New Series of Oxalato-Gallophosphate Structures Containing Transition Metal Centers

Five organic−inorganic hybrid mixed-metal oxalatophosphates, (C₃H₁₂N₂)₂[(VO)₂(ox)Ga₂(PO₄)₄] (1), (C₁₀H₂₈N₄)[(VO)₂(ox)Ga₂(PO₄)₄]·2H₂O (2), (C₇H₂₁N₃)_0.5(H₃O)[Mn(H₂O)₂Ga₄F₂(ox)(PO₄)₄]·4H₂O (3), (C₅H₁₄N₂)[Mn(H₂O)₂Ga₄F₂(ox)(PO₄)₄]·3H₂O (4), and (C₄H₁₆N₃)[MnGa₂(ox)₂(HPO₄)₂(PO₄)] (5) (ox = C₂O₄^2-), with varied framework topologies, have been synthesized under mild hydrothermal conditions and characterized by single-crystal X-ray diffraction, magnetic susceptibility, and TG analysis. They provide foremost examples of organic−metallophosphate hybrid frameworks that contain hetero metal centers, owing to which the structures of 1−5 are able to be indexed into a series. The vanadium compounds 1 and 2 are layered, whereas the manganese compounds 3, 4, and 5, compositionally and structurally related to 1 or 2, are 3D materials. The oxalate anion can act as a bis-bidentate ligand in all five compounds as well as a monobidentate ligand in 5. Besides homo bioctahedral units of M‘₂(ox)O₆ (M‘ = (VO) for 1 and 2, (GaF) for 3 and 4), we observe the first hetero chelating MnGa(ox)O₈ unit, formed of an unusual Mn^[6p]O₆ trigonal prism and a GaO₆ octahedron, and unique trimeric polyhedral Mn(H₂O)₂(GaF)₂O₁₂ and MnGa₂O₁₆ units. The fundamental frameworks for 1−5 effectively display a series that is constructed from a substructure of 1D or 2D plus a four-ring linker and/or Mn²⁺ ions into 2D or 3D structures. The hetero metals have imposed magnetic property to the Ga(ox)PO lattices and led to the first well-defined M−X−Ga (X = O, F) bonds ever observed in the metal phosphate chemistry.