Ca₃[BN₂]I₃: The First Halide‐Rich Alkaline Earth Nitrido­borate with Isolated [BN₂]^3– Units

Abstract

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 R32 [no. 155, Pearson code: hR96; 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 2014 trigonal antiprisms (ᮀ = void). In Ca 3 [BN 2 ]I 3 two crystallograhically distinct [BN 2 ] 3anions 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 ϱh symmetry of the discrete linear [N-B-N] 3moieties, considering the site symmetry reduction and the presence of two distinct [BN 2 ] 3groups.