• extended Zintl–Klemm concept;
  • connectivity;
  • silicate skeletons

The structures of the three dimeric cyclotrisilicate anions [Si6O17]10−, [Si6O16]8− and [Si6O15]6− forming part of the compounds Rb10[Si6O17] or Rb14[Si4][Si6O17], Cs8[Si6O16] and Na3Y[Si6O15], respectively, have been described as different ways of condensing the more elemental cyclotrisilicate anions [Si3O9]6− [Hlukhyy & Fässler (2013). Z. Anorg. Allg. Chem. 639, 231–233]. Such a description prevents a rational explanation of the connectivity between the Si atoms. So, in this article the Si skeletons of the above silicate anions are put on a common basis in light of the extended Zintl–Klemm concept. Their connectivity is directly related to the ratio Ψ-S/Ψ-P resulting from the number of electrons transferred from the electropositive Na, Y, Rb and Cs atoms, offering a new example of the fact that there exists a univocal link between chemical composition (in terms of pseudo-atoms) and structure: the generalized Zintl–Klemm concept. The three skeletons fit the connectivity of hypothetical Zintl polyanions of composition [Ψ-S4P2]10–, [Ψ-S2P4]8– and [Ψ-P6]6− respectively.