Ternary nitridoborates. Part 2. Synthesis, crystal structure, and vibrational spectra of new ternary compounds with the [N-B-N]3- anion

Abstract

The isotypic compounds LiM4[BN2]3 (M: Ca, Sr, Ba, Eu), NaSr4[BN2]3 and NaBa4[BN2]3 are prepared by reaction of the corresponding binary nitrides at 1375 K (Li compounds, excess Li3N) or 1275 K (Na compounds, presence of Na metal). Single crystal XRD data are reported for all compounds except of LiBa4[BN2]3, which could be prepared only as polycrystalline product. The compounds crystallize in the cubic space group Imequation imagem with Z = 2. They are stuffed derivatives of the β-PtHg4 type structure. The linear [N—B—N]3- anions have B—N bond lengths between 132.6 and 136.6 pm.