Metal-rich polyantimonides:: internal competition between M-M and Sb-Sb and heteroatomic M-Sb interactions in (Zr,V)13Sb10 and (Zr,V)11Sb8 (M = Zr,V)

The title compounds are accessible by arc-melting of suitable mixtures of Zr, V and ZrSb2. Their crystal structures were determined via single crystal measurements on an IPDS diffractometer. Depending on the M : Sb ratio (M=Zr, V; M: Sb=13 : 10 or 11 : 8), the phases crystallize in two related structure types, namely Zr7.5V5.5Sb10 and Cr11Ge8. The lattice dimensions of Zr7.46(5)V3.54Sb8 are a=1514.7(1), b=570.77(5), c=1811.1(2) pm, V=1565.8(2) x 10(6) pm(3) (Pnma, Z=4). The structures may be considered as intergrowths of (distorted) fragments of the W5Si3 and NiAs structure types. In addition to M-Sb and homonuclear (and heteronuclear) M-M bonds, Sb-Sb bonding interactions, with Sb-Sb distances shorter than in elemental antimony, occur in the linear Sb chains of the W5Si3-analogous structural motifs. The entropy-stabilized phases decompose by annealing at lower temperatures. The metallic character was confirmed via extended Huckel calculations as well as measurements of the electrical resistivities.