Amine-Templated Anionic Metal–Organic Frameworks with the 4,4′-(Hexafluoroisopropylidene) Bis(benzoic acid) Ligand

Three new compounds with anionic metal–organic frameworks [M₃(hfbba)₄]^2–, M = Mn²⁺ or Co²⁺, hfbba = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), have been synthesized by solvothermal techniques in the presence of different amines. Their structures were determined from single crystal X-ray data. All three structures are based on linear trimers of metal oxide polyhedra. (C₆H₁₁NH₃)₂Mn₃(hfbba)₄, 1, has a three-dimensional (3D) structure with large cages that are filled by pairs of cyclohexylammonium cations. ((C₄H₁₁)₂NH₂)₂Co₃(hfbba)₄, 2, has a complex layered structure with intralayer lateral channels. One half of the dibutylammonium cations are located inside the channels and are orientationally disordered, while the other half of the dibutylammonium cations are located in the interlayer spaces and are ordered. (H₂tdpip)Co₃(hfbba)₄, 3, tdpip = 4,4′-trimethylenedipiperidine, also has a layered structure with the H₂tdpip cations located between the layers. The magnetic properties of compounds 1, 2, and 3 were determined from 10 to 300 K.