A new sodium indium phosphate Na 6In 4[P 7O 24(OH) 5]·4H 2O was synthesized under a mild hydrothermal condition and its structure was determined by means of single-crystal X-ray diffraction methods. The title compound crystallizes in a hexagonal system, space group P6 3, with a= 0.950 23(5) nm, b=0.950 23(5) nm, c=1.694 2(2) nm, α=90°, β=90°, γ=120°, V=1.324 8(2) nm 3, Z=8, structure refined to R=0.052 8 and wR=0.116 5 for 2 134 independent observed reflections. The three-dimensional network structure consists of helical chains formed by apex-sharing polyhedra. The connection of the chains results in 4- and 8-polyhedral rings and cages centered by three indium metal connecting oxygen atoms formed by three 4-rings. The three-connected oxygen atom is firstly observed in indium phosphate systems.
