德国弗莱堡阿尔伯特路德维希大学Krossing, Ingo团队报道了低价Al4⁺团簇阳离子盐的合成。相关研究成果于2022年8月4日发表在国际知名学术期刊《自然—化学》。

低价铝化合物是非常活泼的主族物质，因此已被广泛研究。自1991年分离出稳定的分子 Al(I)化合物[(AlCp*)4] (Cp*=[C5Me5]–)以来，已开发出多种高反应性中性或阴离子低价铝络合物。相比之下，它们的阳离子对应物仍然难以获得。

该文中，研究人员报道了通过 [(AlCp*)4] 和 Li[Al(ORF)4]之间的简单复分解反应合成[Al(AlCp*)3]+[Al(ORF)4]– (RF=C(CF3)3)。出乎意料的是，[Al(AlCp*)3]⁺盐在固态和浓溶液中形成二聚体。路易斯碱的加入导致单体化和与唯一形式的Al⁺原子的配位，产生[(L)xAl(AlCp*)3]⁺盐，其中L为六苯基碳二膦（x=1）、四甲基乙二胺（x=2）或4-二甲氨基吡啶（x=3）。生成的[(L)xAl(AlCp*)3]⁺簇阳离子中的Al⁺-AlCp*键可以在非常强（无配体L）到非常弱且接近孤立的 [Al(L)3]⁺离子（当L为二甲氨基吡啶时）之间精确调整。

附：英文原文

Title: Synthesis of a low-valent Al4+ cluster cation salt

Author: Dabringhaus, Philipp, Willrett, Julie, Krossing, Ingo

Issue&Volume: 2022-08-04

Abstract: Low-valent aluminium compounds are very reactive main-group species and have therefore been widely investigated. Since the isolation of a stable molecular Al(I) compound in 1991, [(AlCp*)4] (Cp*=[C5Me5]–), a variety of highly reactive neutral or anionic low-valent aluminium complexes have been developed. By contrast, their cationic counterparts have remained difficult to access. Here, we report the synthesis of [Al(AlCp*)3]+[Al(ORF)4]– (RF=C(CF3)3) through a simple metathesis reaction between [(AlCp*)4] and Li[Al(ORF)4]. Unexpectedly, the [Al(AlCp*)3]+ salt forms a dimer in the solid state and concentrated solutions. Addition of Lewis bases results in monomerization and coordination to the unique formal Al+ atom, giving [(L)xAl(AlCp*)3]+ salts where L is hexaphenylcarbodiphosphorane (x=1), tetramethylethylenediamine (x=1) or 4-dimethylaminopyridine (x=3). The Al+–AlCp* bonds in the resulting [(L)xAl(AlCp*)3]+ cluster cations can be finely tuned between very strong (with no ligand L) to very weak and approaching isolated [Al(L)3]+ ions (when L is dimethylaminopyridine).

DOI: 10.1038/s41557-022-01000-4

Source: https://www.nature.com/articles/s41557-022-01000-4