Silicophosphates containing SiO6 octahedra – anhydrous synthesis under ambient conditions†
Abstract
Reactions of anhydrous H3PO4 with different tetraalkoxysilanes (Si(OR)4, R = Me, Et, iPr, nBu) in a 1 : 1 molar ratio in diethylether at room temperature and normal pressure generate silicophosphates (SiPOs). Solid state 29Si NMR investigations clearly indicate that the precipitates contain large amounts of SiO6-species. The substructures of the products are strongly influenced by the alkyl substituents R of the tetraalkoxysilanes, as further supported by 31P MAS, 13C CP/MAS NMR and FTIR spectroscopy. All solid products are amorphous containing P : Si-ratios of 1.2–1.7, which was proved by powder XRD and elemental analysis. Since small amounts of water may be formed in the H3PO4–Si(OR)4-systems upon condensation and esterification reactions (which results in reaction mixtures being not completely anhydrous), the reactivity of P4O10 towards tetraethoxysilane was investigated at room temperature confirming the formation of SiO6-units as well.
Please wait while we load your content...
