These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Formation of the [Ge4O16Al48(OH)108(H2O)24]20+ Tetramer from Condensation of ε-GeAl12 Keggin Polycations
preprintsubmitted on 03.09.2020, 01:41 and posted on 03.09.2020, 12:46 by Mohammad Shohel, Jennifer Bjorklund, Jack Smith, Sara E. Mason, Tori Z. Forbes
Keggin-type polyaluminum cations belong to a unique class of polyoxometalates (POMs) with their large positive charge, hydroxo bridges, and divergent isomerization/oligomerization. Previously reported oligomerizations of the polyaluminum cations were driven solely by the δ-Keggin isomer, which created Al26, Al30, and Al32 dimeric species. We herein report the isolation of largest ever Keggin-type structure for this system through a unique mode of self-condensation among four ε-GeAl128+ to form [NaGe4O16Al48(OH)108(H2O)24]21+(Ge4Al48). Elemental analysis confirms the Ge4+ substitution, and dynamic light scattering experiments indicated that these larger species exist in the thermally aged solutions. DFT calculations have revealed that a single atom Ge substitution in tetrahedral site of ε-Al137+ is the key for the formation this cluster because it activates the deprotonation at certain octahedral sites to assist self-condensation in a specific mode.