Chiral Fluorous Dialkoxy-Diamino Zirconium Complexes: Synthesis and Use in Stereospecific Polymerization of 1-Hexene

Fluorine in metal-catalyzed asymmetric transformations: the lightest halogen causing a massive effect

This review aims at providing an overview of the most significant applications of fluorine-containing ligands reported in the literature starting from 2001 until mid-2021. The ligands are classified according to the nature of the donor atoms involved. This review highlights both metal-ligand interactions and the structure-reactivity relationships resulting from the presence of the fluorine atom or fluorine-containing substituents on chiral catalysts.

Synthesis and spectroscopic characterization of group 4 post-metallocenes bearing (σ-aryl)-2-phenolate-6-pyridyl and -isoquinolinyl auxiliaries

A new series of group 4 bis(benzyl) complexes supported by (σ-aryl)-2-phenolate-6-pyridyl [O,C,N] ligands have been prepared, and all derivatives have been characterized by multinuclear NMR spectroscopy. In the (1)H NMR spectrum of the Ti derivative where [N] = (ortho-F)-substituted isoquinolinyl, one of the two CH2 resonances is observed as a doublet of doublets (collapsing to a normal d upon (19)F-decoupling), whereas the [(1)H,(19)F]-HMQC correlation spectrum reveals a strong crosspeak for this dd resonance only, thus indicating the presence of intramolecular C-HF-C interactions. [(1)H,(19)F]-HMBC experiments have been performed which reveal a significant scalar component for this coupling and confirm that the interactions are genuine. The contrasting NMR spectral patterns for the (ortho-F)-pyridyl Hf analogue, which exhibits two sets of non-identical doublet of doublets for the methylene resonances, have been rationalized. The activities of the isoquinolinyl-based Ti-[O,C,N] catalysts for ethylene polymerization are superior to those of pyridyl-based congeners.

Extremely active α-olefin polymerization and copolymerization with ethylene catalyzed by a dMAO-activated zirconium(iv) dichloro complex having an [OSSO]-type ligand

We report here the polymerization of α-olefins and copolymerization of ethylene with 1-hexene catalyzed by a zirconium complex incorporating an [OSSO]-type ligand with dried methylaluminoxane (dMAO) as an activator.

Synthesis of β-amino-α-trifluoromethyl alcohols and their applications in organic synthesis

A comprehensive overview on methods applied for syntheses of β-amino-α-trifluoromethyl alcohols, including stereocontrolled variants, is presented. In addition, reported cases of the exploration of β-amino-α-trifluoromethyl alcohols for the preparation of trifluoromethylated peptidomimetics and other biologically active, fluorinated compounds are discussed. Attractive opportunities for their applications as organocatalysts are also presented.

Highly Active Syndiospecific Living Polymerization of Higher 1-Alkene with ansa-Fluorenylamidodimethyltitanium Complex

1-Hexene polymerization was conducted by [t-BuNSiMe(2) (3,6-t-Bu(2) Flu)]TiMe(2) (1) using trialkylaluminum-free modified methylaluminoxane (dMMAO) as a cocatalyst in toluene. The system produced living syndiotactic poly(1-hexene) with high turnover frequency of propagation (TOF, 98 s(-1) ) at 0 °C. The propagation rate was increased linearly against the 1-hexene concentration, which indicates that the first-order dependence of the propagation rate on monomer concentration. Polymerizations of 1-octene, 1-decene and 1-dodecene were also conducted for investigating the effect of chain length of 1-alkene on propagation rate by means of the livingness of this system. The propagation rate decreased according to the chain length until 1-decene but almost unchanged in longer 1-alkene: TOF, 1-octene (62 s(-1) )>1-decene (32 s(-1) ) ≈ 1-dodecene (31 s(-1) ).

Interplay of metal-allyl and metal-metal bonding in dimolybdenum allyl complexes

Addition of PMe3 to Mo2(allyl)4 afforded Mo2(allyl)4(PMe3)2, in which two of the allyl groups adopt an unprecedented micro2-eta1,eta3 bonding mode; theoretical studies elucidate the roles of the sigma- and pi-donor ligands in the interplay of metal-allyl and metal-metal bonding.