Ba₁₂[BN₂]_6.67H₄: A Disordered Anti-Skutterudite filled with Nitridoborate Anions

Skutterudites are of high interest in current research due to their diversity of structures comprising empty, partially filled and filled variants, mostly based on metallic compounds. We herein present Ba-12[BN2](6.67)H-4, forming a non-metallic filled anti-skutterudite. It is accessed in a solid-state ampoule reaction from barium subnitride, boron nitride and barium hydride at 750 degrees C. Single-crystal X-ray and neutron powder diffraction data allowed to elucidate the structure in the cubic space group Im (no. 204). The barium and hydride atoms form a three-dimensional network consisting of corner-sharing HBa6 octahedra and Ba-12 icosahedra. Slightly bent [BN2](3-) units are located in the icosahedra and the voids in-between. H-1 and B-11 magic angle spinning (MAS) NMR experiments and vibrational spectroscopy further support the structure model. Quantum chemical calculations coincide well with experimental results and provide information about the electronic structure of Ba-12[BN2](6.67)H-4.