An alternative approach to rationalizing the structures of the cyclotrisilicates: Rb_(10)[Si_6O_(17)], Cs_8[Si_6O_(16)] and Na_3Y[Si_6O_(15)] by viewing them in light of the extended Zintl–Klemm concept

摘要

The structures of the three dimeric cyclotrisilicate anions [Si_6O_(17)]~(10-), [Si_6O_(16)]~(8-) and [Si_6O_(15)]~(6-) forming part of the compounds Rb_(10)[Si_6O_(17)] or Rb_(14)[Si_4][Si_6O_(17)], Cs_8[Si_6O_(16)] and Na_3Y[Si_6O_(15)], respectively, have been described as different ways of condensing the more elemental cyclotrisilicate anions [Si_3O_9]~(6-) [Hlukhyy & F?ssler (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-S_4P_2]~(10–), [Ψ-S_2P_4]~(8–) and [Ψ-P_6]~(6–) respectively.