The title phases are obtained in high yield from the reactions of stoichiometric quantities of Y, YI3, and graphite at 850-950°C in welded Nb containers. The crystal structures of the two phases determined by standard X-ray diffraction means are related to those published for Er4I3 and Er6I7 (C2/m, Z = 2, a = 18.479 (6) and 21.557 (8) Å, b = 3.947 (1) and 3.909 (1) Å, c = 8.472 (3) and 12.374 (6) Å, β = 103.22 (4) and 123.55 (3)°, R/Rw = 4.6/5.4 and 3.2/3.7% for Y4I5C and Y6I7C2, respectively). The two compounds contain infinite single and double chains of carbon-centered yttrium octahedra, respectively, condensed by edge-sharing and sheathed by edge-bridging iodine atoms together with square-planar iodine atoms that bridge between chains. Extended Hückel MO band calculations were carried out for the empty and the carbon-centered compounds in both structures. Metal-based bands near EF in the empty chains exhibit characteristic strong interactions with carbon valence orbitals that generate low-lying valence bands. EF in both cases falls within a broad, metal-based conduction band. Resistivity and magnetic susceptibility measurements on Y6I7C2 support the predicted metallic character.
|Original language||English (US)|
|Number of pages||7|
|State||Published - 1988|
ASJC Scopus subject areas
- Inorganic Chemistry