Catalytic Dehydrocoupling of Amine–Boranes using Cationic Zirconium(IV)–Phosphine Frustrated Lewis Pairs
作者:Owen J. Metters、Stephanie R. Flynn、Christiana K. Dowds、Hazel A. Sparkes、Ian Manners、Duncan F. Wass
DOI:10.1021/acscatal.6b02211
日期:2016.10.7
series of novel, intramolecular Zr(IV)/P frustrated Lewis pairs (FLPs) based on cationic zirconocene fragments with a variety of ancillary cyclopentadienyl and 2-phosphinoaryloxide (−O(C6H4)PR2, R = tBu and 3,5-CF3-(C6H3)) ligands are reported and their activity as catalysts for the dehydrocoupling of dimethylamine–borane (Me2NH·BH3) assessed. The FLP system [(C9H7)2ZrO(C6H4)PtBu2][B(C6F5)4] is shown to
一系列新颖的分子内Zr(IV)/ P沮丧的Lewis对(FLP),基于带有各种辅助环戊二烯基和2-膦基芳氧基(-O(C 6 H 4)PR 2,R = t Bu和报告了3,5-CF 3-(C 6 H 3))配体,并评估了它们作为二甲胺-硼烷(Me 2 NH·BH 3)脱氢偶联催化剂的活性。FLP系统[(C 9 H 7)2 ZrO(C 6 H 4)P t Bu 2 ] [B(C 6 F5)4 ]被证明可以为基于4族金属(TOF≥600 h –1)的催化剂提供前所未有的周转频率(TOF ),同时也被证明是迄今为止报道的最有效的FLP催化剂。已使用类似的分子间Zr(IV)/ P FLP探测了该反应的机理,从而使在路易斯酸性和碱性位点发生的反应都可以解卷积。对这种机制的阐明揭示了一个有趣的合作两循环过程,其中一个循环是FLP介导的,另一个循环是线性二硼氮烷中间体的重新分布,完全依赖于Zr(IV)Lewis酸的存在。