The Simplest Amino‐borane H 2 B=NH 2 Trapped on a Rhodium Dimer: Pre‐Catalysts for Amine–Borane Dehydropolymerization

The μ‐amino–borane complexes [Rh 2 (L R ) 2 (μ‐H)(μ‐H 2 B=NHR′)][BAr F 4 ] (L R =R 2 P(CH 2 ) 3 PR 2 ; R=Ph, i Pr; R′=H, Me) form by addition of H 3 B⋅NMeR′H 2 to [Rh(L R )(η 6 ‐C 6 H 5 F)][BAr F 4 ]. DFT calculations demonstrate that the amino–borane interacts with the Rh centers through strong Rh‐H and Rh‐B interactions. Mechanistic investigations show that these dimers can form by a boronium‐mediated route, and are pre‐catalysts for amine‐borane dehydropolymerization, suggesting a possible role for bimetallic motifs in catalysis.