NH₄[BGe₃O₈]: A New Borogermanate Framework Made of Infinite-Chain Building Blocks

A new microporous borogermanate NH4[BGe3O8] has been synthesized by a molten boric acid flux method with “reagent” quantities of water in which GeO2, ethylenediamine, H2O, and H3BO3 (5:8:14:25) were heated together at 513 K for 4 days. The structure consists of {Ge6O18}n chains, further linked together via BO4 tetrahedra, forming a three-dimensional open framework with intersecting channel systems including one-dimensional 10-membered-ring (MR) channels. Interestingly, the infinite chains {Ge6O18}n as building blocks, built of alternating 4- and 6-MRs made of vertex-sharing GeO4 tetrahedra, construct the borogermanate framework. It is noteworthy that the high viscosity of the reactive medium and the quantity of water play important roles in the formation of the compound.