Study of the N−H···H−B Dihydrogen Bond Including the Crystal Structure of BH₃NH₃ by Neutron Diffraction

Abstract

Boraneamines tend to have close N-H δ+ ‚‚‚ δ-H-B contacts as a result of the intermolecular interaction of the NH proton with the BH bond by a novel type of hydrogen bond (the dihydrogen bond). A CSD structural search provides characteristic metric data for the interaction: the H‚‚‚H distance is in the range 1.7-2.2 Å, and the N-H‚‚‚H group tends to be linear while B-H‚‚‚H tends to be bent. The reported X-ray structure of BH 3 NH 3 seemed to provide a singular exception in having bent N-H‚‚‚H and linear B-H‚‚‚H. Our neutron diffraction structure of BH 3 NH 3 now shows that the B and N atoms must be reversed from the assignment previously published. With the correct assignment we find the expected bent B-H‚‚‚H and linear N-H‚‚‚H arrangement in the closest intermolecular N-H‚‚‚H-B interaction (d HH ) 2.02 Å).

Ruthenium Bis(σ‐BH) Aminoborane Complexes from Dehydrogenation of Amine–Boranes: Trapping of H2BNH2

“…[9,15] The most striking features are the shortening of the BÀN distance (1.396(3) ) with respect to that of ammonia-borane (1.58 (2) as determined by neutron diffraction), [16] and the increase of the BÀH bond distances (1.25(2) and 1.22(3) ) compared to 1.15(3) and 1.18(3) in H 3 B À NH 3 . [16] DFT ( Figure S3). The most stable isomer is the bis(s-BÀH) adduct 3 a, the model for 2 a.…”

Unconventional hydrogen and dihydrogen bonded supramolecular array of a 2,6-dioxa-9,16-diaza-1,3(1,2),4(1,4)-tribenzenacycloheptadecaphane-borane adduct

“…It exhibits multiple N-H···H-B intermolecular interactions in the solid state with H···H distance of 2.02 Å. 6 Besides, it has been proposed that some physical properties of this compound come from the dihydrogen bonds. Borane-amine adducts are widely used in modern synthetic organic chemistry because of their capability to carry out reductions of aldehydes and ketones, reductive aminations, olefin hydroborations, and amide reductions.…”

Positional disorder in ammonia borane at ambient conditions

“…Ammonia borane NH 3 BH 3 has drawn significant interest in recent years because of its potential as a hydrogen storage material, with a gravimetric storage density of 19.6 mass% [1][2][3][4][5][6][7]. The structure of its solid phase has been explored previously [8][9][10][11][12][13], but the literature does not agree about the hydrogen behavior at room temperature. The molecule consists of a dative B-N bond and a trio of H atoms (henceforth referred to as a "halo") bonded to each of those two atoms, forming an hourglass shape, visible in Fig.…”

“…The structure of its solid phase has been explored previously [8][9][10][11][12][13], but the literature does not agree about the hydrogen behavior at room temperature. The molecule consists of a dative B-N bond and a trio of H atoms (henceforth referred to as a "halo") bonded to each of those two atoms, forming an hourglass shape, visible in Fig.…”

“…Since ammonia borane is a strong van der Waals complex [16,17], the inclusion of van der Waals forces is essential [10,18,19]; we thus use vdW-DF1 [20][21][22] (i.e., revPBE exchange and local-density approximation correlation in addition to the nonlocal contribution) as the exchange-correlation functional for all calculations. Car-Parrinello molecular dynamics (CPMD) was performed with the CP code (part of QUANTUM-ESPRESSO version 5.0.2; the vdW-DF capability in CP is a new feature, which we have just implemented) [23], using ultrasoft pseudopotentials and wave function and density cutoffs of 475 and 5700 eV.…”