Synthesis of Sb<sub>68</sub><sup>8–</sup>:\nCrafting a Homoatomic Antimony Nanotorus

Pure-element cyclic molecules have\ngarnered extensive\nattention\nowing to their intriguing structures and promising applications. Among\nthese, carbon-based cyclic molecules such as <i>cyclo</i>[<i>n</i>]carbon (C<sub><i>n</i></sub>, <i>n</i> = 10–26) and carbon nanotori have ignited significant\ninterest in both experimental and theoretical investigations. However,\nsystematic investigations of analogous cyclic counterparts of heavier\nmain-group elements are limited, with only a few known by theoretical\nstudies. Furthermore, these corresponding cyclic structures lack synthetic\nexamples in the condensed phase, primarily attributed to their high\nreactivity resulting from lone electron pairs and the absence of electronic\ndelocalization, which typically aids in stabilizing the structure.\nIn this work, we introduce the pioneering synthesis of a pure antimony-based\ninorganic nanotorus, denoted as Sb<sub>68</sub><sup>8–</sup>, facilitated by the incorporation of C<sub>60</sub> for oxidation\nby utilizing wet-chemistry methodologies. The unique nanotorus structure\nwas meticulously examined via single-crystalline X-ray diffraction,\nunveiling its composition of 68 antimony atoms and forming a tubular\nstructure with approximate dimensions of 18.5 × 18.4 Å<sup>2</sup> in a square shape. Theoretical calculations further revealed\nthat the nanotorus structure, characterized by 16 delocalized electrons\ndistributed across eight 3c-2e σ bonds, effectively saturated\nthe eight two-coordinated Sb atoms within the cluster. This study\nunveils an innovative approach to synthesizing cyclic compounds solely\nfrom pure elements, departing from traditional methods dependent on\nchemical vapor deposition or surface synthesis, and heralds a profound\nparadigm shift in physical science.