Styrene polymerization catalyzed by nickel complexes bearing hydroxyindanone-iminate ligands

Half-Sandwich Chromium(III) Catalysts Bearing Hydroxyindanimine Ligands for Ethylene Polymerization

“…The highest activity of the hydroxyindanimine chromium catalysts (1.68 × 10 5 g PE (mol Cr) −1 h −1 ) was higher than that of Cp*Cr(acac)Cl/Et 3 Al and β-ketoiminato and β-diketiminate complexes, but lower than that of salicylaldiminato chromium(III) complexes (4.04 × 10 6 g PE (mol Cr) −1 h −1 , 5 bar) . The molecular weights of the obtained PE produced by the hydroxyindanimine chromium catalysts ((5.45−9.23) × 10 5 g mol −1 ) were lower than that of the salicylaldiminato chromium(III) complexes ((1.00−1.45) × 10 6 g mol −1 ), which indicated that the introduction of a five-membered ring made the ligand more robust and limited the opening degree of the chromium center space …”

“…Like the hydroxyindanimine nickel, copper, and iridium complexes, the five-remembered ring is not completely in the plane of the phenoxy ring in complex 2c (Figure ). The six atoms [Cr1−O1−C1−C6−C7−N1] form one six-membered ring, which however, is not in a plane (Figure ).…”

“…The ligands 1a − 1e were synthesized according to the literature. , Reactions of Cp*Cr(THF)Cl 2 with the corresponding sodium salts of the hydroxyindanimine ligands 1a − 1e (Scheme ) in THF at −78 °C resulted in the green-colored half-sandwich Cr(III) complexes 2a − 2e in ca. 50−70% yields.…”

“…Recently, our group designed and synthesized a series of nickel, copper, and iridium complexes based on hydroxyindanimine ligands ( II ) (Chart ), which have the same basic fragment as salicylaldimine for norbornene, MMA, and styrene polymerization with high activity . Herein we report the half-sandwich chromium(III) complexes bearing hydroxyindanimine ligands, which show high activity for ethylene polymerization to produce high molecular weight PE activated with only a small amount of triethylaluminum (Scheme ).…”

Unusual Cationic Trinuclear Nickel Clusters Incorporating Oxazolines orN,N,N′,N′-Tetramethylethylene-1,2-diamine: Applications in Olefin Polymerization

“…As the class of clusters described here contains Ni 2+ centers and is inherently cationic (in addition to the fact that the related dihydroxy complex of Fossey et al is an effective Lewis acid catalyst), we chose to investigate whether complexes such as 1 and 2 can be used to produce useful quantities of desirable polymers such as polystyrene (PS) or poly(methyl methacrylate) (pMMA). The initial screening of 1 for PS syntheses , at room temperature revealed (Table S-1 in the SI), in contrast to typical nickel-mediated polymerizations, ,, that activation of the precatalyst with excesses of MAO resulted in poorer polydispersity index (PDI) values of the resulting polymers (Table S-1 in the SI; compare run 5 to runs 8, 10, and 11 and compare run 19 to run 20). Hence, approximately 1 equiv of MAO (per Ni) was found to be optimal for good polymer yields, high M w values (up to ∼2 × 10 6 g mol –1 ), and low polymer polydispersities (PDI ≤ ∼1.7; Table S-1 in the SI, run 5) .…”