A Hybrid Open-Framework Structure: Synthesis and Structure of an Iron Phosphate Oxalate, [C₁₀N₄H₂₈][Fe₂(HPO₄)₃(C₂O₄)]₂

A new inorganic-organic hybrid structure has been synthesized hydrothermally in the iron phosphate oxalate family using 1,4-bis(3- aminopropyl)piperazine as the structure-directing agent. Crystal data for I, [C ₁₀ N ₄ H ₂₈ ][Fe ₂ (HPO ₄ ) ₃ (C ₂ O ₄ )] ₂ : M= 589.8, monoclinic, space group = P2 ₁ /n (no. 14), a = 10.829(1), b=12.747(1), c= 12.397(1)Å, ?=95.1(1)°, V= 1704.4(3)Å ³ , Z=4, R. =. 0. 0. 3. 6. and R(w)=0.083 [1860 observed reflections with I> 2?(I)]. The structure comprises a network of FeO ₆ octahedra and PO ₄ tetrahedra forming inorganic layers which are bridged by the oxalate units forming 8-membered channels in which the amine molecule resides. Magnetic susceptibility studies indicate an antiferromagnetic behavior with T(N) = ~40 K, the highest known in an open-framework material.