An open-framework three-dimensional indium oxalate: [In(OH)(C2O4)(H2O)]3·H2O

By hydrothermal reaction of In2O3 with H2C2O4·2H2O in the presence of H3BO3 at 155 °C, an open-framework three-dimensional indium oxalate of formula [In(OH)(C2O4)(H2O)]3·H2O (1) has been obtained. The compound crystallizes in the trigonal system, space group R3c with image, image, image, image, image at 298 K. The small pores in 1 are filled with water molecules. It loses its filled water at about 180 °C without the change of structure, then the bounded water at 260 °C, and completely decompounds at 324 °C. The residue is confirmed to be In2O3.