexane), allylmagnesium bromide
(1.0 M in THF), 1,3-butadiene, and (E)-1,3-pentadiene were
purchased from Aldrich. Benzyl chloride, trans-4-methylcinnamalde-
hyde, methyltriphenylphosphonium bromide, trans-cinnamaldehyde,
and p-methylbenzenesulfonyl hydrazide (TSH) were purchased from
the National Medicine Co. (China) and were used without further
purification. [Ph3C][B(C6F5)4],22 4-phenyl-1-butene,21a (Flu-NHC)-
Lu(CH2SiMe3)2,12a and (Am-NHC)Lu(CH2SiMe3)212c were prepared
according to the literature. 1H and 13C NMR spectra were recorded on
ASSOCIATED CONTENT
■
S
* Supporting Information
1
IR, H, 13C, 13C CPMAS NMR spectra, WAXD pattern, and
DSC thermogram of the selected polymer samples; table for
the polymerization of butadiene, (E)-1,3-pentadiene, and (E)-
1-phenyl-1,3-butadiene. This material is available free of charge
via the Internet at http://pubs.acs.org.
a Bruker AV 400 (FT, 400 MHz for H; 100 MHz for 13C). The
1
number-average molecular weights (Mn) and molecular weight
distributions (Mw/Mn) of the polymer samples were measured by
means of gel permeation chromatography (GPC) on a TOSOHHLC-
8220 GPC apparatus (column: SuperHZM-Hx3) at 40 °C using THF
as the eluent (the flowing rate is 0.35 mL/min) against polystyrene
standards or on a PL-GPC 220 type high-temperature chromatography
equipped with three PL-gel 10 μm Mixed-B LS type columns at 150
°C. The IR spectrum was recorded on a VERTEX 70 FT-IR
AUTHOR INFORMATION
Corresponding Authors
*E-mail dmcui@ciac.ac.cn (D.C.).
*E-mail wuchunji@ciac.ac.cn (C.W.).
Notes
■
The authors declare no competing financial interest.
2004
DOI: 10.1021/acs.macromol.5b00226
Macromolecules 2015, 48, 1999−2005

Macromolecules
Article
(16) Ishihara, N.; Seimiya, T.; Kuramoto, M.; Uoi, M. Macromolecules
1986, 19, 2464.
(17) (a) Bovey, F.; Tiers, G. J. Polym. Sci. 1960, 44, 173. (b) Nishioka,
A.; Watanabe, H.; Abe, K.; Sono, Y. J. Polym. Sci. 1960, 48, 241.
(18) Ashitaka, H.; Inaishi, K.; Ueno, H. J. Polym. Sci., Polym. Chem.
Ed. 1983, 21, 1973.
ACKNOWLEDGMENTS
■
This work was partly supported by the MST for “973” project
No. 2015CB654702 and NSFC for projects Nos. 21374112 and
21304088.
(19) (a) Elgert, K.; Quack, G.; Stutzel, B. Makromol. Chem. 1974,
175, 1955. (b) Kumar, D.; Rama Rao, M.; Rao, K. J. Polym. Sci., Polym.
Chem. Ed. 1983, 21, 365.
̈
REFERENCES
■
(1) Baugh, L.; Canich, A. Stereoselective Polymerization with Single-Site
Catalysts; CRC Press: Boca Raton, FL, 2007.
(2) (a) Porri, L.; Giarrusso, A.; Ricci, G. Prog. Polym. Sci. 1991, 16,
405. (b) Ricci, G.; Sommazzi, A.; Masi, F.; Ricci, M.; Boglia, A.; Leone,
G. Coord. Chem. Rev. 2010, 254, 661.
(3) (a) Zhang, L.; Suzuki, T.; Luo, Y.; Nishiura, M.; Hou, Z. Angew.
Chem., Int. Ed. 2007, 46, 1909; Angew. Chem. 2007, 119, 1941.
(b) Gao, W.; Cui, D. J. Am. Chem. Soc. 2008, 130, 4984.
(4) (a) Bonnet, F.; Visseaux, M.; Pereira, A. Macromolecules 2005, 38,
3162. (b) Zimmermann, M.; Tornroos, K.; Anwander, R. Angew.
Chem., Int. Ed. 2008, 47, 775.
(5) (a) Zhang, L.; Luo, Y.; Hou, Z. J. Am. Chem. Soc. 2005, 127,
14562. (b) Zhang, L.; Nishiura, M.; Yuki, M.; Luo, Y.; Hou, Z. Angew.
Chem., Int. Ed. 2008, 47, 2642.
(20) (a) Chai, M.; Holley, A.; Kruskamp, M. Chem. Commun. 2007,
168. (b) Chai, M.; Niu, Y.; Youngs, W. Macromolecules 2000, 33, 5395.
(c) Chai, M.; Niu, Y.; Youngs, W.; Rinaldi, P. J. Am. Chem. Soc. 2001,
123, 4670.
(21) (a) Wang, L.; Wan, D.; Zhang, Z.; Liu, F.; Xing, H.; Wang, Y.;
Tang, T. Macromolecules 2011, 44, 4167. (b) Spaleck, W.; Kuber, F.;
Winter, A.; Rohrmann, J.; Bachmann, B.; Antberg, M.; Dolle, V.;
Paulus, E. Organometallics 1994, 13, 954.
(22) Chein, J.; Tsai, W.; Rausch, M. J. Am. Chem. Soc. 1991, 113,
8570.
(6) (a) Liu, B.; Wang, X.; Pan, Y.; Lin, F.; Wu, C.; Qu, J.; Luo, Y.;
Cui, D. Macromolecules 2014, 47, 8524. (b) Ashitaka, H.; Jinda, K.;
Ueno, H. J. Polym. Sci., Polym. Chem. Ed. 1983, 21, 1989. (c) Ricci, G.;
Forni, A.; Boglia, A.; Motta, T.; Zannoni, G.; Canetti, M.; Bertini, F.
Macromolecules 2005, 38, 1064.
(7) (a) Masuda, T.; Mori, T.; Higashimura, T. J. Polym. Sci., Polym.
Chem. Ed. 1974, 12, 1385. (b) Asami, R.; Hasegawa, K.; Onoe, T.
Polym. J. 1976, 8, 43. (c) Asami, R.; Murai, H. Polym. Prepr. (Jpn.)
1967, 176. (d) Suzuki, T.; Tsuji, Y.; Takegami, Y. Macromolecules
1978, 11, 639.
(8) Pragliola, S.; Cipriano, M.; Boccia, A.; Longo, P. Macromol. Rapid
Commun. 2002, 23, 356.
(9) Suzuki, T.; Tsuji, Y.; Watanabe, Y.; Takegami, Y. Macromolecules
1980, 13, 849.
(10) (a) Meermann, C.; Tornroos, K.; Nerdal, W.; Anwander, R.
Angew. Chem., Int. Ed. 2007, 46, 6508. (b) Fischbach, A.; Meermann,
C.; Eickerling, G.; Scherer, W.; Anwander, R. Macromolecules 2006, 39,
6811. (c) Zimmermann, M.; Froystein, N.; Fischbach, A.; Sirsch, P.;
Dietrich, H.; Tornroos, K.; Herdtweck, E.; Anwander, R. Chem.Eur.
J. 2007, 13, 8784. (d) Wang, L.; Cui, D.; Hou, Z.; Li, W.; Li, Y.
Organometallics 2011, 30, 760. (e) Lv, K.; Cui, D. Organometallics
2010, 29, 2987. (f) Li, D.; Li, S.; Cui, D.; Zhang, X. Organometallics
2010, 29, 2186. (g) Jian, Z.; Tang, S.; Cui, D. Chem.Eur. J. 2010, 16,
14007.
(11) (a) Liu, H.; He, J.; Liu, Z.; Lin, Z.; Du, G.; Zhang, S.; Li, X.
Macromolecules 2013, 46, 3257. (b) Zimmermann, M.; Tornroos, K.;
Sitzmann, H. Chem.Eur. J. 2008, 14, 7266. (c) Liu, D.; Cui, D.
Dalton Trans. 2011, 40, 7755. (d) Rong, W.; Liu, D.; Zuo, H.; Pan, Y.;
Jian, Z.; Li, S.; Cui, D. Organometallics 2013, 32, 1166.
(12) (a) Wang, B.; Lv, K.; Cui, D. Macromolecules 2008, 41, 1983.
(b) Li, S.; Cui, D.; Li, D.; Hou, Z. Organometallics 2009, 28, 4814.
(c) Yao, C.; Liu, D.; Li, P.; Wu, C.; Li, S.; Liu, B.; Cui, D.
Organometallics 2014, 33, 684. (d) Liu, B.; Li, L.; Sun, G.; Liu, J.;
Wang, M.; Li, S.; Cui, D. Macromolecules 2014, 47, 4971. (e) Du, G.;
Wei, Y.; Ai, L.; Chen, Y.; Xu, Q.; Liu, X.; Zhang, S.; Hou, Z.; Li, X.
Organometallics 2011, 30, 160.
(13) (a) Ashitaka, H.; Jinda, K.; Ueno, H. J. Polym. Sci., Polym. Chem.
Ed. 1983, 21, 1973. (b) Bazzini, C.; Giarrusso, A.; Porri, L. Macromol.
Rapid Commun. 2002, 23, 922. (c) Ricci, G.; Morganti, D.; Sommazzi,
A.; Santi, R.; Masi, F. J. Mol. Catal. A: Chem. 2003, 204, 287. (d) Ricci,
G.; Battistella, M.; Porri, L. Macromolecules 2001, 34, 5766. (e) Tang,
Y.; Dai, Q.; Zhang, X. Chin. J. Appl. Chem. 2013, 30, 11.
(14) (a) Ricci, G.; Motta, T.; Boglia, A.; Alberti, E.; Zetta, L.; Bertini,
F.; Arosio, P.; Famulari, A.; Meille, S. Macromolecules 2005, 38, 8345.
(b) Ricci, G.; Bertini, F.; Boccia, A.; Zetta, L.; Alberti, E.; Pirozzi, B.;
Giarrusso, A.; Porri, L. Macromolecules 2007, 40, 7238.
(15) Hatada, K.; Kitayama, T. NMR Spectroscopy of Polymers;
Springer-Verlag: Berlin, 2004.
2005
DOI: 10.1021/acs.macromol.5b00226
Macromolecules 2015, 48, 1999−2005