Synthesis and Characterization of Dichlorotitanium Alkoxide Complex and Its Activity in the Polymerization of α-Olefins

Abstract

We present the synthesis, characterization, X-ray molecular structure, and catalytic activity of a [(HOEt)Ti(µ-OEt)OEt(Cl) 2 ] 2 (1) dimeric complex. Complex 1 was found to undergo, in solution, a succession of fluxional processes involving the rotation of the ligands, rapid exchange between the anionic ethoxide ligands, and exchange of the hydroxylic hydrogen. The complex, when activated by methylalumoxane (MAO), undergoes an abstraction of the ligands through a heterobimetallic intermediate with ethoxide bridges between the aluminum and titanium atoms. We propose that this intermediate is the active species in the polymerization of R-olefins. The complex displays unexpectedly a single site behavior in contradiction to other titanium alkoxide complexes. The resulting polymers were found to show elastomeric properties with intermediate tacticities.

Novel bis(benzoin) titanium catalyst for homo- and copolymerization of norbornene with ethylene: Synthesis, characterization and catalytic properties

“…The active species as a heterobimetallic intermediate with oxobridge between titanium and aluminum atoms can be formed by reaction of complex 1 with MAO. Similar result has been confirmed by Eisen using a dichlorotitanium ethoxide complex as catalyst precursor [8]. For E-NB copolymerization, complex 1/MAO also exhibits long lifetime and keeps high activity after 4 h. Compared to copolymerization at 30 C, the copolymerization at 50 C has a higher activity and produces a copolymer with higher NB incorporation (comparing entry 16 with 15, and 21 with 17 in Table 4).…”

“…Recently, a [(HOEt)Ti(m-OEt)OEt(Cl) 2 ] 2 dimeric complex was found to react with MAO to be catalyst for the polymerization of propylene and ethylene. The lifetime of this catalyst is sufficiently long to allow an effective polymerization [8].…”

Ethylene polymerization using novel titanium catalytic precursors bearing N,N‐dialkylcarbamato ligands

“…In particular, bis(phenoxyimine) complexes of group 4 metals, which were discovered independently by Mitsui Chemical and by Coates et al,19, 20 represent the most outstanding precursors for ethylene polymerization. During the last decade, precursors containing chelate di(amido),21–24 alkoxo,25, 26 and amidinate27 ligands gained great interest for the synthesis of potential postmetallocene catalysts for the polymerization of olefins.…”

Synthesis of a new zirconium catalyst for ethylene polymerization

“…In 1995, Schaverien and coworkers3 published a study with several titanium and zirconium complexes with sterically hindered chelating phenoxide ligands as catalysts for the olefin polymerization. Recently, Eisen and coworkers4 synthesized a dimeric titanium complex with ethoxide group bridges; this complex was tested for ethylene and propylene polymerizations in the presence of methylaluminoxane (MAO). The propylene obtained presented an intermediate tacticity and high molecular weight.…”