Experimental and Theoretical Studies of the Potential Interconversion of the Amine–Borane iPr₂NH·BH(C₆F₅)₂ and the Aminoborane iPr₂N=B(C₆F₅)₂ Involving Hydrogen Loss and Uptake

The amine–borane adduct i Pr 2 NH · BH(C 6 F 5 ) 2 ( 1 ) and the aminoborane i Pr 2 N=B(C 6 F 5 ) 2 ( 2 ) have been prepared and crystallographically characterised. Interconversion between the two compounds has been attempted using thermal and transition‐metal‐catalysed dehydrogenation and hydrogenation protocols and the overall reaction thermodynamics were probed by computational methods. Thermal dehydrogenation of 1 was found to yield 2 , together with uncharacterised by‐products. Treatment of 1 with the carbene 1,3‐di‐ tert ‐butyl‐4,5‐dihydroimidazol‐2‐ylidene ( 3 ) under ambient conditions did not lead to the elimination of hydrogen, but instead to the loss of C 6 F 5 H to afford i Pr 2 N=B(H)C 6 F 5 ( 4 ). Attempts to hydrogenate aminoborane 2 were unsuccessful with no reaction observed either thermally or in the presence of transition‐metal catalysts. A computational study of the interconversion between compounds 1 and 2 indicated a thermodynamically unfavourable hydrogenation reaction, which was inverse to that demonstrated for the analogous phosphane–borane/phosphanylborane pair, i Pr 2 PH · BH(C 6 F 5 ) 2 ( 5 ) and i Pr 2 P–B(C 6 F 5 ) 2 ( 6 ). The contrasting reactivity was attributed to the different N–B and P–B π‐bond strengths in 2 and 6 , respectively.