Addition Oligomerization of Dicyclopentadiene: Reactivity of <i>Endo</i>
 and <i>Exo</i>
 Isomers and Postmodification

Zanchin, Giorgia; Leone, Giuseppe; Pierro, Ivana; Rapallo, Arnaldo; Porzio, William; Bertini, Fabio; Ricci, Giovanni

doi:10.1002/macp.201600602

Cited by 19 publications

(27 citation statements)

References 61 publications

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“…The copolymer microstructure was established by 13 C NMR . In the case of E/DCPD copolymers, the peaks at 130.6 and 128.8 ppm in 13 C NMR spectrum (Figure ) and those at about 5.5 and 5.4 ppm in the 1 H NMR spectra (Figure S8) were assigned to sp 2 C and H atoms, respectively, revealing that the copolymers contain unreacted cyclopentene units . This suggests that the reaction took place selectively at the norbornene unit and that no cross-linking occurred.…”

Section: Results and Discussionmentioning

confidence: 97%

Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

et al. 2018

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The synthesis and the characterization of a series of phosphine adducts of (imido)vanadium(IV) dichloride complexes of the type V(NR)Cl 2 (PMe 2 Ph) 2 [R = 2,6-Cl 2 -Ph (1), 2,6-i Pr 2 -Ph (2), and t Bu (3)] and V( N t Bu)Cl 2 (PMe 3 ) 2 (3′) are reported. The solid-state structures of 1 and 3′ were determined by X-ray crystallography. The complexes present a geometry around the metal center between a distorted trigonal-bipyramid and a square pyramid, with an almost linear N−V−C bond. Complexes 1−3 were evaluated as catalyst precursors for the polymerization of ethylene and ethylene copolymerization with various cyclic olefins (i.e., norbornene, dicyclopentadiene, 5-ethylidene-2-norbornene, and 5-vinyl-2-norbornene). In combination with Et 2 AlCl (500 equiv to V) and Cl 3 CCO 2 Et (ETA, 10 equiv to V), 1−3 are versatile and promising catalysts for the synthesis of high molecular weight linear poly(ethylene)s and alternating copolymers with efficient comonomer incorporation, unimodal molecular weight distributions, and uniform composition under mild conditions. Differences in the homo-and copolymerization of ethylene regarding the activity, stability over temperature, reactivity toward the target comonomers, and (co)polymer chain growth were investigated to probe the effects of imido ligand substitution. The introduction of more electron-donating groups led to an increase in polymers molecular weight and provided increased stability over temperature to the catalysts, particularly for 3. Both of these effects are likely because the tert-butyl imido moiety in 3 strengthens the V−N bond, thus improving the stability of the active intermediate. The steric shielding of the tert-butyl group may also contribute to inhibit the associative chain transfer. Control over the molecular weight of the resultant copolymers proved to be possible also by varying the ETA loading. ETA acts as a reoxidant, restarting the catalytic cycle, but it behaves also like a chain transfer agent and to a different extent strongly depending on the type of imido ligand.

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Section: Results and Discussionmentioning

confidence: 97%

Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

et al. 2018

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“…The exo ‐face is less sterically hindered and in the case of model compounds the insertion was only on the exo‐ face of norbornene in the presence of Pd‐catalysts . The exo‐ insertion was also confirmed by the X‐ray analysis of oligomers prepared from norbornene or dicyclopentadiene . To the best of our knowledge, there are not published examples of the endo‐ face insertion of norbornenes during addition polymerization in the presence of transition metal catalysts .…”

Section: Resultsmentioning

confidence: 77%

“…31 The exo-insertion was also confirmed by the X-ray analysis of oligomers prepared from norbornene [32][33][34][35] or dicyclopentadiene. 36,37 To the best of our knowledge, there are not published examples of the endoface insertion of norbornenes during addition polymerization in the presence of transition metal catalysts. 38 Therefore, we assume that the insertion occurred also via exo-face of exo-5trimethylsilylnorbornene.…”

Section: Addition Polymerizationmentioning

confidence: 99%

Stereoselective synthesis and polymerization of Exo‐5‐trimethylsilylnorbornene

Alentiev

Bermeshev

Старанникова

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Herein the stereoselective two‐step synthesis of pure exo‐5‐trimethylsilylnorbornene is reported. The monomer proved to be highly reactive in both metathesis and addition polymerization. ROMP polymerization was catalyzed by the first‐generation Grubbs catalyst. High‐molecular‐weight saturated addition polymers were prepared using nickel or palladium complexes as precatalysts and Na+[B(3,5‐(CF3)2C6H3)4]− and/or MAO as cocatalysts. The obtained addition polynorbornenes are highly gas permeable and microporous materials possessing large free volume and BET surface area (up to 540 m2/g). The influence of the substituent orientation (exo‐ vs. exo‐/endo‐mixture) on polymer properties was established. The metathesis polymer based on exo‐isomer exhibits 1.5‐ to 2‐fold increase of permeability coefficients for all gases in comparison to the similar polymer based on the mixture of exo‐ and endo‐isomers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1234–1248

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“…The absorption band at 942 cm −1 is assigned to the bending of the C−H bonds in the ring system of NB, thus confirming that also the oligomerization of DCPD occurs through a 2,3-addition rather than via ROMP (Scheme 5). 95 The obtained products were characterized by thermal analysis. DSC scans carried out from −40 to 200 °C did not show any thermal event.…”

Section: Effects Of Polymerizationmentioning

confidence: 99%

Concerted Electron Transfer in Iminopyridine Chromium Complexes: Ligand Effects on the Polymerization of Various (Di)olefins

et al. 2018

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A study of reactions among CrCl2, CrCl3(THF)3, and iminopyridine ligands differing in the nature of the substituents at the iminic carbon and at the ortho positions of the aryl ring (2,6-R1 2C6H3NCR2(C5H3N) (R1 = R2 = H (L1); R1 = iPr, R2 = H (L2); R1 = H, R2 = CH3 (L3)) but featuring close electron-accepting properties has provided a new example of the redox chemistry of chromium complexes. The reactions of unsubstituted aniline L1 and of L3 with CrCl2 give rise to [(L1 •)CrIIICl2(THF)]− (Cr1) and [(L3 •)CrIIICl2(THF)]− (Cr3) complexes, respectively, containing chromium in the physical trivalent oxidation state and the ligand in the monoanionic radical state (L•)− as a result of a one-electron transfer from the metal to the ligand. In contrast, the reactions of CrCl2 with the ortho-substituted L2 and of CrCl3(THF)3 with the unsubstituted L1 give rise to [(L2)CrIICl2(THF)]0 (Cr2) and [(L1)CrIIICl3(THF)]0 (Cr4) having the chromium in the divalent and trivalent oxidation states, respectively, and the unperturbed ligand in the neutral state. All four complexes were used, in combination with methylaluminoxane (MAO), as catalyst precursors for the polymerization of ethylene, cyclic olefins (i.e., norbornene and dicyclopentadiene), and 1,3-butadiene. A chromium to ligand synergy, coupled with a good stability of the active intermediate in the presence of the Al activator, proven particularly effective in the polymerization of ethylene, especially for Cr1, giving high molecular weight linear poly(ethylene)s. The formalism in the metal oxidation state does not affect the reactivity toward the cyclic olefins and 1,3-butadiene, while ligand steric effects emerge clearly. The use of bulky ortho substituents shuts down the activity in the polymerization of cyclic olefins, particularly for the bulkier dicyclopentadiene, and reverses the catalyst chemoselectivity in the polymerization of 1,3-butadiene.

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Addition Oligomerization of Dicyclopentadiene: Reactivity of Endo and Exo Isomers and Postmodification

Cited by 19 publications

References 61 publications

Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

Stereoselective synthesis and polymerization of Exo‐5‐trimethylsilylnorbornene

Concerted Electron Transfer in Iminopyridine Chromium Complexes: Ligand Effects on the Polymerization of Various (Di)olefins

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