Collect. Czech. Chem. Commun. 1997, 62, 1254-1262

1-Carba-arachno-pentaborane(10) Derivatives

Bernd Wrackmeyer and Hans-Jörg Schanz

Laboratorium für Anorganische Chemie, Universität Bayreuth, D-95440 Bayreuth, Germany


The formation of organo substituted 1-carba-arachno-pentaborane(10) derivatives is shown to proceed in high yield via in situ generated 1,1,1-tris(diethylboryl)propane (2) from diethyl(propyn-1-yl)borane (1) by hydroboration with an excess of diethylborane (hydride bath). In the hydride bath, exchange reactions between 2 and other geminal bis(diethylboryl)alkanes take place until the carbaborane skeleton is formed. If tris(diethylboryl)methane is used under the same conditions, the corresponding 1-carba-arachno-pentaborane(10) derivatives 11 and 12 are formed in mixture with other unknown boranes or carboranes. 11B and 13C NMR data are presented to allow for straightforward identification of the 1-carba-arachno-pentaboranes(10).

Keywords: Carboranes; Boranes, propyn-1-yl, vinyl; Hydroboration; Exchange reactions, Et2BH-catalyzed; NMR, 11B, 13C.