13C, 15N and 29Si NMR spectra of triazasilatranes

¹³C, ¹⁵N and ²⁹Si chemical shifts and ²⁹Si¹H, ²⁹Si¹³C and ²⁹Si¹⁵N coupling constants as well as SiH bond stretching frequencies in the triazasilatranes (I) (2,5,8,9-tetraaza-1-silatricyclo[3.3.3.0^1,5] undecanes) and model compounds, tris(alkylamino)silanes with R_Si = H, Me, CH₂CH (Vi) and C₆H₅ (Ph) were measured. A stronger intramolecular N → Si bonding was revealed in I compared with their oxygen analogues, silatranes (II). This was assumed to be caused by the higher polarity of the equatorial SiX bonds in I (X = NH) in comparison with II (X = O).