Organoboron Compounds 351. Study of the thermal reactions of tetraalkyldiboranes by NMR methods

Conclusions The methods of¹¹B NMR spectroscopy have been used to demonstrate that the 1,1,2-trial-kyldiboranes are the principal products from the disproportionation of the lower tetraalkyl-diboranes (tetraethyl-, tetra-n-propyl-, tetra-n-butyl-, and tetraisobutyldiboranes) at temperatures in excess of 70C, the 1,1- and 1,2-dialkyldiboranes being formed in considerably smaller amounts. The general direction of the disproportionation reaction is not affected by a change in the size of the alkyl radical, or by the replacement of a bridging hydrogen by a deuterium atom. The amount of trialkylboranes in the equilibrium mixture increases with increasing size of the radical, and the rate of the disproportionation reaction falls off when the bridging hydrogen is replaced by a deuterium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 314–318, February, 1979.The authors would like to thank V. S. Bogdanov who obtained and interpreted the NMR spectra.