Z. Naturforsch. 2014, 69b, 1097 – 1104
La2NiSb – A Ternary Ordered Version of the Bi3Ni Type with Highly Polar Bonding
Konrad Schäfer1, Anna Isaeva2, Michael Ruck2,3, Birgit Gerke1, Christian Schwickert1, and Rainer Pöttgen1
1 Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
2 Fachrichtung Chemie und Lebensmittelchemie, Technische Universität Dresden, Helmholtzstrasse 10, 01069 Dresden, Germany
3 Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden, Germany
Reprint requests to R. Pöttgen. E-mail: pottgen@uni-muenster.de
Received June 27, 2014 / published online December 19, 2014
Dedicated to Professor Hubert Schmidbaur on the occasion of his 80th birthday
The lanthanum-rich antimonide La2NiSb was synthesized by annealing a cold-pressed pellet of the elements in a sealed silica glas tube at 1120 K. La2NiSb was characterized by powder and single-crystal X-ray diffraction: ordered Bi3Ni type, Pnma, Z = 4, a = 825.6(3), b = 452.2(2), c = 1195.5(4) pm, wR = 0.0695, 856 F2 values, 26 variables. The nickel atoms form infinite zig-zag chains (259 pm Ni–Ni) with trigonal-prismatic lanthanum coordination for each nickel atom. The antimony atoms cap the rectangular faces of the lanthanum prisms (336 pm La–Sb) and thereby coordinate also the nickel atoms (271 pm Ni–Sb). These rods run parallel to the b axis and form a herringbone pattern, similar to the FeB-type structure of GdNi. Although metallic conductivity is expected for La2NiSb from DFT-based band structure calculations, the real-space bonding analysis shows prominent localization of electrons on antimonide anions and positively charged lanthanum cations. The chain substructure is strongly bonded by polar covalent Ni–Sb and multicenter Ni–Ni interactions. The nickel atoms, which are involved in multicenter bonding with adjacent nickel and lanthanum atoms, provide a conductivity pathway along the prismatic strands. 121Sb Mössbauer spectroscopic data at 78 K show a single signal at an isomer shift of −7.62(3) mm s−1, supporting the antimonide character. La2NiSb shows weak paramagnetism with a susceptibility of 2.5 × 10−3 emu mol−1 at room temperature.
Key words: Lanthanum, Antimonide, Metal-rich Compound, Crystal Structure, Chemical Bonding
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