Sodium, calcium, aluminium, zinc and europium salts of p-phenylenebis(silanetriolate). Access to a new class of organosilicates

Abstract

The crystalline sodium salt of p-phenylenebis(silanetriolate), (NaO)₃SiC₆H₄Si(ONa)₃·14H₂O has been prepared in quantitative yield by reaction of the corresponding alkoxysilane with NaOH. Characterization of its structure indicates two different environments for the silicon atoms (X-ray and ¹³C, ²⁹Si, ¹H NMR) in the solid state. Drying of the salt by thermal treatment between 20 and 180 °C (TG analysis) led to a modification of the structure without loss of the organic group. Elimination of C₆H₆ occurs above 200 °C and formation of the sodium silicate Na₂SiO₃ can be identified above 400 °C (X-ray diffraction). Quantitative replacement of the sodium cation with Al³⁺, Zn²⁺, Ca²⁺ and Eu³⁺ has been achieved resulting in the formation of the corresponding silanetriolates (EDX and elemental analyses). X-Ray diffraction analysis suggests the presence of a lamellar structure on very small domains or a short range order.