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

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).