Synthesis of a New Polydentate Ligand Obtained by Coupling 2,6-Bis(imino)pyridine and (Imino)pyridine Moieties and Its Use in Ethylene Oligomerization in Conjunction with Iron(II) and Cobalt(II) Bis-halides

Asymmetric bis-salicylaldiminato binuclear titanium complexes for ethylene polymerization and copolymerization

Asymmetric binuclear Ti complexes were synthesized, which exhibited excellent activity for ethylene homopolymerization and copolymerization with 1-hexene or norbornene and high comonomer insertion efficiency under MMAO activation.

Research progress of iron-based catalysts for selective oligomerization of ethylene

Linear α-olefins are widely used as raw materials in the chemical industry. Selective ethylene oligomerization is an important development direction of the linear α-olefin production process. Iron-based catalysts have become a research hotspot in selective ethylene oligomerization due to their advantages like high activity, high selectivity and convenience of adjusting their ligand structures. In this paper, the research progress of catalysts for selective oligomerization of ethylene was reviewed in terms of the cocatalysts, ligand structure, and immobilization of homogeneous catalysts.

Probing the effect of ortho-cycloalkyl ring size on activity and thermostability in cycloheptyl-fused N,N,N-iron ethylene polymerization catalysts

The depicted iron(ii) precatalysts displayed exceptionally high activities for ethylene polymerization at temperatures of up 100 °C producing linear polyethylene with a wide range of molecular weights.

1,5-Naphthyl-linked bis(imino)pyridines as binucleating scaffolds for dicobalt ethylene oligo-/polymerization catalysts: exploring temperature and steric effects

The title dinuclear Co complexes showed high activity for ethylene oligo-/polymerization with the run temperature having an unexpected effect on the PE to oligomer ratio.

Methylene-bridged bimetallic bis(imino)pyridine-cobaltous chlorides as precatalysts for vinyl-terminated polyethylene waxes

Dicobalt precatalysts displayed high activities for polymerizing ethylene to highly linear vinyl-polyethylenes.

C 1 and Cs 2-pyridylethylanilido zirconium(iv), yttrium(iii) and lutetium(iii) complexes: synthesis, characterization and catalytic activity in the isoprene polymerization

Organolanthanide containing C_s and C₁-symmetric 2-pyridylethylanilido ligands have been scrutinized as catalyst precursors for the isoprene polymerization.

Iminopyridine-Based Cobalt(II) and Nickel(II) Complexes: Synthesis, Characterization, and Their Catalytic Behaviors for 1,3-Butadiene Polymerization

A series of iminopyridine ligated Co(II) (1a–7a) and Ni(II) (1b–7b) complexes were synthesized. The structures of complexes 3a, 4a, 5a, 7a, 5b, and 6b were determined by X-ray crystallographic analyses. Complex 3a formed a chloro-bridged dimer, whereas 4a, 5a, and 7a, having a substituent (4a, 5a: CH₃; 7a: Br) at the 6-position of pyridine, producing the solid structures with a single ligand coordinated to the central metal. The nickel atom in complex 5b features distorted trigonal-bipyramidal geometry with one THF molecule ligating to the metal center. All the complexes activated by ethylaluminum sesquichloride (EASC) were evaluated in 1,3-butadiene polymerization. The catalytic activity and selectivity were significantly influenced by the ligand structure and central metal. Comparing with the nickel complexes, the cobalt complexes exhibited higher catalytic activity and cis-1,4-selectivity. For both the cobalt and nickel complexes, the aldimine-based complexes showed higher catalyst activity than their ketimine counterparts.

A practical ethylene polymerization for vinyl-polyethylenes: synthesis, characterization and catalytic behavior of α,α′-bisimino-2,3:5,6-bis(pentamethylene)pyridyliron chlorides

A series of α,α′-bis(arylimino)-2,3:5,6-bis(pentamethylene)pyridyliron chlorides exhibits high activities toward ethylene polymerization, yielding highly linear vinyl-polyethylenes.

Group IV organometallic compounds based on dianionic "pincer" ligands: synthesis, characterization, and catalytic activity in intramolecular hydroamination reactions

Neutral Zr(IV) and Hf(IV) diamido complexes stabilized by unsymmetrical dianionic N,C,N' pincer ligands have been prepared through the simplest and convenient direct metal-induced Caryl-H bond activation. Simple ligand modification has contributed to highlight the non-innocent role played by the donor atom set in the control of the cyclometallation kinetics. The as-prepared bis-amido catalysts were found to be good candidates for the intramolecular hydroamination/cyclization of primary aminoalkenes. The ability of these compounds to promote such a catalytic transformation efficiently (by providing, in some cases, fast and complete substrate conversion at room temperature) constitutes a remarkable step forward toward catalytic systems that can operate at relatively low catalyst loading and under milder reaction conditions. Kinetic studies and substrate-scope investigations, in conjunction with preliminary DFT calculations on the real systems, were used to elucidate the effects of the substrate substitution on the catalyst performance and to support the most reliable mechanistic path operative in the hydroamination reaction.

Azaindenoisoquinolines as topoisomerase I inhibitors and potential anticancer agents: a systematic study of structure-activity relationships

A comprehensive study of a series of azaindenoisoquinoline topoisomerase I (Top1) inhibitors is reported. The synthetic pathways have been developed to prepare 7-, 8-, 9-, and 10-azaindenoisoquinolines. The present study shows that 7-azaindenoisoquinolines possess the greatest Top1 inhibitory activity and cytotoxicity. Additionally, the introduction of a methoxy group into the D-ring of 7-azaindenoisoquinolines improved their biological activities, leading to new lead molecules for further development. A series of QM calculations were performed on the model "sandwich" complexes of azaindenoisoquinolines with flanking DNA base pairs from the Drug-Top1-DNA ternary complex. The results of these calculations demonstrate how changes in two forces contributing to the π-π stacking (dispersion and charge-transfer interactions) affect the binding of the drug to the Top1-DNA cleavage complex and thus modulate the drug's Top1 inhibitory activity.