Paramagnetic Titanium(III) and Zirconium(III) Metallocene Complexes as Precatalysts for the Dehydrocoupling/Dehydrogenation of Amine-Boranes
Paramagnetic Titanium(III) and Zirconium(III) Metallocene Complexes as Precatalysts for the Dehydrocoupling/Dehydrogenation of Amine-Boranes
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DOI：
10.1002/anie.201207903
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发表时间：
2013-01-01
影响因子：
16.6
通讯作者：
Manners, Ian
中科院分区：
文献类型：
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作者：
Helten, Holger;Dutta, Barnali;Manners, Ian
胺-硼烷加合物的催化脱氢偶联/脱氢已成为过去十年快速增长的领域。[1]这一发展是由储氢、[1, 2] 有机底物的转移氢化和还原，[3] 以及新型无机聚合物和固态材料的制备等方面的潜在应用推动的。[4, 5] 已经开发出多种催化剂系统来促进该反应，[6-10] 其中大多数基于第二和第三行后过渡金属的配合物。对这些转化的机理兴趣也导致了与胺-硼烷和氨基硼烷配体相关的配位化学新领域的出现。[11-13]尽管开发程度较低，但膦-硼烷的催化脱氢似乎提供了类似的潜力。[14]我们之前报道过由[Cp2TiCl2]和nBuLi原位生成的第一排第4族茂金属[Cp2Ti] （2当量）或来自可分离的 TiII 预催化剂 [Cp2Ti (PMe3) 2]，作为仲胺-硼烷加合物 1 脱氢生成环二硼氮烷 2 的高效均相催化剂（方案 1）。 [7] Chirik [8] 以及最近的 Rosenthal [9] 及其同事描述了一系列用于 1 脱氢偶联的活性 TiII 和 ZrII 预催化剂的类似研究。一般来说，Ti-
Catalytic dehydrocoupling/dehydrogenation of amine–borane adducts has become a field of rapid growth over the past decade.[1] This development has been driven by potential applications with respect to hydrogen storage,[1, 2] transfer hydrogenations and reductions of organic substrates,[3] and the preparation of new inorganic polymeric and solid-state materials.[4, 5] A wide variety of catalyst systems have been developed that promote this reaction,[6–10] most of which are based on complexes of second-and third-row late transition metals. Mechanistic interest in these transformations has also led to the emergence of an interesting new area of coordination chemistry associated with amine–borane and aminoborane ligands.[11–13] Although much less developed, the catalytic dehydrogenation of phosphine–boranes appears to offer similar potential.[14]We have previously reported that the first-row Group 4 metallocene [Cp2Ti], generated in situ from [Cp2TiCl2] and nBuLi (2equiv) or, alternatively, from the isolable TiII precatalyst [Cp2Ti (PMe3) 2], functions as an efficient homogeneous catalyst for the dehydrogenation of secondary amine–borane adduct 1 to give the cyclodiborazane 2 (Scheme 1).[7] Chirik [8] and, more recently, Rosenthal [9] and co-workers have described analogous studies of a series of active TiII and ZrII precatalysts for the dehydrocoupling of 1. In general, the Ti-