(NH4)2ZrGe3O9: a new microporous zirconogermanate.

A new microporous zirconogermanate, diammonium zirconium trigermanate, (NH(4))(2)ZrGe(3)O(9) (FDZG-2), analogous to wadeite (K(2)ZrSi(3)O(9)), was hydrothermally synthesized using ZrO(NO(3))(2).2H(2)O as the source of zirconium and 1,4-diaminobutane as a structure-directing agent. Single-crystal X-ray diffraction analysis reveals that the framework structure is built up of cyclic trigermanate units crosslinked by ZrO(6) octahedra. The Zr atom lies at a site with -3 symmetry and the unique N atom of the ammonium ion lies at a site with threefold symmetry. Large cages are observed, with two NH(4)(+) cations in each. The structure contains intersecting six- and three-membered ring (6MR and 3MR) channels, but only the 6MR channels can accommodate the NH(4)(+) ions.