Synthesis and structure of tris(trialkylstannyl)- and tris(dialkylhalostannyl)amines; of the Sn3N by Sn-X-Sn

Article abstract of DOI:10.1002/cber.19961290211

Tris(triorganylstannyl)amines (R₂R′Sn)₃N (1, 2) with substituents R = R′ = Me, Bu or R = Me and R′ = iPr, tBu are obtained by metathesis from R₂R′SnX and NaNH₂ in liquid ammonia or by transamination of R₃SnNMe₂ with NH₃. Tris(diorganylhalostannyijamines (R₂XSn)₃N (3) are synthesized by stannazane cleavage of (Me₃Sn)₃N (1) with R₂SnX₂. Information from multinuclear magnetic resonance spectra ascertain the planarity of the Sn₃N skeleton of type 2 and 3, as well as the relationship between the coupling constants ₁J(¹¹⁹Sn¹⁵N) and ²J(¹¹⁹Sn¹¹⁷Sn) and the Sn-N bond length as determined by the X-ray structure analysis of 1, 3b and 3r. Compound 3b shows an almost undistorted D_3h symmetry with a planar Br₃Sri₃N skeleton and SnN bond lengths of 1.99 A, which beside those of 3a are the shortest found so far. According to MNDO approximate and ab initia calculations it interactions between the lone electron pair at the N atom and empty orbitals at the Sn atoms can be excluded. Therefore, the tristannylamines discussed here have a trigonal planar nitrogen center with its lone electron pair in a p-type orbital. Further characteristic features of the molecular structures of typ 3 compounds are the intramolecular Sn-X-Sn bridges (X = Cl, Br, I) found in the solid state as well as in solution. The molecular geometries of the tristannylamines are supported by MS fragmentation patterns as well as by infrared and Raman spectra. VCH Verlagsgesellschaft mbH 1996.