Preparation, crystal structure, and properties of barium pernitride, BaN2

Stoichiometric barium pernitride, BaN2, was prepared from the elements under N-2 pressure of 5600 bar in an autoclave at 920 K. The compound is isotypic to ThC2 (space group C2/c, Z = 4) according to powder X-ray (neutron) diffraction data with a = 7.1712(1), b = 4.3946(1), c = 7.2362(1) Angstrom, and beta = 104.864(1)degrees (a = 7.1745(1), b = 4.3963(1), c = 7.2393(1) Angstrom, beta = 104.876(1)degrees). The N-N distance of 1.221(4) Angstrom (based on the neutron diffraction data) is indicative of a double bond in the N-2(2-) dumbbells. BaN2 is metallic according to magnetic susceptibility measurements and TB-LMTO band structure calculations.