LaSr3F5(CN2)2: a prototype structure for mixed-valent Eu4F5(CN2)2.

The new compound LaSr(3)F(5)(CN(2))(2) was prepared and structurally characterized as a prototype structure for the remarkably distorted mixed-valent compound Eu(4)F(5)(CN(2))(2), which contains four distinct europium ions in the structure: one Eu(3+) and three Eu(2+). Instead of repeating the given distorted structural pattern, LaSr(3)F(5)(CN(2))(2) forms a structure which can be considered as an ideal high-symmetry structure for Eu(4)F(5)(CN(2))(2), due to the occupation of La(3+) and Sr(2+) 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.

Solid state synthesis of homoleptic tetracyanamidoaluminates.

Tetracyanamidoaluminates of the type LiM(2)[Al(CN(2))(4)] with M = Eu and Sr were prepared by solid-state metathesis reactions departing from EuF(2) (or SrF(2)), AlF(3), and Li(2)(CN(2)) in a 2 : 1 : 4 molar ratio. The ignition temperature of the exothermic formation of LiSr(2)[Al(CN(2))(4)] was obtained near 420 °C. An X-ray single-crystal structure refinement performed for LiEu(2)[Al(CN(2))(4)] revealed the presence of the novel homoleptic [Al(CN(2))(4)](5-) ion in the structure.

Refined crystal structure and idealized structure of mixed-valent Eu4F5(CN2)2: transition possible.

The new europium fluoride carbodiimide Eu(4)F(5)(CN(2))(2) was synthesized by solid state reaction from mixtures of EuF(3) and Li(2)(CN(2)) at 700 °C. The crystal structure as refined by single crystal X-ray diffraction (P ̅42(1)c, no. 114, a = 16.

Crystal structures, phase-transition, and photoluminescence of rare earth carbodiimides.

Rare earth carbodiimides with the general formula RE 2(CN 2) 3 crystallize with two modifications. A monoclinic( C2/m) modification is obtained for RE = Y, Ce-Tm and a rhombohedral ( R3 c) modification for RE = Tm-Lu. The space group R3 c is confirmed by single-crystal structure determination on Lu 2(CN 2) 3 and indexed powder patterns of RE = Tm, Yb and Lu.