Exploration of the Mechanism of the Dimerization of Hydroxymethylsilanetriol Using Electronic Structure Methods

Hydroxymethylsilanetriol undergoes condensation reactions to form new structures with an organic part in the formed bridges. As a first step to explore the formation of these bridges, we studied the corresponding mechanisms using simple models and theoretical methods. Three mechanisms were studied for the formation of dimers of hydroxymethylsilanetriol with bridges: Si-O-C-Si, Si-O-Si, and Si-C-O-C-Si. Energies are calculated using M06/6-311+G(d,p) single-point calculations on B3LYP-optimized geometries in solution and including B3LYP thermodynamic corrections. The first mechanism for the formation of the Si-O-C-Si bridge consists of one step. The second mechanism for the formation of the Si-O-Si bridge consists of two steps. The barrier for the last mechanism for the formation of the Si-C-O-C-Si bridge is too high and cannot occur at room temperature. The energy barriers are 31.8, 27.6, and 65.9 kcal mol^-1 for the first, second, and third mechanisms, respectively. When adding one explicit water molecule, these energies are 25.9, 22.9, and 80.3 kcal mol^-1, respectively. The first and second mechanisms can occur at room temperature, which is in agreement with the experimental results.