Mass spectrometric investigation of small silicate polyhedra in solution

The hydrolysis of tetra-methyl-ortho-silicate (TMOS) or tetra-ethyl-ortho-silicate (TEOS) in aqueous solutions at pH values of 1-2 was investigated by electrospray mass spectroscopy. In this study, small oligomer intermediates of silicates were formed and detected. Some of the structures are secondary building units as found in zeosils and zeolites. Here, we present the first H/D-exchange mass spectrometric experiments to determine the structure of silicates formed in acidic solution. Most of the observed oligomers take on polyhedral geometries. The results are compared with experiments of other groups, which have performed complementary experiments in alkaline solutions in presence of template molecules.