Homogeneous Catalytic Dehydrocoupling/Dehydrogenation of Amine−Borane Adducts by Early Transition Metal, Group 4 Metallocene Complexes
作者:Matthew E. Sloan、Anne Staubitz、Timothy J. Clark、Christopher A. Russell、Guy C. Lloyd-Jones、Ian Manners
DOI:10.1021/ja909535a
日期:2010.3.24
The efficient catalytic dehydrocoupling of a range of amine-borane adducts, R'RNH x BH(3) (R' = R = Me 1a; R' = R = (i)Pr 1b; R' = Me, R = CH(2)Ph 1c) by a series of group 4 metallocene type precatalysts has been demonstrated. A reduction in catalytic activity was detected upon descending the group and also on substitution of the cyclopentadienyl (Cp) ligands with sterically bulky or electron-donating
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 cationiczirconocene 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。
Rh(I) diolefin amides, [Rh(trop2N)(L)] (trop2N = bis(5H-dibenzo[a,d]cyclohepten-5-yl)amide), form the corresponding hydrido amine species, [RhH(trop2NH)(L)], by reaction with Me2HN-BH3 (DMAB). Both amide and amine complexes are active dehydrocoupling catalysts, forming the monomer [Me2N = BH2], the linear [Me2NHBH2NMe2BH3] and the cyclic dimer [Me2BNH2]2. Good catalytic activity was observed especially
Iron-Catalyzed Dehydrocoupling/Dehydrogenation of Amine–Boranes
作者:James R. Vance、André Schäfer、Alasdair P. M. Robertson、Kajin Lee、Joshua Turner、George R. Whittell、Ian Manners
DOI:10.1021/ja410129j
日期:2014.2.26
complexes, [CpFe(CO)2]2 (1) and CpFe(CO)2I (2) (Cp = η-C5H5), were found to be efficient precatalysts for the dehydrocoupling/dehydrogenation of the amine-borane Me2NH·BH3 (3) to afford the cyclodiborazane [Me2N-BH2]2 (4), upon UV photoirradiation at ambient temperature. In situ analysis of the reaction mixtures by (11)B NMR spectroscopy indicated that different two-step mechanisms operate in each case
Catalytic dehydrocoupling of H3B·NMe2H using the in situ system Cp2Zr(Cl)(μ-Me3SiC3SiMe3)Zr(Cl)Cp2 (1)/MeLi was studied as a model for previously reported dehydropolymerisation of H3B·NMeH2. NMR and UV-vis spectroscopic monitoring of the precatalyst activation sequence as well as a series of stoichiometric experiments showed that formation of a zirconocene dimethyl complex (2) is not relevant for activation