Boosting Low-Valent Aluminum(I) Reactivity with a Potassium Reagent.
Boosting Low-Valent Aluminum(I) Reactivity with a Potassium Reagent.
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DOI：
10.1002/anie.202006693
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发表时间：
2020-09-07
期刊：
影响因子：
--
通讯作者：
Harder S
中科院分区：
文献类型：
--
作者：
Grams S;Eyselein J;Langer J;Färber C;Harder S
预计试剂RK [R=CH（SiMe 3）2或N（SiMe 3）2]与低价（DIPPBDI）Al（DIPPBDI=HC[C（Me）N（DIPP）]2，DIPP= 2，6-iPr-苯基）反应，得到[（DIPPBDI）AlR]−K+。然而，观察到配体骨架中Me基团的去质子化，并且[H2 C =C（N-DIPP）-C（H）=C（Me）-N-DIPP] Al-K+（1）结晶为亮黄色产物（73%）。像大多数阴离子AlI配合物，1形成二聚体，其中形式上带负电荷的Al中心由K+离子桥接，显示出强的K+-双金属间的DIPP相互作用。较短的Al-K键[3.499（1）-3.588（1）π]表明二聚体的键合较紧密。 根据DOSY NMR分析，1在C6 H6中是二聚体，在THF中是单体，但与两种溶剂反应缓慢。在与C6 H6的反应中，观察到两个C-H键活化，并且仅分离出具有帕拉亚苯基部分的产物。密度泛函理论计算证实了1中的Al中心比（DIPPBDI）Al中的Al中心具有更高的反应活性。计算表明，Al I和K+协同工作并决定了1的反应活性。 维生素 K对铝：试图通过加入钾试剂来增强β-二酮亚胺化Al I络合物的反应性，导致配体去质子化，产生不同的高反应性阴离子Al I络合物。苯的加成只在帕拉产生两个C-H键活化。
The reagent RK [R=CH(SiMe3)2 or N(SiMe3)2] was expected to react with the low‐valent (DIPPBDI)Al (DIPPBDI=HC[C(Me)N(DIPP)]2, DIPP=2,6‐iPr‐phenyl) to give [(DIPPBDI)AlR]−K+. However, deprotonation of the Me group in the ligand backbone was observed and [H2C=C(N‐DIPP)−C(H)=C(Me)−N−DIPP]Al−K+ (1) crystallized as a bright‐yellow product (73 %). Like most anionic AlI complexes, 1 forms a dimer in which formally negatively charged Al centers are bridged by K+ ions, showing strong K+⋅⋅⋅DIPP interactions. The rather short Al–K bonds [3.499(1)–3.588(1) Å] indicate tight bonding of the dimer. According to DOSY NMR analysis, 1 is dimeric in C6H6 and monomeric in THF, but slowly reacts with both solvents. In reaction with C6H6, two C−H bond activations are observed and a product with a para‐phenylene moiety was exclusively isolated. DFT calculations confirm that the Al center in 1 is more reactive than that in (DIPPBDI)Al. Calculations show that both AlI and K+ work in concert and determines the reactivity of 1. Vitamin K for Al: Attempts to enhance the reactivity of a β‐diketiminate AlI complex by addition of a potassium reagent led to ligand deprotonation, yielding a different highly reactive anionic AlI complex. Addition of benzene gave two C−H bond activations exclusively in para‐positions.
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