The Hydride-Ion Affinity of Borenium Cations and Their Propensity to Activate H<sub>2</sub>in Frustrated Lewis Pairs
作者:Ewan R. Clark、Alessandro Del Grosso、Michael J. Ingleson
DOI:10.1002/chem.201203318
日期:2013.2.11
A range of frustrated Lewis pairs (FLPs) containing borenium cations have been synthesised. The catechol (Cat)‐ligated borenium cation [CatB(PtBu3)]+ has a lower hydride‐ion affinity (HIA) than B(C6F5)3. This resulted in H2 activation being energetically unfavourable in a FLP with the strong base PtBu3. However, ligand disproportionation of CatBH(PtBu3) at 100 °C enabled trapping of H2 activation products
合成了一系列含硼阳离子的沮丧的路易斯对(FLP)。邻苯二酚(Cat)连接的硼阳离子[CatB(P t Bu 3)] +具有比B(C 6 F 5)3更低的氢化物离子亲和力(HIA)。这导致在具有强碱P t Bu 3的FLP中,H 2活化在能量上不利。然而,CatBH(P t Bu 3)的配体歧化在100°C能够捕获H 2活化产物。在M06-2X / 6-311G(d,p)/ PCM(CH 2 Cl 2)水平表明,用氯化物替代邻苯二酚会显着增加氯离子亲和力(CIA)和HIA。经计算,二氯-硼阳离子[Cl 2 B(胺)] +的HIA比B(C 6 F 5)3大得多。对照反应证实,HIA计算可用于成功预测硼阳离子与中性硼烷之间的氢化物转移反应性。硼阳离子[Y(Cl)B(2,6-lutidine)] +(Y = Cl或Ph)与P(mesityl)3形成FLP,在20°C下对卢剔啶的邻甲基进行缓慢去质子化反应,形成四元硼环[[CH