Ancillary Ligand Effect on Single-Site Styrene Polymerization:  Isospecificity of Group 4 Metal Bis(phenolate) Catalysts

Abstract

Styrene is polymerized isospecifically by group 4 metal complexes that contain a C2-symmetrically coordinated 1,4-dithiabutane-linked bis(phenolato) ligand activated by methylaluminoxane.

Synthesis of amphiphilic diblock copolymers of isotactic polystyrene-block-isotactic poly(p-hydroxystyrene) using a titanium complex with an [OSSO]-type bis(phenolate) ligand and sequential monomer addition

“…The active species were formed from the dichloro complex as a result of methyl exchange between aluminum and titanium. 40 The insertion of monomers into the Ti-CH 3 bond occurred in a 2, 1-or secondary fashion, and the polymerization was highly regioselective in either the initiation step or the propagation step. The b-hydrogen reaction did not represent an irreversible termination reaction, and the unsaturated polymer chain represented a resting state.…”

Synthesis and olefin homo- and copolymerization behavior of new vanadium complexes bearing [OSSO]-type ligands

“…For example, catalysts based on phenoxy-imine complexes may be not only more active than the metallocene catalysts, but they make it possible to produce a variety of polyolefinic materials, inclusive of ultra-high-molecular-weight PEs, welldefined multimodal PEs, selective vinyl-and Al-terminated PEs, isotactic and syndiotactic PPs, as well as stereo-and regioirregular high-molecular weight poly(1-olefin)s [1]. Group 4 transition metal complexes which incorporate tetradentate [OSSO]-type bis(phenolate) ligands have also been quite extensively studied in homo-and copolymerization of olefins as well as in polymerization of styrene and its derivatives, and in olefin-styrene copolymerization [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The titanium complex of the tetradentate [OSSO]-type diphenolate ligand with the 1,4-dithiabutanediyl-bridge yielded isotactic PS at very high activity.…”

“…The titanium complex of the tetradentate [OSSO]-type diphenolate ligand with the 1,4-dithiabutanediyl-bridge yielded isotactic PS at very high activity. Polystyrene materials with the same microstructures were produced by Zr and Hf complexes bearing the identical ligand but with low yields [8]. On the other hand, titanium complexes with the longer and more flexible 1,5-dithiapentanediyl bridge promote syndiospecific styrene polymerization with relatively low activity [11].…”

Stereospezifischer Styroleinbau an einem Titanzentrum mit einem helicalen Ligandengerüst: Hinweis auf die Bildung von homochiralem Polystyrol

“…[8] Isotaktisches Polystyrol war zuvor mithilfe von Heterogenkatalysatoren vom Ziegler-Typ hergestellt und als erstes kristallisierbares Poly-(a-olefin) von Natta et al charakterisiert worden.…”

“…Entsprechend unseren vorherigen Studien zur homogenen Styrolpolymerisation [8,11] wurde das Racemat der TitanKatalysatorvorstufen 2 a mit Methylaluminoxan (MAO) aktiviert (dabei werden konfigurationsstabile Alkylkationen mit homotopen Koordinationsstellen [11b] erzeugt) und zur Styrolpolymerisation eingesetzt. Wie erwartet zeigte das entstandene isotaktische Polystyrol keine optische Aktivität.…”