Ming-Tsz Chen

Magnesium complexes containing bis-amido-oxazolinate ligands as efficient catalysts for ring opening polymerisation of L-lactide

A series of magnesium bis(amido-oxazolinate) complexes have been described. Reactions of six amido-oxazolinate ligand precursors, HNC(2)(Me)Oxa, HNC(2)(OMe)Oxa, HNC(2)(StBu)Oxa, HNPhOxa, HNPh(OMe)Oxa or HNPh(SMe)Oxa, with half molar equivalent of Mg(n)Bu(2) in hexane yield the magnesium bis(amido-oxazolinate) complexes, (NC(2)(E)Oxa)(2)Mg [C(2)(E) = propyl, (NC(2)(Me)Oxa)(2)Mg (1); C(2)(E) = 2-methoxyethyl, (NC(2)(OMe)Oxa)(2)Mg (2); C(2)(E) = 2-tert-butylthioethyl, (NC(2)(StBu)Oxa)(2)Mg (3)], or magnesium bis(anilido-oxazolinate) complexes, (NArOxa)(2)Mg [Ar = phenyl, (NPhOxa)(2)Mg (4); Ar = 2-methoxyphenyl, (NPh(OMe)Oxa)(2)Mg (5); Ar = 2-methylthiophenyl, (NPh(SMe)Oxa)(2)Mg (6)], respectively. The molecular structures are reported for compounds 1, 2, 5 and 6. Their catalytic activities toward the ring opening polymerisation of L-lactide in the presence of benzyl alcohol are also under investigation.

Palladacyclic complexes bearing CNN-type ligands as catalysts in the Heck reaction

Preparations of novel unsymmetrical, tridentate nitrogen ligand precursors, PhN=C(CMe2)(NPh)C=N(CH2)2NMe2(1) and PhN=C(CMe2)(NPh)C=N(CH2)Py (2), are described. Treatment of 1 with 1 molar equiv. (COD)PdCl2 in the presence of NEt3 or with 1 molar equiv. Pd(OAc)2 affords orthometallated palladium(II) complexes, [PhN=C(CMe2)(N-eta1-Ph)C=N(CH2)2NMe2]PdX (X=Cl (3); X=OAc (4)), respectively. Compound can be yielded via the reaction of with an excess of LiCl in methanol. Treatment of with 1 molar equiv. of (COD)PdCl2, Pd(OAc)2 or Pd(TFA)2 affords orthometallated palladium(II) complexes, [PhN=C(CMe2)(N-eta1-Ph)C=NCH2Py]PdX (X=Cl (5); X=OAc (6); X=TFA (7)), respectively. The crystal and molecular structures are reported for compounds 2, 3, 5 and 6. The application of these novel palladacyclic complexes to the Heck reaction with aryl halide substrates was examined.