Cobalt complex bearing β‐ketoamine ligand: syntheses, structure, catalytic behavior for styrene and methyl methacrylate polymerization

Abstract

Cobalt complex based on β-ketoamine ligand [(Z)-4-((2,5-dimethylphenylamino) (phenyl)methylene)-3-methyl-1-phenyl-1 H-pyrazol-5(4H)-one] was successfully synthesized. The produced catalyst showed satisfactory activities in the cobalt-mediated radical polymerization of styrene and methyl methacrylate with the common initiator of AIBN. The resulting polymerizations have the characteristics of living radical polymerization and displayed a nearly linear correlation between the number-average molecular weight and monomer conversion. Low polydispersity was obtained for all polymerizations, and the polydispersity index decreased with the increase of conversion. These improvements facilitate the implementation of styrene and methacrylate cobalt-mediated radical polymerization, and open the door to the scale-up of the process.

Divalent cobalt and copper coordination complexes of κ2-N, O-derivatives of (Z)-1-R-2-(2′-oxazolin-2′-yl)-eth-1-en-1-ates: Structure and reactivity patterns

“…[44] Bond lengths and angles of the ligand framework are typical [43,45] and the Co−O and Co−N interactions are also of normal length for enolates and oxazolines bound to formally Co 2+ , respectively. [26,41,[63][64][65][66][67][68][69][70][71][72][73][74][75][76][77] A useful structural comparison can be made to the species bis-(2-[2'-oxazolin-2'yl]phenolato)cobalt(II). This material features very similar bonding parameters (τ4 =0.829; Co−Nav = 1.961 Å; Co−Oav = 1.936 Å).…”

Dual Catalysis of the Selective Polymerization of Biosourced Myrcene and Methyl Methacrylate Promoted by Salicylaldiminato Cobalt(II) Complexes with a Pendant Donor

“…Although many cobalt complexes have been developed for mediating radical (co)­polymerization of polar monomers such as MMA, vinyl acetate, acrylonitrile, and ethylene, coordinative polymerization of polar monomers by cobalt metal is still a challenging endeavor, because simple coordination of the functional group to the metal may hamper monomer activation. Till now, reported catalysts have been limited to N , N -di­(2-picolyl)­amine Co­(II), bis­(salicylaldiminate)-Co­(II) complexes, and Co­(II)­Pyridyl bis­(imine)/MAO for low efficiency MMA polymerization. The strong binding of ester functionality to the metal center via η 4 -chelation retarding the chain-growth reaction is responsible for the low activities, and so far there have been no general ways to improve the catalytic activity and selectivity, as well as the stability.…”