Ge32 Co9-x : Creating "Empty" Space by High Pressure.

The compound Ge32 Co9-x (x=0.54(6), a=10.9861(3) Å, space group Im 3 ‾ $\bar 3$ m) prepared under high pressure and at high temperature is metastable under ambient conditions. It crystallizes in a new structure type, Pearson symbol cI82-1.08. The crystal structure represents a slightly distorted cubic primitive arrangement of germanium atoms with part of the Ge cubes filled by cobalt. Analysis of the chemical bonding by real-space methods revealed three-core cluster units Ge16 Co3 and seemingly empty regions comprising either covalent inter-polyhedral Ge-Ge bonds or lone-pairs located at the germanium atoms. The electrical conductivity is metal-like.

The Quasi-Binary Acetonitriletriide Sr3 [C2 N]2.

The first quasi-binary acetonitriletriide Sr3 [C2 N]2 has been synthesised and characterised. The nearly colourless crystals were obtained from the reaction of Sr metal, graphite, and elemental N2 , generated by decomposition of Sr(N3 )2 , in a sealed Ni ampoule with the aid of an alkali metal flux. The structure of this compound was analysed via single-crystal X-ray diffraction and the identity of the [C2 N]3- anion was confirmed by Raman spectroscopy and further investigated by quantum-chemical methods. Computed interatomic distances within the [C2 N]3- anion strikingly match the obtained experimental data.

Ferromagnetic ε-Fe2MnN: High-Pressure Synthesis, Hardness and Magnetic Properties.

The iron manganese nitride Fe2MnN was obtained by high-pressure-high-temperature synthesis from ζ-Fe2N and elemental Mn at 15(2) GPa and 1573(200) K. The phase crystallizes isostructural to binary ε-Fe3N. In comparison to the corresponding binary iron nitride, the microhardness of ε-Fe2MnN is reduced to 6.2(2) GPa. Above about 800 K the ternary compound decomposes exothermally under loss of nitrogen. ε-Fe2MnN is ferromagnetic with a Curie temperature of roughly 402 K.

High-Pressure NiAs-Type Modification of FeN.

The combination of laser-heated diamond anvil cells and synchrotron Mössbauer source spectroscopy were used to investigate high-temperature high-pressure chemical reactions of iron and iron nitride Fe2 N with nitrogen. At pressures between 10 and 45 GPa, significant magnetic hyperfine splitting indicated compound formation after annealing at 1300 K. Subsequent in situ X-ray diffraction reveals a new modification of FeN with NiAs-type crystal structure, as also rationalized by first-principles total-energy and chemical-bonding studies.