Synthesis of Boron-Halogenated Diborylamines and Diborylhydrazines by Cleavage of Stannazanes

The diborylamines R′–N(BRX)2 (3; × = Cl, Br) are obtained by stannazane cleavage of distannylorganylamines R′–N(SnMe3)2 (4) with alkyldihaloboranes RBX2 in a 1:2 molar ratio. The presence of the sterically demanding substituents R and R′ also causes carbon–tin bond cleavage, resulting in low yields of 3. However, carbon–tin bond cleavage can be suppressed by the use of bis(dimethylchlorostannyl)organylamines 5 as the nitrogen source for the synthesis of diborylamines. This results in almost quantitative yields of the compounds 3. Treatment of the distannylhydrazines R2N–N(SnMe3)2 (7) with RBX2 in a 1:2 molar ratio leads to the formation of N,N-bis(alkylhaloboryl)hydrazines 8 under mild conditions and in good yield. The molecular structures of 3 and 8 were determined by multinuclear magnetic resonance spectra in solution as well as by X-ray structure analysis in the case of 8d. A typical structural feature of 8d is the intramolecular BN adduct formation. Support for the constitutions of compounds 8c comes from MS fragmentation patterns as well as from IR spectra.