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

Synthesis and Structure of Bis(trimethylstannyl) and Bis(dimethylhalostannyl) Amines: The Role of the Nitrogen Lone Pair Monoaminostannanes RNH— SnMe 3 ( 1 ) with substituents R = t Bu, Mes, 2,6‐ i Pr 2 C 6 H 3 are obtained by transmetallation from Me 3 SnX and RNH—Li, the distannylamines RN(SnMe 3 ) 2 ( 2 ) by transamination of Et 2 N —SnMe 3 with RNH 2 , and bis(dimethylhalostannyl)amines R—N(SnMe 2 X) 2 ( 8 ) by stannazane cleavage of 2 with Me 2 SnX 2 or by SnC cleavage with BX 3 ( 8n, o ). Me 2 Sn(N t BuH) 2 , prepared from t BuNHLi and Me 2 SnBr 2 , decomposes with t BuNH 2 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 2 J ( 119 Sn 117 Sn) 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 C 2 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 Sn 2 N 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 (ClMe 2 Sn) 2 NMe ( 8a ) is actually a dimer, whose unexpected structure contains a diazadistannetidine unit bearing two Me 2 SnCl 2 groups at its nitrogen atoms in cis ‐configuration. This arrangement allows the formation of weak intramolecular SnCl bonds.