Hybrid Layered Double Perovskite Halides of Transition Metals

Hybrid layered double perovskite (HLDP) halides comprise hexacoordinated 1+ and 3+ metals in the octahedral sites within a perovskite layer and organic amine cations between the layers. Progress on such materials has hitherto been limited to compounds containing main group 3+ ions isoelectronic with PbII (such as SbIII and BiIII). Here, we report eight HLDP halides from the A 2 M I M III X 8 family, where A = para-phenylene­diammonium (PPDA), 1,4-butane­diammonium (1,4-BDA), or 1,3-propane­diammonium (1,3-PDA); M I = Cu or Ag; M III = Ru or Mo; X = Cl or Br. The optical band gaps, which lie in the range 1.55 to 2.05 eV, are tunable according to the layer composition, but are largely independent of the spacer. Magnetic measurements carried out for (PPDA)2AgIRuIIICl8 and (PPDA)2AgIMoIIICl8 show no obvious evidence of a magnetic ordering transition. While the t 2g 3 MoIII compound displays Curie–Weiss behavior for a spin-only d3 ion, the t 2g 5 RuIII compound displays marked deviations from the Kotani theory.