Stereospecific polymerization of 1,3-butadiene catalyzed by cobalt complexes bearing N-containing diphosphine PNP ligands

Lin, Chen; Ai, Pengfei; Gu, Jiande; Jie, Suyun; Li, Bo‐Geng

doi:10.1016/j.jorganchem.2012.05.051

Cited by 38 publications

(24 citation statements)

References 56 publications

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“…For example, upon activation with methylaluminoxane (MAO), CoCl 2 [12e14] and cobalt 2-ethylhexanoate [15] are stereoselective to produce cis-1,4-PBDs; however, the addition of alkylphosphines or pyridyl adducts will lead to the obvious increase of 1, [26,27] or various tridentate ligands [28e37]. Except for the above achievements, we also explored the welldefined cobalt complexes for the stereospecific polymerization of 1,3-butadiene, including dinuclear cobalt(II) complexes with [NOO e ] ligands [38], cobalt dichloride complexes with tridentate [NNO] ligands [39,40] and P-containing ligands [41,42]. In order to investigate the influence of ligand structures and different type of coordinated atoms on the catalytic activity and properties of PBDs, a new type of [NNO] ligands, {[2-(4,5-diphenyl-imidazolyl)phenylimino]methyl}phenols, has been designed and synthesized.…”

Section: Introductionmentioning

confidence: 99%

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

Jie

2015

Journal of Organometallic Chemistry

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Section: Introductionmentioning

confidence: 99%

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

Jie

2015

Journal of Organometallic Chemistry

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“…For instance, the C1/AlEt 2 Cl catalytic system gained the 80.0% conversion of butadiene and the resulting polymer had relatively lower molecular weight and cis-1,4 content (entry 5 in Table 3). In comparison, EASC afforded the highest monomer conversion (94.8% in 1 h) and the highest cis-1,4 content (95.6%) in the resulting polymers even if a small amount was used (Al/Cat = 40, entry 6 in Table 3), which was also a good cocatalyst for the butadiene polymerization catalyzed by the neutral cobalt complexes [26,28,31,48]. Therefore, EASC was employed for the further investigations under various reaction parameters to optimize the polymerization conditions.…”

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confidence: 99%

Polymerization of 1,3-butadiene catalyzed by ion-pair cobalt complexes with (benzimidazolyl)pyridine alcohol ligands

Chen

Jie

et al. 2013

Journal of Molecular Catalysis A: Chemical

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“…[2, 3] Some of these even work well at ambient temperature. The present work describes the successful application of (PNHP Ph )CoCl 2 (Co-4), ac atalysth itherto known for the stereospecific polymerization of 1,3-butadiene [17] and the reduction of carboxylic acid esters andnitriles. Thus, catalysts based on cheap metals like iron [5] and nickel [6] have been used for the isomerization of allylic alcohols recently.N evertheless, the requirement of either activateds ubstrates [5b] or the need for activation of the catalyst make those systemsl ess desirable.…”

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confidence: 99%

“…The present work describes the successful application of (PNHP Ph )CoCl 2 (Co-4), ac atalysth itherto known for the stereospecific polymerization of 1,3-butadiene [17] and the reduction of carboxylic acid esters andnitriles. We have tested an umber of cobalt PNP pincer complexes having different substituents on the phosphorus atoms (Figure1).…”

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Additive‐Free Isomerization of Allylic Alcohols to Ketones with a Cobalt PNP Pincer Catalyst

Spiegelberg

Dell'Acqua

Xia

et al. 2019

Chemistry A European J

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Catalytic isomerization of allylic alcohols in ethanol as ag reen solventw as achieved by using air and moisture stable cobalt (II) complexes in the absence of any additives. Under mild conditions, the cobaltP NP pincer complex substituted with phenyl groups on the phosphorusa toms appeared to be the most active. High rates were obtaineda t1 20 8C, even thought he addition of one equivalent of base increases the speed of the reaction drastically.A lthough some evidencew as obtained supporting ad ehydrogenation-hydrogenation mechanism, it was proven that this is not the major mechanism. Instead, the cobalt hydride complex formed by dehydrogenation of ethanol is capable of double-bond isomerization through alkene insertion-elimination.Isomerization reactions comply with the principles of green chemistry. [1] The catalytic isomerization of allylic alcohols into the saturated carbonyl compounds is an elegant synthetic process that eliminates the more conventional two-step oxidation and reduction pathway. [2] During the last half century, many preciousm etal catalysts for allylic alcoholi somerization, based on Ir,R u, Rh or Pd have been developed. [2, 3] Some of these even work well at ambient temperature. [4] Although noble metals playa ni ndispensable role in catalysis, they are rather expensive, less abundant and generally not used in the last step of drug synthesis. Thus, catalysts based on cheap metals like iron [5] and nickel [6] have been used for the isomerization of allylic alcohols recently.N evertheless, the requirement of either activateds ubstrates [5b] or the need for activation of the catalyst make those systemsl ess desirable. Recently,r eports have appeared on the sole use of base as catalystfor the isomerization of allylic alcohols to the corresponding ketones. [7] To the best of our knowledge,t here is only one report on the use of a cobalt catalyst[ HCo(CO) 4 ]t hat can promote the isomerization of an allylic alcohol to an aldehyde or ak etone, but harsh conditions including the use of toxic carbon monoxide were required to achievel ow conversionsa nd selectivities towards the desired products. [8] Recently,c obalt pincer complexes have been discovered to be effective catalysts [9] for hydrogenation, [10] dehydrogenation, [10g, 11] transfer hydrogenation, [12] hydrosilylations-hydroborations, [13] alkene isomerization [14] and N 2 activation. [15] Hanson and co-workersh ave reportedacationic cobalt(II) alkyl complex, which was appliedf or the hydrogenation of aldehydes, ketones and imines,a sw ell as for the isomerizationo fa lkenes. [16] Furthermore, Liu andc o-workers have recently reported impressive findings about pincerc obalt complexest hat are suitable catalysts for regioselective olefin isomerizationb yu sing ammonia borane as the activation source. [13] Althoughm any catalytic reactions have been performed with pincerc obalt catalysts, isomerization reactions of allylic alcohols with this type of complexes are still unknown.Herein, we report the first cobalt(II) catalyzed isomeri...

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Stereospecific polymerization of 1,3-butadiene catalyzed by cobalt complexes bearing N-containing diphosphine PNP ligands

Cited by 38 publications

References 56 publications

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

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

Polymerization of 1,3-butadiene catalyzed by ion-pair cobalt complexes with (benzimidazolyl)pyridine alcohol ligands

Additive‐Free Isomerization of Allylic Alcohols to Ketones with a Cobalt PNP Pincer Catalyst

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