Sethio D, Daku LML, Hagemann H, Kraka E. Quantitative Assessment of B-B-B, B-H
b -B, and B-H
t Bonds: From BH
3 to B
12 H
12 2.
Chemphyschem 2019;
20:1967-1977. [PMID:
31063616 DOI:
10.1002/cphc.201900364]
[Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/06/2019] [Indexed: 12/28/2022]
Abstract
We report the thermodynamic stabilities and the intrinsic strengths of three-center-two-electron B-B-B and B-Hb -B bonds ( H b : bridging hydrogen), and two-center-two-electron B-Ht bonds ( H t : terminal hydrogen) which can be served as a new, effective tool to determine the decisive role of the intermediates of hydrogenation/dehydrogenation reactions of borohydride. The calculated heats of formation were obtained with the G4 composite method and the intrinsic strengths of B-B-B, B-Hb -B, and B-Ht bonds were derived from local stretching force constants obtained at the B3LYP-D2/cc-pVTZ level of theory for 21 boron-hydrogen compounds, including 19 intermediates. The Quantum Theory of Atoms in Molecules (QTAIM) was used to deepen the inside into the nature of B-B-B, B-Hb -B, and B-Ht bonds. We found that all of the experimentally identified intermediates hindering the reversibility of the decomposition reactions are thermodynamically stable and possess strong B-B-B, B-Hb -B, and B-Ht bonds. This proves that thermodynamic data and intrinsic B-B-B, B-Hb -B, and B-Ht bond strengths form a new, effective tool to characterize new (potential) intermediates and to predict their role for the reversibility of the hydrogenation/dehydrogenation reactions.
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