Low‐Temperature Topochemical Transformation of Bi13Pt3I7 into the New Layered Honeycomb Metal Bi12Pt3I5

Ordered single‐crystals of the metallic subiodide Bi₁₃Pt₃I₇ were grown and treated with n‐butyllithium. At 45 °C, complete pseudomorphosis to Bi₁₂Pt₃I₅ was achieved within two days. The new compound is air‐stable and contains the same ${{{hfill 2atop hfill infty }}}$ [(PtBi_8/2)₃I]ⁿ⁺ honeycomb nets and iodide layers as the starting material Bi₁₃Pt₃I₇, but does not include ${{{hfill 1atop hfill infty }}}$ [BiI₂I_4/2]^? iodidobismuthate strands. Electron microscopy and X‐ray diffraction studies of solid intermediates visualize the process of the topochemical crystal‐to‐crystal transformation. In the electronic band structures of Bi₁₃Pt₃I₇ and Bi₁₂Pt₃I₅, the vicinities of the Fermi levels are dominated by the intermetallic fragments. Upon the transformation of Bi₁₃Pt₃I₇ into Bi₁₂Pt₃I₅, the intermetallic part is oxidized and the Fermi level is lowered by 0.16 eV. Whereas in Bi₁₃Pt₃I₇ the intermetallic layers do not interact across the iodidobismuthate spacers (two‐dimensional metal), they couple in Bi₁₂Pt₃I₅ and form a three‐dimensional metal.