Ethylenepolymerization using catalysts derived from activation of zirconocene aluminohydride complexes with either methyl aluminoxane or B(C6F5)3 is reported. Variable-temperature NMR spectra of mixtures of Cp*2ZrH3AlH2 or Cp‘2ZrH3AlH2 and excess B(C6F5)3 reveal the formation of di- or polynuclear metallocenium ion-pairs featuring terminal or both terminal and bridging borohydride counteranions HB(C6F5)3
报道了使用衍生自锆茂铝氢化物配合物与甲基铝氧烷或B(C 6 F 5)3活化的催化剂的乙烯聚合。Cp的混合物的变温NMR谱* 2 ZRH 3的AlH 2或CP” 2 ZRH 3的AlH 2和过量的B(C 6 ˚F 5)3揭示了二-或多核茂金属离子对的形成设有一个末端或两个末端并桥接因氢化物夺取而产生的硼氢化物抗衡阴离子HB(C 6 F 5)3。在更高T,具有末端HB(C 6 F 5)3抗衡离子的离子对分解,释放出的AlH 3降解B(C 6 F 5)3以提供(C 6 F 5)n AlH 3 - n的混合物在Cp * 2 ZrH 3 AlH 2的情况下,新的离子对与二硼氢化物抗衡阴离子[Cp * 2 ZrH] [(μ-H)2 B(C 6 F 5)2]。后一种化合物是由Cp * 2 ZrH 2和HB(C 6 F 5)2独立制备的,并且在乙烯聚合中具有活性。然而,它的活性比由Cp * 2 ZrH 3
A C(sp<sup>2</sup>
)−H Dehydrogenation of Heteroarenes and Arenes by a Functionalized Aluminum Hydride
functionalized aluminum hydride (2-TMP-C6H4)AlH2 has been prepared. The inherent N/Al donor/acceptor pair cooperatively activates the C(sp2)−H bond, which improves the aluminum hydride reactivity by the elusive C(sp2)−H dehydroalumination of N-heteroarenes and multiple-bond-containing arenes. These reactions open a straightforward route to heteroaryl and unique heterocyclic aluminum compounds.
制备了官能化的氢化铝(2-TMP-C 6 H 4)AlH 2。固有的N / Al供体/受体对可协同激活C(sp 2)-H键,通过N-杂芳烃和含多个键的芳烃的C(sp 2)-H脱铝难以实现的氢化铝反应性的提高。这些反应为杂芳基和独特的杂环铝化合物开辟了一条直接途径。
Ring-Opening of THF via an Intramolecular P/Al-Based Frustrated Lewis Pair: Assistance by C<sub>6</sub>F<sub>5</sub> Groups beyond Electronegativity?
A frustratedLewispair composed of an acidic aluminum function (AlR2) and a basic phosphine entity, linked by a xanthene spacer, is capable of cleaving THF. The rate of the ring-opening reaction is higher by a factor of 10 for R = C6F5 than that for R = Mes. Structural and theoretical investigations revealed for the case of C6F5 aromatic interactions in the secondary coordination sphere which─in case
由酸性铝官能团 (AlR 2 ) 和碱性膦实体组成的受挫路易斯对能够裂解 THF。R = C 6 F 5的开环反应速率比 R = Mes的开环反应速率高 10 倍。结构和理论研究揭示了二级配位中 C 6 F 5芳烃相互作用的情况——如果它们也存在于过渡态——可以通过反应功能的预取向来帮助开环。然而,在详细的计算研究中发现这些发生并没有显着降低激活障碍。