Bell-like [Ga${}_5$] clusters in Sr${}_3$Li${}_5$Ga${}_5$. Synthesis, crystal structure and bonding analysis

During the search for a possible replacement of the europium in the structure Eu${}_3$Li${}_{5+x}$Ga${}_{5-x}$ (x = 0.15) in order to facilitate the analysis of the chemical bonding in the bell-like [Ga${}_5$] clusters, the isostructural compound Sr${}_3$Li${}_5$Ga${}_5$ (space group R$\overline{3}$ m, a = 9.6040(5) Å, c = 22.061(1) Å) was discovered. A detailed investigation of the bonding situation in the first five-membered nonconvex Ga cluster utilizing the electron localizability approach became possible, revealing not only first signs of a transition from a Zintl to a Wade cluster, but also the presence of a [Sr${}_6$] polycation. (© 2021 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbH)