Ca 3 [BN 2 ]I 3 : The First Halide‐Rich Alkaline Earth Nitrido­borate with Isolated [BN 2 ] 3– Units

The title compound Ca 3 [BN 2 ]I 3 was obtained from reactions of mixtures of the starting materials Ca 3 [BN 2 ] 2 and CaI 2 in a 1:4 ratio in sealed Nb tubes at 1223 K. The crystal structure was solved from powder synchrotron diffraction data. Ca 3 [BN 2 ]I 3 is the first example of a halide‐rich nitridoborate crystallizing in the rhombohedral space group R 32 [no. 155, Pearson code: hR 96; Z = 12; a = 16.70491(2) Å, c = 12.41024(2) Å]. The crystal structure is built up by two interpenetrating networks of condensed edge‐sharing [BN 2 ]@Ca 6 and [□]@I 6 trigonal antiprisms (□ = void). In Ca 3 [BN 2 ]I 3 two crystallograhically distinct [BN 2 ] 3– anions are present with d (B1–N) = 1.393(2) Å and d (B2–N) = 1.369(9) Å. Their bond angles are practically linear, varying only slightly: N–B1–N = 179(1)° and N–B2–N = 180°. Vibrational spectra were interpreted based on the D ∞ h symmetry of the discrete linear [N–B–N] 3– moieties, considering the site symmetry reduction and the presence of two distinct [BN 2 ] 3– groups.