ENCAPSULATION OF THE PLATINUM AND NEIGHBORING METALS WITHIN CLUSTER IODIDES OF RARE-EARTH ELEMENTS

Syntheses of new cluster phases containing encapsulated heterometals have been explored through reactions between the rare-earth metal Y, Pr, or Gd (R), RI3, and a 3d, 4d, or 5d element (Z) at 750-1000 °C in sealed Nb containers. New Pr7I12Z (Sc7Cl12N-type) phases are obtained for Z = Cu, Ru, Rh, Pd, Re, Os, Ir, and Pt. New Gd7I12Z phases occur for Z = Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt, and Au. In contrast, new Y6I10Z analogues of the previously reported Y6I10Ru occur with Z = Co, Ni, Rh, Os, Ir, and Pt and as Pr6I10Os. The structures of Y6Il0Os and Y6I10Ir have been refined for comparison with Y6I10Ru ([formula omitted], Z = 1; a = 7.6268 (8), 7.6154 (7) Å, b = 9.518 (1), 9.535 (1) Å, c = 9.617 (1), 9.577 (1) Å, α = 107.72 (1), 107.67 (1)°, β = 97.17 (1), 97.1 1 (1)°, γ = 105.13 (1), 105.15 (1)°; R/Rw = 3.1/4.2, 3.7/4.3%, respectively). The sizable tetragonal compression observed earlier in the Y6I10Ru cluster and thought to be electronically driven is only 44% as great in the isoelectronic Os phase and is virtually absent in Y6I10Ir. Relativistic effects may be important in the bonding of the 5d interstitials. Unsuccessful syntheses, orbital populations in the various clusters, volume changes seen among the R7I12Z phases, and matrix effects in intercluster bonding are also discussed and interrelated. © 1990, American Chemical Society. All rights reserved.