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 Pb (such as Sb and Bi). Here, we report eight HLDP halides from the family, where = -phenylenediammonium (PPDA), 1,4-butanediammonium (1,4-BDA), or 1,3-propanediammonium (1,3-PDA); = Cu or Ag; = 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)AgRuCl and (PPDA)AgMoCl show no obvious evidence of a magnetic ordering transition. While the Mo compound displays Curie-Weiss behavior for a spin-only d ion, the Ru compound displays marked deviations from the Kotani theory.