Theoretical study on the dimerization of Si(OH)4 in aqueous solution and its dependence on temperature and dielectric constant

We have also calculated 29Si-NMR shieldings and Raman frequencies for Si(OH)4, Si2O7H6 and some other oligomeric silicates. We correctly reproduce the separation of monomer and dimer peaks observed in the 29Si-NMR spectrra at ambient T and P. The Raman spectral data are somewhat ambiguous, and the new peaks seen at high T and P could arise either from the dimer or from a 3-ring trimer, which is calculated to be highly stabilized entropically at high T.