title: Ba2[Ni3N2]: a low-valent nitridonickelate-synthesis, crystal structure, and physical properties.
abstract: The ternary alkaline-earth nitridonickelate Ba2[Ni3N2] (Ba2[NiI2Ni0N2]) was prepared by the reaction of mixtures of Ba2N and Ni in nitrogen gas of ambient back-pressure at 1173 K. The crystal structure determined by X-ray single-crystal and powder diffraction methods as well as from neutron diffraction data at various temperatures between 2 and 298 K is orthorhombic (Cmca (no. 64), 298 K: a=715.27(18) pm, b=1032.99(21) pm, c=740.12(20) pm) and provides the first example of a nitridonickelate with a two-dimensional complex anion. The Ni2 atom is described with a split position and the corresponding superstructure variants are investigated by theoretical full-potential nonorthogonal local-orbital calculations (FPLO). The average oxidation state of Ni in Ba2[Ni3N2] is +0.67, the lowest average value observed in nitridonickelates so far. Investigations of the physical properties demonstrate that Ba2[Ni3N2] acts as a "poor" metal with a large resistivity of approximately 2.7 mOmega cm at 300 K and exhibits low-dimensional magnetism with antiferromagnetic ordering at T approximately 90 K. XAS spectra correspond with low-valent Ni states.
authors.affiliation: Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany.
authors.forename: Akash
authors.initials: A
authors.lastname: Mehta
authors.forename: Peter
authors.initials: P
authors.lastname: Höhn
authors.forename: Walter
authors.initials: W
authors.lastname: Schnelle
authors.forename: Vivien
authors.initials: V
authors.lastname: Petzold
authors.forename: Helge
authors.initials: H
authors.lastname: Rosner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Burkhardt
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Kniep