Original Paper

Journal of Molecular Modeling

, Volume 12, Issue 5, pp 569-576

First online:

Theoretical study of hydrogenation of the doubly aromatic B 7 cluster

  • Anastassia N. AlexandrovaAffiliated withDepartment of Chemistry and Biochemistry, Utah State University
  • , Eldon KoyleAffiliated withDepartment of Chemistry and Biochemistry, Utah State University
  • , Alexander I. BoldyrevAffiliated withDepartment of Chemistry and Biochemistry, Utah State University Email author 

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We have studied the influence of hydrogenation on the relative stability of the low-lying isomers of the anionic B 7 cluster, computationally. It is known that the pure-boron B 7 cluster has a doubly (σ- and π-) aromatic C6v (3A1) quasi-planar wheel-type triplet global minimum (structure 1), a low-lying σ-aromatic and π-antiaromatic quasi-planar singlet C2v (1A1) isomer 2 (0.7 kcal mol−1 above the global minimum), and a planar doubly (σ- and π-) antiaromatic C2v (1A1) isomer 3 (7.8 kcal mol−1 above the global minimum). However, upon hydrogenation, an inversion in the stability of the species occurs. The planar B7H 2 (C2v, 1A1) isomer 4, originated from the addition of two hydrogen atoms to the doubly antiaromatic B 7 isomer 3, becomes the global minimum structure. The second most stable B7H 2 isomer 5, originated from the quasi-planar triplet wheel isomer 1 of B 7 , was found to be 27 kcal mol−1 higher in energy. The inversion in stability occurs due to the loss of the doubly aromatic character in the wheel-type global minimum isomer (C6v, 3A1) of B 7 upon H2−addition. In contrast, the planar isomer of B 7 (C2v, 1A1) gains aromatic character upon addition of two hydrogen atoms, which makes it more stable.


The B7H2-global minimum structure and its σ-aromatic and π-antiaromatic MOs


Multiple aromaticity Boron hydrides Boron clusters