Direct Synthesis of Functional Thermoplastic Elastomer with Excellent Mechanical Properties by Scandium-Catalyzed Copolymerization of Ethylene and Fluorostyrenes.

Herein, we report copolymerizations of ethylene (E) and ortho-/meta-/para-fluorostyrenes (S =oFS/mFS/pFS) by using quinolyl methylene fluorenyl scandium complex (Flu-CH -Qu)Sc(CH SiMe ) . The copolymerizations proceed in a controlled fashion to afford copolymers composed of "soft" ethylene-fluorostyurene (E-S ) random segments (T =-22.2-5.

Access to Hydroxy-Functionalized Polypropylene through Coordination Polymerization.

Preparation of polyethylenes containing hydroxy groups has been already industrialized through radical copolymerization under harsh conditions followed by alcoholysis. By contrast, hydroxy-functionalized polypropylene has proven a rather challenging goal in polymer science. Propylene can't be polymerized through a radical mechanism, and its coordination copolymerization with polar monomers is frustrated by catalyst poisoning.

cis-1,4-Selective Copolymerization of Ethylene and Butadiene: A Compromise between Two Mechanisms.

Introducing ethylene units into polybutadiene backbones is an approach to synthesize advanced rubber materials, which has been a research challenge because of distinct polymerization mechanisms of the two monomers. To date, only trans-1,4- and 1,2-regulated copolymers have been obtained. Herein, we reported the unprecedented cis-1,4 selective copolymerization of ethylene and butadiene by using the thiophene-fused cyclopentadienyl-ligated scandium complexes.

Stereoselective Copolymerization of Unprotected Polar and Nonpolar Styrenes by an Yttrium Precursor: Control of Polar-Group Distribution and Mechanism.

Styrene underwent unprecedented coordination-insertion copolymerization with naked polar monomers (ortho-/meta-/para-methoxystyrene) in the presence of a pyridyl methylene fluorenyl yttrium catalyst. High activity (1.26×10  g mol  h ) and excellent syndioselectivity were observed, and high-molecular-weight copolymers (24.

Highly isoselective coordination polymerization of ortho-methoxystyrene with β-diketiminato rare-earth-metal precursors.

Stereoselective coordination/insertion polymerization of the polar ortho-methoxystyrene has been achieved for the first time by using the cationic β-diketiminato rare-earth-metal species. High activity and excellent isoselectivity (mmmm>99 %) were acheived. The unmasked Lewis-basic methoxy group does not poison the Lewis-acidic metal center, but instead activates the polymerization through σ-π chelation to the active species together with the vinyl group, thus lower the coordination and activation energies as compared with those of styrene derivatives lacking the methoxy group.

Syndioselective coordination polymerization of unmasked polar methoxystyrenes using a pyridenylmethylene fluorenyl yttrium precursor.

Unprecedented coordination-insertion polymerizations of polar methoxyl substituted styrene derivatives, in despite of the position of the substituent, have been achieved using a pyridyl methylene fluorenyl yttrium bis(alkyl) precursor with high activity to give polar polystyrenes of high molecular weight and perfect syndiotacticity.

Lutetium-methanediide-alkyl complexes: synthesis and chemistry.

The first four-coordinate methanediide/alkyl lutetium complex (BODDI)Lu2 (CH2 SiMe3 )2 (μ2 -CHSiMe3 )(THF)2 (BODDI=ArNC(Me)CHCOCHC(Me)NAr, Ar=2,6-iPr2 C6 H3 ) (1) was synthesized by a thermolysis methodology through α-H abstraction from a Lu-CH2 SiMe3 group. Complex 1 reacted with equimolar 2,6-iPrC6 H3 NH2 and Ph2 C+O to give the corresponding lutetium bridging imido and oxo complexes (BODDI)Lu2 (CH2 SiMe3 )2 (μ2 -N-2,6-iPr2 C6 H3 )(THF)2 (2) and (BODDI)Lu2 (CH2 SiMe3 )2 (μ2 -O)(THF)2 (3). Treatment of 3 with Ph2 C=O (4 equiv) caused a rare insertion of Lu-μ2 -O bond into theC=O group to afford a diphenylmethyl diolate complex 4.

An NCN-pincer ligand dysprosium single-ion magnet showing magnetic relaxation via the second excited state.

Single-molecule magnets are compounds that exhibit magnetic bistability purely of molecular origin. The control of anisotropy and suppression of quantum tunneling to obtain a comprehensive picture of the relaxation pathway manifold, is of utmost importance with the ultimate goal of slowing the relaxation dynamics within single-molecule magnets to facilitate their potential applications. Combined ab initio calculations and detailed magnetization dynamics studies reveal the unprecedented relaxation mediated via the second excited state within a new DyNCN system comprising a valence-localized carbon coordinated to a single dysprosium(III) ion.