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Abstract

The di-cationic nitridometalate LiSr2[CrN3] is an example of almost elusive nitridochromates(IV)withslightly pyramidal trigonal units [CrN3](5-). Magnetic measurements, vibrational spectroscopy, as well as shorterCr-N bond lengths in comparison with reported nitridochromatesindicate the presence of Cr(IV). LiSr2[CrN3]is nonmagnetic and a semiconductor according to band structure calculations.The bonding situation is characterized by highly polar N-dominatedN-Cr and Cr-dominated multi-atom bonds.
The quaternary nitridochromate(IV)LiSr2[CrN3] crystallizes in a new structuretype with the non-centrosymmetricspace group P2(1) (no. 4) with a = 5.5685(7) & ANGS;, b = 5.3828(8) & ANGS;, c = 7.5381(1) & ANGS;, and & beta; = 92.291(8)& DEG;. Predominantstructural features of the compound are slightly nonplanar trigonalunits [CrN3](5-), which are connected bythree-fold coordinated lithium to form slabs in the (001) plane. ShorterCr-N bond lengths in comparison with reported nitridochromates(III),as well as diamagnetic behavior and vibrational spectroscopy dataindicate Cr(IV), which is in a good agreement with the charge balance.According to electronic structure calculations, the compound is asemiconductor with a band gap of 1.19 eV.