论文题目：Carbon-free sandwich compounds based on arsenic and antimony with icosahedral metal cores
论文作者：Xu-Hui Yue,Wei-Xing Chen,Tao Yang,Alvaro Munoz-Castro,Gernot Frenking&Zhong-Ming Sun*
发表期刊：Nat. Synth., 2023, DOI: 10.1038/s44160-023-00247-0
Abstract:
Traditionally, a metallocene complex comprises a metal centre sandwiched between two aromatic organic ligands and such complexes have been extensively investigated. Carbon-free analogues of metallocene with homoleptic As5 or Sb5 ligands, however, have remained experimentally elusive, especially analogues of higher nuclearity. Here we report the synthesis and characterization of sandwich-type clusters [Pn@M12Pn10(Pn5)2]4–/5– (Pn = As, Sb; M = Co, Fe), where the endohedral icosahedral cluster [Pn@M12] can be regarded as a spherical-like three-dimensional coordination centre surrounded by a Pn10 ring and two Pn5 pentagonal caps. Quantum chemical calculations reveal that the [Pn@M12] has orbitals that mimic 1S, 1P and 1D electronic shells, which can interact with the outer (Pn5)2 ring layer. These interactions occur because the frontier orbitals are dominated by the (n − 1)d block orbitals of the metal atoms. The π1-As5 orbitals interact with 1S and part of the 1P shell of the central core, while the π2- and π3-As5 orbitals interact with the symmetry-allowed part of the 1P and 1D shells. The characteristics of this orbital interaction are analogous to those of mononuclear metallocenes.