Highly active and stereospecific polymerization of 1,3-butadiene catalyzed by bis{[2-(4,5-diphenylimidazolyl)phenylimino]phenolate}cobalt(II) complexes

Capability of PN3-type Cobalt Complexes toward Selective (Co-)Polymerization of Myrcene, Butadiene, and Isoprene: Access to Biosourced Polymers

“…Alternatively, an increase of the cis -1,4-content is observed at 300 equiv and further increasing of the Al-to-Co ratio to 500 slightly decreases the cis -1,4-content. In addition, the influence of the polymerization temperature on yield was also evaluated (Table , runs 2 and 4–6), the yield was found to change reversely to the polymerization temperature from 30 to 80 °C, probably since the active species are partially deactivated at higher temperature, in consistent to the reported cobalt systems . The stereo specficity of Co1 shows little sensitivity to changes in temperature which implies that structure of active species are thermally stabilized.…”

“…In (co)­polymerization of conjugated dienes, a cobalt-based system has unambiguously shown distinguished performances and received the earliest recognition in the academic and commercial production of cis -1,4 and 1,2-polybutadiene due to facile availability, high air and thermal stability of compound. Particularly, the versatility as well as tunable regio and stereoselectivity in polymerization of some substituted butadienes; − for example, the unique 1,2 stereospecificity toward butadiene ,,,,, as well as 3-methyl-1,3-pentadiene, affording semicrystalline to crystalline materials whose properties can be tuned by the catalyst formula as well as polymerization procedures . Nevertheless, cobalt has been less known for catalytic polymerization of isoprene and myrcene, ,, and the reason why subtle monomer difference causes large differences in reactivity and selectivity has not yet been explored.…”

Dienes Polymerization: Where We Are and What Lies Ahead

“…Highly cis -1,4-polybutadienes (∼95%) were obtained with catalysts based on bidentate phosphine Co complexes (CoCl 2 [R 2 P­(CH 2 ) n PR 2 ]–MAO; R = Me, Et, Ph; n = 1, 2), independently of the type of bidentate phosphine ligand bonded to the cobalt atom. ,, Predominantly cis -1,4-polybutadienes were also recently obtained with several new catalytic systems based on cobalt complexes with bi- and tridentate ligands containing N and/or O as donor atoms (e.g., bis-imines, bis-imino-pyridines, keto-imines, and keto-pyridinimines), regardless of the nature of the ligand coordinated to the cobalt atom. ,,,,− …”

“…Cobalt complexes with 2,6-bis­(imidate)­pyridyl ligands, bis­{[2-(4,5-diphenylimidazolyl)­phenylimino­[phenolate} ligands, 2,6-bis­(dimethyl-2-oxazolin-2-yl)­pyridine ligands, mixed ligands such as N - i - O -butyl­phosphino-6-(2′-methyl­benzoimidazole)-2-aminopyridine, and pyridine–imino ligands with bulky aryl substituents, in combination with MAO or EASC, also gave high cis -1,4-polybutadienes (Figure ).…”

A new Co(III) complex of Schiff base derivative for electrochemical recognition of nitrite anion

“…These bond lengths are comparable to those reported for corresponding cobalt complexes with Schiff base ligands. [50][51][52][53] The N-Co-N, O-Co-O, and N-Co-O bond angles are within the range of 84.0(2) • and 179.11 (19) • .…”