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Synthesis and Structure of Tris(trialkylstannyl)‐ and Tris(dialkylhalostannyl)amines; Stabilization of the Sn 3 N Skeleton by Intramolecular Sn–X–Sn Bridges
Author(s) -
Appel Andrea,
Kober Christian,
Neumann Christine,
Nöth Heinrich,
Schmidt Martin,
Storch Wolfgang
Publication year - 1996
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19961290211
Subject(s) - chemistry , intramolecular force , crystallography , planarity testing , lone pair , tris , bond length , molecular orbital , stereochemistry , molecule , crystal structure , biochemistry , organic chemistry
Tris(triorganylstannyl)amines (R 2 R'Sn) 3 N ( 1, 2 ) with substituents R = R' = Me, Bu or R = Me and R' = i Pr, t Bu are obtained by metathesis from R 2 R'SnX and NaNH 2 in liquid ammonia or by transamination of R 3 SnNMe 2 with NH 3 . Tris(diorga‐nylhalostannyl)amines (R 2 XSn) 3 N ( 3 ) are synthesized by stannazane cleavage of (Me 3 Sn) 3 N ( 1 ) with R 2 SnX 2 . Information from multinuclear magnetic resonance spectra ascertain the planarity of the Sn 3 N skeleton of type 2 and 3 , as well as the relationship between the coupling constants 1 J ( 119 Sn 15 N) and 2 J ( 119 Sn 117 Sn) 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 Br 3 Sn 3 N skeleton and SnN bond lengths of 1.99 Å, which beside those of 3a are the shortest found so far. According to MNDO approximate and ab initio calculations π interactions between the lone electron pair at the N atom and empty orbitals at the Sn atoms can be excluded. Therefore, the tristan‐nylamines 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.