Effect of coordinated water on the mechanism of neutral hydrolysis of silicon dioxide in gas phase: a first principles study

Abstract

Ab initio quantum chemical studies are reported at the B3LYP/6-311++G(d,p), MP2/6-311++G(d,p), and MP2/cc-pVTZ levels for the neutral hydrolysis of silicon dioxide in gaseous phase. These mechanistic studies predict that hydrolysis of silicon dioxide to orthosilicic acid is significantly controlled by the coordinated water molecule at the silicon. The catalytic activity of second water molecule coordinated to silicon lowers the reaction barrier by more than 50% than the first water molecule. The overall reaction is a low barrier process with barrier heights <2 kcal/mol at the MP2/cc-pVTZ level. This is in contrast to the hydration of carbon dioxide, where the second coordination at the carbon is less feasible. At all the three levels of calculations, the reaction follows similar trend.