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

Abstract

The amine-borane adduct iPr 2 NH·BH(C 6 F 5 ) 2 (1) and the aminoborane iPr 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

B=N Bonds and BCN Rings – Reactivity and Charge Density Studies

“…In the pentafluorophenyl‐substituted compound 1 the B(1)–N(1) bond length is 1.372(2) Å. This is in the range expected for a C 6 F 5 substituted monomeric aminoborane with partial B–N multiple bond [1.376(4) Å in (C 6 F 5 ) 2 BN i Pr 2 21]. The B–N distance in the CF 3 substituted aminoborane 2 has a value of 1.356(3) Å and is thus 0.016 Å shorter than 1 [cf.…”

Amino and Alkyl B-Substituted P-Stabilized Borenium Salts

“…The P–B distance (2.867(2) Å) is much longer than the sum of covalent radii (1.91 Å) . Both the boron and nitrogen atoms are in trigonal-planar environments (∑ α B = 357.2°, ∑ α N = 359.7°), and the N–B bond is short (1.385(3) Å, in comparison with the sum of covalent radii of 1.55 Å), indicating significant double-bond character …”

Boron, aluminium, gallium, indium and thallium

“…175 The topic of hydrogen storage and the development of amine-borane adducts and their derivatives has continued to be a topic of significant interest during 2011, and has attracted attention from researchers developing new B-N compounds [176][177][178][179][180][181] to those developing both Main Group [182][183][184][185] and transition metal dehydrogenation reagent catalysts [186][187][188][189][190] as well as those investigating mechanisms of dehydrogenation, both experimentally and computationally. [191][192][193][194][195][196] While a full review of this topic is beyond the scope of a document, a review on the topic of transition metal catalysed dehydrogenation has been published. 197 The nature of B-N multiple bonds in a wide range of B'N, B-N and BQN bond containing compounds have been studied using quantum mechanical calculations.…”