Chains of Condensed IrIn7 Polyhedra in Ir2In12Ga4O15.

The new low valent iridiumindiumoxogallate Ir₂In₁₂Ga₄O₁₅ was prepared by heating intimate mixtures of Ir, In, In₂O₃, and Ga₂O₃ in a platinum crucible under an atmosphere of argon (1400 K, 70 h). The compound has an orange color. X-ray powder diffraction patterns can be indexed on the basis of a primitive orthorhombic unit cell with lattice parameters a = 1954.5(1) pm, b = 674.0(1) pm, and c = 745.9(1) pm. The crystal structure of Ir₂In₁₂Ga₄O₁₅ was solved from powder diffraction data and refined using the Rietveld method ( Pnn2, R(prof.) = 4.4 %, R(int.) = 2.5 %). Ir₂In₁₂Ga₄O₁₅ is according to [IrIn₅In_2/2]⁹⁺₂[GaO₄]^5-₂[Ga₂O₇]^8- an ortho-gallate- pyro-gallate with chains of corner sharing [IrIn₇]⁹⁺ polyhedra, [GaO₄]^5-₂ tetrahedra, and [Ga₂O₇]^8- double tetrahedra. The Ir-In distances within the IrIn₇ polyhedra are shorter than in Ir-In intermetallic phases and lie between 256-261 pm. [ABSTRACT FROM AUTHOR]