Asymmetric hydrodimerization of styrene by a chiral zirconium complex containing a tetradentate [OSSO]-type bis(phenolato) ligand

The chiral non racemic (\u39b,R,R)-[OSSO]Zr(CH2Ph) 2 (1a) activated by methylaluminoxane (MAO) and in presence of H 2 produces the chiral hydrodimer (S)-1,3-diphenylbutane with good selectivity respect to the achiral 1,4-diphenylbutane. The absolute configuration of the chiral dimer and the effect of the hydrogen pressure on the ratio between 1,3-diphenylbutane and 1,4-diphenylbutane give useful information about the regiochemistry and stereochemistry of insertion of the styrene into the Zr-H bond. \ua9 2011 Elsevier B.V. All rights reserved

A new post-metallocene catalyst for alkene polymerization: Copolymerization of ethylene and 1-hexene with titanium complexes bearing N,N-dialkylcarbamato ligands

New catatytic systems based on N,N-dialkylcarbamato Ti(IV) precursors for copolymerization of ethylene and 1-hexene are presented. High 1-hexene content in the copolymers and a multi-site nature of the catalytic systems were ascertained. A new type of post-metallocene polymerization catalyst based on titanium complexes with N,N-dialkylcarbamato ligands was used to copolymerize ethylene and 1-hexene. These easy-to-synthesize and stable complexes in combination with different organoaluminium co-catalysts produce random ethylene/1-hexene copolymers characterized by a broad molecular weight distribution and high 1-hexene incorporation, as confirmed by SEC, DSC and 13C NMR analysis. The influence of the main reaction parameters on the polymerization reactions was studied including the type of catalyst components, solvent, temperature, the ethylene partial pressure and the [Al]/[Ti] ratio in the catalyst. A higher activity and a higher 1-hexene incorporation were achieved with AlMe3-depleted methylalumoxane as co-catalyst and chlorobenzene as solvent. �� 2013 Society of Chemical Industry

A Novel [OSSO]-Type Chromium(III) Complex as a Versatile Catalyst for Copolymerization of Carbon Dioxide with Epoxides

A new chromium(III) complex, bearing a bis-thioether-diphenolate [OSSO]-type ligand, was found to be an efficient catalyst in the copolymerization of CO2 and epoxides to achieve poly(propylene carbonate), poly(cyclohexene carbonate), poly(hexene carbonate) and poly(styrene carbonate), as well as poly(propylene carbonate)(cyclohexene carbonate) and poly(propylene carbonate)(hexene carbonate) terpolymers

Binary Copolymerization of p-Methylstyrene with Butadiene and Isoprene Catalyzed by Titanium Compounds Showing Different Stereoselectivity

The synthesis of p-methylstyrene–butadiene and p-methylstyrene–isoprene binary copolymers promoted by the titanium complexes Ti(η5-C5H5)-(κ2-MBMP)Cl (1) (MBMP = 2,2′-methylenebis(6-tert-butyl-4-methylphenoxo)) and chloro{1,4-dithiabutanediyl-2,2′-bis(4,6-di-tert-butylphenoxy)}titanium (2) activated by methylaluminoxane (MAO) is reported. Syndiotactic poly(p-methylstyrene)-co-cis-1,4-poly(butadiene) and syndiotactic poly(p-methylstyrene)-co-cis-1,4-polyisoprene were obtained using catalyst 1, whereas isotactic poly(p-methylstyrene)-co-trans-1,4-poly(butadiene) and isotactic poly(p-methylstyrene)-co-trans-1,4-polyisoprene were obtained using the catalyst 2. 13C NMR analysis of the copolymer microstructure allowed to assess the monomer block lengths and distribution in the polymer chain, revealing a blocky distribution of the two monomers along the polymer chain in the presence of the catalyst 1 and a random distribution with the catalyst 2 for both binary copolymers