Local symmetry force field of the silatrane cage

Abstract The problem of the redundancies inherent to the tricyclic structure of the silatranes is solved and the symmetry coordinates of the reduced space for the cage are settled. In this space, the local symmetry force field of the skeleton is built, then refined looking at the wavenumbers common to numerous silatranes. These parameters are used to interpret the spectra of simple derivatives. Moreover, it constitutes transferable information available for performing an a priori computation of the vibrational normal modes of homologous molecules.