Layered Structures Constructed from New Linkages of Ge₇(O,OH,F)₁₉ Clusters

Three new germanate solids, ASU-19, ASU-20-DAPe, and ASU-20-DACH, have been synthesized under hydrothermal conditions using respectively 1,4-diaminobutane (DAB), 1,5-diaminopentane (DAPe), and 1,4-diaminocyclohexane (DACH) as bases. The structures of ASU-19 and ASU-20-DACH have been characterized by single-crystal X-ray diffraction: ASU-19, Ge14O29X4·[GeOX2]·[H2DAB]3·3.8H2O (X = F or OH), space group P1̄, a = 11.4191(5), b = 12.0525(6), c = 18.1847(8) Å, α = 90.704(1)°, β = 92.635(1)°, γ = 91.389(1)°, V = 2499.1(2) Å3; ASU-20-DACH: Ge7O14X3·[H2DACH]1.5·2H2O, space group C2/c, a = 15.9525(11), b = 17.5476(12), c = 19.0027(13) Å, β = 109.446(1)°, and V = 5015.9(6) Å3. The structure of ASU-20-DAPe, Ge7O14X3·[H2DAPe]1.5·H2O, has been determined from X-ray powder diffraction data: space group C2/c, a = 16.3180(5), b = 16.6125(4), c = 17.8898(6) Å, β = 99.684(2)°, V = 4780.5(3) Å3. All three structures are based on the assembly of the same cluster Ge7(O,OH,F)19. The two ASU-20 structures consist of a slab of four-connected clusters. In ASU-19, the same layers are connected pairwise through a GeO2X2 spacer, generating a slab structure, with slab thickness ca. 20 Å. The existence of the same layer in the presence of three different organic bases shows the adaptability of the structures to molecules differing in size, shape, and symmetry.