Niedrige Valenz und Gemischtvalenz Lanthanoid Komplexe: Reaktivität und Katalyse

本提案旨在发展苄基镧系元素化学。重点介绍了中性均相双苄基-Ln(II)和三苄基-Ln(III)配合物的合成和结构表征。在我们的初步研究中，我们分离和表征了第一个同质的Ln(II)-苄基，并成功地找到了(o-Me2N-C6H4CH2)3Y(III)和(o-Me2N-C6H4CH2)3La(III)的简单合成路线，证明它们是等结构的。由于这些高活性的苄基稀土元素是合成稀土催化剂的潜在前体，我们希望在这一领域扩大我们的努力。我们特别感兴趣的是均相的苄基稀土络合物的合成，这些络合物不是由苄基碳上的电子吸引基团稳定的，也不包含分子内的Lewis碱。我们的部分研究包括对苄基稀土络合物的分解反应的研究，以及分离可从结构上研究的可溶的、定义明确的镧系元素-亚苄基化合物的挑战。这组化合物尚不清楚，但可能会显示出有趣的反应性和催化活性。这些研究的第三部分包括苯乙烯与Ln(II)-苄基的聚合，这些聚合部分是从我们的初步研究中获得的，部分将在本项目中制备。用这些体系得到的聚苯乙烯具有意想不到的高间规度(r=95%)，这需要在这一领域进行进一步的研究。我们特别致力于活性和间规的苯乙烯聚合，这将使热塑性材料具有增强的性能。

The present proposal aims at the development of benzyllanthanide chemistry. Emphasis is on the syntheses and structural characterization of neutral homoleptic bis-benzyl-Ln(II) and trisbenzyl-Ln(III) complexes. In our preliminary investigations we isolated and structurally characterized the first homoleptic Ln(II)-benzyls and successfully found simple synthetic routes to (o-Me2N-C6H4CH2)3Y(III) and (o-Me2N-C6H4CH2)3La(III) which were shown to be isostructural. Since these highly reactive benzyllanthanides are potential precursors in the syntheses of lanthanide catalysts, we would like to expand our efforts in this area. We are especially interested in the syntheses of homoleptic benzyllanthanide complexes, that are not stabilized by electron-withdrawing groups at the benzylic carbon and also do not contain an intramolecular Lewis-base. Part of our research includes studies on the decomposition reactions of benzylic lanthanide complexes and the challenge to isolate soluble well-defined lanthanide-benzylidenes that could be structurally investigated. This group of compounds is still unknown, but could show interesting reactivity and catalytical activity. The third part of these studies encompass styrene polymerization with Ln(II)-benzyls that are partly available from our preliminary research and partly will be prepared within this project. The unexpected high syndiotacticity (r = 95 %) of the polystyrene obtained with these systems calls for further research activity in this area. We especially aim at a living and syndiotactic styrene polymerization, which would give access to thermoplastic materials with enhanced properties.