Oligomeric rare-earth-metal halide clusters. Three structures built of (Y16Z4)Br36 units (Z=Ru,Ir)

Suitable reactions in sealed Nb tubing at 850-950 degrees C produced good yields of a family of oligomeric cluster phases that were characterized by single-crystal X-ray diffraction methods. The basic Y16Z4 units can be obtained from 2+2 condensation of centered Y6Br12Z-type clusters or as tetracapped truncated tetrahedra Y16 that are centered by a large tetrahedral Z4. These are surrounded by 36 bromine atoms which bridge edges or cap faces of the Y16Z4 nuclei and, in part, bridge to metal atoms in other clusters.