Single crystals of (NH
4)
4[(UO
2)
5(MoO
4)
7](H
2O)
5 have been synthesized hydrothermally using (NH
4)
6Mo
7O
24, (UO
2)(CH
3COO)
2·2H
2O, and H
2O at 180
![](/images/entities/deg.gif)
C. The phase has been characterized by single-crystal X-ray diffraction using amerohedrally twinned single crystal: it is hexagonal,
P6
1,
a = 11.4067(5) Å,
c = 70.659(5) Å,
V = 7961.9(7) Å
3,and
Z = 6. The structure is based upon an open framework with composition [(UO
2)
5(MoO
4)
7]
4- that is composedof UO
7 pentagonal bipyramids that share vertexes with MoO
4 tetrahedra. The framework has large channels (effectivepore size: 4.8 × 4.8 Å
2) parallel to the
c axis and a system of smaller channels (effective pore size: 2.5 × 3.6 Å
2)parallel to [100], [110], [010], [
![](/images/entities/onemacr.gif)
10], [1
![](/images/entities/onemacr.gif)
0], and [
![](/images/entities/onemacr.gif)
![](/images/entities/onemacr.gif)
0]. The channels are occupied by NH
4+ cations and H
2O molecules.The topological structure of the uranyl molybdate framework can be described either in terms of fundamentalchains of UO
7 pentagonal bipyramids and MoO
4 tetrahedra or in terms of tubular building units parallel to the
caxis.