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.
Several indium borophosphates have been reported recently,including K In[BP 2 O 8 (OH)]( Ⅰ )and NaIn[BP 2 O 8 (OH)]( Ⅱ ).The latter two compounds were synthesized under mild hydrothermal condit ions,and have the same molar ratio(M Ⅰ ∶In∶B∶P∶O∶H)in molecular formula but with different structure types.C ompound Ⅰ crystallizes in the triclinic system with space group P1(No.2), a =0.52638(4)nm, b =0.84791(5)nm, c =0.81469(9)nm,α=91.1741(7)°,β=93.061(7) °,γ=79.823(5)°, V =0.3573nm 3 ,Z=2;while compound Ⅱ possesses a monoclinic structure with space group P 2 1 / n (No.14)with a =0.5177(1)nm, b =1.6815(3)nm, c =0.7684(2)nm,β=94.10(3)°, V =0.6672(2)nm 3 ,Z=4.Eight-membered-ring and six-membered-ring are formed by alterna ting borate,phosphate tetrahedra and In-coordination octahedron sharing corner s via common oxygen atoms in compound Ⅰ and Ⅱ respectively.The polyhedra in the structure are oriented along certain dire ction to form alternating layered fragments.These two structure types can be co nsidered as intergrowth structures,which consist of the same layered fragments growing in different orientations.Other structure intergrowth possibilities are also expected in similar systems.CSD: Ⅰ ,409583; Ⅱ ,413343.
