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The Stannides AuNiSn 2 and AuCuSn 2 – Bulk Synthesis and Superstructure Determination
Author(s) -
Lange Stefan,
Nilges Tom,
Hoffmann RolfDieter,
Pöttgen Rainer
Publication year - 2006
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200500414
Subject(s) - octahedron , crystallography , superstructure , ampoule , crystal structure , crystal chemistry , transition metal , tin , single crystal , hexagonal crystal system , group (periodic table) , materials science , chemistry , copper , metallurgy , physics , thermodynamics , biochemistry , catalysis , organic chemistry
The stannides AuNiSn 2 and AuCuSn 2 were prepared by melting of the elements in silica ampoules at 1300 K followed by slow cooling to room temperature. The structures of both compounds were refined on the basis of single crystal X‐ray data: $P{\bar 3}m{\rm 1}$ , a = 412.41(14), c = 529.24(11) pm, wR2 = 0.0268, 159 F 2 values, 10 variables for AuNiSn 2 and a = 425.97(17), c = 526.88(15) pm, wR2 = 0.0507, 159 F 2 values, 11 variables for AuCuSn 2 (twinned crystal, BASF = 0.305(4)). These stannides crystallize with a superstructure of the NiAs type with a complete ordering of the transition metal atoms. They derive from a AuSn subcell structure, where every other layer of octahedral voids in the hexagonal closest packing of the tin atoms is filled by nickel in AuNiSn 2 and by copper in AuCuSn 2 . Due to the symmetry reduction smaller NiSn 6/6 (CuSn 6/6 ) and larger AuSn 6/6 octahedra alternate along the c axis. The crystal chemistry is discussed on the basis of a group‐subgroup scheme.