LaSr3F5(CN2)2: A Prototype Structure for Mixed-Valent Eu4F5(CN2)2

The new compound LaSr3F5(CN2)2 was prepared and structurally characterized as a prototype structure for the remarkably distorted mixed-valent compound Eu4F5(CN2)2, which contains four distinct europium ions in the structure: one Eu3+ and three Eu2+. Instead of repeating the given distorted structural pattern, LaSr3F5(CN2)2 forms a structure which can be considered as an ideal high-symmetry structure for Eu4F5(CN2)2, due to the occupation of La3+ and Sr2+ ions on one and the same crystallographic position. The crystal symmetry of this structure is an interesting issue to compare with what has been previously proposed.