Investigation of the GeO₂-1,6-Diaminohexane-Water-Pyridine-HF Phase Diagram Leading to the Discovery of Two Novel Layered Germanates with Extra-Large Rings

The systematic exploration of the phase diagram of the GeO₂-1,6-diaminohexane-water-pyridine-HF system has allowed the identification of specific roles of the HF, H₂O contents, and HF/H₂O ratio in the formation of Ge₇X₁₉ (Ge₇), Ge₉X₂₅₋₂₆ (Ge₉), and Ge₁₀X₂₈ (Ge₁₀) clusters (X = O, OH, F). This work has led to the discovery of two novel structures with extra-large 18-membered rings accommodating 1,6-diaminohexane (DAH): SU-63, |1.5H₂DAH|[Ge₇O₁₄X₃]·2H₂O, a layered germanate constructed from Ge₇ clusters with the Kagomé topology, and SU-64, |11H₂DAH|[Ge₉O₁₈X₄][Ge₇O₁₄X₃]₆·16H₂O, a germanate built of two-dimensional slabs containing both Ge₇ and Ge₉ clusters (X = OH or F). We also put SU-64 in context with previously reported cluster germanate compounds with related topologies by means of a simple crystal deconstruction study.