Synthesis of Lewis Acid–Base Adducts between Trialkyltriels and Heavy Bis(trimethylsilyl)pnictogenides

Lewis acid–base adducts between potassium bis­(trimethylsilyl)­pnictogenides [KPn­(SiMe3)2]­(Pn = Sb and Bi) and trimethyltriels (EMe3 (E = Al, Ga, In) were synthesized and crystallized using 18-crown-6 as ligand for the potassium ions. In the course of these investigations, we were able to fully characterize a row of compounds of the type [K­(18c6)­(thf)0–2]­[Pn­(SiMe3)2(EMe3)n] (n = 1, 2) with a different amount of Lewis acids bonding to the group 15 element. Moreover, we investigated the influence of the steric demand of the Lewis acids through the use of GaEt3 and GatBu3. All isolated compounds were examined by NMR spectroscopy, IR spectroscopy, elemental analysis and X-ray structure analysis. The obtained adducts of negatively charged [Pn­(SiMe3)2]− fragments with Lewis acids represent a new class of compounds, which illustrate the HSAB concept and show the different extents of the inert pair effect between antimony and bismuth. In particular, the dative bonds between the higher homologues of both main groups have so far been underdeveloped in research.

以18-冠-6作为钾离子的配体，成功合成并结晶了双(三甲基硅基)氮族元素钾盐[KPn(SiMe₃)₂]（其中Pn=锑Sb和铋Bi）与三甲基硼族元素化合物EMe₃（E=铝Al、镓Ga、铟In）之间的路易斯酸碱加合物。在本研究过程中，我们对一系列通式为[K(18c6)(四氢呋喃(thf))₀–₂][Pn(SiMe₃)₂(EMe₃)ₙ]（n=1,2）的化合物完成了全面表征，这类化合物中与第15族元素成键的路易斯酸数目各不相同。此外，我们通过使用三乙基镓(GaEt₃)和三叔丁基镓(GatBu₃)，探究了路易斯酸的空间位阻对体系的影响。所有分离得到的化合物均通过核磁共振波谱、红外光谱、元素分析以及X射线晶体结构分析进行了表征。所获得的带负电的[Pn(SiMe₃)₂]⁻片段与路易斯酸形成的加合物代表了一类新型化合物，它们阐释了软硬酸碱理论(HSAB)，并展现了锑与铋之间惰性电子对效应的差异程度。尤为关键的是，这两个主族的更高同系物之间的配位键，此前在相关研究中尚未得到充分探索。