Dehydrocoupling of catecholborane catalyzed by group 4 compounds

The early transition metal compounds [Cp2TiCl2], [Cp2ZrCl2] and [Cp2HfCl2] were employed as pre-catalysts for the dehydrocoupling of catecholborane. The product of this reaction, bis(catecholato)diborane (B2Cat2), was generated with turnover numbers of up to 90. Heterogeneous catalysis yielded lower turnover numbers, but the metal powders used in these reactions turned out to also display the general ability to promote the dehydrocoupling reaction.