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

本建议旨在更深入地从机理上理解三价钛的烷基中间体在“限制几何”钛催化剂和所谓的Lovacat催化剂中的作用，这两种催化剂在工业上都用于乙烯与1-辛烯的无规共聚合。我们试图通过使用官能化的环戊二烯配体的合成和机理研究来阐明含四价钛中心的单位催化剂和含三价钛中心的单位催化剂之间的关系。类似于高效的单(环戊二烯)钛(III)催化剂用于苯乙烯的间规聚合，我们试图开发用于α-烯烃、1，3-二烯和苯乙烯的聚合催化剂。作为抗磁模型化合物，我们将尝试合成具有相同官能化的环戊二烯基配体与氨基和氨基供体的等电子钪配合物。连接的双(苯酚)、双(氨基)和苯氧亚胺配体，结合了半亲核的给体功能，将被测试为新型的辅助配体系统，用于亲电的三价金属中心钪、钛和铝的络合。同时含有钛和铝的双金属衍生物可能为多相Ziegler催化剂和更耐极性官能团的催化剂提供有用的模型。三价钛络合物也可能导致催化剂在插入和受控自由基链传播机制之间切换。这类基于金属的引发剂在合理合成新的大分子结构方面具有相当大的潜力，例如具有非极性和极性链段的嵌段共聚物。

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.