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Abstract:
Red cuboid crystals of the water-rich iodidobismuthate(III) (H3O)Rb3BiI7 center dot 4H(2)O crystallize from a solution of RbI and BiIO in concentrated aqueous HI at ambient conditions. X-ray diffraction reveale an orthorhombic structure with space group Pnma (no. 62). In the crystal structure, [BiI6](3-) octahedra are arranged in layers parallel to (010). Nine-fold coordinated Rb+ and additional I- ions connect the iodidobismuthate(III) groups into a three-dimensional framework, which hosts protonated water complexes (1)(infinity)[H11O5](+), i.e. infinite zigzag chains of hydrogen-bonded water molecules and oxonium cations. (H3O)Rb3BiI7 center dot 4H(2)O decomposes in air at ambient temperature within few days, resulting in fragmentation and amorphization of the crystals. Fast and complete dehydration occurs between 50 degrees C and 100 degrees C. Hydrates like this are possible intermediates in the slow hydrolysis of bismuth-based halide perovskites, which are currently discussed as lead-free alternatives to the solar cell absorber material methylammonium lead triiodide (MAPI).
