Salalen Titanium Complexes in the Highly Isospecific Polymerization of 1‐Hexene and Propylene

Abstract

All lined up: C1‐symmetric octahedral titanium complexes (see structure, Ti dark gray, N blue, O red, I purple) whose labile positions reside in different electronic environments were designed using the readily available salalen ligands. With methylalumoxane as co‐catalyst, highly active catalysts were obtained, which yielded high‐molecular‐weight polypropylene with ultra‐high isotacticities (see 13C NMR spectrum) and melting transitions.

Catalyst activation and the dimerization energy of alkylaluminium compounds

“…This exercise results in recommendations for protocols expected to produce reliable results for such systems. In Part 2, we then apply our recommendations to a study of alkylation of catalyst precursors (LTiX 2 ; L ¼ Salan [12,13], Salalen [14], Cp 2 ; X ¼ halide, alkoxide, amide; see Scheme 1) by aluminium alkyls. Such alkylation is a crucial step in the activation of many polymerization catalysts.…”

Aminopyridinate–FI Hybrids, Their Hafnium and Titanium Complexes, and Their Application in the Living Polymerization of 1‐Hexene

“…Herein, we report a newly designed ligand system, named Ap‐FI ligands, which represents a combination of these above‐described FI (phenoxyimine) and Ap ligands (Figure 1, left). Recently, one very successful example of the combination of FI ligands with another ligand system was reported by Kol and co‐workers 6. This ligand hybrid was a combination of “half‐salan”7 and “half‐salen” ligands8 (salalen; Figure 1, right) that were linked through an ethylene bridge 9.…”

Olefin Polymerization with Non-metallocene Catalysts (Early Transition Metals)

“…This may be due to the fact that 6 folds pseudo-trigonal bipyramidal geometry whereas the complexes 5 fold distorted octahedral geometry around the metal center, which lead to the different bond angles between two benzyl (Bn) group (117.48 in 6 and 93.78 in 5) [37]. More recently, Kol demonstrated that octahedral C 1 -symmetric titanium catalysts containing salalen ligand (7) are highly effective for isospecific propylene polymerization to afford polymers with extraordinary high isotacticity with high melting transition temperature ([mmmm] [ 99.6 %, T m = 169.9 8C) [43]. Zirconium complexes bearing two salicylaldiminato-type ligands (8 in Scheme 3.4) exhibited remarkable catalytic activities for ethylene polymerization [44].…”