Rb3CoO2, a Novel Oxocobaltate(I) Synthesized via the Azide/Nitrate Route

Rb₃CoO₂ was prepared via the azide/nitrate route. Stoichiometric mixtures of the precursors (Co₃O₄, RbN₃ and RbNO₃) were heated in a special regime up to 500 °C and annealed at this temperature for 100 h in silver crucibles. The crystal structure of the obtained red product was solved and refined by powder methods (Pnma, Z = 4, 12.3489(2), 7.6648(1), 6.2251(1) Å). Rb₃CoO₂ is isostructural with K₃CoO₂ and contains Co¹⁺, which is coordinated by two oxygen atoms forming a slightly distorted dumb‐bell. Rb₃CoO₂ decomposes at 580 °C to Rb₂O, Co and CoO.