SU-22 and SU-23: Layered Germanates Built from 4-Coordinated Ge₇ Clusters Exhibiting Structural Variations on the 4⁴ Topology

Two novel layered germanates, denoted as SU-22 and SU-23, have been synthesized hydro(solvo)thermally by using diethylenetriamine (DETA) and 1,7-diaminoheptane (DAHep) as structure directing agents (SDAs), respectively. Their structures were determined by single-crystal X-ray diffraction. Both structures are built from the same Ge7 clusters which are 4-coordinated following a 44 topology with different modes of linkage. SU-23 is the first example of a different mode leading to the formation of 10-rings, instead of 8- and 12-rings observed in the ASU-20 compounds and SU-22. A third type of linkage is also proposed. The study of the hydrogen bonding interaction pattern is developed to provide insight into the formation of these different modes in relation with the size and geometry of the SDAs, as they have a significant effect on the rotation and arrangements of Ge7 clusters. SU-22, [C4N3H15]1.5[Ge7O14X3]·H2O (X = OH or F), monoclinic, space group C2/c, a = 16.0583(8), b = 16.4484(10), c = 17.7788(8) Å, β = 98.151(6)°, R1 = 0.0430, for 4248 reflections with I < 2σ(I). SU-23, [C7N2H19][C7N2H20][Ge7O14X3][GeO2]0.2·3H2O, monoclinic, space group P21/n, a = 13.036(3), b = 9.4726(19), c = 30.814(6) Å, β = 100.03(3)°, R1 = 0.0349 for 5741 reflections with I < 2σ(I).