Manganese(iii) fluorophosphate frameworks

Abstract

Nine new manganese(III) fluorophosphates have been synthesised hydrothermally in a fluoride-rich medium, through the use of MnF₃, HPF₆ and monovalent metal fluorides as reactants. Products have been structurally characterised using single crystal X-ray diffraction. Reaction in fluoride-rich conditions produces chain, layer and three dimensional framework structures containing new and unusual structural features based on the linking of PO₃F, PO₂(OH,F)₂ and Mn(O_6−n,F_n) octahedra, with n averaging 2.8 over the family of compounds. The Mn(III), d⁴, oxidation state is stabilised under these reaction conditions and products frequently show Jahn–Teller distorted Mn(O,F)₆ units with axially elongated Mn–O or, less commonly, Mn–F distances. Structures exhibiting inter-layer spaces and channels frequently have these lined by terminal fluoride anions of the PO₃F, PO₂(OH,F)₂ and Mn(O,F)₆ octahedra.