[1-(2-Phenylethyl)-2,3,4,5-tetramethylcyclopentadienyl]- titanium Compounds. Synthesis and Their Use for the Syndiospecific Polymerization of Styrene

• DOI: 10.1021/om960475s
• Publication Date: 2002-07-26T05:01:06Z
• Authors: Juan C. Flores; John S. Wood; James C. W. Chien; Marvin D. Rausch
• Keywords: Methylaluminoxane; Cationic polymerization; Cyclopentadienyl complex

A series of monocyclopentadienyltitanium complexes containing the 1-(2-phenylethyl)-2,3,4,5-tetramethylcyclopentadienyl ligand (C5Me4CH2CH2Ph) have been synthesized and characterized. The reaction C5Me4(SiMe3)CH2CH2Ph (2) with TiCl4 was used to trichloro complex (C5Me4CH2CH2Ph)TiCl3 (3), molecular structure which confirmed by an X-ray diffraction study. Compound 3 further converted into (C5Me4CH2CH2Ph)TiMe3 (4). Reaction latter 1 equiv [Ph3C][B(C6F5)4] almost quantitative give "cationic" compound [(C5Me4CH2CH2Ph)TiMe2]+[B(C6F5)4]- (5). Complex 5 thermally unstable in solution very moisture sensitive. 4 readily hydrolyzed [(C5Me4CH2CH2Ph)TiMe2]2(μ-O) (6) upon recrystallization wet pentane. Structural data indicate intramolecular coordination phenyl group titanium 5, whereas there are no such indications for 3, 4, or 6. catalytic performance styrene polymerization activated methylaluminoxane (MAO) has compared nonsubstituted reference (C5Me5)TiCl3 (7). prepared situ reacting [Ph3C][B(C6F5)4], also found be active syndiospecific styrene. lead tentative suggestion that species is equilibrium between two states, one without Ti. These findings would consistent postulated multihapto both vinylic double bond aromatic ring metal center during process.