Ni(II) and Pd(II) complexes bearing novel bis(β-ketoamino) ligand and their catalytic activity toward copolymerization of norbornene and 5-norbornene-2-yl acetate combined with B(C6F5) 3

Article abstract of DOI:10.1002/pola.24767

Two complexes Mt{C₁₀H₈(O)C[N(C₆H ₅)]CH₃}₂ [Mt = Ni(II); Mt = Pd(II)] were synthesized, and the solid-state structures of the complexes have been determined by single-crystal X-ray diffracti

Full text of DOI:10.1002/pola.24767

Ni(II) and Pd(II) Complexes Bearing Novel Bis(b-ketoamino) Ligand
and Their Catalytic Activity toward Copolymerization of Norbornene
and 5-Norbornene-2-yl Acetate Combined with B(C6F5)3
KAITI WANG, YIWANG CHEN, XIAOHUI HE, YUEMAN LIU, WEIHUA ZHOU
Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031, China
Received 25 March 2011; accepted 8 May 2011
DOI: 10.1002/pola.24767
Published online 26 May 2011 in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: Two complexes Mt{C10H8(O)C[N(C6H5)]CH3}2 [Mt ¼
Ni(II); Mt ¼ Pd(II)] were synthesized, and the solid-state struc-
tures of the complexes have been determined by single-crystal
X-ray diffractions. Homopolymerization of norbornene (NB)
and copolymerization of NB and 5-norbornene-2-yl acetate
(NB-OCOCH3) were carried out in toluene with both the two
complexes mentioned above in combination with B(C6F5)3.
Both the catalytic systems exhibited high activity toward the
homopolymerization of NB (as high as 2.7 ꢀ 105 gpolymer/molNi h,
for Ni(II)/B(C6F5)3 and 2.1 ꢀ 105 gpolymer/molPd h for Pd(II)/
B(C6F5)3, respectively.). Although the Pd(II)/B(C6F5)3 shows very
lower activity toward the copolymerization of NB with NB-
OCOCH3, Ni(II)/B(C6F5)3 shows a high activity and produces the
addition-type copolymer with relatively high molecular weights
(MWs; 1.80–2.79 ꢀ 105 g/mol) as well as narrow MW distribu-
tion (1.89–2.30). The NB-OCOCH3 content in the copolymers
can be controlled up to 5.8–12.0% by varying the comonomer
feed ratios from 10 to 50%. The copolymers exhibited high
transparency, high glass transition temperature (Tg > 263.9 ꢁC),
better solubility, and mechanical properties compared with the
homopolymer of NB. The reactivity ratios of the two mono-
mers were determined to be rNB-OCOMe ¼ 0.08, rNB ¼ 7.94 for
Ni(II)/B(C6F5)3 system, and rNB-OCOMe ¼ 0.07, rNB ¼ 6.49, for
C
V
Pd(II)/B(C6F5)3 system by the Kelen-Tudo˜ s method.
2011
¨
Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49:
3304–3313, 2011
KEYWORDS: additional
polymerization; late-transition-metal
catalyst; norbornene; olefin polymerization catalyst; organo-
metallic catalysis; polymer synthesis; reactivity ratio
INTRODUCTION Norbornene (NB; bicycle[2.2.1]hept-2-ene)
is polymerized by cationic or radical polymerization,1–3 ring-
opening metathesis polymerization,4–11 and vinyl-type addi-
tion polymerization.12–21 The increasing interest in vinyl-
type polynorbornene (PNB) is due to its high glass transition
temperature, high optical transparency, low dielectric con-
stant, and low birefringence. However, it shows poor proc-
essability and poor solubility. To modify the disadvantages
and get functionalized PNB, a series of copolymers of
NB with ethylene,22–28 propylene,29–31 higher 1-alkene,32
polar monomer,33–35 and NB derivatives36–40 have been also
studied.
temperatures of copolymers are increased relative to
polystyrene. The solubility and processability of the copoly-
mers are improved relative to PNB. Kaita et al.36 used cyclo-
pentadienyl nickel and palladium complexes catalyzed the
copolymerization of NB with NB carboxylic acid esters. The
copolymers of NB with 5-norbornene-2-carboxylic acid methyl
ester has high molecular weights (MWs; Mn ¼ 234,100–
109,500), narrow MW distributions (Mw/Mn ¼ 1.78–1.89), and
high glass transition temperature (352.8–316.0 ꢁC). The content
of 5-norbornene-2-carboxylic acid methyl ester in the copoly-
mers is 17.4–60.7%, and the copolymer can be dissolved in
common organic solvents.
Shiono et al.32 prepared the copolymer of NB with 1-hexene,
1-octene, and 1-decene. The 1-alkene content of the copoly-
mers is 7.0–58.0%, and the copolymer can be dissolved in
common organic solvents. The copolymer films obtained
from CH2Cl2 exhibited high transparence. Mi et al.34 got the
copolymers of NB and styrene by Pd- and Ni-based novel
bridged dinuclear diimine complexes and methylaluminoxane
The vinyl-type PNB can be obtained through Ziegler-
Natta,22–25,30–32 metallocene,12,29 rare earth metal,26,33,41 and
late transition metal catalysts.13–21,27,28,34–40,42–47 The late
transition metal catalysts are simple to synthesize and show
more stable to polar NB detectives. The common late transi-
tion metal catalysts are Ni(II) and Pd(II) complexes. The
complexes usually contain O, OA, O, NA, N, NA donor, and
phosphines ligand. The solubility of PNB catalyzed by Ni(II)
complexes are better than those catalyzed by Pd(II)
complexes.
(MAO). The reactivity ratios were rstyrene ¼ 0.281 and rNB
¼
18.7. The styrene incorporated are 0.6–46.5 mol %, and the
packing density, thermostability, and the glass transition
Additional Supporting Information may be found in the online version of this article. Correspondence to: X. He (E-mail: hexiaohuishulei@yahoo.
com.cn) or Y. Chen (E-mail: ywchen@ncu.edu.cn)
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Journal of Polymer Science Part A: Polymer Chemistry, Vol. 49, 3304–3313 (2011) 2011 Wiley Periodicals, Inc.
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ARTICLE
5-Norbornene-2-yl acetate was purchased from Aldrich and
purified by anhydrous Magnesium Sulfate. Other commer-
cially available reagents were purchased and used without
purification.
Characterization
The intensity data of the single crystals were collected on
the CCD-Bruker Smart APEX II system. The element analysis
was performed on elementar-vario EL cube elemental ana-
lyzer. The nuclear magnetic resonance (NMR) of the poly-
mers was recorded on a Bruker ARX 600 NMR spectrometer
at ambient temperature, with CDCl3 as the solvent. The
XT4A melting point measure instrument (BeiJing KeYi elec-
tro-optic instrument factory, China) was used to test the
melting point temperature. The gel permeation chromatogra-
phy (GPC) was conducted with a Breeze Waters system
equipped with a Rheodyne injector, a 1515 Isocratic pump,
and a Waters 2414 differential refractometer using polystyr-
enes as the standard and chloroform (CHCl3) as the eluent at
SCHEME 1 The synthetic route of the complexes.
In last decade, some b-ketoamino catalysts39,40,42,43 have
been synthesized and exhibited excellent activity on poly-
merization of NB, and there is a phenomenon that the elec-
tron-drawing group (such as ACF3, AC6H5) can increase the
activity of the complexes. The polymerization usually
requires both organometallics complexes and cocatalyst.
MAO, modified MAO (MMAO), or B(C6F5)3 were often chosen
as cocatalyst. In this article, the copolymerization behavior of
NB and 5-norbornene-2-yl acetate (NB-OCOCH3) catalyzed
by two Ni(II) and Pd(II) catalysts bearing novel b-ketoamino
combined with B(C6F5)3 cocatalyst was reported, the new
ligand, which contains benzocyclohexan ring on 2-acetyl-1-
tetralone and phenyl ring on aniline, which show a big steric
effect and strong electronic effect, the conjugation effect of
phenyl and benzocyclohexan rings also enhances the elec-
tronic effect, so the two new catalysts would show better
stability and higher catalytic activity. The thermal, optical,
and mechanical properties of the copolymer were also
shown in this article.
ꢁ
a flow rate of 1.0 mL/min and 40 C through a Styragel col-
umn set, Styragel HT3, and HT4 (19 ꢀ 300 mm2, 103 þ 104
Å) to separate MW ranging from 102 to 106. The IR spectra
were recorded by a Shimadzu IR Prestige-21 FTIR spectro-
photometer. The wide-angle X-ray diffraction (WXRD) curves
were recorded on a Bruker D8 Focus X-ray diffractometer,
operating at 40 kV and 40 mA with a copper target (k ¼
1.54 Å) and at a scanning rate of 2ꢁ/min. The thermal gravi-
metric analysis (TGA) measurements were performed on a
Perkin-Elmer instrument TGA 7 from room temperature to
600 ꢁC at a rate of 20 ꢁC/min under nitrogen atmosphere.
The differential scanning calorimetry (DSC) measurements
were obtained on a Shimadzu DSC-60 with a heating/cooling
rate of 10 ꢁC/min under nitrogen atmosphere. The dynamic
thermomechanical analysis (DMA) was performed on a TA
EXPERIMENTAL
Materials
All the reactions were performed under an atmosphere of
dry and oxygen-free argon using standard vacuum, Schlenk,
or under nitrogen atmosphere in glove box (MBraun). Tolu-
ene was refluxed and distilled from sodium and benzophe-
none under dry nitrogen. NB was purchased from Alfa Aesar
and purified through drying by sodium and distilled under
dry nitrogen, then made a solution (4.25 mol/L) in toluene.
SCHEME 2 Copolymerization of norbornene and 5-norbornene-
FIGURE 1 ORTEP plots of Ni(II) complex showing the atom-
2-yl acetate catalyzed by Ni(II) and Pd(II) complexes.
labeling scheme. Hydrogen atoms are omitted for clarity.
Ni(II) AND Pd(II) COMPLEXES, WANG ET AL.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
heated to 50 ꢁC and of {C10H8(O)C[HN(C6H5)]CH3 (1.27 g,
0.005 mol) was added. The solution changed to red brown
as {C10H8(O)C[HN(C6H5)]CH3} completely reacted with t-
BuOK. The reaction mixture was stirred for another 20 min.
The solution was then slowly cooled down to environmental
temperature, and [Et4N]2NiBr4 (1.87 g, 0.003mol) was intro-
duced, the reacting mixture immediately formed a dark-
green precipitate. After stirring vigorously for several hours
at room temperature, the excess t-BuOH was removed in
vacuo. The reacting slurry was extracted successively with
hot toluene, and the mixture was filtrated quickly. The fil-
trate was allowed to crystallize by cooling slowly overnight.
The product was isolated and dried under reduced pressure.
Additional recrystallization from n-hexane/toluene mixture
solution gave blocks of dark-green crystals.
Yield: 43.2%, 1H NMR (CDCl3), d (ppm): 7.30–8.03 (m, 8H,
C10H8); 6.23–7.06 (m, 10H, C6H5); 2.41–2.64 (m, 8H, C10H8);
1.62 (s, 6H, CH3). 13C NMR (CDCl3), d (ppm): 21.11 (s, 2C,
TABLE 1 Crystallographic Data for Ni(II) and Pd(II) Complexes
FIGURE 2 ORTEP plots of Pd(II) complex showing the atom-
labeling scheme. Hydrogen atoms are omitted for clarity. [Color
figure can be viewed in the online issue, which is available at
wileyonlinelibrary.com.]
Ni(II) Complex
Pd(II) Complex
Empirical formula
Fw (g/mol)
C36H32N2O2Ni
583.35
C36H32N2O2Pd
631.04
ꢁ
Q800 DMA at a heating rate of 3 C/min and a frequency of
Crystal color
Crystal system
Space group
Green
Yellow
1 Hz. The UV–vis spectra were recorded on a Hitachi UV-
2300 spectrophotometer. The mechanical properties were
measured on a CMT8502 Machine model GD203A (ShenZhen
Sans Testing Machine, China) at a speed of 5 mm/min.
Monoclinic
P2(1)/c
Monoclinic
P2(1)/c
˚
a (A)
13.231(2)
11.092(2)
9.5054(17)
90.00
13.345(2)
11.178(2)
9.4960(17)
90.00
˚
b (A)
Ligands and Complexes Syntheses
˚
c (A)
The complexes bearing bis-(b-ketoamino) ligands Mt{C10H8(O)
C[N(C6H5)]CH3}2 [Mt ¼ Ni(II), Mt ¼ Pd(II)], were synthesized
according to the method reported in our previous work.42 The
synthetic route was shown in Scheme 1.
a (deg)
b (deg)
c (deg)
100.895(2)
90.00
101.032(2)
90.00
3
˚
V (A )
1369.8(4)
2
1390.3(4)
2
{C10H8(O)C[HN(C6H5)]CH3}
Z
2-Acetyl-1-tetralone (4.71 g, 0.025 mol), aniline (2.28 mL,
0.025 mol), and a catalytic amount of p-toluenesulfonic acid
in toluene (150 mL) were combined and refluxed for 3 h.
Water was removed as a toluene azeotrope at 125–130 ꢁC
using a water separator. Volatile was removed in vacuo and
yellow crystals of {C10H8(O)C[HN(C6H5)]CH3} was obtained
by recrystallization from n-hexane.
Dc (Mg/m3)
1.414
1.507
Absorption
0.746
0.705
coefficient (mmꢃ1
F(000)
)
612
648
Crystal size (mm)
hmax (deg)
0.25 ꢀ 0.12 ꢀ 0.06 0.15 ꢀ 0.15 ꢀ 0.16
25.50
25.10
Yield: 64.7%, Mp: 117 ꢁC. 1H NMR (CDCl3), d (ppm): 14.12
(s, 1H, OꢂꢂꢂHAN); 7.31–8.04 (m, 4H, C10H8); 6.74–7.25 (m,
5H, C6H5); 2.61–2.90 (m, 4H, C10H8); 2.14 (s, 3H, CH3). 13C
NMR (CDCl3), d (ppm): 16.61 (s, 1C, RCH3); 24.85 (s, 1C,
RCH2R); 29.11 (s, 1C, RCH2R); 102.79 (s, 2C, C6H5); 125.12
(s, 1C, C6H5); 125.39 (s, 1C, C10H8); 126.50 (s, 1C, C10H8);
126.64 (s, 1C, C10H8); 127.18 (s, 1C, C10H8); 129.18 (s, 1C,
Index ranges
ꢃ16 ꢄ h ꢄ 16
ꢃ13 ꢄ k ꢄ 12
ꢃ11 ꢄ l ꢄ 11
188
ꢃ15 ꢄ h ꢄ 15
ꢃ13 ꢄ k ꢄ 13
ꢃ9 ꢄ l ꢄ 11
189
No. of params.
Goodness-of-fit
on S (F 2)a
1.322
1.074
Final R indices
0.0337; 0.0712
0.0186; 0.0499
C
10H8); 130.95 (s, 2C, C6H5); 135.66 (s, 1C, R2C¼¼R); 139.15
[I >2o´(I )]
(s, 1C,
C
10H8); 141.28 (s, 1C, NC¼¼R); 159.77 (s, 1C,
R indices (all data)
0.0521; 0.0765
0.0248; 0.0546
NAC6H5); 184.77 (s, 1C, R2C¼¼O).
Largest diff
0.315 and ꢃ0.231
0.256 and ꢃ0.267
Ni{C10H8(O)C[N(C6H5)]CH3}2
3
˚
peak and hole (e/A
)
Potassium (0.4g, 0.01mol) was dissolved in 25 mL of dried
t-BuOH. After the potassium had dissolved, the solution was
P
P
P
P
R ¼ llFolꢃlFcll lFol; Rw ¼ [
(Fo ꢃFc2)2/ w (Fo2)2]1/2
2
w
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ARTICLE
˚
TABLE 2 Selected Bond Lengths (A) and Angles (deg) for Ni(II) and Pd(II) Complexes
Ni(II) Complex
Pd(II) Complex
Bond
Length
Bond
Length
Ni(1)AO(1)
1.8338 (13)
1.8338 (13)
1.9170 (17)
1.9170 (17)
1.299 (32)
1.376 (3)
Pd(1)AO(1)
1.9721 (14)
1.9721 (14)
2.0216 (15)
2.0216 (15)
1.296 (2)
Ni(1)AO(1)#1
Pd(1)AO(1)#1
Pd(1)AN(1)
Ni(1)AN(1)
Ni(1)AN(1)#1
Pd(1)AN(1)#1
C(1)AO(1)
C(1)AO(1)
C(1)AC(10)
C(1)AC(10)
1.385 (3)
C(1)AC(2)
1.492 (3)
C(1)AC(2)
1.490 (3)
C(7)AC(8)
1.501 (3)
C(7)AC(8)
1.486 (3)
C(8)AC(9)
1.510 (3)
C(8)AC(9)
1.502 (3)
C(9)AC(10)
1.523 (3)
C(9)AC(10)
1.526 (3)
C(10)AC(11)
1.422 (3)
C(10)AC(11)
C(11)AN(1)
1.429 (3)
C(11)AN(1)
1.324 (3)
1.322 (2)
C(11)AC(12)
1.523 (3)
C(11)AC(12)
C(13)AN(1)
1.519 (3)
C(13)AN(1)
1.448 (3)
1.442 (2)
Bond
Angle
Bond
Angle
O(1)ANi(1)AO(1)#1
O(1)ANi(1)AN(1)
O(1)#1ANi(1)AN(1)
O(1)ANi(1)AN(1)#1
O(1)#1ANi(1)AN(1)#1
N(1)ANi(1)AN(1)#1
C(11)AN(1)ANi(1)
C(13)AN(1)ANi(1)
C(1)AO(1)ANi(1)
O(1)AC(1)AC(10)
O(1)AC(1)AC(2)
C(10)AC(1)AC(2)
C(7)AC(8)AC(9)
C(8)AC(9)AC(10)
C(1)AC(10)AC(11)
C(1)AC(10)AC(9)
C(11)AC(10)AC(9)
N(1)AC(11)AC(10)
N(1)AC(11)AC(12)
C(10)AC(11)AC(12)
C(14)AC(13)AC(18)
C(14)AC(13)AN(1)
C(18)AC(13)AN(1)
C(11)AN(1)AC(13)
180.00 (2)
91.67 (6)
O(1)APd(1)AO(1)#1
O(1)APd(1)AN(1)
O(1)#1APd(1)AN(1)
O(1)APd(1)AN(1)#1
180.000
90.64 (6)
88.33 (6)
89.36 (6)
88.33 (6)
89.36 (6)
91.67 (6)
O(1)#1APd(1)AN(1)#1
N(1)APd(1)AN(1)#1
C(11)AN(1)APd(1)
C(13)AN(1)APd(1)
C(1)AO(1)APd(1)
O(1)AC(1)AC(10)
O(1)AC(1)AC(2)
90.64 (6)
180.000
180.000 (1)
125.99 (13)
117.30 (12)
127.25 (12)
126.94 (18)
113.28 (16)
119.77 (17)
112.42 (18)
113.44 (18)
123.68 (17)
117.87 (18)
118.38 (17)
124.66 (17)
118.54 (17)
116.80 (17)
119.74 (19)
120.51 (18)
119.71 (18)
116.72 (15)
126.94 (13)
118.91 (13)
129.99 (13)
125.44 (19)
114.84 (18)
119.70 (19)
111.7 (2)
C(10)AC(1)AC(2)
C(7)AC(8)AC(9)
112.57 (19)
121.24 (19)
118.71 (18)
119.95 (19)
123.84 (19)
119.84 (18)
116.33 (19)
119.7 (2)
C(8)AC(9)AC(10)
C(1)AC(10)AC(11)
C(1)AC(10)AC(9)
C(11)AC(10)AC(9)
N(1)AC(11)AC(10)
N(1)AC(11)AC(12)
C(10)AC(11)AC(12)
C(14)AC(13)AC(18)
C(14)AC(13)AN(1)
C(18)AC(13)AN(1)
C(11)AN(1)AC(13)
120.76 (19)
119.36 (19)
114.15 (17)
RCH3); 25.03 (s, 2C, RCH2R); 28.98 (s, 2C, RCH2R); 104.80
(s, 4C, C6H5); 125.65 (s, 2C, C6H5); 125.75 (s, 2C, C10H8);
125.76 (s, 2C, C10H8); 125.85 (s, 2C, C10H8); 127.58 (s, 2C,
Pd{C10H8(O)C[N(C6H5)]CH3}2
The Pd complex was synthesized followed with the route of
Ni(II) complex. [Et4N]2PdCl4 was introduced instead of
[Et4N]2NiBr4, and yellow crystals were obtained.
C10H8); 128.23 (s, 2C, C10H8); 128.53 (s, 4C, C6H5); 129.19
(s, 2C, R2C¼¼R); 131.52 (s, 2C, C10H8); 133. 05 (s, 2C,
NC¼¼R); 149.25 (s, 2C, NAC6H5); 165.07 (s, 2C, R2C¼¼O).
Anal. Tested for: C, 74.17; H, 5.48; N, 4.82. Anal. Calcd for:
Yield: 41.5%, 1H NMR (CDCl3), d (ppm): 7.32–8.03 (m, 4H,
C
10H8); 6.16–7.15 (m, 5H, C6H5); 2.46–2.70 (m, 4H, C10H8);
1.73 (s, 3H, CH3). 13C NMR (CDCl3), d (ppm): 21.42 (s, 2C,
C36H32O2N2Ni: C, 74.12; H, 5.53; N, 4.80.
Ni(II) AND Pd(II) COMPLEXES, WANG ET AL.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
was added via a syringe into a 100-mL two-necked round-
bottomed flask containing a magnetic stirrer, the complexes
solution was then introduced followed by B(C6F5)3 solution.
The total volume was kept constant at 10 mL. The polymer-
ꢁ
ization was performed at 60 C for 30 min. The polymeriza-
tion was quenched by ethanol/HCl (v/v ¼ 9/1) solution and
stayed overnight. The polymers were then obtained through
filtration or centrifugation and washed by ethanol several
times and were dried at 40 ꢁC for 24 h in a vacuum oven.
The o-dichlorobenzene solutions of different copolymers
were used to prepare the copolymer films on glass slides.
The transparent films that were obtained had thickness of
about 40 lm. The copolymerization procedure and the struc-
ture of the catalysts are shown in Scheme 2.
RESULTS AND DISCUSSION
FIGURE 3 GPC curves of NB/NB-OCOCH3 copolymers with: (a)
5.8%, (b) 10.3%, (c) 12.0%, (d) 3.5%, and (e) 3.7% of NBE-
OCOCH3 molar ratio. a, b, and c are obtained by Ni(II)/B(C6F5)3.
d and e are obtained by Pd(II)/B(C6F5)3.
The Structures of the Two Complexes
The molecular structures of the two complexes were deter-
mined by single crystal X-ray diffraction. Single crystal of
complexes suitable for X-ray diffraction study was grown
from a concentrated toluene solution at room temperature.
The ORTEP plots are shown in Figures 1 and 2. The crystal-
lographic data are summarized in Table 1. CIF data of
Ni{C10H8(O)C[N(C6H5)]CH3}2 and Pd{C10H8(O)C[N(C6H5)]
CH3}2 complexes are available as Supporting Information.
Table 2 lists the selected bond lengths and angles. The coordi-
nation geometries of the two complexes were demonstrated to
be very similar in the solid state. They are both mononuclear
and four coordinate. The center metal ion in the complexes
and the N,O-chelator create two stable six-member chelate
rings. The angle of NAMtAN and OAMtAO are 180.0ꢁ, the
NAMtAO angles are slightly more than 90ꢁ (NANiAO is
91.67(6), NAPdAO is 90.64(6)), the NAMtAO#1 angles are
slightly less than 90ꢁ (NANiAO#1 is 88.33(6), NAPdAO#1
RCH3); 26.67 (s, 2C, RCH2R); 28.99 (s, 2C, RCH2R); 105.35
(s, 4C, C6H5); 124.02 (s, 2C, C6H5); 124.86 (s, 2C, C10H8);
125.59 (s, 2C, C10H8); 125.61 (s, 2C, C10H8); 126.08 (s, 2C,
C10H8); 126.68 (s, 2C, C10H8); 127.72 (s, 4C, C6H5); 128.77
(s, 2C, R2C¼¼R); 128.89 (s, 2C, C10H8); 134.25 (s, 2C, NC¼¼R);
149.36 (s, 2C, NAC6H5); 165.53 (s, 2C, R2C¼¼O). Anal. Tested
for: C, 68.46; H, 5.20; N, 4.53. Anal. Calcd for C36H32O2N2Pd:
C, 68.52; H, 5.11; N, 4.44.
Polymerization
All procedures were carried out under purified nitrogen
atmosphere. A typical copolymerization procedure is as fol-
low: a toluene solution of NB and 5-norbornene-2-yl acetate
TABLE 3 Copolymerization of Norbornene (NB) and 5-Norbornene-2-yl Acetate (NB-OCOCH3) Catalyzed by Ni(II) or Pd(II) Complex
Combined with B(C6F5)3
Mol % of
NB/NB-OCOCH3
(mol/mol)
Yield
(%)
Activity
Mw
(g/mol)a
NB-OCOCH3
in Copolymersb
a
c
Tg (ꢁC)
Entry
[Mt]
(gpolymer/molMt h)
Mn/Mw
1
2
Ni
Ni
Ni
Ni
Ni
Pd
Pd
Pd
Pd
Pd
100/0
90/10
70/30
50/50
0/100
100/0
90/10
70/30
50/50
0/100
71.1
56.8
33.9
14.4
Trace
54.4
4.9
2.7 ꢀ 105
2.3 ꢀ 105
1.5 ꢀ 105
7.1 ꢀ 104
Insoluble
2.79 ꢀ 105
2.47 ꢀ 105
1.80 ꢀ 105
–
–
0
5.8
10.3
12.0
–
302.4
277.5
274.6
263.9
–
2.30
2.27
1.89
–
3
4
d
5
–
6
2.1 ꢀ 105
Insoluble
5.06 ꢀ 103
4.53 ꢀ 103
–
–
0
275.0
268.3
243.2
–
7
2.0 ꢀ 104
2.04
2.53
–
3.5
3.7
–
8
0.9
4.2 ꢀ 103
9
Trace
Trace
–
–
a
10
–
–
–
–
Conditions: n[complex] is 5.0 ꢀ 10ꢃ6 mol, cocatalyst is B(C6F5)3, B/com-
plex/monomer (n/n/n) is 20/1/2000, polymerization temperature is 60 ꢁC,
polymerization time is 30 min, the solvent is toluene, the total volume
is 10 mL.
Determined by GPC versus polystyrene standards in CHCl3.
Determined by 1H NMR spectroscopy in CDCl3.
Determined by DSC analysis.
b
c
d
Not determined.
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TABLE 4 Copolymerization of NB and NB-OCOCH3 Catalyzed by Ni(II) or Pd(II) Complex Combined with B(C6F5)3
The Amount
of Mt (10ꢃ6 mol)
NB/NB-OCOCH3
(mol/mol)
Mol % of NB-OCOCH3
in Copolymera
Entry
[Mt]
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
9
10
a
Ni
Ni
Ni
Ni
Ni
Pd
Pd
Pd
Pd
Pd
0.5
0.5
0.5
0.5
0.5
1
60/40
50/50
40/60
30/70
20/80
90/10
80/20
70/30
60/40
50/50
0.33
0.42
2
5.32
5.51
1.48
2.05
0.75
4.71
4.71
3.39
1.81
0.76
7.39
9.04
12.80
20.45
22.70
1.61
12
12
12
1
12
1.93
1
12
4.03
1
12
8.05
1
12
9.25
Determined by 1H NMR spectroscopy in CDCl3.
is 89.36(6)). The NANi length is 1.9170(17), OANi length is
1.8338(13) in Ni(II) complex, NAPd length is 2.0216(15),
OAPd length is 1.9721(14) in Pd(II) complex.
Ni(II)/B(C6F5)3 are all up to 105, the Mw of the polymers
obtained by Pd(II)/B(C6F5)3 are as low as 5.06–4.53 ꢀ 103,
and WMD of the obtained polymers are all relative narrow
(WMD ¼ 1.89–2.53).
The MWDs are relative narrow and appear as a single modal
in the GPC chromatogram, which indicate copolymerization
occurs at the single active site, and the products are the true
copolymers instead of blends of the homopolymers, and the
results of polymerizations are presented in Table 3.
Copolymerization of NB and NB-OCOCH3
All the experiments were carried out with Ni(II) or Pd(II)
complex in the presence of B(C6F5)3 in toluene at 60 ꢁC for
30 min under nitrogen atmosphere. Both of complexes, acti-
vated with B(C6F5)3, exhibit high catalytic activity for the
vinyl-type addition homopolymerization of NB and Ni(II)/
B(C6F5)3 exhibit high catalytic activity on copolymerization
of NB and NB-OCOCH3. The activity of homopolymerization
Polymer yields and catalytic activities depended on the reac-
tion conditions. As shown in Table 3, the catalytic activities of
Ni(II)/B(C6F5)3 are higher than that of Pd (II)/B(C6F5)3, and
the catalytic activities of the complexes decrease with the
content of NB-OCOCH3 increasing in the comonomer feed
ratio. But, the Pd (II)/B(C6F5)3 complex shows lower activity
on the copolymerization of NB and NB-OCOCH3. Almost no
homopolymer of NB-OCOCH3 were obtained by both of
complexes. This is common for functionalized NB detectives,
which oxygen atom competing with the double-bond for the
coordination. High concentration of oxygen atom will impede
double-bond coordination. When NB and NB-OCOCH3 were
of NB catalyzed by Ni(II)/B(C6F5)3 is up to 2.7 ꢀ 105 gpolymer
/
molNi h. The obtained PNB show good solubility in both of
o-dichlorobenzene and cyclohexane, while the PNB obtained
by Pd(II)/B(C6F5)3 can only be dissolved in o-dichloroben-
zene. The copolymers of NB and NB-OCOCH3, however, are
soluble in common organic solvents (such as CHCl3, CH2Cl2,
cyclohexane) as well as o-dichlorobenzene.
The obtained copolymers were characterized by GPC and
shown in Figure 3. The Mw of the copolymers obtained by
FIGURE 4 Linear fitting of the NB/NB-OCOCH3 copolymeriza-
FIGURE 5 Linear fitting of the NB/NB-OCOCH3 copolymeriza-
tions system catalyzed by Ni(II)/B(C6F5)3 and according to
tions system catalyzed by Pd(II)/B(C6F5)3 and according to
Kelen–Tudo˜ s method.
¨
Kelen–Tudo˜ s method.
¨
Ni(II) AND Pd(II) COMPLEXES, WANG ET AL.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
FIGURE 6 FTIR curves of NB/NB-OCOCH3 copolymers with: (a)
0%, (b) 5.8%, (c) 10.3%, (d) 12.0%, (e) 3.5%, and (f) 3.7% of
NBE-OCOCH3 molar ratio. a, b, c, and d are obtained by Ni(II)/
B(C6F5)3. e and f are obtained by Pd(II)/B(C6F5)3.
FIGURE 8 WXRD curves of NB/NB-OCOCH3 copolymers with:
(a) 0%, (b) 5.8%, (c) 10.3%, (d) 0%, (e) 3.5%, (d) 3.7%. a, b, and
c are obtained by Ni(II)/B(C6F5)3. d, e, and f are obtained by
Pd(II)/B(C6F5)3.
catalyzed to copolymerize by the complexes, a coordinated
bond will be formed between metal atom and both of oxygen
atoms and double-bond of NB-OCOCH3 and NB.48–50 The yields
and the catalytic activities decreased obviously when the con-
tent of NB-OCOCH3 increased in the comonomer feed ratio.
g ¼ G=ða þ FÞ; n ¼ F=ða þ FÞ
g ¼ ðrNBꢃOCOCH3 þ rNB=aÞn ꢃ rNB=a
(3)
(4)
For Ni(II)/B(C6F5)3, the reactivity ratio of NB-OCOCH3 is
0.08, and the reactivity ratio of NB is 7.94; For Pd(II)/
B(C6F5)3, the reactivity ratio of NB-OCOCH3 is 0.07, and the
reactivity ratio of NB is 6.49.
To obtain the reactivity ratios of the two monomers, we
change the polymerization time and the feed content of cata-
lysts to control the conversion rate to be under 10%. The
results are shown in Table 4. The reactivity ratios are deter-
mined by the Kelen–Tu¨do˜s method51 (Figs. 4 and 5), which
is shown in eqs 1–4.
FTIR Spectra of Copolymers
The structures of copolymers were characterized by FTIR
spectra and shown in Figure 6. The signal of double-bond at
1710 cmꢃ1, assigned to the C¼¼C bond of the ROMP structure
of PNB, was not observed. The signals at about 941 cmꢃ1
could be attributed to the ring of bicyclo[2.2.1]heptanes further
x ¼ ½NB ꢃ OCOCH3ꢅ=½NBꢅ; y ¼ d½NB ꢃ OCOCH3ꢅ=d½NBꢅ (1)
0:5
F ¼ x2=y; G ¼ xðy ꢃ 1Þ=y; a ¼ ðFmax ꢀ Fmin
Þ
(2)
FIGURE 9 TGA curves of NB/NB-OCOCH3 copolymers with:
(a) 0%, (b) 5.8%, (c) 10.3%, (d) 12.0%, (e) 0%, (f) 3.5%, (g) 3.7%
of NBE-OCOCH3 molar ratio. a, b, c, and d are obtained by
Ni(II)/B(C6F5)3, and e, f, and g are obtained by Pd(II)/B(C6F5)3.
The Td of the polymers are: (a) 421.1 ꢁC, (b) 336.3 ꢁC, (c) 323.7
ꢁC, (d) 319.9 ꢁC, (e) 400.0 ꢁC, (f) 329.2 ꢁC, (g) 317.5 ꢁC.
FIGURE 7 The 1H NMR spectra of NB/NB-OCOCH3 copolymers
with: (a) 5.8%, (b) 10.3%, (c) 12.0%, (d) 3.5%, (e) 3.7% of NBE-
OCOCH3 molar ratio. a, b, and (c) obtained by Ni(II)/B(C6F5)3,
(d) and (e) obtained by Pd(II)/B(C6F5)3.
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ARTICLE
FIGURE 12 The UV–vis curves of NB/NB-OCOCH3 copolymer
films with: (a) 5.8%, (b) 10.3%, (c) 12.0% of NB-OCOCH3 molar
ratio and obtained by Ni(II)/B(C6F5)3.
FIGURE 10 DSC curves of NB/NB-OCOCH3 copolymers with: (a)
0%, (b) 5.8%, (c) 10.3%, (d) 12.0%, (e) 0%, (f) 3.5%, and (g) 3.7%
of NBE-OCOCH3 molar ratio. a, b, c, and d are obtained by
Ni(II)/B(C6F5)3, and e, f, and g are obtained by Pd(II)/B(C6F5)3.
in copolymers can be calculated by the following eq 5,39,40,52
and are (a) 5.8%, (b) 10.3%, (c) 12.0%, (d) 3.5%, (e) 3.7%.
illustrating the monomers via vinyl-type addition polymeriza-
tion. The observation at 1735 cmꢃ1 in the spectra is the signal
of C¼¼O, and the signal became strong with increase of content
of NB-OCOCH3 and confirmed that the NB-OCOCH3 has been
inserted into the chains of the copolymers and to be true co-
polymer rather than blend polymer.
0
NB ꢃ OCOCH3 % ¼ 2 ꢀ I =I
(5)
ð5Þ ð7 =7Þ
WXRD Analyses of the Copolymers
The WXRD curves of the copolymers with different NB-
OCOCH3 content prepared by Ni(II)/B(C6F5)3 and Pd(II)/
B(C6F5)3 are shown in Figure 8. There is no trace of Bragg
reflection in the characteristic of crystalline regions, so the
polymers are noncrystalline. The peaking of the polymer
whose content of NB-OCOCH3 is 6.64% and changes little,
but to other polymers, the intensity of both halos becomes
weaker with the increase of NB-OCOCH3 content. This result
shows that NB-OCOCH3 have insert into the polymer chain
and further proved the obtained polymers are copolymer.
Two broad halos at 2y values of 7.38–10.70 and 18.54–
18.89, which are characteristic for PNB were observed. The
interchain distance is calculated according to eq 634 and are
1H NMR Spectra of Copolymers
The structures of the copolymers were also characterized by
1
1H NMR spectra and shown in Figure 7. As shown in the H
NMR spectra, it proves that the polymers are vinyl-addition
type by the absence of the resonance of the proton hydrogen
connected to the double bond at 5.3–5.9 ppm. The peaks at
0.9–1.3 ppm can be assigned to the hydrogen corresponding
to 50/60/6, the peaks at 1.5–1.7 ppm can be assigned to the
hydrogen corresponding to 70/7, the peaks at 1.9–2.2 ppm
can be assigned to the hydrogen corresponding to 10/20/30/
40/1/2/3/4/8, and the peaks at 5.0 ppm can be assigned to
the hydrogen corresponding to 5. The content of NB-OCOCH3
FIGURE 13 The tensile curves of NB/NB-OCOCH3 copolymer
films with: (a) 5.8%, (b) 10.3%, (c) 12.0% of NB-OCOCH3 molar
ratio and obtained by Ni(II)/B(C6F5)3. The curves were recorded
at a speed of 5 mm/min.
FIGURE 11 The loss modulus curves of NB/NB-OCOCH3 copoly-
mer films with 12.0% of NB-OCOCH3 molar ratio and obtained
by Ni(II)/B(C6F5)3
Ni(II) AND Pd(II) COMPLEXES, WANG ET AL.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
TABLE 5 The Mechanical Properties of NB/NB-OCOCH3
UV–Vis Spectra of the Films
Copolymer Films
The UV–vis curves of the copolymer films with different NB-
OCOCH3 content are shown in Figure 12. The films show
high transmission in 400–800 nm and strong absorption in
250–400 nm. The copolymer film shows higher transmission
with the NB-OCOCH3 content decreased in the copolymers,
the copolymer film, which contains 5.8% NB-OCOCH3 shows
highest transmission and up to 87.74%.
Tensile
Elastic
Elongation
Sample
Strength (MPa)
Modulus (GPa)
at Break (%)
a
b
c
7.7
18.2
22.7
1.04
1.11
1.32
4
3.4
3.7
Mechanical Properties of the Films
Conditions: a, 5.8%; b, 10.3%; c, 12.0% of NB-OCOCH3 molar ratio obtained
by Ni(II)/B(C6F5)3. The dates are recorded at a speed at 5 mm/min.
The tensile curves of the copolymer films with different
NB-OCOCH3 content are shown in Figure 13, and the me-
chanical properties are presented in Table 5. As can be
seen, the copolymer film shows better mechanical proper-
ties with the content of NB-OCOCH3 increasing in the
copolymers. The film of copolymer that contains 12.0% NB-
OCOCH3 shows best mechanical properties, the tensile
strength is 22.7 MPa, the elastic modulus is 1.32 GPa. This
phenomenon is due to the NB-OCOCH3 can make the poly-
mer chains flexible.
(a) 10.09 Å, (b) 10.55 Å, (c) 10.98 Å, (d) 10.49 Å, (e)
10.61 Å, and (f) 14.62 Å. The packing density became smaller
with the increasing of NB-OCOCH3 content in the copolymers,
and the packing density of the copolymers obtained by Pd(II)/
B(C6F5)3 is smaller than those obtained by Ni(II)/B(C6F5)3.
dinterchain ¼ 1:22dBragg ¼ 1:22k=ð2 sin hÞ
(6)
TGA and DSC Analyses of Copolymers
CONCLUSIONS
The TGA curves of the copolymers with different NB-OCOCH3
content prepared by Ni(II)/B(C6F5)3 are shown in Figure 9.
The decompose temperature (Td) of the polymers are as
high as 317.5–421.1 ꢁC and decreases with NB-OCOCH3
increased in copolymers. The Td of the polymers obtained by
Pd(II)/B(C6F5)3 are lower than that of the polymers obtained
by Ni(II)/B(C6F5)3.
Two bis(b-ketoamino) type late transition metal complexes
were synthesized, characterized by single crystal X-ray tech-
nique, and used for the copolymerization of NB and NB-
OCOCH3 together with B(C6F5)3. The catalytic activities of
two complexes on homopolymerization of NB are as high as
105 gpolymer/molMt h. Toward the copolymerization of NB
and NB-OCOCH3, Ni (II)/B(C6F5)3 shows high activity,
whereas Pd(II)/B(C6F5)3 shows very lower activity and the
catalytic activities decreased with increasing of NB-OCOCH3
in feed content. The reactivity ratios were determined to
be rNB-OCOMe ¼ 0.08, rNB ¼ 7.94 for Ni(II)/B(C6F5)3; and
rNB-OCOMe ¼ 0.07, rNB ¼ 6.49 for Pd(II)/B(C6F5)3 by Kelen–
Tu¨do˜s method. The structures of the obtained polymers are
The DSC curves and glass transition temperature (Tg) of the
copolymers with different NB-OCOCH3 content prepared by
Ni(II)/B(C6F5)3 are shown in Figure 10. The Tg of the poly-
mers are up to 243.2–302.4 ꢁC when the content of NB-
OCOCH3 increased in the copolymers. The Tg of the polymers
obtained by Pd(II)/B(C6F5)3 are lower than the polymers
obtained by Ni(II)/B(C6F5)3.
1
confirmed to be vinyl-addition polymer by H NMR and FTIR
The polymers with different NB-OCOCH3 content prepared
by Ni(II)/B(C6F5)3 were dissolved in CHCl3 and homopoly-
mer of NB prepared by Ni(II)/B(C6F5)3 and Pd(II)/B(C6F5)3
were dissolved in o-dichlorobenzene as the mass fraction is
3%, after the solvent evaporated; the transparent polymer
films were obtained. Unfortunately, the films of NB homopoly-
mer cannot be obtained because of its brittle nature, and the
copolymers prepared by Pd(II)/B(C6F5)3 also cannot be
obtained because of its low MW.
characterizations. The copolymers of NB and NB-OCOCH3
exhibited better solubility and mechanical properties than
that of NB homopolymer and show high transparency and
high glass transition temperature (Tg ¼ 263.9–277.5 ꢁC).
With the increase of NB-OCOCH3 content, the MW, Tg, and Td
decreased, whereas the mechanical properties became better
and the packing density became smaller. When compared
with the copolymers obtained by Ni(II)/B(C6F5)3, copolymer
obtained by Pd (II)/B(C6F5)3 shows relative lower Tg, Td,
MW, and packing density.
DMA Analyses of the Films
Financial support for this work was provided by the National
Natural Science Foundation of China (51073076, 50902067,
and 51003045).
The DMA curves of the copolymer films with different NB-
OCOCH3 content were recorded by a TA Q800 DMA. The
films became too brittle to break with the increase of the
temperature and only the Tg of copolymer with 12.0% NB-
OCOCH3 content can be prepared. The loss factor curve of
the copolymer with NB-OCOCH3 content of 12.0% was
shown in Figure 11. Following the insertion of NB-OCOCH3,
the b relaxation appeared due to the NB-OCOCH3 group, and
the Tg of copolymer in the a relaxation region can be also
observed in the range of 242.9–264.8 ꢁC. These results are
consistent with that observed by DSC.
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