Accessing One-Dimensional Chains of Halogenoindates(III) in Organic-Inorganic Hybrids

Organic-inorganic hybrids of halogenoindates(III) are typically represented by one of the zero-dimensional units: InX₄^-, InX₅^2-, InX₆^3-, or In₂X₁₁^5-. Higher dimensional anionic forms, although not forbidden, have remained almost elusive. Here we report for the first time In³⁺-based organic-inorganic hybrids, (C₄H₅N₂S)₂InCl₅ and (C₄H₅N₂S)₂InBr₅, with 1D anionic chains of trans-halide-bridged InX₆ octahedra whose formation is guided by 2-mercaptopyrimidinium cations (C₄H₅N₂S⁺). The chains are characterized by the significant ease of deformation, which is reflected in the elongation of the bridging bonds or the displacement of In³⁺ ions. The materials show a robust band gap predominantly governed by C₄H₅N₂S⁺ cations. Dielectric relaxation processes in (C₄H₅N₂S)₂InBr₅ arise from the cations' dynamics and suggest the ability of the brominated system to accommodate even larger cations. Our work represents a successful attempt to expand the structural diversity of halogenoindates(III) and opens a pathway to reach multifunctional 1D In³⁺-based hybrids.