Tridentate ligands and beyond in group IV metal α-olefin homo-/co-polymerization catalysis

Abstract

The opening up of new markets, particularly in the Far East, is expected to increase the industrial demand for more (and new) plastic materials. In turn, this will drive the need for further catalyst development, with increased efficiency and with the capacity to easily control the resulting polymer properties being high on the agenda. With this in mind, tailoring the pre-catalyst structure has proved to be a very successful strategy, and has allowed for the elucidation of a number of structure-activity trends. A particularly fruitful synthetic avenue has been the deployment of multi-dentate ancillary ligands bearing one or more substituents containing additional functionality, capable of weakly binding to the metal. Such a method is versatile and allows for the incorporation of a wide range of functionality. Furthermore, benefits of such an approach include the ability to control the % incorporation of co-monomers, in situ screening, low co-catalyst loadings (versus activity enhancement) as well as control over the resultant polymer structure. This review underlines the efforts made in the last few years with regard to the use of tridentate ligands and beyond in the field of α-olefin polymerization using catalytic systems based on group IV metals.

Imines in the Titanium Coordination Sphere: Highly Reactive Titanaaziridines and Larger Titanacycles Formed by Subsequent C–C Coupling Reactions

“…For this purpose, Cp N TiCl 3 (1e) appeared especially suitable to us, because its hemilabile Ndonor has been very useful in the organometallic chemistry of titanium complexes. [25,31] In this way, we performed the reductive complexation of imine 2e with 1e as the titanium precursor. Indeed, by this pathway, we were able to isolate the titanaaziridine 3f, which is distinguished by a further chlorido ligand in addition to the hemilabile Cp N ligand, in a yield of 68 % as a dark green solid (Scheme 7).…”

Design of Efficient Molecular Catalysts for Synthesis of Cyclic Olefin Copolymers (COC) by Copolymerization of Ethylene and α-Olefins with Norbornene or Tetracyclododecene

“…For examples, activities (TCD content) by [Et(Ind)2]ZrCl2 [32], [Ph2C(Ind)(Cp)]ZrCl2 [33], [Ph2C(Cp)(Flu)]ZrCl2 [33], [Me2C(3-MeC5H3)(Flu)]ZrCl2 [3], [Me2C(3-t BuC5H3)(Flu)]ZrCl2 [3] were 25 kg-polymer/mol-Zr•h (35 mol %), 31 (85 mol % at 90 °C), 24 (68), 1.3 (40), 0.4 (44), and respectively. Design of molecular catalysts for synthesis of new polymers with specified functions is one of the most attractive targets in the field of catalysis, polymer chemistry, and organometallic chemistry [37][38][39][40][41][42][43][44][45][46][47][48]. In this minireview, reported examples of copolymerization of COs (NBE, TCD) with olefins (ethylene, propylene, 1-hexene, 1-octene, etc.…”

Phosphine-Thiophenolate Half-Titanocene Chlorides: Synthesis, Structure, and Their Application in Ethylene (Co-)Polymerization

“…In addition, the NBE incorporation was lower than that obtained by complex A, especially at NBE concentration of 1.0 mol/L (2a: 33.8%, A: 53.2%, respectively). The resultant copolymers possessed relatively high molecular weights (MWs) with unimodal molecular weight distributions (MWDs), and the MW of the copolymers decreased upon the increasing NBE concentration (entries [1][2][3][4] …”

“…The development of well-defined, single-site group 4 metal catalysts has attracted much attention for olefin polymerization [1][2][3]. Many studies have also been focused on the relationship between the structure and catalytic properties of a given catalyst with respect to polymer chain composition and architecture [4][5][6][7].…”