Rare-earth-doped nitridosilicates exhibit outstanding luminescence properties and have been intensively studied for solidstate lighting. Here, we describe the new nitridolithosilicate Ca 3 Mg-[Li 2 Si 2 N 6 ]:Eu 2+ with extraordinary luminescence characteristics. The compound was synthesized by the solid-state metathesis reaction in sealed Ta ampules. The crystal structure was solved and refined on the basis of single-crystal X-ray diffraction data. Ca 3 Mg[Li 2 Si 2 N 6 ]:Eu 2+ crystallizes in the monoclinic space group C2/m (no. 12) [Z = 4, a = 5.966(1), b = 9.806(2), c = 11.721(2) Å, β = 99.67(3)°, V = 675.9(2) Å 3 ] and exhibits a layered anionic network made up of edge-and cornersharing LiN 4 tetrahedra and [Si 2 N 6 ] 10− bow-tie units. The network charge is compensated by Ca 2+ and Mg 2+ ions. Upon irradiation with UV to blue light, red emission at exceptionally long wavelengths (λ em = 734 nm, fwhm ≈2293 cm −1 ) is observed. According to emission in the near-infrared, application in LEDs for horticultural lighting appears promising.

The nitridomagnesogermanate Ca2Mg5GeN6 was synthesized at 780 °C using a sodium flux in sealed tantalum ampules. Pure metals were used as starting materials and sodium azide NaN3 was added as nitrogen source. Ca2Mg5GeN6 was obtained as a byproduct in the form of colorless platelet‐like crystals. Solution and refinement of the crystal structure [space group P63/mmc (no. 194), Z = 1, a = 3.453(2), c = 17.506(13) Å and V = 180.8(2) Å3] were performed on the basis of single‐crystal X‐ray diffraction data. Ca2Mg5GeN6 represents the first layered nitridogermanate. Its structure is made up of corner‐sharing (Mg/Ge)N4 tetrahedra and corner‐sharing trigonal planar (Mg/Ge)N3 units with mixed occupancy of Mg and Ge. Ca2+ ions are located in between the sheets. The crystal structure is closely related to that of the nitridomagnesoaluminate CaMg2AlN3 as well as to the carbides ScAl3C3 and UAl3C3.

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Nitridomagnesogermanate Ba[Mg3GeN4]:Eu2+ was synthesized by the NaN3 route in weld‐shut tantalum ampules by reaction of the elements in molten sodium with NaN3 as nitrogen source at 780 °C. The crystal structure was solved and refined on the basis of single‐crystal X‐ray diffraction data. Ba[Mg3GeN4]:Eu2+ crystallizes in the UCr4C4 structure type [space group I4/m (no. 87), a = 8.3921(12), c = 3.4813(7) Å, Z = 2] and exhibits a highly condensed anionic network made up of statistically disordered (Mg/Ge)N4 tetrahedra, which are connected to each other by common vertices and edges to form vierer ring channels along [001]. Ba2+ is located in every second channel and has cubelike coordination by eight N atoms. Theoretical calculations of the electronic properties of Ba[Mg3GeN4]:Eu2+ are discussed to understand the absence of photoluminescence in the visible range and for comparison with other luminescent materials that are structurally related to Ba[Mg3GeN4]:Eu2+.

The quaternary nitrides Ca4Mg5Ge3N10 and Sr2Mg3GaN4.33 were synthesized by employing the Na azide route in weld‐shut Ta ampules. The two compounds are homotypic and crystallize in the monoclinic space group C2/m (no. 12). The crystal structures were solved and refined on the basis of single‐crystal X‐ray diffraction data [Ca4Mg5Ge3N10: a = 11.269(3), b = 3.3267(11), c = 8.008(3) Å, β = 109.80(2)°, V = 282.44(16) Å3, Z = 1; Sr2Mg3GaN4.33: a = 11.737(2), b = 3.4610(7), c = 7.8610(16) Å, β = 108.03(3)°, V = 303.65(12) Å3, Z = 1]. The three‐periodic anionic substructures of both nitrides are made up of MN4 tetrahedra with mixed occupation of central atoms M = Mg/Ge and Mg/Ga, respectively. Corner‐ and edge‐sharing of MN4 tetrahedra results in vierer and sechser ring channels along [010]. Alkaline earth metal ions are located within sechser ring channels. The crystal structures are also homeotypic with that of known Ca2MgGa3N5 and represent a more highly condensed variant of the MII2Si5N8 (MII = Sr, Ba) type of structure.