Hydro-flux synthesis and crystal structure of TlIO.

Single-crystals of thallium(I) iodide oxide TlIO were obtained as by-product in a hydro-flux synthesis at 473 K for 10 h. A potassium hydroxide hydro-flux with a water-base molar ratio of 1.6 and the starting materials TlNO, RhI and Ba(NO) was used, resulting in a few black needle-shaped crystals. X-ray diffraction on a single-crystal revealed the hexa-gonal space group 6/ (No. 194) with lattice parameters = 7.1512 (3) Å and = 6.3639 (3) Å. TlIO crystallizes as hexa-gonal anti-perovskite (anti-BaNiO type) and is thus structurally related to the alkali-metal halide/auride oxides O ( = K, Rb, Cs; = Cl, Br, I, Au). The oxygen atoms center thallium octa-hedra. The [OTl] octa-hedra share faces, forming a linear chain along [001]. Twelve thallium atoms surround each iodine atom in an [ITl] anti-cubocta-hedron. Thallium and iodine atoms together form a hexa-gonal close-sphere packing, in which every fourth octa-hedral void is occupied by oxygen.