Stereoselective Copolymerization of Unprotected Polar and Nonpolar Styrenes by an Yttrium Precursor: Control of Polar‐Group Distribution and Mechanism

Abstract

Styrene underwent unprecedented coordination-insertion copolymerization with naked polar monomers (ortho-/meta-/para-methoxystyrene) in the presence of a pyridyl methylene fluorenyl yttrium catalyst. High activity (1.26×10 g mol h ) and excellent syndioselectivity were observed, and high-molecular-weight copolymers (24.6×10 g mol ) were obtained. The insertion rate of the polar monomers could be adjusted in the full range of 0-100 % simply by changing the loading of the polar styrene monomer. Strikingly, the copolymers had tapered, gradient, and even random sequence distributions, depending on the position of the polar methoxy group on the phenyl ring and thus on its mode of coordination to the active metal center, as shown by tracking the polymerization process and DFT calculations.

Rapid Syndiospecific (Co)Polymerization of Fluorostyrene with High Monomer Conversion

“…DFT calculations were employed to elucidate the different catalytic behaviors of complexes 1 and 4 . According to our previous reports about the stereospecific polymerization of styrene and its derivatives, the cationic metal complex with two monomer units attached is adopted exclusively as the active species, and the 2,1‐insertion of p FS into the active species is the only considered insertion mode. Firstly, the energy profiles for the transition states and intermediates arising from the coordination‐insertion reactions between p FS and the unlinked half‐sandwich benzyl‐fluorenyl ligated complex 4 were simulated.…”

Coordination‐Insertion Copolymerization of Norbornene and p‐Substituted Styrenes Using Anilinonaphthoquinone‐Ligated Nickel Complexes

“…Typical 13 C NMR spectra of the N/MeOS, N/MeS, and N/ClS copolymers (Run 2, 9, and 18) are shown in Figures 1b, 2b, and 3b. Each signal of the N/MeOS copolymer was assigned as follows in reference to those of N/S copolymer obtained by the same catalyst23 and S/MeOS copolymer obtained by an yttrium‐based catalyst24,25: 137.0 ppm for C 1 , 112.9 ppm for C 2 , 128.1 ppm for C 3 , 157.5 for C 4 , 54.9 for C 5 , 47.0 and 39.3 ppm for C 6 and C 7 of the MeOS segment; 49–52.7 ppm for C 8 , 36.5–38.8 ppm for C 9 , 33.8–36 ppm for C 10 , and 28.0–31.9 ppm for C 11 of the N unit. The phenyl carbons of the MeOS units in the regions of 113–157 ppm and methoxy carbon in the regions of 55 ppm indicate the presence of the MeOS units in the N/MeOS copolymer (Figure 1b).…”

Emerging Palladium and Nickel Catalysts for Copolymerization of Olefins with Polar Monomers

“…Palladium has been the dominant player in this field, with more high-performance nickel catalysts emerging.M eanwhile,the utilization of other transition metals such as iron, [98] titanium, [99] and rare-earth metals [100][101][102][103][104] has been investigated. Most research in this field has been focused on the identification of ac apable catalyst system, and subsequent improvements through modifications of the ligand electronics and sterics.The search for alternative and general strategies is highly desired, especially when dealing with the polar monomer problem.…”