AM2Net Advanced Macromolecular Materials By Transition Metal Catalysis; Group 2: "Post Metallocene Catalysis"; Post-metallocene polymerization catalysts for alpha-olefins and dienes

本文的目的是对三价烷基钛中间体在“限制几何”钛催化剂和所谓的Lovacat催化剂中的作用有更深入的机理理解，这两种催化剂都用于乙烯与1-辛烯的无规共聚。我们试图阐明，通过合成和机械研究，使用功能化的配体，单中心催化剂含有四价钛中心和那些含有三价钛中心之间的关系。类似于用于苯乙烯间规聚合的高效单（双）钛（III）催化剂，我们尝试开发用于α-烯烃、1，3-二烯和苯乙烯的聚合催化剂。作为抗磁性模型化合物，我们将尝试合成含相同功能化配体的钪配合物。连接的双（酚盐），双（酰胺基），和苯氧基亚胺配体，纳入hemilabile供体功能，将被测试作为新类型的辅助配体系统的亲电三价金属中心钪，钛，铝络合。在同一配体组中含有钛和铝的双金属衍生物可能导致用于多相齐格勒催化剂的有用模型和对极性官能团更耐受的催化剂。三价钛络合物还可以导致催化剂在插入和受控自由基链增长机制之间可切换。此类金属基引发剂在合理合成新的大分子结构如具有非极性和极性链段的嵌段共聚物方面具有相当大的潜力。

The present proposal aims at a deeper mechanistc understanding of the role of trivalent titanium alkyl intermediates in the "constrained geometry" titanium catalysts and the so-called Lovacat catalytsts, both industrially used for the random copolymerization of ethylene with 1-octene. We seek to elucidate, by synthetic and mechanistic studies using functionalized cyclopentadienyl ligands, the relationship between single-site catalysts containing tetravalent titanium centers and those containing trivalent titanium centers. In analogy to the highly efficient mono(cyclopentadienyl)titanium(III) catalysts for the syndiospecific polymerization of styrene, we attempt to develop polymerization catalysts for alpha-olefins, 1,3-diene, and styrene. As diamagnetic model compounds the synthesis of isoelectronic scandium complexes containing the same functionalized cyclopentadienyl ligands with amido and amino donors will be attempted. Linked bis(phenolate), bis(amido), and phenoxyimine ligands, incorporating hemilabile donor functions, will be tested as new types of ancillary ligand systems for the complexation of the electrophilic trivalent metal centers scandium, titanium, and aluminum. Bimetallic derivatives containing titanium and aluminum within the same ligand set may lead to useful models for the heterogeneous Ziegler catalysts and to catalysts more tolerant to polar functional groups. Trivalent titanium complexes may also result in catalysts switchable between insertion and controlled radical chain propagation mechanisms. Such metal based initiators bear considerable potential for the rational synthesis of new macromolecular architectures such as block copolymers with nonpolar and polar segments.