Synthese und Struktur von Bis(trimethylstannyl)‐ und Bis(dimethylhalogenstannyl)aminen: zur Rolle des Stickstoff‐Elektronenpaares

Abstract

Synthesis and Structure of Bis(trimethylstannyl) and Bis(dimethylhalostannyl) Amines: The Role of the Nitrogen Lone PairMonoaminostannanes RNH— SnMe3 (1) with substituents R = tBu, Mes, 2,6‐iPr2C6H3 are obtained by transmetallation from Me3SnX and RNH—Li, the distannylamines RN(SnMe3)2 (2) by transamination of Et2N —SnMe3 with RNH2, and bis(dimethylhalostannyl)amines R—N(SnMe2X)2 (8) by stannazane cleavage of 2 with Me2SnX2 or by SnC cleavage with BX3 (8n, o). Me2Sn(NtBuH)2, prepared from tBuNHLi and Me2SnBr2, decomposes with tBuNH2 elimination into the diazadistannetidine 4 already below room temperature. Information from multinuclear NMR spectra of type 2, 4, and 8 compounds ascertain the proposed relation between the value of the geminal coupling constant 2J(119Sn117Sn) of distannazanes and the Sn—N—Sn bond angle as determined by the X‐ray structure analysis of 2c and of (8a)2 as well as the participation of the electron pair at the nitrogen atom in bonding. 2c has C2 symmetry, contains a planar nitrogen atom with SnN bond lengths of 2.044 Å and an Sn—N—Sn bond angle of 125.0°. The aryl group stands perpendicular to the Sn2N plane. These data exclude any π interaction between the N atom and the substituents. 2c, therefore, represents an example of a tertiary amine with the lone electron pair at the nitrogen atom in a p‐type orbital. The supposed distannylamine (ClMe2Sn)2NMe (8a) is actually a dimer, whose unexpected structure contains a diazadistannetidine unit bearing two Me2SnCl2 groups at its nitrogen atoms in cis‐configuration. This arrangement allows the formation of weak intramolecular SnCl bonds.