Clusters of atoms often have properties that are different from both single atoms and the corresponding bulk material. The controlled synthesis of materials from such clusters can be challenging. Cluster-assembled tin species, for example, are elusive.

Alexander I. Boldyrev, Utah State University, Logan, USA, Zhong-Ming Sun, Nankai University, Tianjin, China, and colleagues have synthesized the “naked” tin cluster anion Sn₃₆^8‒. The cluster anion was obtained in form of the salt [K(2,2,2-crypt)]₈Sn₃₆ (2,2,2-crypt = 2.2.2-cryptand) via oxidative coupling reactions of Sn₉^4‒ clusters (a type of Zintl ion). The team reacted K₄Sn₉, dissolved in ethylenediamine, with Na[Zn(C₅H₅)₃] as an oxidant in the presence of 2,2,2-crypt. The product was isolated in the form of green crystals.

The synthesized [K(2,2,2-crypt)]₈Sn₃₆ was characterized using single-crystal X-ray diffraction. The team found that the compound contains tetrameric Sn₃₆^8‒ clusters (pictured), which form a nanorod/nanowire with a length of ca. 2.7 nm. According to the researchers, the cluster is the first example of a tin cluster assembled from Zintl-ion fragments, as well as the first synthesized tin nanorod.

• Sn₃₆^8‒: A 2.7 nm Naked Aromatic Tin Rod,
  Nikolay V. Tkachenko, Wei-Xing Chen, Harry W. T. Morgan, A. Muñoz-Castro, Alexander Boldyrev, Zhong-Ming Sun,
  Chem. Commun. 2022.
  https://doi.org/10.1039/d2cc01745h