P-C-Activated Bimetallic Rhodium Xantphos Complexes: Formation and Catalytic Dehydrocoupling of Amine-Boranes

Abstract

{Rh(xantphos)}-based phosphido dimers form by P-C activation of xantphos (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) in the presence of amine-boranes. These dimers are active dehydrocoupling catalysts, forming polymeric [H2BNMeH]n from H3B·NMeH2 and dimeric [H2BNMe2]2 from H3B·NMe2H at low catalyst loadings (0.1 mol %). Mechanistic investigations support a dimeric active species, suggesting that bimetallic catalysis may be possible in amine-borane dehydropolymerization.