Open-framework germanates show interesting pore structures due to their flexible building units. Germanates with different topology built from the Ge 9 cluster can be prepared in several amine systems. This paper reports, the Si modified germanate ICMM6 (denoted as HUT-2) prepared in ethylene diamine solution through a hydrothermal synthesis route. HUT-2 is a silicogermanate with space group C222 1 (a=12.1299(6) Å, b=13.9329(11) Å, c=14.2205(6) Å, V=2403.33(25) Å 3 ) formed by the Si modified Ge 9 cluster. A variation of unit cell parameters is observed that is in accordance with Si-content. Powder X-ray diffraction, ICP and TGA-DSC analysis were recorded to determine the Si-composition at the tetrahedral sites. Structure refinements against the X-ray powder diffraction (XRPD) pattern determined the occupancy of Si at the two tetrahedral sites. An approximate Si/Ge ratio of 0.13-0.18 is obtained based on these characterizations. TGA-DSC analysis showed obvious weight loss of amine at 315 °C, which is higher than the reported pure germanate ICMM6. This further confirms the existence of Si within the structure of HUT-2.

Si Modified Ge 10 Cluster: The Preparation and Characterization of Single Crystal Na4(Ge,Si)9O20. -The title compound with approximate composition Na4Ge7.68Si1.32O20 is hydrothermally prepared from a GeO2/xH2O/5en/2-methyl pentanethylenediamine/yNaSiO3·9H2O (x = 35-46; y = 0.1-0.5) mixture (autoclave, 160°C, 7 d) and characterized by powder and single crystal XRD. It crystallizes in the space group I4 1 and has the same structure as Na 4 Ge 9 O 20 with partial Si substitution at the tetrahedral sites. -(XIAO, P.-Y.; REN*, T

A Si modified Ge 10 cluster with structure Na 4 (Ge,Si) 9 O 20 (denoted as HUT-1) was synthesized by hydrothermal synthesis at 160 °C with a sodium silicate source. The compound was characterized by single crystal, powder X-ray diffraction and TGA-DSC analysis. HUT-1 crystallizes in space group I4 1 (80) with calculated unit cell (a=14.966(5) Å, c=7.343(2) Å, V=1644.8(9) Å 3 ), which has the same structure as Na 4 Ge 9 O 20 . HUT-1 has a high Si/Ge ratio with an approximate formula of Na 4 Ge 7.68 Si 1.32 O 20 . Single crystal X-ray structure refinements together with results from X-ray powder diffraction (XRPD) confirm the occupancy of Si at two tetrahedral sites.