Synthesis and characterization of zirconium and hafnium aryloxide compounds and their reactivity towards lactide and ε-caprolactone polymerization

Kun Chun Hsieh, Wen Yi Lee, Li Feng Hsueh, Man Lee Hon, Jui Hsien Huang

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Reactions of 2 equiv. pyrrole with [C4H3N(CH 2NMe2)-2]2M(NEt2)2 in toluene generated tetra-pyrrolyl metal compounds [C4H 3N(CH2NMe2)-2]2M(C4H 4N)2 (3, M = Zr; 4, M = Hf) in moderate yields. Similarly, treatment of metal amides [C4H3N(CH2NMe 2)-2]2M(NEt2)2 with 2,6-dimethylphenol or 2,6-diisopropylphenol in heptane resulted in the elimination of diethylamine along with the formation of the corresponding metal alkoxides [C4H3N(CH2NMe2)-2] 2M(OR)2 (5, M = Zr, R = C6H3-2,6- Me2; 6, M = Hf, R = C6H3-2,6-Me2; 7, M = Zr, R = C6H3-2,6-iPr2; 8, M = Hf, R = C6H3-2,6-iPr2) in moderate yields. All the new compounds were characterized by 1H and 13C NMR spectroscopy and the structures of 3, 4, 6, 7, and 8 have also been determined by X-ray crystallographic studies. The aryloxides and the substituted pyrrolyl ligands in both compounds 5 and 6 show fluxionality as observed by 1H NMR signals. A kinetic study on the ring-opening polymerization of lactide exhibits a first-order reaction of lactide monomer with compound 8. The catalytic properties of all the metal complexes have been studied for the ring-opening polymerization of ε-caprolactone.

Original languageEnglish
Pages (from-to)2306-2312
Number of pages7
JournalEuropean Journal of Inorganic Chemistry
Issue number11
Publication statusPublished - 2006 Jun 2


All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry

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