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Wiley, Chemistry - A European Journal, 3(13), p. 923-935, 2007

DOI: 10.1002/chem.200600895

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Chiral fluorous dialkoxy-diamino zirconium complexes: Synthesis and use in stereospecific polymerization of 1-hexene

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

2010302010048 ; 化學系 ; New catalysts for the isospecific polymerization of 1-hexene based on cationic zirconium complexes incorporating, the tetradentate fluorous dialkoxy-diamino ligands [OC(CF3)(2)CH2N(Me)(CH2)(2)N(Me)CH2C(CF3)(2)O](2-) [((ONNO)-N-2)(2-)] and [OC(CF3)(2)CH2N(Me)(1R,2R-C6H10)N(Me)CH2C-(CF3)(2)O](2-) [((ONNO)-N-Cy)(2-)] have been developed. The chiral fluorous diamino-diol [((ONNO)-N-Cy)H-2, 2] was prepared by ring-opening of the fluorinated oxirane (CF3)(2)COCH2 with (R,R)-N,N'-dimethyl-1,2-cyclohexanediamine. Proligand 2 reacts cleanly with [Zr(CH2Ph)(4)] and [Ti(OiPr)(4)] precursors to give the corresponding dialkoxy complexes [Zr(CH2Ph)(2)((ONNO)-N-Cy)] (3) and [Ti(OiPr)(2)((ONNO)-N-Cy)] (4), respectively. An X-ray diffraction study revealed that 3 crystallizes as a 1:1 mixture of two diastereomers (Lambda-3 and Delta-3), both of which adopt a distorted octahedral structure with trans-O, cis-N, and cis-CH2Ph ligands. The two diastereomers Lambda-3 and Delta-3 adopt a C-2-symmetric structure in toluene solution, as established by NMR spectroscopy. Cationic complexes [Zr(CH2Ph)((ONNO)-N-2)(THF)(n)](+) (n = 0, anion = [B(C6F5)(4)](-), 5; n = 1, anion = [PhCH2B(C6F5)(3)](-), 6) and [Zr(CH2Ph)((ONNO)-N-Cy)(THF)](+) [PhCH2B(C6F5)(3)](-) (7) were generated from the neutral parent precursors [Zr(CH2Ph)(2)((ONNO)-N-2)] (H) and [Zr(CH2Ph)(2)((ONNO)-N-Cy)] (3), and their possible structures were determined on the basis of H-1, F-19, and C-13 NMR spectroscopy and DFT methods. The neutral zirconium complexes H and 3 (Lambda-3/Delta-3 mixture), when activated with B(C6F5)(3) or [Ph3C](+)[B(C6F5)(4)](-), catalyze the polymerization of 1-hexene with overall activities of up to 4500 kg PH mol Zr-1 h(-1), to yield isotactic-enriched (up to 74 % mmmm) polymers with low-to-moderate molecular weights (M-w = 4800-47200) and mono-disperse molecular-weight distributions (M-w/M-n = 1.17-1.79).