Styrene polymerization catalyzed by metal porphyrin complex/MAO for in situ synthesizing polystyrene containing air stable π cation radicals

Unusual cationic trinuclear nickel clusters incorporating oxazolines or N,N,N',N'-tetramethylethylene-1,2-diamine: applications in olefin polymerization

The synthesis and characterization of two rare examples of the nickel(II)-containing trinuclear clusters of the general formula μ(3)-halido-μ(3)-hydroxotris(μ-halido)tris(L) trinickel(II) halide [halide = Cl (2), Br (3); L = 4,4-dimethyl-2-(o-anilinyl)-2-oxazoline] are described. These materials are compared and contrasted to the "parent" chloride salt (1) of this series (L = N,N,N',N'-tetramethylethylene-1,2-diamine and halide = Cl) and its congeners; 2 and 3 represent the first oxazoline-containing clusters of this structural class. Both 1 and 2 are shown to be active catalysts for the polymerization of olefins (styrene, methyl methacrylate, etc.) using a stoichiometric equivalent of methylaluminoxane as the copromoter, a situation that gives good yields of syndiotactic rich polymers. Density functional theory (B3LYP/6-31G*/LANL2DZ) is employed to hypothesize the likely origin of the activity demonstrated by these compounds.

Towards chiral polystyrene based materials: controlled polymerization of p-(2,2′-diphenylethyl)styrene

p-(2,2′-Diphenylethyl)styrene (DPES) was polymerized with the homochiral postmetallocene catalyst dichloro{trans-1,2-dithiocyclohexanediyl-2,2′-bis(4,6-di-tert-butylphenolato)}titanium/MAO. Optically active isotactic polymers were obtained by a controlled reduction of the molecular weight, employing diethylzinc as CTA. Polymers with molecular weights below M_n of 50,000 g mol⁻¹ showed specific rotation values ([α]23D) between ±0.2 and 2.2.