A General, Rhodium-Catalyzed, Synthesis of Deuterated Boranes and N-Methyl Polyaminoboranes.

The rhodium complex [Rh(Ph2 PCH2 CH2 CH2 PPh2 )(η6 -FC6 H5 )][BArF4 ], 2, catalyzes BH/BD exchange between D2 and the boranes H3 B⋅NMe3 , H3 B⋅SMe2 and HBpin, facilitating the expedient isolation of a variety of deuterated analogues in high isotopic purities, and in particular the isotopologues of N-methylamine-borane: R3 B⋅NMeR2 1-dx (R=H, D; x=0, 2, 3 or 5). It also acts to catalyze the dehydropolymerization of 1-dx to give deuterated polyaminoboranes. Mechanistic studies suggest a metal-based polymerization involving an unusual hybrid coordination insertion chain-growth/step-growth mechanism.