Research News, Oct. 17th, 2012

Published on 2012-10-17

Rare-Earth Metal Tris(trimethylsilylmethyl) Anionic Complexes Bearing One 1-Phenyl-2,3,4,5-tetrapropylcyclopentadienyl Ligand: Synthesis, Structural Characterization and Application

Ling Xu, Zitao Wang, Wen-Xiong Zhang,* and Zhenfeng Xi*

Inorg. Chem. 2012,DOI: 10.1021/ic-2012-018369.

It is of great interest and importance to explore the synthesis and application of the isolable and soluble half-sandwich rare-earth anionic alkyl complexes. It will become a promising field if the reactivity of such anionic alkyl complexes is much closer to or better than that of neutral complexes because of their easy availability.

This paper reports the first synthesis of rare-earth metal tri(trimethylsilylmethyl) anionic complexes bearing one 1-phenyl-2,3,4,5-tetrapropylcyclopentadienyl ligand [Cp4PrPhLn(CH2SiMe3)3][Li(thf)n(OEt2)4-n] (1-Ln: Y, Er, Tm and Lu: n = 3, Ho: n = 4), whose structures are fully characterised. These soluble anionic compounds show good reactivity in the stoichiometric reaction with dibenzoylmethane. More importantly, they can serve as excellent catalyst precursors for the addition of ArRNH or ArAr’NH to carbodiimides yielding efficiently guanidines. Previously, such addition cannot be accomplished efficiently by the reported catalysts. Our results show clearly the reactivities of anionic trialkyl precursors are comparable with the corresponding neutral alkyl complex, but exhibit better catalytic activity than the known catalysts.

背景介绍

稀土金属烷基化合物的设计、合成、结构鉴定及催化应用在稀土金属导向有机合成化学和聚合物化学领域中有重要的应用前景，一直是金属有机化学的一个前沿且具挑战性的研究领域。中性的单茂稀土金属双烷基化合物的合成主要集中在Sc，Y，Gd-Lu等金属配合物，它们在聚合反应中有广泛的应用前景，然而，相应的单茂稀土金属多烷基ate配合物的合成，由于其溶解度较低，它们的合成和应用较少受到人们的关注。

本研究室经过几年的努力，利用自己发展的1-苯基-2,3,4,5-四丙基环戊二烯配体(Zhao, C.; Li, P.; Cao, X.; Xi, Z. Chem. –Eur. J. 2002, 8, 4292; Xi, Z.; Li, P. Angew. Chem. Int. Ed. 2000, 39, 2950.)，成功合成了一系列易溶的单Cp4PrPh稀土金属三烷基ate配合物。通过与二酮（DBM）反应，合成了单Cp4PrPh双二酮化合物，并通过单晶鉴定了其结构。尽管已有较多的催化剂种类能实现胺对碳二亚胺的加成反应，但还没有催化剂能实现ArRNH 或ArAr’NH对碳二亚胺的加成。此类ate配合物具有很好的催化活性，是第一个通用的催化剂，高效实现不同胺对碳二亚胺的催化加成反应。