Publication: Diverse pathways of activation and deactivation of half-sandwich aryloxide titanium polymerization catalysts
Issued Date
2006-01-02
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ISSN
02767333
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2-s2.0-30344488757
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Mahidol University
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SCOPUS
Bibliographic Citation
Organometallics. Vol.25, No.1 (2006), 214-220
Suggested Citation
Khamphee Phomphrai, Andrew E. Fenwick, Shalini Sharma, Phillip E. Fanwick, James M. Caruthers, W. Nicholas Delgass, Mahdi M. Abu-Omar, Ian P. Rothwell Diverse pathways of activation and deactivation of half-sandwich aryloxide titanium polymerization catalysts. Organometallics. Vol.25, No.1 (2006), 214-220. doi:10.1021/om0507272 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/23183
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Title
Diverse pathways of activation and deactivation of half-sandwich aryloxide titanium polymerization catalysts
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Abstract
A series of half-sandwich aryloxide titanium complexes, [CpTi(OAr)Me2] (Cp = C5H5; OAr = OC6H3Me2-2,6, OC6H3Et2-2,6, OC6H3iPr2-2,6, OC6H3tBu2-2,6, and OC6HPh4-2,3,5,6), have been synthesized. These compounds react with B(C6F5)3to give thermally unstable complexes [CpTi(OAr)Me][MeB(C6F5)3]. Two different deactivation pathways have been identified within the series. The tetraphenylphenoxide cationic methyl compound decomposes cleanly at room temperature to give [CpTi(OC6HPh4-2,3,5,6)(C6F5){CH2B(C6F5)2}] and methane with a first-order rate constant of 7.6(2) × 10-4s-1at 25°C. For relatively smaller aryloxide ligands, OAr = OC6H3iPr2-2,6, OC6H3tBu2-2,6, a Me/C6F5exchange takes place, yielding CpTi(OAr)Me(C6F5) and MeB(C6F5)2. The cationic titanium complexes are shown to be active for the polymerization of 1-hexene. At -20 and 0°C, first-order dependence on the concentration of 1-hexene is observed. The rate of polymerization decreases with increasing steric hindrance of aryloxides except for OAr = OC6HPh4-2,3,5,6. © 2006 American Chemical Society.