Article pubs.acs.org/Organometallics
Copolymerization of Ethylene with 1‑Hexene and 1‑Octene Catalyzed by Fluorenyl N‑Heterocyclic Carbene Ligated Rare-Earth Metal Precursors Changguang Yao,†,‡ Chunji Wu,† Baoli Wang,†,‡ 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 ‡ Graduate School of the Chinese Academy of Sciences, Beijing 100039, People’s Republic of China S Supporting Information *
ABSTRACT: Rare-earth metal bis(alkyl) complexes (Flu−NHC)Ln(CH2SiMe3)2 (Ln = Dy (1), Er (2), Sc (3)) attached by fluorenyl-modified N-heterocyclic carbene ligands ((Flu H−NHC−H)Br) have been synthesized by treatment of (FluH−NHC− H)Br with (trimethylsilylmethyl)lithium (LiCH2SiMe3) and rare-earth metal tris(alkyl)s (Ln(CH2SiMe3)3(THF)2) via doubledeprotonation reactions in moderate to high yields. Under mild conditions (40 °C and normal ethylene pressure), the scandium precursor 3, upon activation of AliBu3 and [Ph3C][B(C6F5)4], showed high activity (4120 kg molSc−1 h−1 atm−1) for the copolymerization of ethylene and 1-hexene with moderate 1-hexene insertion ratio (20.2%), although the analogous complexes 1 and 2 were inert. In addition, this system displayed excellent catalytic performances for the copolymerization of ethylene and a higher α-olefin 1-octene with an activity of up to 3640 kg molSc−1 h−1 atm−1. The content of 1-octene could be controlled swiftly from 2.1% to 38.7% by varying the 1-octene feed ratio. Thus the isolated P(E-co-Oct) polymers varied from opaque crystalline solids with high melting points, e.g., Tm = 103.6 °C, to transparent elastomers. This represents the first rare-earth metal based homogeneous catalyst that can initiate the copolymerization of ethylene and 1-octene, the catalytic performances of which are comparable with those reported for the most active group 4 metallocene systems.
■
INTRODUCTION Polyethylene bearing a small amount of branches commercially known as linear low-density polyethylene (LLDPE) has been extensively investigated in the past decades and found a wide application as film, packaging material, and lubricant owing to its reduced density, crystallinity (Xc), and rigidity as compared with polyethylene (PE) and the obviously improved clarity and impact strength performances over PE.1 To date, three methods are adopted to prepare LLDPE:2 (i) copolymerization of ethylene with α-olefins; (ii) copolymerization of ethylene with ethylene oligomer generated in situ in the polymerization; (iii) ethylene homopolymerization catalyzed by nickel-diimine complexes through the “chain walking” mechanism. Among these, the copolymerization of ethylene with higher α-olefins such as 1-hexene or 1-octene has received increasing attention; it is a more straightforward manner to precisely control the molecular weight, molecular weight distribution, monomer sequences, and especially the length and content of the © 2013 American Chemical Society
branches of the polymer that govern significantly the properties of the resultant LLDPE.3 The most extensively investigated catalysts for the copolymerization of ethylene and α-olefins are Ziegler−Natta heterogeneous multisite catalysts4 and welldefined homogeneous discrete group 4 metallocene catalysts.5 Although a variety of rare-earth metal complexes have been successfully employed as single-component catalysts or precursors of the cationic active species upon activation with aluminum alkyl, methyl aluminum oxide, or organoborate in various polymerizations of ethylene, styrene, 1,3-conjugated dienes, and polar monomers such as methacrylates and cyclic esters,6 few can initiate the homopolymerization of α-olefins and show low or no activity toward the copolymerization of ethylene with α-olefins.7 Very recently a cationic half-sandwich rare-earth metal alkyl species arising from the system Received: January 28, 2013 Published: March 19, 2013 2204
dx.doi.org/10.1021/om4000709 | Organometallics 2013, 32, 2204−2209
Organometallics
Article
Scheme 1. Synthesis of Fluorenyl N-Heterocyclic Carbene (Flu-NHC) Ligated Rare-Earth Metal Bis(alkyl) Complexes 1−3
Figure 1. X-ray structures of complexes 1 (left) and 2 (right) with 40% probability thermal ellipsoids. Hydrogen atoms and solvent molecules are omitted for clarity.
Cp′Sc(CH2SiMe3)2(THF)/[Ph3C][B(C6F5)4] was reported to exhibit a high activity for ethylene and 1-hexene copolymerization.7g As far as we are aware, the copolymerization of ethylene with a higher α-olefin using rare-earth metal catalysts has still remained less explored, which is an obvious fascinating but challenging subject. Recently we focused on the study of the synthesis and catalysis of novel rare-earth metal complexes bearing cyclopentadienyl derivatives or non-cyclopentadienyl ligands.8 We found that aminophenyl- and pyridinyl-cyclopentadienyl rareearth metal complexes, the so-called constrained-geometryconfiguration catalysts (CGC), in combination with organoborate (or borane in some cases) and aluminum alkyls, displayed living-chain-transfer catalysis on the (co)polymerization of conjugated dienes and dual catalysis on high syndio-selective polymerization of styrene and highly cis1,4-selective polymerization of 1,3-conjugated dienes.8d−f Similar to the previous results, most of these catalysts are inactive toward ethylene and α-olefin polymerizations, whereas, when the fluorenyl-functionalized carbene ligands were introduced to support the scandium dialkyl moiety, the resultant CGC complexes, upon activation with AliBu3 and [Ph3C][B(C6F5)4], exhibited a high activity for the copolymerization of ethylene and norbornene.8c Herein, we report the exploration of such CGC precursors based on Dy, Er, and Sc metals on the copolymerizations of ethylene with higher αolefins such as 1-hexene and 1-octene, realizing for the first time excellent activity and high α-olefin incorporation rate comparable to the notable group 4 metallocene catalysts, giving elastic and transparent butyl and hexyl branched polyethylene.
The competitive polymerization ratios were provided as comparison.
■
RESULTS AND DISCUSSION The fluorenyl carbene ligated rare-earth metal bis(alkyl) complexes (Flu-NHC)Ln(CH2SiMe3)2 (Scheme 1, Ln = Dy (1), Er (2)) were prepared following the previously reported procedure.8b X-ray diffraction analysis revealed that the overall molecular structure of these complexes is solvent-free monomer with a tetragonal geometry (Figure 1 for complexes 1 and 2) analogous to the scandium complex 3 (Ln = Sc),8b indicating that the ligand provides enough steric protection to the metal centers irrespective of their ionic radii (Dy3+ = 0.912 Å, Er3+ = 0.890 Å, Sc3+ = 0.745 Å). However, the difference of central metal type arouses different bond lengths and bond angles. For instance, the average Ln−Cring increases with ionic radius of the central metal ion, Dy−Cring (2.709 Å) > Er−Cring (2.685 Å) > Sc−Cring (2.557 Å), as do the distances between the central metal ions and the centers of the five-membered rings, Dy− Ccent (2.419(3) Å) > Er−Ccent (2.392(2) Å) > Sc−Ccent (2.250(2) Å). In contrast, the bite angle (Ccent−Ln−C(16)) decreases slightly with the ionic radius, Ccent−Dy−C(16) (99.99(11)°) < Ccent−Er−C(16) (100.68(4)°) < Ccent−Sc− C(16) (105.53(11)°) (Table 1). All these complexes as single-component catalysts were inactive for the homopolymerization of either ethylene (E) or 1-hexene (1-Hex) or 1-octene (1-Oct). The scandium complex 3 activated by [Ph3C][B(C6F5)4] and AliBu3 gave cationic species, which showed moderate activity for the homopolymerization of E (100 kg molSc−1 h−1 atm−1), although its Dy and Er derivatives still remained inert, which might be due to the 2205
dx.doi.org/10.1021/om4000709 | Organometallics 2013, 32, 2204−2209
Organometallics
Article
Table 1. Selected Bond Lengths [Å] and Angles [deg] for Complexes 1−38b Ln−C(32) Ln−C(28) Ln−C(16) Ln−C(13) Ln−C(12) Ln−C(7) Ln−C(6) Ln−C(1) Ln−Cring Ln−Ccent C(28)−Ln−C(32) C(28)−Ln−C(16) C(32) −Ln−C(16) Ccent−Ln−C(16)
Ln = Dy
Ln = Er
Ln = Sc
2.372(4) 2.344(4) 2.502(3) 2.691(4) 2.710(4) 2.684(4) 2.720(4) 2.740(4) 2.709(4) 2.419(3) 104.56(16) 104.01(14) 107.41(13) 99.99(11)
2.351(8) 2.333(8) 2.473(11) 2.657(8) 2.714(11) 2.702(8) 2.667(7) 2.683(7) 2.685(8) 2.392(2) 104.0(3) 104.2(3) 106.4(3) 100.68(4)
2.208(4) 2.193(4) 2.343(4) 2.508(3) 2.575(4) 2.583(4) 2.560(4) 2.558(4) 2.557(4) 2.250(3) 103.68(15) 102.24(14) 104.35(14) 105.53(11)
Table 3. Copolymerization of Ethylene with 1-Oct by 3/ AliBu3/[Ph3C][B(C6F5)4]a
1-Oct feed time entry (mol/L) (min) 1 2 3 4 5 6 7f
0.1 0.2 0.3 0.4 0.5 0.8 4.0
5 5 5 5 5 5 240
activityb
1-Oct cont.c (mol %)
1.68 1.97 2.63 2.97 3.25 3.64
2.1 5.0 14.0 16.9 23.9 38.7
Mwd (104)
Mw/ Mnd
Tme (°C)
3.10 2.52 1.90 1.49 0.95 0.86 0.59
2.4 2.2 2.4 2.3 2.2 2.9 1.2
103.6 84.8
Conditions: Sc (20 μmol), [Ph3C][B(C6F5)4] (20 μmol), AliBu3 (400 μmol), toluene = 200 mL, pethylene = 1 atm. b106 g of copolymer g molSc−1 h−1 atm−1. cDetermined by 13C NMR spectroscopy. d Determined by means of gel permeation chromatography (GPC) against polystyrene standards. eDetermined by differential scanning calorimetry (DSC). fpethylene = 0 atm, toluene = 5 mL. a
Lewis acidity of the scandium ion enhancing the complexation of the olefin and central metal. Thus scandium-dominant activity was found in many other catalytic systems such as in the polymerizations of 1-hexene7g and styrene6i and in the copolymerization of ethylene−norbornene6k,lq by using the unlinked half-lanthanidocenes as the precursors. In a few other cases the activity of the cationic rare-earth metal based catalyst systems for ethylene polymerization increases with the central metal ionic radius.6p To our delight, this scandium ternary system can also initiate homopolymerization of higher α-olefins such as 1-Oct, which was the first example of a rare-earth metal based precursor having such a property (Table 3, entry 7). Moreover, this system displayed a high activity for the copolymerizations of E with 1-Hex and E with 1-Oct performed at 40 °C and a constant ethylene atmosphere (1 atm). In both copolymerizations, the catalyst activity increased almost linearly with the increase of the comonomer concentrations, achieving up to 4.12 × 106 and 3.64 × 106 g molSc−1 h−1 atm−1, respectively, which were much higher than those of homopolymerizations of these monomers. This result constituted a rare example of positive “comonomer effect” in copolymerizations of ethylene with an α-olefin.9 In the meantime, the contents of the α-olefins in the copolymers increased correspondingly with the 1-Hex or 1-Oct concentrations, meaning that copolymers with various compositions could be swiftly obtained by adjusting the monomer feed ratios. As shown in Table 2, when the 1-Hex concentration varied
from 0.1 mol/L to 0.8 mol/L, the content of the 1-Hex units increased from 2.95 mol % to 20.2 mol %, while when the 1Oct concentration varied from 0.1 mol/L to 0.8 mol/L, the content of the 1-Oct units increased from 2.1 mol % to 38.7 mol %. Noteworthy was that the contents of 1-Oct in P(E-coOct)s were higher than those of 1-Hex in P(E-co-Hex)s at comparable monomer feed concentrations, which might be attributed to the higher competitive polymerization rate for 1Oct (rO = 0.19 vs rE = 34.9, calculated based on the Finmann− Ross equation, Figure S1) than 1-Hex (rH = 0.03 vs rE = 23.2, Figure S2). This result was in contrast to the previous reports that 1-Oct is usually less active than 1-Hex.10 The molecular weights of the resultant P(E-co-Hex)s and P(E-co-Oct)s became lower when the comonomer incorporation ratio was higher. The presence of the α-olefin might accelerate βhydrogen elimination reaction in the copolymerization process as well as the chain-transfer reaction toward α-olefins.11,7g This could be proved by the formation of −CHCH2 chain-ends (Figure S3). On the basis of 13C NMR data,12 all possible triad sequences probably occurring in the copolymers are summarized in Tables S1 and S2. The 13C NMR spectrum of a selected P(E-co-Hex) sample (1-Hex 20.2%) shows a singlet at δ 38.34 attributed to
Table 2. Copolymerization of Ethylene with 1-Hex by 3/AliBu3/[Ph3C][B(C6F5)4]a
entry
1-Hex feed (mol/L)
time (min)
activityb
1-Hex cont.c (mol %)
Mwd (104)
Mw/Mnd
Tme (°C)
1 2 3 4 5 6
0.1 0.2 0.3 0.4 0.5 0.8
5 5 5 5 5 5
0.76 1.55 2.26 3.23 3.65 4.12
2.95 3.54 5.74 14.3 17.7 20.2
5.52 4.62 4.13 1.58 1.54 1.44
1.9 2.2 2.2 2.2 2.3 2.3
116.8 95.7 78.0
Conditions: Sc (20 μmol), [Ph3C][B(C6F5)4] (20 μmol), AliBu3 (400 μmol), toluene = 200 mL, pethylene = 1 atm. b106 g of copolymer g molSc−1 h−1 atm−1. cDetermined by 13C NMR spectroscopy. dDetermined by means of gel permeation chromatography (GPC) against polystyrene standards. e Determined by differential scanning calorimetry (DSC). a
2206
dx.doi.org/10.1021/om4000709 | Organometallics 2013, 32, 2204−2209
Organometallics
Article
Figure 2. 13C NMR spectrum of P(E-co-Hex) with 3/AliBu3/[Ph3C][B(C6F5)4] (Table 2, entry 6).
Figure 3. 13C NMR spectrum of P(E-co-Oct) with 3/AliBu3/[Ph3C][B(C6F5)4] (Table 3, entry 6).
homopolymerization of 1-Oct was successful for the first time by using a rare-earth metal precursor in a 75% yield within 4 h. The physical properties of the copolymers were characterized by the DSC analysis, as shown in Figures 4 and 5, which show two endothermic peaks consistent with the previous report.14 In general, a decrease of the melting point and broadening of the peak are observed as a result of higher α-olefin content in the copolymer. The P(E-co-Hex) with a lower 1-Hex percentage (2.95 mol %) has a relatively higher melting temperature, Tm = 116.8 °C (Figure 4 A), which drops drastically to 78.0 °C with a minor increase in the 1-Hex content (5.74 mol %). No obvious Tm can be observed when the content of 1-Hex reaches over 14%, suggesting that the presence of butyl side chains interrupts the crystallinity of the ethylene sequences efficiently. Thermograms of P(E-co-Oct)s have the same tendency as described for P(E-co-Hex)s. The Tm value of P(E-co-Oct) dropped from 103.6 °C to 84.8 °C in accordance with the 1-Oct content increasing slightly from 2.1% to 5.0%. Because of the long hexyl side chains, the P(E-co-
the EHE methine carbon and the resonance at 30.13 arising from polyethylene sequences. The signals at δ 35.23(αγ), 34.75(αδ+), 31.12(γγ), 30.63(γδ+), 27.45(βδ+), and 24.71(ββ) are ascribed to the methylene carbons from EEH, HEH, and EHE triads, while the butyl side chains give resonances at δ 34.30(4B4), 29.67(3B4), 23.49(2B4), and 14.20(1B4) ppm (Figure 2). No contiguous 1-Hex units are found (δ 40−41 ppm).7g The 13C NMR spectrum of a selected P(E-co-Oct) sample (1-Oct content = 38.7 mol %) (Table 3, entry 6) gives a different topology from that of E-co-Hex. Besides the signals from the joint EOE, EEO, OEO, and EEE units, the signals at δ 41.03, 40.38, and 36.00 ppm arise obviously from αα and CHEOO carbons, indicating the presence of the contiguous Oct−Oct sequences in the polymer chain (Figure 3).13 The complexity of the spectrum also suggests the random arrangement of the two types of sequences. When the 1-Oct incorporation ratio achieves 38.7 mol %, the resonance correlating with the OOO triad is also visible. In fact, when the polymerization temperature was raised to 80 °C, 2207
dx.doi.org/10.1021/om4000709 | Organometallics 2013, 32, 2204−2209
Organometallics
Article
solvents were purified from an MBraun SPS system. AliBu3 (1.0 M in hexane), 1-Hex (97%), and 1-Oct (98%) were purchased from Aldrich. Polymerization grade ethylene was donated by the China Petroleum & Chemical Corporation. Toluene, 1-Hex, and 1-Oct were purified over Na/K alloy and distilled under reduced pressure prior to polymerization. (Flu-NHC)Sc(CH2SiMe3)28b and [Ph3C][B(C6F5)4]15 were prepared according to the literature. Elemental analyses were performed at National Analytical Research Centre of Changchun Institute of Applied Chemistry (CIAC). 1H and 13C NMR spectra were recorded on a Bruker AV 400 (FT, 400 MHz for 1H; 100 MHz for 13C). Crystallographic data were collected at −86.5 °C on a Bruker SMART APEX diffractometer with a CCD area detector (Mo K, λ = 0.710 73 Å). The determination of crystal class and unit cell parameters was carried out by the SMART program package. The structures were solved by using the SHELXTL program. Synthesis of Complex (Flu−NHC)Dy(CH2SiMe3)2 (1). (FluH− NHC−H)Br (0.168 g, 0.366 mmol), LiCH2SiMe3 (0.035 g, 0.366 mmol), and 10 mL of toluene were added to a flask. After reacting for 20 min under vigorous stirring, the reaction mixture was added to a toluene solution (10 mL) of Dy(CH2SiMe3)3(THF)2 (0.208 g, 0.366 mmol). The mixture remained stirring for another 2 h until it turned to a clear solution. Concentration, filtration, and cooling at −30 °C afforded yellow single crystals of complex 1 (0.168 g, 64.3%). Anal. Calcd for C35H47DyN2Si2 (%): C 58.75; H 6.64; N 3.92. Found: C 58.05; H 6.37; N 3.71. Synthesis of Complex (Flu−NHC)Er(CH2SiMe3)2 (2). Following the procedure described for the formation of 1, the reaction of (FluH− NHC−H)Br (0.168 g, 0.366 mmol) with LiCH2SiMe3 (0.035 g, 0.366 mmol) and Er(CH2SiMe3)3(THF)2 (0.210 g, 0.366 mmol) afforded 2 (0.155 g, 58.9%). Anal. Calcd for C35H47ErN2Si2 (%): C 58.45; H 6.60; N 3.90. Found: C 57.73; H 6.38; N 3.68. Ethylene and 1-Oct (or 1-Hex) Copolymerization Procedure. In the glovebox, a Schlenk flask containing a magnetic stirring bar was charged with a toluene solution of alkyl aluminum, which was equipped with an ampule bottle filled with 2 mL of a toluene solution of (Flu-NHC)Ln(CH2SiMe3)2, AliBu3, and [Ph3C][B(C6F5)4]. The flask was taken out of the glovebox, connected to the Schlenk line, set in a thermostated oil bath, and then degassed and saturated with ethylene, which was followed by injecting the α-olefin comonomer and stirring vigorously for 15 min. Then the toluene solution containing the catalyst in the ampule bottle was quickly transferred to the flask, which immediately initiated the copolymerization. The polymerization was terminated by addition of acidified ethanol. The reaction mixture was slowly poured into 300 mL of ethanol to give a precipitate that was purified by filtration, washing with mass ethanol, and drying under vacuum at 60 °C for several hours. The obtained polymer was a white solid or transparent elastomer depending on the α-olefin content. Polymer Characterization. 13C NMR spectra for the copolymers were obtained on a Bruker AV400 (FT, 400 MHz for 1H; 100 MHz for 13C) working at 125 °C, and the sample solutions were prepared at 10% by weight in 1,2,4-trichlorobenzene. Hexamethyldisiloxane was used as internal reference. The α-olefin contents in the copolymers were calculated from the 13C NMR spectra.12 The number average molecular weights (Mn) and molecular weight distributions (Mw/Mn) of the copolymer samples were measured by means of gel permeation chromatography (GPC) on a PL-GPC 220 type high-temperature chromatograph equipped with three PL-gel 10 μm Mixed-B LS type columns at 150 °C. 1,2,4-Trichlorobenzene (TCB) containing 0.05 w/ v % 2,6-di-tert-butyl-p-cresol (BHT) was employed as the eluent at a flow rate of 1.0 mL/min. The calibration was made by the polystyrene standard Easi Cal PS-1 (PL Ltd.). Tm of the copolymer was measured through differential scanning calorimetry (DSC) analysis, which was carried out on a METTLER TOPEM DSC instrument under a nitrogen atmosphere. The instrument was calibrated for temperature and enthalpy using pure indium (mp = 156.6 °C) and sapphire before experiment. Measurements during the first heating from 25 to 180 °C and then the first cooling from 180 to 25 °C as well as the second heating from 25 to 180 °C at 10 °C min−1 were performed.
Figure 4. Thermograms of P(E-co-Hex)s obtained with 3/AliBu3/ [Ph3C][B(C6F5)4] under the 1-Hex feed concentrations (mol/L): A, 0.1; B, 0.2; C, 0.3; D, 0.4.
Figure 5. Thermograms of P(E-co-Oct)s obtained with 3/AliBu3/ [Ph3C][B(C6F5)4] under the 1-Oct feed concentrations (mol/L): E, 0.1; F, 0.2; G, 0.3.
Hex) varied from crystalline plastic to a sticky liquid with the change of 1-Oct unit content.
■
CONCLUSION We have demonstrated that a ternary catalyst system composed of a CGC scandium bis(alkyl) complex bearing a fluorenylfunctionalized NHC ligand and AliBu3 and [Ph3C][B(C6F5)4] provides high activity for the copolymerization of ethylene with 1-Hex or with 1-Oct, while those based on other large ionic metals such as Dy and Er are inert. The microstructures of the copolymers are random. The 1-Hex units exist only as isolated fragments in the P(E-co-Hex) chains, while there are two or more 1-Oct-linked segments in P(E-co-Oct) because 1-Oct has a higher copolymerization competitive rate as compared with 1Hex. Thus linear low-density polyethylene with different length branches and α-olefin incoporation rates have been obtained by using scarce rare-earth metal based precursors via copolymerization of ethylene with higher α-olefins.
■
EXPERIMENTAL SECTION
General Considerations. All manipulations were performed under a dried and oxygen-free argon atmosphere using standard high-vacuum Schlenk techniques or in an MBraun glovebox. All 2208
dx.doi.org/10.1021/om4000709 | Organometallics 2013, 32, 2204−2209
Organometallics
■
Article
(6) (a) Hou, Z.; Wakatsuki, Y. Coord. Chem. Rev. 2002, 231, 1. (b) Gromada, J.; Carpentier, J.; Mortreux, A. Coord. Chem. Rev. 2004, 248, 397. (c) Hyeon, J.; Gottfriendsen, J.; Edelmann, F. Coord. Chem. Rev. 2005, 249, 2787. (d) Bambirra, S.; Bouwkamp, M.; Meetsma, A.; Hessen, B. J. Am. Chem. Soc. 2004, 126, 9182. (e) Kretschmer, W.; Meetsma, A.; Hessen, B.; Schmalz, T.; Qayyum, S.; Kempe, R. Chem.Eur. J. 2006, 12, 8969. (f) Zeimentz, P.; Arndt, S.; Elvidge, B.; Okuda, J. Chem. Rev. 2006, 106, 2404. (g) Hultzsch, K.; Voth, P.; Beckerle, K.; Spaniol, T.; Okuda, J. Organometallics 2000, 19, 228. (h) Luo, Y.; Yao, Y.; Shen, Q. Macromolecules 2002, 35, 8670. (i) Luo, Y.; Baldamus, J.; Hou, Z. J. Am. Chem. Soc. 2004, 126, 13910. (j) Kirillov, E.; Lehmann, C.; Razavi, A.; Carpentier, J. J. Am. Chem. Soc. 2004, 126, 12240. (k) Li, X.; Hou, Z. Macromolecules 2005, 38, 6767. (l) Li, X.; Baldamus, J.; Hou, Z. Angew. Chem., Int. Ed. 2005, 44, 962. (m) Yasuda, H.; Yamamoto, H.; Yokota, K.; Miyake, S.; Nakamura, A. J. Am. Chem. Soc. 1992, 114, 4908. (n) Piers, W.; Emslie, D. Coord. Chem. Rev. 2002, 233, 131. (o) Cabaret, O.; Vaca, B.; Bourissou, D. Chem. Rev. 2004, 104, 6147. (p) Arndt, S.; Spaniol, T.; Okuda, J. Angew. Chem., Int. Ed. 2003, 42, 5075. (q) Ravasio, A.; Zampa, C.; Okuda, J. Macromolecules 2008, 41, 9565. (7) (a) Jeske, G.; Schock, L.; Swepston, P.; Schumann, H.; Marks, T. J. Am. Chem. Soc. 1985, 107, 8103. (b) Koo, K.; Fu, P.; Marks, T. Macromolecules 1999, 32, 981. (c) Yasuda, H.; Desurmont, G. Polym. Int. 2004, 53, 1017. (d) Ward, B.; Bellemin-Laponnaz, S.; Gade, L. Angew. Chem., Int. Ed. 2005, 44, 1668. (e) Lukešová, L.; Ward, B.; Gade, L. Organometallics 2007, 26, 4652. (f) Ward, B.; Lukešová, L.; Gade, L. Eur. J. Inorg. Chem. 2009, 866. (g) Luo, Y.; Hou, Z. Stud. Surf. Sci. Catal. 2006, 161, 95. (8) (a) Wang, B.; Wang, D.; Cui, D.; Gao, W.; Tang, T.; Chen, X.; Jing, X. Organometallics 2007, 26, 3167. (b) Wang, B.; Cui, D.; Lv, K. Macromolecules 2008, 41, 1983. (c) Wang, B.; Tang, T.; Li, Y.; Cui, D. Dalton Trans. 2009, 8963. (d) Jian, Z.; Cui, D.; Hou, Z. Chem. Commun. 2010, 46, 3022. (e) Jian, Z.; Tang, S.; Cui, D. Chem.Eur. J. 2010, 16, 14007. (f) Jian, Z.; Tang, S.; Cui, D. Macromolecules 2011, 44, 7675. (g) Jian, Z.; Cui, D. Organometallics 2012, 31, 4267. (h) Jian, Z.; Cui, D.; Hou, Z. Chem.Eur. J. 2012, 18, 2674. (i) Pan, Y.; Rong, W.; Cui, D. Macromolecules 2012, 45, 1248. (j) Gao, W.; Cui, D. J. Am. Chem. Soc. 2008, 130, 4984. (9) (a) Chien, J.; Nozaki, T. J. Polym. Sci., Part A: Polym. Chem. 1993, 31, 227. (b) Irwin, L.; Reibenspies, J.; Miller, S. J. Am. Chem. Soc. 2004, 126, 16716. (10) Smit, M.; Zheng, X.; Chadwick, J. J. Polym. Sci., Part A: Polym. Chem. 2006, 44, 6652. (11) (a) Jaberb, I.; Fink, G. Macromol. Chem. Phys. 1994, 195, 2491. (b) Quijada, R.; Scipioni, R.; Mauler, R.; Galland, G.; Miranda, M. Polym. Bull. 1995, 35, 299. (c) Uozurni, T.; Toneri, T.; Soga, K. Macromol. Rapid Commun. 1997, 18, 9. (d) Joung, U.; Lee, B. Polyhedron 2005, 24, 1256. (12) (a) Kakugo, M.; Miyatake, T.; Mizunuma, K. Macromolecules 1991, 24, 1469. (b) Hsieh, E.; Randall, J. Macromolecules 1982, 15, 1402. (c) Seger, M.; Maciel, G. Anal. Chem. 2004, 76, 5734. (d) Liu, W.; Ray, D., III; Rinaldi, P. Macromolecules 1999, 32, 3817. (e) Liu, W.; Rinaldi, P. Macromolecules 2001, 34, 4757. (13) (a) Xu, G.; Ruckenstein, E. Macromolecules 1998, 31, 4724. (b) Randall, J. J. Macromol. Sci., Polym. Rev. 1989, 29, 201. (14) Czaja, K.; Białek, M. Polymer 2001, 42, 2289. (15) Chien, J.; Tsai, W.; Rausch, M. J. Am. Chem. Soc. 1991, 113, 8570.
ASSOCIATED CONTENT
S Supporting Information *
Cif files for the structural analyses and copolymerization data are available free of charge via the Internet at http://pubs.acs. org.
■
AUTHOR INFORMATION
Corresponding Author
*Fax: +86-431-85262773. E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work was partly supported by The National Natural Science Foundation of China for project nos. 51073148 and 21104072 and the Ministry of Science and Technology of China for project no. 2011DFR50650.
■
REFERENCES
(1) (a) James, D. Linear Low Density Polyethylene. In Encyclopedia of Polymer Science and Engineering; Mark, H.; Bikales, N.; Overberger, C.; Menges, G., Eds.; Wiley-Interscience: New York, 1985; Vol. 6, p 429. (b) Karol, F.; Jacobson, F. Catalysis and the Unipol Process. In Studies in Surface Sciences and Catalysis; Keii, T.; Soga, K. Elsevier Science: Amsterdam, 1986; Vol. 25. (c) Hennico, A.; Leonard, J.; Forestire, A.; Glaize, Y. Hydrocarbon Process. 1990, 69, 73. (d) Tait, P.; Berry, I. In Comprehensive Polymer Science; Pergamon: Oxford, 1989; Vol. 4, p 575. (e) Peacock, A. Handbook of Polyethylene: Structures, Properties, and Applications; M. Dekker: New York, 2000. (f) Mülhaupt, R. Macromol. Chem. Phys. 2003, 204, 289−327. (2) (a) Komon, Z.; Bazan, G. Macromol. Rapid Commun. 2001, 22, 467. (b) Quijada, R.; Rojas, R.; Bazan, G.; Komon, Z.; Mauler, R.; Galland, G. Macromolecules 2001, 34, 2411. (c) Wasilke, J.; Obrey, S.; Baker, R.; Bazan, G. Chem. Rev. 2005, 105, 1001. (d) Zhang, K.; Ye, Z.; Subramanian, R. Macromolecules 2009, 42, 2313. (e) McKnight, A.; Waymouth, R. Chem. Rev. 1998, 98, 2587. (f) Olabisi, O.; Atiqullah, M.; Kaminsky, W. Rev. Macromol. Chem. Phys. 1997, 37, 519. (g) Soga, K.; Shiono, T. Prog. Polym. Sci. 1997, 22, 1503. (h) Krentsel, B.; Kissin, Y.; Kleiner, V.; Stotskaya, L. Polymers and Copolymers of Higher αOlefins; Hanser/ Gardner Publications Inc.: Cincinnati, OH, 1997; p 243. (i) Sperber, O.; Kaminsky, W. Macromolecules 2003, 36, 9014. (j) Musikabhumma, K.; Spaniol, T.; Okuda, J. J. Polym. Sci., Part A: Polym. Chem. 2003, 41, 528. (k) Komon, Z.; Bu, X.; Bazan, G. J. Am. Chem. Soc. 2000, 122, 1830. (l) Komon, Z.; Bu, X.; Bazan, G. J. Am. Chem. Soc. 2000, 122, 12379. (m) Nomura, K.; Naga, N.; Miki, M.; Yanagi, K. Macromolecules 1998, 31, 7588. (3) (a) Cho, H.; Lee, W. Kor. J. Chem. Eng. 2002, 19, 557. (b) Müller, A.; Hernandez, Z.; Arnal, M.; Sábchez, J. J. Polym. Bull. 1997, 39, 465. (c) Krentsel, B.; Kissin, Y.; Kleiner, V.; Stotskaya, L. In Polymers and Copolymers of Higher α-Olefins; Carl Hanser Verlag: Munich, 1997; pp 243−335. (4) (a) Soga, K.; Kaminaka, M. Makromol. Chem. 1993, 194, 1745. (b) Wu, Q.; Wang, H.; Lin, S. Makromol. Chem. Rapid Commun. 1992, 13, 357. (c) Soares, J.; Hamielec, A. Polymer 1996, 37, 4599. (d) Li, C.; Shan, P.; Chu, K.; Soares, J.; Penlidis, A. Macromol. Chem. Phys. 2000, 201 (2), 195. (e) Mirabella, F.; Ford, E. J. Polym. Sci., Part B: Polym. Phys. 1987, 25 (7), 77−90. (5) (a) Köppl, A.; Babel, A.; Alt, H. J. Mol. Catal. A: Chem. 2000, 153, 109. (b) Carlini, C.; Alessio, A.; Giaiacopi, S.; Po, R.; Pracella, M.; Galletti, A.; Sbrana, G. Polymer 2007, 48, 1185. (c) Nomura, K.; Komatsu, T.; Imanishi, Y. J. Mol. Catal. A: Chem. 2000, 152, 249. (d) Murray, M.; Baird, M. J. Polym. Sci., Part A: Polym. Chem. 2000, 38, 3966. (e) Yano, A.; Hasegawa, S.; Kaneko, T.; Sone, M.; Sato, M.; Akimoto, A. Macromol. Chem. Phys. 1999, 200, 1542. (f) Wang, W.; Fan, Z.; Feng, L. Eur. Polym. J. 2005, 41, 2380. (g) Dankova, M.; Waymouth, R. Macromolecules 2003, 36, 3815. 2209
dx.doi.org/10.1021/om4000709 | Organometallics 2013, 32, 2204−2209
