Ba

Abstract

Single crystals of Ba21[BN2]11[C2]4 were obtained by the reaction of barium metal, graphite and hexagonal boron nitride in silica-jacketed niobium capsules at 1030°C. They occur as shiny black, intergrown square platelets and adopt a new structure type crystallising in the tetragonal space group I4̄, exhibiting the cell parameters a = 1538.79(6) pm and c = 1007.36(4) pm (c/a = 0.655, Z = 2). The Raman spectrum was used to corroborate the nature of the anionic moieties: linear [BN2]3− and [C2]2− groups. They provide coordination spheres with seven to nine atoms from their respective termini for the Ba2+ cations. More structural features and the Raman data are discussed and compared with related compounds.