Isoprene Polymerization with Pyrazolylimine Cobalt(II) Complexes: Manipulation of 3,4‐Selectivities by Ligand Design and Use of Triphenylphosphine

Fang, Liang; Zhao, Wenpeng; Han, Chao; Liu, Heng; Hu, Yanming; Zhang, Xuequan

doi:10.1002/ejic.201801107

Cited by 15 publications

(7 citation statements)

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“…A search of the literature regarding Cl-bridged cobalt complexes revealed the following: (i) one, two and three Cl-bridges between Co atoms have been reported, (ii) one Cl-bridge was reported in co-existence with other bridges based on O or N atoms [ [53] , [54] , [55] ], (iii) in the case of two [ [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] ] and three Cl-bridges [ [66] , [67] , [68] ], the compounds were di- [ [56] , [57] , [58] , [59] ], tri- [ 60 , 61 ] or poly-nuclear [ 62 , 63 ] and in few cases polymeric [ 64 , 65 ], (iv) in complexes having only Cl-bridges, the reported Co…Co separation distance was in the range 3.024–4.006 Å [ [66] , [67] , [68] ]. Considering all these data, we may suggest that the structure of complex 1 is among the rare cases containing the existence of a unique Cl-bridge between Co atoms and the reported Co…Co of 3.988 Å is within the range found for Cl-bridged cobalt atoms.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, structural determination, in vitro and in silico biological evaluation of divalent or trivalent cobalt complexes with indomethacin

Perontsis

Geromichalou

Perdih

et al. 2020

Journal of Inorganic Biochemistry

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The interaction of cobalt chloride with the non-steroidal anti-inflammatory drug indomethacin (Hindo) led to the formation of the polymeric complex [Co(indo-O) 2 (H 2 O) 2 (μ-Cl)] n ·n(MeOH·H 2 O) bearing one chlorido bridge between the cobalt atoms. The presence of the nitrogen-donor co-ligands 2,2′-bipyridine (bipy), 2,2′-bipyridylamine (bipyam), 1,10-phenanthroline (phen) or 1 H -imidazole (Himi) resulted in the isolation of complexes [Co 2 (μ-indo-O,O′) 2 (indo-O) 2 (bipy) 2 (μ-H 2 O)]·3.3MeOH, [Co(indo-O,O′) 2 (bipyam)]·0.9MeOH·0.2H 2 O, [Co(indo-O,O′) 2 (phen)] ( 4 ) and [Co(indo-O) 2 (Himi) 2 ] ( 5 ), respectively, where the indomethacin ligands were coordinated in diverse manners. The study of the affinity of the complexes for calf-thymus DNA revealed their intercalation between the DNA-bases. The binding of the complexes to albumins was also examined and the corresponding binding constants and binding subdomain were determined. The free radical scavenging activity of the compounds was evaluated towards 1,1-diphenyl-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid). Molecular modeling calculations may usually provide a molecular basis for the understanding of both the impairment of DNA by its binding with the studied complexes and the ability of these compounds to transportation through serum albumin proteins. This study can provide information for the elucidation of the mechanism of action of the compounds in a molecular level.

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Section: Resultsmentioning

confidence: 99%

Synthesis, structural determination, in vitro and in silico biological evaluation of divalent or trivalent cobalt complexes with indomethacin

Perontsis

Geromichalou

Perdih

et al. 2020

Journal of Inorganic Biochemistry

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“…273,275 Stereoblock polybutadienes have also been obtained with catalytic systems based on neodymium 269 and transition metals (Cr, Fe, Co). 266 Stereoblock polymers have also been prepared in the case of isoprene, using catalytic systems based on cobalt 270,271,274 and lanthanides (Y, Nd). 263,264,267,268,272 6.…”

Section: Stereoblock Diene Polymersmentioning

confidence: 99%

“…The recent discovery and introduction of new catalytic systems having not only high catalytic activity and selectivity but also some living features and the ability to change their selectivity during polymerization while maintaining their living nature can be extremely useful for this purpose. The strategies adopted to modify the selectivity during the polymerization runs are of different types, ranging from adding a specific ligand to changing the cocatalyst (i.e., different type of aluminum alkyl) and from increasing the Al/Mt molar ratio to modifying the polymerization temperature. ,,− …”

Section: Stereoblock Diene Polymersmentioning

confidence: 99%

Dienes Polymerization: Where We Are and What Lies Ahead

Ricci¹,

Pampaloni

Sommazzi

et al. 2021

Macromolecules

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Recently, the research activity in the field of the stereospecific polymerization of conjugated dienes has focused on the use of catalysts based on organometallic complexes having a well-defined structure and containing ligands of various types (e.g., phosphines, bis-imines, and pyridylimines), since it has been observed that the nature of the ligand, as expected on the basis of the diene polymerization mechanism proposed several years ago by Porri, is able to exert a strong influence on the polymerization regioand stereoselectivity, on the polymer molecular weights and their distribution, and in some cases to impart a living feature to the catalysts themselves. In this Perspective we highlight the most recent results obtained in this field and discuss possible future developments in this area.

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“…Despite the successes achieved in the field of polyisoprene synthesis, the preparation of polydienes with the desired properties is still the focus of attention of researchers. Another challenge is the development of highly selective catalysts for the synthesis of trans -1,4- − and 3,4-PIPs, − as well as catalytic systems capable of switching their stereoselectivity depending on their composition. − …”

Section: Introductionmentioning

confidence: 99%

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

et al. 2021

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The isolable bis(tetramethylaluminate) lanthanide complexes [2-R2,6-XC6H4NC(tBu)(2,6-R1 2C6H3)]Ln(AlMe4)2 (R1 = R2 = X = Me, Ln = La (1); R1 = R2 = X = Me, Ln = Nd (2); R1 = iPr, R2 = H, X = OMe, Ln = La (3); R1 = iPr, R2 = H, X = OMe, Ln = Nd (4)) coordinated by bi- and tridentate amidinate ligands were synthesized by the reactions of the amidines 2,6-Me2C6H3NC(tBu)NH-2,6-Me2C6H3 and 2,6-iPr2C6H3NC(tBu)NH-2-MeOC6H4 with Ln(AlMe4)3 (Ln = La, Nd) and were isolated in 81, 75, 86, and 74% yields, respectively. X-ray analyses revealed that complexes 3 and 4 feature intramolecular coordination of an OMe group to the metal ions. Both AlMe4 fragments in complexes 3 and 4 coordinate to the metal centers in a κ2 mode, while in Nd complex 2 one AlMe4 group adopts a κ2 and the second a κ3-coordination mode. Complexes 1–4 were evaluated as precatalysts for isoprene polymerization. The ternary catalytic systems 1–4/[Ph3C][B(C6F5)4],[PhNHMe2][B(C6F5)4]/nAlR3 (AlR3 = AlMe3, n = 10; AliBu2H, n = 1; AliBu3, n = 10) enable 82–100% conversions of 1000 equiv of monomer at 25 °C within 5–60 min. cis-1,4-Selectivity of the ternary catalytic systems proved to be affected by the type of ligand, the borate, the AlR3 cocatalyst, and the nature of the metallo center and varied in the range of 34.4–91.8%. The binary systems 1–4/[Ph3C][B(C6F5)4],[PhNHMe2][B(C6F5)4] also catalyze isoprene polymerization and afford polyisoprenes containing 96.2–99.0% of cis-1,4 units in polymer chains. The stereoselectivity of binary systems containing complex 1 dramatically depends on the type of borate: 66.8% of trans-1,4 for [Ph3C][B(C6F5)4] and 87.8% of cis-1,4 for [PhNHMe2][B(C6F5)4].

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Isoprene Polymerization with Pyrazolylimine Cobalt(II) Complexes: Manipulation of 3,4‐Selectivities by Ligand Design and Use of Triphenylphosphine

Cited by 15 publications

References 57 publications

Synthesis, structural determination, in vitro and in silico biological evaluation of divalent or trivalent cobalt complexes with indomethacin

Synthesis, structural determination, in vitro and in silico biological evaluation of divalent or trivalent cobalt complexes with indomethacin

Dienes Polymerization: Where We Are and What Lies Ahead

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

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