Kun Jin

Ethylene oligomerization by salen-type zirconium complexes to low-carbon linear α-olefins

A series of zirconium salen-type complexes were prepared by using ZrCl4 and sodium salts of the tetradentate Schiff base ligands. In combination with Et2AlCl, they displayed moderate to high cataly ...

Polymerization of rac-lactide catalyzed by group 4 metal complexes containing chiral N atoms

The hydroxyl- and phenoxy-bridged dinuclear zirconium and hafnium complexes, 1 and 2, containing a chiral N atom in the N2O2 ligand (H2Lxa0=xa02-(((2-pyridylmethyl)(2-hydroxyphenyl)amino)methyl)-4,6-di(tert-butyl)phenol) were used as catalysts for the ring-opening polymerization of rac-lactide. Experiments prove that 1 and 2 are living and controlled catalytic systems with activity up to 3.25xa0gpolxa0mmolini−1xa0h−1. The isotactic-rich polylactides in a narrow polydispersity (Mw/Mnxa0=xa01.01–1.13) were produced with enantiomeric complexes 1 and 2 (Pmxa0=xa00.65–0.73). The kinetic studies show a first-order dependency in both monomer and initiator. The initiation mechanism is discussed on the basis of the MALDI-TOF MS and 1H NMR spectra of the rac-LA oligomer prepared by 1.

Synthesis of chiral salen Mn(III) complexes covalently linked to Re(I)-based photosensitizers

Two Mn(III)Re(I) binuclear complexes were prepared as catalyst-photosensitizer models, in which the chiral pyrrolidine salen Mn(III) unit was covalently bonded to an Re(I) bipyridyl carbonyl moiety via a carboxamide linkage. The spectral and electrochemical properties of the Mn(III)Re(I) complexes were studied. *Corresponding authors. Tel.:u2009+86-411-88993886. Fax:u2009+86-411-83702185. Email: symbueno@vip.sina.com