Conformational Characters and Si Nuclear Shielding Ab initio Calculations of Some Sample Silatrane Compounds

Simulated anealing method is currently employed to study the molecular conformation of 1-methyl and 1-vinyl silatranes. It is found that the common silatranes exist in two lowenergy conformations in the endo-form. the exo-form is not found, and furthermore. The conformation transition may take place in the solution. The result are very consistent with the known NMR experimental results.
Ab initio Si nuclear shielding calculation are carried outfor F and CH₃ substituted silatrane molecular. From the calculations, it can be concluded that the calculated shielding tensor is sensitive to used basis set and geometry. The tensor direction is in good aggreement with the experiment. but the value is consistent with the experiment qualitatively only since the configuration interaction is not included in the calculation yet.