The unusual Au3+ ternary halide AuPb2I7 has been isolated from reactions of AuI, PbI2, and I2. AuPb2I7 crystallizes in the triclinic P1̄ space group as micron-scale needles with cell dimensions a = 4.5170(3) Å, b = 7.3847(4) Å, c = 12.2970(7) Å, α = 76.374(4)°, β = 83.711(4)°, γ = 72.987(3)° at room temperature with p = 6.538 g/cm3 and has no structural phase transition down to 100 K. The title compound has a unique three-dimensional structure composed of [Pb2I7]3- pseudolayers extending in  bridged by square planar Au3+ at an oblique angle in the  direction. The pseudolayers are composed of 1/∞[Pb2I2]2+ chains propagating down  linked by square planar I- ions through . AuPb2I7 has a bandgap of 1.17 eV and is stable in air for several days, before degrading to PbI2, Au0, and I2. Density functional theory calculations show that AuPb2I7 is an indirect bandgap semiconductor where the bandgap stems predominantly from Au-I metal-ligand charge transfer.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry