Aminopropylsilances versus silatranes: an experimental and theoretical study

The H-1-, C-13-, N-15- and Si-29-NMR spectra of 3-aminopropyltrimethoxysilane and N,N-dimethylamino-propyltrimethoxysilane have been recorded. An analysis of the spectra together with GIAO calculations leads to the conclusion that these compounds exist as open-chain structures and not as ring-closed silatranes. The N --> Si interaction is important only when there is at least one cycle in the structure, although two of three cycles (silatranes) are a more favorable disposition. (C) 2001 Elsevier Science B,V. Ah rights reserved.