Olefin polymerization behavior of titanium(IV) alkoxo complexes with fluorinated diolate ligands: The impact of the chelate ring size and the nature of organoaluminum compounds

Abstract

Titanium(IV) coordination compounds are effectively used as precatalysts for ethylene polymerization and copolymerization with other olefins. New titanium(IV) complexes 3b-d with ligands containing two diphenylcarbinol fragments linked by the perfluorinated hydrocarbon units-CF 2or-C 2 F 4were synthesized. The structures of complexes 3b and 3d were determined by X-ray diffraction. Titanium atoms in 3b have a distorted trigonal-bipyramidal coordination environment while spiro-complex 3d is characterized by tetrahedral molecular geometry. The catalytic behavior of complexes activated by mixtures of Bu 2 Mg and alkylaluminium chlorides from among Me 2 AlCl, Et 2 AlCl, EtAlCl 2 , and Et 3 Al 2 Cl 3 were studied. The resulting catalytic systems catalyze ethylene polymerization to afford ultra-high molecular weight polyethylene, suitable for modern processing methods, and the solvent-free solid state formation of super high-strength (1.37-2.75 GPa) and high-modulus (up to 138 GPa) oriented film tapes. The same catalytic systems catalyze ethylene copolymerization with 1-hexene to afford high molecular weight semicrystalline elastomeric polymers containing up to 20% of comonomer units.

The Effect of Titanium Tetra-Butoxide Catalyst on the Olefin Polymerization

“…These results show that the copolymerization of 1-hexene, 1-octene, and ethylene was strongly activated by the comonomer. Tuskaev et al [ 23 ], Hongrui et al [ 26 ], and Muñoz-Escalona et al [ 33 ] have studied the notable preliminary enhancement in activity by α-olefin, which is known as the comonomer effect. These studies were grouped or categorized according to physical and chemical effects.…”

“…Recently, it has been discovered that the use of Ti(IV) alkoxide complexes—with 1,2- and 1,4-diolate ligands activated by a binary activator {Bu 2 Mg + Et 2 AlCl} and as a catalyst during the polymerization process of ethylene—results in the formation of an ultrahigh molecular weight polyethylene (UHMWPE) [ 23 ]. Ti(IV) complexes with diolate ligands are also very efficient in the copolymerization of ethylene and α-olefins.…”

“…Ti(IV) complexes with diolate ligands are also very efficient in the copolymerization of ethylene and α-olefins. However, the effectiveness of the various diolate complexes differs based on the size of the chelate ring and the amount of aluminum chloride used [ 23 ].…”

Synthesis, Structural and Physicochemical Characterization of a Titanium(IV) Compound with the Hydroxamate Ligand N,2-Dihydroxybenzamide

“…The design, synthesis, and physicochemical characterization of polyoxo-titanium clusters (PTCs) have been an active research area over the last decade, due to their interesting electronic properties for various applications in nanotechnology [ 1 , 2 , 3 , 4 , 5 , 6 ], photocatalytic hydrogen production [ 7 , 8 , 9 ], degradation of environmental pollutants [ 10 , 11 ], catalysis [ 12 , 13 , 14 , 15 , 16 , 17 ], solar energy conversion [ 18 , 19 ], and copolymerization of carbon dioxide [ 20 ]. At this point, it is worth noting that according to an excellent review, published very recently, the chemistry of group IV elements is underexplored [ 21 ].…”

“…Density Functional Theory (DFT) calculations reveal that in the experimental and theoretically predicted IR absorbance spectra of the ligand and Ti-complex, the main bands observed in the experimental spectra are also present in the calculated spectra supporting the proposed structural model. 1 H and 13 C NMR solution (CD 3 OD) studies of 1 reveal that it retains its integrity in CD 3 OD. The observed NMR changes upon addition of base to a CD 3 OD solution of 1, are due to an acid-base equilibrium and not a change in the Ti IV coordination environment while the decrease in the complex's lability is due to the improved electron-donating properties which arise from the ligand deprotonation.…”