A new molecular precursor for magnesia–silica materials

The new molecular precursor Mg[OSi(OtBu)3]2 was synthesized in high yield from Mg(Bu)2 and HOSi(OtBu)3. Thermolytic decomposition of this precursor in toluene solution leads to a magnesia–silica monolith. The monolith can be processed to isolate xerogels or aerogels with surface areas of 245 and 640 m2 g−1, respectively. The MgO·2SiO2 materials are very acidic, as determined by ammonia temperature programmed desorption (TPD). Additionally, CO2 TPD revealed that these materials have a very low basic site density. The TPD results can be explained by a very high dispersion of MgO in an SiO2 matrix, and are consistent with predictions based on charge balancing in binary oxides.