Communications: Tin cluster anions (Snn−, n=18, 20, 23, and 25) comprise dimers of stable subunits

Abstract

The gas phase structures of tin cluster anions Sn(n)(-) have been studied by a combination of trapped ion electron diffraction and density functional theory calculations. In the size range of n=18-25 these clusters comprise dimers of stable subunits. In particular Sn(18)(-) and Sn(20)(-) are homodimers of Sn(9) and Sn(10) subunits, respectively. In Sn(23)(-) two Sn(10) units are linked by three additional bridging atoms and Sn(25)(-) is a heterodimer of Sn(10) and Sn(15) subunits. This rather unexpected growth mode is rationalized by the extraordinary stability of the building blocks Sn(9), Sn(10), and Sn(15).