Li80Ba39N9: the first Li/Ba subnitride

The crystal structure of Li80Ba39N9, a new representative of alkali-alkaline-earth metal subnitrides prepared from the metals and barium azide, was investigated based on single-crystal X-ray diffraction data. The compound has a novel crystal structure with a tetragonal unit cell, space group I(-)42m, a = 16.0763(8) A, c = 32.267(2) A, Z = 2, and V = 8330.0(8) A3. The structure can be described in terms of subnitride clusters with internal ionic bonding and metallic bonding in the rest of the space. The compound contains a new cluster Li12Ba5N6 and polytetrahedral Li clusters based on centered Li13 icosahedra, which are typical for Li-rich intermetallic compounds.