Sb-Sb Interactions in the Hafnium-Rich Antimonide Hf(6)TiSb(4)

(Hf,Ti)(7)Sb(4) is accessible via arc-melting of suitable mixtures of Hf, Ti, and HfSb(2). Its crystal structure is the first representative of a new structure type, as was determined by single-crystal analysis for Hf(7)(-)(x)()Ti(x)()Sb(4) with x = 1.05(7) approximately 1. Hf(6)TiSb(4) crystallizes in the monoclinic space group P2(1)/c, with the lattice dimensions a = 841.0(1), b = 1102.9(1), c = 1099.3(1) pm, and beta = 111.13(1) degrees (Z = 4). All seven independent metal sites are statistically occupied by different mixtures of hafnium and titanium, forming a three-dimensional network of metal atoms M which includes the Sb atoms in its (capped) square antiprismatic voids. The metal substructure can be described on the basis of semiregular 488 nets. Besides numerous M-Sb and M-M bonds, a nonlinear Sb(3) unit is present with bonding Sb-Sb interactions. Extended Hückel calculations, performed on the hypothetical model structure Hf(7)Sb(4), point to metallic properties.