Trigonal planar (D_3h) AuI₃ complex stabilized in a solid lattice

An unprecedented molecular AuI₃ complex has been stabilized in the interlayer space of the Bi₂Sr₂CaCu₂O_y lattice by reacting Au metal with IBi₂Sr₂CaCu₂O_y. at 235 °C. The stoichiometry of this new intercalate phase is determined as (AuI₃)_0.25Bi₂Sr₂CaCu ₂O_y by thermogravimetry and X-ray photoelectron spectroscopy. MicroRaman and Au L₃-edge extended X-ray absorption fine structure analyses reveal that Au and I are stabilized as the molecular AuI₃ (D_3h) in the Bi₂Sr₂CaCu₂O_y lattice with a uniform Au-I bond length of 2.56 Å. According to the powder X-ray diffraction pattern analysis, the basal spacing increases from 15.30 to 18.55 Å with an expansion of 3.25 Å implying that the AuI₃ molecules are intercalated into the [Bi-O] double layers with a parallel geometry. The present AuI₃ entity is the first of the three coordinated molecular Au-complexes to be stabilized in a solid matrix at room temperature.