Mixed Inorganic–Organic Anion Frameworks: Synthesis and Crystal Structure of Fe4(PO4)2(C2O4)(H2O)2

A novel inorganic–organic framework material has been prepared hydrothermally in the iron(II)–phosphate–oxalate system. Fe4 (PO4)2(C2O4)(H2O)2crystallizes in space groupP21/n,a=7.974(3) ?,b=4.817(3) ?,c=14.169(3) ?,=94.70(3)°,V=542.4(4) 3,Z=2, finalR,Rw=0.023, 0.025 for 817 observed data (I-3(I)). The structure consists of sheets of interconnected FeO6, FeO5, and PO4polyhedra in theabplane, which are bridged via C2O2-4groups along thec-axis to form an infinite three-dimensional network enclosing small cavities into which terminal FeOH2groups protrude.