Polarity and Structure of Silatranes with Planar Fragments

The structure of silatranes N[CH 2 (RMeC 6 H 2 )O] 3 SiR 1 with planar fragments in six-membered semi-rings was established by the methods of dipole moments and density functional theory calculations. They are endo-structures with transannular interaction N → Si in which the oxygen atoms located adjacent to the silicon participate besides the nitrogen and silicon atoms.