Heptasodium tetra-aluminium tetra-kis-(diphosphate) orthophosphate, Na(7)Al(4)(P(2)O(7))(4)(PO(4)).
The asymmetric unit of title compound contains three Na(+), one Al(3+), three P(5+) and eight O(2-) atoms, with one Na(+) atom lying on a twofold rotation axis and one Na(+) and one P(5+) atom on fourfold rotoinversion axes. The fundamental building units of the title structure are isolated PO(4) tetra-hedra, AlO(6) octa-hedra and P(2)O(7) groups, which are further inter-locked by corner-sharing O atoms, forming a three-dimensional framework structure. The Na(+) atoms are located within the cavities of the framework, showing coordination numbers of 4, 6 and 7.
Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, Henan 454000,  People's Republic of China.
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Zhao