Preparation, Crystal Structure, and Properties of Barium Pernitride, BaN2

Abstract
Stoichiometric barium pernitride, BaN2, was prepared from the elements under N2 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) Å, and β = 104.864(1)° (a = 7.1745(1), b = 4.3963(1), c = 7.2393(1) Å, β = 104.876(1)°). The N−N distance of 1.221(4) Å (based on the neutron diffraction data) is indicative of a double bond in the N22- dumbbells. BaN2 is metallic according to magnetic susceptibility measurements and TB-LMTO band structure calculations.