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. 2022 Jul 4;13(1):3844.
doi: 10.1038/s41467-022-31267-7.

3D and 2D aromatic units behave like oil and water in the case of benzocarborane derivatives

Jordi Poater  1   2 , Clara Viñas  3 , Miquel Solà  4 , Francesc Teixidor  5
Affiliations

3D and 2D aromatic units behave like oil and water in the case of benzocarborane derivatives

Jordi Poater et al. Nat Commun. .

Abstract

A large number of 2D/2D and 3D/3D aromatic fusions that keep their aromaticity in the fused compounds have been synthesized. In addition, we have previously proven the electronic relationship between the 3D aromaticity of boron hydrides and the 2D aromaticity of PAHs. Here we report the possible existence of 3D/2D aromatic fusions that retain the whole aromaticity of the two units. Our conclusion is that such a 3D/2D aromatic combination is not possible due to the ineffective overlap between the π-MOs of the planar species and the n + 1 molecular orbitals in the aromatic cage that deter an effective electronic delocalization between the two fused units. We have also proven the necessary conditions for 3D/3D fusions to take place, and how aromaticity of each unit is decreased in 2D/2D and 3D/3D fusions.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. 3D/3D systems formed from [B7H7]2−.
Computed NICS (in ppm) at the center of the five-membered ring of each cluster are enclosed. Boron atoms in orange and H atoms in white.
Fig. 2
Fig. 2. 3D/3D systems formed from [B12H12]2−, B10H14, and [B10H10]2−.
Computed NICS (in ppm) at the center of different five- and four-membered rings and at the center of each cluster are enclosed. Boron atoms in orange and H atoms in white.
Fig. 3
Fig. 3. 3D/3D systems formed from [CB11H12]− and C2B10H12.
Computed NICS (in ppm) at the center of different five-membered rings and at the center of each cluster are enclosed. Boron atoms in orange, C atoms in gray, and H atoms in white.
Fig. 4
Fig. 4. 3D/3D systems formed from [Sn12]2− and [Sn10]2−.
Computed NICS (in ppm) at the center of different five- and four-membered rings and at the center of each cluster are enclosed. Sn atoms in gray.
Fig. 5
Fig. 5. 3D/3D systems formed from the fusion of [B6H6]2− and [B12H12]2− or [B10H10]2−.
Computed NICS (in ppm) at the center of different four- and five-membered rings and at the center of each cluster are enclosed. Boron atoms in orange, and H atoms in white.
Fig. 6
Fig. 6. 3D + 2D formation.
a [2 + 2 + 2] cycloaddition between o-carboryne and alkynes; b structures of fused carborane and PAHS.
Fig. 7
Fig. 7. Fused systems between o-carborane C2B10H12 and benzene.
NICS (in ppm) and nomenclature of the different isomers (BBo states for BB bond next to CC, whereas BBp states for the BB bond at the opposite site to the CC bond). NICS for C2B10H12 are −33.3 and −27.3 ppm for the center of the B4C ring and center of the cluster (values in italics), respectively, and −8.1 ppm for benzene (see also Supplementary Tables 1 and 2). Boron atoms in orange, C atoms in gray, and H atoms in white.
Fig. 8
Fig. 8. Fused systems between o-carborane C2B10H12 and benzene, naphthalene, anthracene, and phenanthrene.
NICS (in ppm) for the five-membered rings and center of the carborane and MCI (in au) for the PAHs with and without (in italics) the carborane being attached (see also Supplementary Tables 1 and 2). Boron atoms in orange, C atoms in gray, and H atoms in white. Larger MCI values indicate higher electron delocalization in the ring.
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References

    1. Aihara J. Three-dimensional aromaticity of polyhedral boranes. J. Am. Chem. Soc. 1978;100:3339–3342. doi: 10.1021/ja00479a015. - DOI
    1. Pitochelli AR, Hawthorne MF. The Isolation of the Icosahedral B12H12-2 Ion. J. Am. Chem. Soc. 1960;82:3228–3229. doi: 10.1021/ja01497a069. - DOI
    1. Bakouri OES, et al. Fully π-conjugated macrocycles: when 3D-aromatic and when 2D-aromatic-in-3D? J. Am. Chem. Soc. 2022;144:8560–8575. doi: 10.1021/jacs.1c13478. - DOI - PMC - PubMed
    1. Poater J, Solà M, Viñas C, Teixidor F. A simple link between hydrocarbon and borohydride chemistries. Chem. Eur. J. 2013;19:4169–4175. doi: 10.1002/chem.201204397. - DOI - PubMed
    1. Poater J, Solà M, Viñas C, Teixidor F. π-Aromaticity and three-dimensional aromaticity: two sides of the same coin? Angew. Chem. Int. Ed. 2014;53:12191–12195. doi: 10.1002/anie.201407359. - DOI - PubMed