A General, Rhodium‐Catalyzed, Synthesis of Deuterated Boranes and <i>N</i>‐Methyl Polyaminoboranes

Abstract

The rhodium complex [Rh(Ph₂ PCH₂ CH₂ CH₂ PPh₂ )(η⁶ -FC₆ H₅ )][BAr^F₄ ], 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-d_x (R=H, D; x=0, 2, 3 or 5). It also acts to catalyze the dehydropolymerization of 1-d_x to give deuterated polyaminoboranes. Mechanistic studies suggest a metal-based polymerization involving an unusual hybrid coordination insertion chain-growth/step-growth mechanism.