Ternary Transition Metal Antimonides T₅T' _1-xSb_2+x (T = Ti, Zr, Hf; T' = Fe, Co, Ni, Cu, Ru, Rh, Pd, Cd) with Nb₅SiSn₂ (Ordered W₅Si₃, Filled V₄SiSb₂) Type Structure

Fifteen new ternary antimonides T₅T' _1-xSb_2+x were synthesized by reaction of the elemental components in an arc-melting furnace. They crystallize with a tetragonal structure first reported for Nb₅SiSn₂ (space group I4/mcm, Z = 4.) A structure refinement from four-circle X-ray diffractometer data of Hf₅Fe_1-xSb_2+x (a = 1086.0(1) pm, c = 550.1(1) pm, R = 0.033 for 270 structure factors and 18 variable parameters) showed deviations from the ideal occupancy for two atomic sites, resulting in the composition Hf_4.929(3)Fe_0.67(1)Sb_2.33(1). Structure refinements from X-ray powder data resulted in the formula Ti₅Ni_0.45(2)Sb_2.55(2), while no deviation from the ideal composition was observed for Ti₅RhSb₂. The crystal structures of these compounds are discussed together with those of related binary and ternary compounds.