Synthesis and crystal structure of cubic V11Cu9Ga46 – A 512-fold super structure of a simple bcc packing

Single crystals of the new ternary compound V11Cu9Ga46 were obtained from the elements. Its crystal structure (cP792; Pm  3¯n, a = 23.362(3) Å, 1797 refl., 170 param., wR2(F2) = 0.058) represents a new structure type which is characterized by motifs of the binary V8Ga41 and the ternary V2Cu3Ga8. The first contains centaur-polyhedra VGa10, linked to a super-cube with a cuboctahedrally coordinated Ga-atom in the center. These super-cubes are packed like the atoms of the Cr3Si-type. The arrangement of vanadium-polyhedra around the GaGa12-centers corresponds to the arrangement of metal–atoms in γ-brass. The second structural element represents a defect- and ordering variant of a bcc packing or CsCl, respectively. The bcc-like regions are located between the super-cubes in a way that Ga-atoms form a cubic primitive packing with V- and Cu-atoms in a part of the cubic voids. Vice versa represents V11Cu9Ga46 like V2Cu3Ga8 an ordered defect variant of CsCl, but with additional GaGa12-cuboctahedra. In total, V11Cu9Ga46 is an 8 × 8 × 8 superstructure of CsCl.

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