A new molecular precursor for magnesia-silica materials

The new molecular precursor Mg[OSi((OBu)-Bu-t)(3)](2) was synthesized in hi gh yield from Mg(Bu)(2) and HOSi((OBu)-Bu-t)(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 m(2) g(-1), respectively. The MgO . 2SiO(2) 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 disper sion of MgO in an SiO2 matrix, and are consistent with predictions based on charge balancing in binary oxides.