[Sn8]6--Bridged Mixed-Valence ZnI/ZnII in {[K2ZnSn8(ZnMes)]2}4- Inverse Sandwich-Type Cluster Supported by a ZnI-ZnI Bond

论文题目：[Sn8]6--Bridged Mixed-Valence ZnI/ZnII in {[K2ZnSn8(ZnMes)]2}4- Inverse Sandwich-Type Cluster Supported by a ZnI-ZnI Bond

论文作者：Hong-Lei Xu, Nikolay V. Tkachenko, Prof. Dr. Alvaro Muñoz-Castro, Prof. Dr. Alexander I. Boldyrev, Prof. Dr. Zhong-Ming Sun*

发表期刊：Angewandte Chemie International Edition, 60(18), 9990-9995, 2021 

Abstract： 

Since [Sn-8](6-) was discovered from the solid-state phase in 2000, its  solution chemistry has been elusive due to the high charges and chemical  activity. Herein, we report the synthesis and characterization of an  inverse sandwich-type cluster dimer {[K2ZnSn8(ZnMes)](2)}(4-) (1 a), in  which the highly charged [Sn-8](6-) is captured by mixed-valence  Zn-I/Zn-II to form the dimer {closo-[Zn2Sn8]}(2) moieties bridged by a  Zn-Zn bond. Such Zn-Sn cluster not only exhibits a novel example of  mixed-valence Zn-I/Zn-II for stabilizing highly active anion species,  but also indicates the [Sn-8](6-) cluster can act as a novel bridging  ligand, like arene, with a eta(4):eta(4)-fashion. Theoretical  calculations indicate that a significant delocalization of electrons  over Zn atoms plays a vital role in the stabilization of the [Sn-8](6-)  species. The AdNDP and magnetic response analyses clearly showed the  presence of local sigma-aromaticity in three cluster fragments: two  ZnSn4 caps and Sn-8 square antiprism.