The first titanium molybdenum antimonide:: Ti5.42Mo2.58Sb9, a substitution variant of Zr2V6Sb9

The new ternary antimonide Ti-5.42(2)Mo2.58Sb9 was uncovered by a reaction of the elements under exclusion of air at 1150 degrees C. It crystallizes in a ternary substitution variant of the V7.5Sb9 type, a structure not known to exist in either the Ti/Sb or the Mo/Sb system. The crystal structure of Ti5.42Mo2.58Sb9 was determined from single crystal X-ray data: space group P4/nmm, with a = 9.8178(8) angstrom, c = 7.1857(8) angstrom, V = 692.6(1) angstrom(3), Z = 2, R1 = 0.025, wR2 = 0.052 (all data). The structure contains four metal atom sites, two thereof occupied solely by Ti atoms, and two by different Ti/Mo mixtures. The former two correspond to the Zr sites, and the latter two to the V sites of the isostructural antimonide Zr2V6Sb9. The crystal structure is comprised of chains of face-sharing TiSb8 square antiprisms, Ti/Mo tetrahedra and Sb atom pairs and squares. The electronic structure, computed with the LMTO approximation, is indicative of metallic properties. In addition to the dominating metal-Sb bonds, strong metal-metal and Sb-Sb bonds exist as well in Ti5,42Mo2.58Sb9. The Mo content per metal site increases with increasing metal-metal interactions.