Syntheses, crystal structures and magnetic properties of three new silver manganese(ii) or manganese(iii) mixed metal iodates

Abstract

Systematic explorations of new compounds in the unexplored Ag⁺–Mn²⁺/Mn³⁺–iodate system led to three new silver Mn²⁺ (or Mn³⁺)-mixed metal iodates, namely, AgMn(IO₃)₃, AgMn(IO₃)₄ and Ag₃Mn(IO₃)₆. These compounds feature the same building units of MnO₆ octahedron and IO₃, but the different coordination modes of the iodate groups in these compounds led to three different types of anionic structures ranging from a zero-dimensional (0D) cluster to a two-dimensional (2D) layer. Interestingly, the dimensions of the anionic structure decrease with an increase in the IO₃/Mn molar ratio in the formula. AgMn(IO₃)₃ exhibits a 2D [Mn₂(IO₃)₆]_n²ⁿ⁻ anionic layer in which the Mn₂O₂ rings are further decorated by terminal iodates and interconnected by bidentate and tridentate bridging iodate groups. AgMn(IO₃)₄ displays a one-dimensional (1D) [Mn(IO₃)₄]_nⁿ⁻ anionic chain in which each pair of MnO₆ octahedra is bridged by a pair of IO₃ groups, and within the chain each manganese center is also attached with two terminal iodate groups from both sides of the chain. Ag₃Mn(IO₃)₆ features isolated 0D [Mn(IO₃)₆]³⁻ anions. The Ag⁺ cations in all three compounds act as spacers between these anions. Optical, thermal stability and magnetic susceptibility measurements for AgMn(IO₃)₃ and AgMn(IO₃)₄ have also been performed.