Crystal Structure and Nontypical Deep-Red Luminescence of Ca<sub>3</sub>Mg[Li<sub>2</sub>Si<sub>2</sub>N<sub>6</sub>]:Eu<sup>2+</sup> PoeslChristine SchnickWolfgang 2017 Rare-earth-doped nitridosilicates exhibit outstanding luminescence properties and have been intensively studied for solid-state lighting. Here, we describe the new nitridolithosilicate Ca<sub>3</sub>Mg­[Li<sub>2</sub>Si<sub>2</sub>N<sub>6</sub>]:Eu<sup>2+</sup> 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<sub>3</sub>Mg­[Li<sub>2</sub>Si<sub>2</sub>N<sub>6</sub>]:Eu<sup>2+</sup> crystallizes in the monoclinic space group <i>C</i>2/<i>m</i> (no. 12) [<i>Z</i> = 4, <i>a</i> = 5.966(1), <i>b</i> = 9.806(2), <i>c</i> = 11.721(2) Å, β = 99.67(3)°, <i>V</i> = 675.9(2) Å<sup>3</sup>] and exhibits a layered anionic network made up of edge- and corner-sharing LiN<sub>4</sub> tetrahedra and [Si<sub>2</sub>N<sub>6</sub>]<sup>10–</sup> bow-tie units. The network charge is compensated by Ca<sup>2+</sup> and Mg<sup>2+</sup> ions. Upon irradiation with UV to blue light, red emission at exceptionally long wavelengths (λ<sub>em</sub> = 734 nm, fwhm ≈2293 cm<sup>–1</sup>) is observed. According to emission in the near-infrared, application in LEDs for horticultural lighting appears promising.