Highly Efficient Ethylene/Cyclopentene Copolymerization with Exclusive 1,2‐Cyclopentene Incorporation by (Cyclopentadienyl)(ketimide)titanium(IV) Complex–MAO Catalysts

Abstract

The (cyclopentadienyl)(ketimide)titanium(IV) complex (t‐BuC5H4)TiCl2[N=C(t‐Bu)2] exhibited remarkable catalytic activities (1.99–3.16×104 kg polymer/mol Ti⋅h) with efficient cyclopentene incorporation in ethylene/cyclopentene copolymerization in the presence of methylaluminoxane (MAO). The polymerization took place with exclusive 1,2‐cyclopentene incorporation, affording high molecular weight (alternating) copolymers (cyclopentene<43.6 mol %) with uniform distributions. The effect of the cyclopentadienyl fragment (Cp′) in the copolymerization using Cp′TiCl2[N=C(t‐Bu)2] [Cp′=indenyl, t‐BuC5H4, C5Me5 (Cp*), C5H5 (Cp)] has been explored in the presence of MAO; the Cp′ plays an important key role in terms of both activity and efficient cyclopentene incorporation.

Design of Efficient Molecular Catalysts for Synthesis of Cyclic Olefin Copolymers (COC) by Copolymerization of Ethylene and α-Olefins with Norbornene or Tetracyclododecene

“…; Y = anionic ancillary donor such as aryloxy, ketimide, imidazolin-2-iminato, etc. )-that efficient catalysts for the desired copolymerization can be tuned by the ligand modification on both the cyclopentadienyl fragment and nature (and substituents) of the anionic donor ligand employed, as demonstrated in the ethylene copolymerization with NBE [22][23][24], TCD [53], cyclohexene [72], cyclopentene [73], 2-methyl-1-pentene [74], and the others [39,41,45], as summarized in Scheme 6. We thus believe that the results demonstrated here are promising in terms of the synthesis of new polymers, and provides a better understanding not only for the polymer design (combination of monomers), but also for the catalyst design for efficient synthesis.…”

Stereo-controlled synthesis of polyolefins with cycloalkane groups by using late transition metals

“…25 Compared with the corresponding homopolymers, the copolymerization of cyclic alkenes with ethylene or a-olefins produces polymers with cycloalkane groups in a relatively low density. [26][27][28][29][30][31][32][33][34] The average density of cyclic units along the polymer chain can be controlled by changing the molar ratio of monomers, and the polymer properties also vary accordingly. However, the accurate control of the distribution of cyclic units in the polymer chain has not been achieved.…”

Microstructure of Copolymers of Norbornene Based on Assignments of 13C NMR Spectra: Evolution of a Methodology

“…The 13 C NMR spectrum of poly(HED) depicted in Figure 11, assigned for comparison to literature data [52][53][54], proved clearly that HED was mainly incorporated as 1,3-cyclopentane (CP) units. This means that intramolecular cyclization of 1,2-inserted HED occurred before the next monomer insertion, and only a small fraction of the incorporated diene formed vinyl terminated branches (Vy) along the polymer backbone.…”

“…2D data allowed us to assign the other signals: (i) from the correlations of the two methyls in the HMBC spectrum, along the proton dimension, it was possible to assign the closest carbon atoms C3, C4, and C5; (ii) the methyl protons at 0.82 ppm, (CH3 at 22.69 ppm) correlate with three carbons at 26.77, 35.65, and 39.34 ppm, respectively, and allowed us to assign the C4 atom, C5 and C3 of trans stereoisomer; (iii) from HMBC spectrum, the resonances of the cis stereoisomer positioning at 30.36, 33.59, and 37.56 ppm were assigned to C5, C4, and C3, respectively; (iv) the other signals were assigned as follows: 42.18 ppm to C1; 37.14 ppm to C2; 33.73 ppm to C6 of the trans stereoisomer; 41.58 ppm to C1; 37.89 ppm to C2; 34.64 ppm to C6 of the cis stereoisomer. Figure 10 shows 13 C NMR spectra and a DEPT for poly(ethylene-co-1-MeCPE) prepared by ( t BuC5H4)TiCl2(O-2,6-Cl2C6H3)-MAO (8) Most resonances were assigned on the basis of DEPT spectra and comparison with those of poly(ethylene-co-CPE) [47][48][49][50][51][52][53].…”

“…HED can be inserted as a linear α-olefin; however, after insertion, Most resonances were assigned on the basis of DEPT spectra and comparison with those of poly(ethylene-co-CPE) [47][48][49][50][51][52][53].…”