Low‐Temperature Topochemical Transformation of Bi 13 Pt 3 I 7 into the New Layered Honeycomb Metal Bi 12 Pt 3 I 5

Ordered single‐crystals of the metallic subiodide Bi 13 Pt 3 I 7 were grown and treated with n ‐butyllithium. At 45 °C, complete pseudomorphosis to Bi 12 Pt 3 I 5 was achieved within two days. The new compound is air‐stable and contains the same ${{{\hfill 2\atop \hfill \infty }}}$ [(PtBi 8/2 ) 3 I] n + honeycomb nets and iodide layers as the starting material Bi 13 Pt 3 I 7 , but does not include ${{{\hfill 1\atop \hfill \infty }}}$ [BiI 2 I 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 Bi 13 Pt 3 I 7 and Bi 12 Pt 3 I 5 , the vicinities of the Fermi levels are dominated by the intermetallic fragments. Upon the transformation of Bi 13 Pt 3 I 7 into Bi 12 Pt 3 I 5 , the intermetallic part is oxidized and the Fermi level is lowered by 0.16 eV. Whereas in Bi 13 Pt 3 I 7 the intermetallic layers do not interact across the iodidobismuthate spacers (two‐dimensional metal), they couple in Bi 12 Pt 3 I 5 and form a three‐dimensional metal.