Two open-framework germanates, SUT-1 and SUT-2, have been synthesized under hydrothermal conditions using ethylenediamine (en, H2NCH2CH2NH2) as templates and Ni(NO3)2·6H2O as the transition-metal source. Their frameworks are built with Ge10 clusters and [Ni(en)2]2+ complexes. In both structures, Ge10 clusters form square nets in the a–c plane, while the [Ni(en)2]2+ complexes bridge the square nets via Ni–O–Ge bonds to form 3D networks. They present the first examples to incorporate Ni2+ complexes into the germanate frameworks. In SUT-2, additional linkages by Ge2O7 clusters between the square nets generate a new type of topology.
