Xu Yu-He, Yang Xing, Yang Ya-Nan, Zhao Lili, Frenking Gernot, Sun Zhong-Ming
State Key Laboratory of Elemento-Organic Chemistry, Tianjin Key Lab of Rare Earth Materials and Applications, School of Material Science and Engineering, Nankai University, Tianjin, China.
State Key Laboratory of Materials-Oriented Chemical Engineering, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, China.
Nat Chem. 2025 Apr;17(4):556-563. doi: 10.1038/s41557-025-01765-4. Epub 2025 Mar 18.
The cyclopentadienyl anion is a π-aromatic five-membered ring ligand that is widely used in organometallic chemistry. By replacing the CH groups in cyclopentadiene with isoelectronic group-15 elements, an inorganic analogue can be obtained. In this line, Pn (Pn = P, Sb) rings have been stabilized in a triple-decker sandwich structure, prepared via high-temperature reactions, and an example of a Bi ring stabilized in a cobalt-based inverse-sandwich-type complex has been reported. Here we report the synthesis and structural characterization of two complexes, [Cp-V(cyclo-Sb)V-Cp] and [Cp-Nb(cyclo-Bi)Nb-Cp], which are stabilized by [K(18-crown-6)] or [K(2.2.2-crypt)] cations at room temperature under mild conditions. Our bonding analysis through various quantum-chemical methods reveals that V‒V and Nb‒Nb bonds pass through the centre of the E rings (E = Sb, Nb). In contrast to free cyclo-E (E = Sb, Bi) the cyclo-E moieties between Cp-E units do not possess any aromatic character because the M‒M (M = V, Nb) bond passes through the centre of the ring.
环戊二烯基阴离子是一种π-芳香性五元环配体，在有机金属化学中广泛应用。通过用等电子的第15族元素取代环戊二烯中的CH基团，可以得到一种无机类似物。按照这种思路，Pn（Pn = P、Sb）环已通过高温反应制备并稳定在三层夹心结构中，并且已报道了一个铋环稳定在钴基反夹心型配合物中的例子。在此，我们报道了两种配合物[Cp-V(环-Sb)V-Cp]和[Cp-Nb(环-Bi)Nb-Cp]的合成及结构表征，它们在温和条件下于室温被[K(18-冠-6)]或[K(2.2.2-穴醚)]阳离子稳定。我们通过各种量子化学方法进行的键合分析表明，V-V和Nb-Nb键穿过E环（E = Sb、Nb）的中心。与游离的环-E（E = Sb、Bi）相比，Cp-E单元之间的环-E部分不具有任何芳香性，因为M-M（M = V、Nb）键穿过环的中心。
