title: Coordination preferences of the alkali cations sodium and caesium in the mixed-cationic Zintl ammoniate Cs(3.2)Na(0.8)Ge₉·5.3NH₃.
abstract: The involvement of two different alkali cations in the nonagermanide ammoniate Cs(3.2)Na(0.8)Ge9·5.3NH3 [tricaesium sodium nonagermanide-ammonia (1/5.3)] provides insights into the coordination behaviour of ammonia towards sodium and caesium cations within one compound and represents the first mixed-cationic solvate structure of nonagermanide tetraanions. The compound crystallizes in the monoclinic space group P2₁/m and, with the presence of pseudomerohedral twinning, mixed-cation sites and disordering of the nonagermanide cage anions, features a combination of crystallographic challenges which could all be resolved during the refinement.
authors.affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, Regensburg 93051, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Gärtner
authors.affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, Regensburg 93051, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Suchentrunk
authors.affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, Regensburg 93051, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Korber
keywords: Zintl anions; ammoniate; crystal structure; disorder; mixed cations; pseudomerohedral twinning