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Several ansa C1-symmetric cyclopentadienyl-fluorenyl metallocenes based on zirconium have been prepared with different substituents at position 3 on the cyclopentadienyl ring. Isotactic polypropylene production from these systems depends highly on the size of these substituents. Therefore, large groups such as 1-methyl-4-tbutylcyclohexyl (metallocene 6), 1-methyl-cyclohexyl (metallocene 7), 1,3,3,5- tetramethylcyclohexyl (metallocene 8), and 2,3,4-trimethyl-3-pentyl (metallocene 9) have been investigated. In combination with methylaluminoxane (MAO), they showed good activity and produced high molecular weight of isotactic polypropylene. In terms of the tacticity of the polymers, metallocene 6 made the best isotactic polypropylene with ~88% mmmm pentad content. Also, it has been found that if the size of this substituent is large as in 2,3,4-trimethyl-3-pentyl (metallocene 9), then it will block the polymerization active site which will deactivate the metallocene. New synthetic pathways for the synthesis of cyclopentadienyl-fluorenyl metallocenes based on titanium have been achieved. Anchoring these types of ligands onto titanium by following the conventional method of using TiCl4 in the metallation step has failed for the production of Me2C(3-(diphenylmethyl)-C5H3)(C13H8)TiCl2 (metallocene 12), Ph2C(C5H4)(C13H8)TiCl2 (metallocene 14), and Ph2C(C5H4)(C13H8)TiMe2 (metallocene 15); this is possibly due to the high reactivity of TiCl4. Therefore, TiCl4·2THF has been prepared and used in that step to produce these new titanocenes with good yields. A new ansa-C2-symmetric substituted bis-indenyl metallocene for isotactic polypropylene production has been successfully prepared. It is known that ansa-C2- symmetric metallocenes are good catalysts for isotactic polypropylene production, but in general, their synthesis suffers from the production of the meso Cs-stereoisomer of these catalysts, which generally produces only atactic polypropylene. Therefore, the meso stereoisomers must be removed and this is considered a loss of the material that increases the cost of the catalysts. Addition of bulky substituents on the indenyl groups as in Me2Si(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenz(f)indenyl)2ZrCl2 (metallocene 5) has prevented the meso stereoisomer production. 5/MAO produces isotactic polypropylene with up to ~80% mmmm pentad content.

Aluminum- and gallium-bridged ansa-zirconocene compounds (Pytsi)Al[1]ZCP (31a) and (Pytsi)Ga[1]ZCP (31b) containing a bulky trisyl-based ligand with a pyridyl donor group [Pytsi = -C(SiMe3)2SiMe2(2-C5H4N)] were synthesized in 31% and 40% yield, respectively, by the reaction of (Pytsi)ECp2 [E = Al (29a), Ga (29b)] with Zr(NMe2)4 followed by reaction with Me3SiCl. Compounds 29a and 29b were prepared by the reaction of (Pytsi)ECl2 [E = Al (28a), E = Ga (28b)] with two equivalents of NaCp. The molecular structures of 29a and 29b were elucidated in solution by 1H and 13C NMR spectroscopy. Species 31a was characterized by multinuclear NMR spectroscopy while 31b was characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy and mass spectrometry. Both species are the only known examples of aluminum- and gallium-bridged ansa-zirconocenes. Compound 31b in combination with MAO was applied and shown to be highly active for ethylene polymerization at room temperature. The activity of 31b was compared to that obtained for Cp2ZrCl2 using a glass reactor system and was found to be comparable. The influence of precatalyst concentration and ethylene pressure on activity of 31b was studied.

Aluminum- and gallium-bridged ansa-zirconocene compounds (Pytsi)Al[1]ZCP (31a) and (Pytsi)Ga[1]ZCP (31b) containing a bulky trisyl-based ligand with a pyridyl donor group [Pytsi = -C(SiMe3)2SiMe2(2-C5H4N)] were synthesized in 31% and 40% yield, respectively, by the reaction of (Pytsi)ECp2 [E = Al (29a), Ga (29b)] with Zr(NMe2)4 followed by reaction with Me3SiCl. Compounds 29a and 29b were prepared by the reaction of (Pytsi)ECl2 [E = Al (28a), E = Ga (28b)] with two equivalents of NaCp. The molecular structures of 29a and 29b were elucidated in solution by 1H and 13C NMR spectroscopy. Species 31a was characterized by multinuclear NMR spectroscopy while 31b was characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy and mass spectrometry. Both species are the only known examples of aluminum- and gallium-bridged ansa-zirconocenes. Compound 31b in combination with MAO was applied and shown to be highly active for ethylene polymerization at room temperature. The activity of 31b was compared to that obtained for Cp2ZrCl2 using a glass reactor system and was found to be comparable. The influence of precatalyst concentration and ethylene pressure on activity of 31b was studied.

Le polypropylène isotactique est un thermoplastique semi-cristallin de grande consommation présentant de nombreux avantages tels que sa résistance chimique, sa haute température de fusion ou sa rigidité. Néanmoins, sa faible résistance à l'état fondu le rend inadapté à certains procédés de mis en forme. La présence branchements longs au sein de la structure polymérique permet toutefois de renforcer significativement les propriétés d'un polymère dans son état fondu. De ce fait, de nombreuses approches ont été développées afin de générer du polypropylène branché (irradiation, addition de peroxides, greffages etc.). La catalyse de polymérisation par les métallocènes est d'une grande flexibilité dès qu'il s'agit de concevoir des polymères de spécialité. De plus, la rhéologie moléculaire est un outil indispensable à la compréhension des liens entre les propriétés viscoélastiques et la structure macroscopique des polymères (distribution des masses, topologie des branchements, etc.). Grâce à l'alliance de ces deux expertises, les travaux de cette thèse se sont focalisés sur la caractérisation structurelle, thermique et rhéologique de matériaux de type LCB-iPP obtenus par catalyse des zirconocènes {Cp'CR2Flu}ZrCl2. L'objectif premier était de jouer sur la génération des branchements longs en modifiant les conditions opératoires de polymérisation du propylène. En parallèle, un gros travail analytique a été fourni afin de développer des protocoles rhéologiques fiables et adaptés. Suite à ces résultats, nous avons démontré qu'un mécanisme via génération/incorporation de macro-α-oléfines était à l'origine de la génération de LCB-iPP, ce qui a permis la synthèse de polypropylènes hautement branchés et de vérifier l'effet positif des branchements longs sur le comportement viscoélastique des matériaux finaux. / Because of its high melting point, high tensile strength, stiffness and chemical resistance, isotactic polypropylene has one of the leading and fast growing thermoplastic polymers in the world. However, commercial PPs usually have relatively low melt strength, which limits their use in applications such as blow molding. Since long-chain branching (LCB) is known to enhance the melt properties of a polymer, several approaches have been developed to make branched polypropylenes (electron beam irradiation, peroxide curing, grafting etc.). Development of metallocene technology provides unprecedented flexibility in polymer design. Many structural features, including LCB, can now be introduced into polymers. In this work, long chain branched isotactic polypropylene (LCB-iPP) was synthesized using {Cp'CR2Flu}ZrCl2 metallocene catalyst and fully characterized (rheological, spectroscopic and thermal analysis). The branching (macro-α-olefins having predominantly vinyl-terminated chain end) was in situ generated and further incorporated by the same catalyst system to obtain LCB-PP/Linear PP blends. The LCB content was increased using a novel tandem catalysts system for converting propylene alone to isotactic polypropylene with long branches which exhibit enhanced melt properties.

Deck and coworkers previously showed that Me3Si substituents adjacent to group 4 metallocene dichlorides (M = Ti, Zr, Hf) are converted to corresponding BrMe2Si groups using BBr3, and that these BrMe2Si substituents are highly reactive to nucleophilic reagents such as water. The high reactivity of the Si-Br bonds suggested that these substituents could react with hydroxyl groups on the surface of partially dehydroxylated silica, forming covalently immobilized metallocene catalysts. This dissertation concerns the synthesis of electrophile-functionalized zirconocene dihalide complexes and the use of functionalized zirconocene dihalides as precursors to silica-supported metallocene olefin polymerization catalysts. Our first objective was to extend the metallocene "functionalization" chemistry to obtain substituents bearing more than one electrophilic bond. The reactivities of Me3Sn and Ph2MeSi substituents were explored in detail. (Me3Sn)2C5H4 combined with CpZrCl3 in toluene to afford (h5-Me3Sn-C5H4)CpZrCl2 (A). Reactions of A with electrophiles (E-X = Cl2B-Cl, I-Cl, and I-I) afforded (ï ¨5-XMe2Sn-C5H4)CpZrCl2 (and E-Me) cleanly. The reaction of A with BBr3 afforded either (ï ¨5-BrMe2Sn-C5H4)CpZrBr2 (25 ï °C, 10 min) or (ï ¨5-Br2MeSn-C5H4)CpZrBr2 (25 ï °C, 15 h). Ph2MeSi-C5H4Li combined with ZrCl4·2THF to afford (h5-Ph2MeSi-C5H4)2ZrCl2 (B). The reaction of B with BCl3 led to incomplete cleavage of the Ph-Si bonds, however treatment of B with BBr3 afforded (h5-Br2MeSi-C5H4)2ZrBr2 (C) efficiently. The Sn-X bonds of the stannylated metallocenes were however relatively unreactive toward water and were excluded as candidates precursors for supported metallocene catalysts. X-ray crystal structures of (h5-ClMe2Sn-C5H4)CpZrCl2·½toluene, (h5-Br2MeSn-C5H4)CpZrBr2·THF, B, and C were obtained. The functionalized metallocene C reacts with water to afford an oligosiloxane-supported zirconocene dibromide. Combinations of solution 1H NMR, solid state CPMAS 13C NMR, and solid state CPMAS 29Si NMR spectroscopy suggested a stereoregular structure in which the metallocene units have local Cs (meso) symmetry. Although only sparingly soluble, the oligomeric substance showed activity for homogeneous ethylene polymerization (toluene solution, MAO cocatalyst, Al:Zr = 5000, 50 ï °C) similar to Cp2ZrCl2. Supported metallocene olefin polymerization catalysts were prepared by combining a functionalized metallocene precursor (Cp2ZrBr2 bearing either BrMe2Si or Br2MeSi groups) and partially dehydroxylated silica. Ethylene polymerization activity of the resulting catalysts was examined as a function of the precursor structure (number of reactive "tethering" groups, one vs. two Si-Br bonds per tethering group) and the immobilization conditions (time, temperature, presence or absence of NEt3 promoter). The activities of the immobilized zirconocene catalysts decreased and the stabilities increased with increasing number of tethers. The immobilized catalyst prepared from (ï ¨5-Br2MeSi-C5H4)2ZrBr2, which is assumed to form two "double-tethers" to silica, was significantly more active than the catalyst prepared from [ï ¨5-1,3-(BrMe2Si)2C5H3]2ZrBr2, which is assumed to form four "single-tethers" to silica. Catalyst leaching was observed in all the immobilized zirconocene catalysts. The use of NEt3 in the immobilization reaction enabled more metallocene to be supported, but the resulting activity was lower. The dissertation also includes model studies on the immobilization reaction and the stability of the Si-O-Si bonds. The reaction of C with tBuMe2SiOH results in the formation of Si-O-Si bonds; addition of NEt3 results in further reaction to afford Si-O-Zr bonds. The reaction of Reaction of Me3Si-O-SiMe3 with MAO showed that Si-O-Si bonds can be cleaved under the conditions of our polymerization reactions. / Ph. D.

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