A NOVEL STRUCTURE TYPE FOR ISOLATED RARE-EARTH-METAL CLUSTERS CENTERED BY TRANSITION-METALS - CS(4)R(6)I(13)Z (R=CE, PR, Z=CO, OS)

The introduction of alkali metals into reactions expands the variety o f quaternary compounds with discrete rare-earth-metal clusters centere d by transition metals and yields compounds with more open structure f rameworks. The larger transition-metal interstitials Co or Os appear l argely responsible for a different linkage of the R(6)I(12) cluster un its into layers rather than into a three-dimensional network known for other compounds with the uncommon stoichiometry R(6)I(13)Z.