Nitridochromate(IV): LiSr 2 [CrN 3 ].

The quaternary nitridochromate(IV) LiSr ₂ [CrN ₃ ] crystallizes in a new structure type with the non-centrosymmetric space group P 2 ₁ (no. 4) with a = 5.5685(7) Å, b = 5.3828(8) Å, c = 7.5381(1) Å, and β = 92.291(8)°. Predominant structural features of the compound are slightly nonplanar trigonal units [CrN ₃ ] ^5- , which are connected by three-fold coordinated lithium to form slabs in the (001) plane. Shorter Cr-N bond lengths in comparison with reported nitridochromates(III), as well as diamagnetic behavior and vibrational spectroscopy data indicate Cr(IV), which is in a good agreement with the charge balance. According to electronic structure calculations, the compound is a semiconductor with a band gap of 1.19 eV.