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[{Th(C8H8)Cl2}3]2− is stable but not aromatic

Nature volume 603, pages E18–E20 (2022)Cite this article

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Matters Arising to this article was published on 23 March 2022

The Original Article was published on 23 August 2021

arising from J. T. Boronski et al. Nature https://doi.org/10.1038/s41586-021-03888-3 (2021).

The term aromaticity in chemistry is reminiscent of symmetric, exceptionally stable structures that have delocalized electrons that sustain diamagnetic ring currents in response to external magnetic fields; the two latter characteristics are sometimes mistakenly thought to be the same1. In a ground-breaking discovery, Liddle and co-workers synthesized a D3h complex with rare thorium (Th)‒Th bonds2. Studying the electronic structure of a neutral singlet model system, K2[{Th(C8H8)Cl2}3] or 3″, showed that the molecule has a delocalized highest occupied molecular orbital (HOMO) between three Th atoms akin to a three-centre–two-electron bond. Using nucleus independent chemical shift (NICS)3 computations and according to the pattern of the NICS scan plot4 of 3″, the authors suggest that the molecule is a σ-aromatic species, as reflected in the title of their paper; but we question whether this molecule is an aromatic one.

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Figure 1: An overview over the current density of 3″.

Data availability

The isosurfaces of current density at J(r) = 0.0003 a.u. (Supplementary Fig. 1), the profile and isosurface plots of the current density of benzene at different values (Supplementary Fig. 2), and details of the computational methods used to perform the present work are presented in the Supplementary Information.

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Acknowledgements

Computational resources were provided by CESNET (LM2015042) and the CERIT Scientific Clouds (LM2015085). This research was funded in whole by National Science Centre, Poland 2020/39/B/ST4/02022. For the purpose of open access, the authors have applied a CC-BY public copyright license to any Author Accepted Manuscript (AAM) version arising from this submission. We thank J. Koča for his support for science in the Czech Republic and his personal support of our work.

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Authors and Affiliations

  1. CEITEC—Central European Institute of Technology, Masaryk University, Brno, Czech Republic

    Ben Joseph R. Cuyacot

  2. Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic

    Ben Joseph R. Cuyacot

  3. Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland

    Cina Foroutan-Nejad

Authors
  1. Ben Joseph R. Cuyacot
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  2. Cina Foroutan-Nejad
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Contributions

B.J.R.C. performed all computations with ReSpect including integration of current densities and assessing the molecular orbital contributions to the current intensity. C.F.-N. performed QTAIM analyses and wrote the paper.

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Correspondence to Cina Foroutan-Nejad.

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Supplementary Information

This file contains Supplementary Figs. 1, 2, Methods and References.

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Cuyacot, B.J.R., Foroutan-Nejad, C. [{Th(C8H8)Cl2}3]2− is stable but not aromatic. Nature 603, E18–E20 (2022). https://doi.org/10.1038/s41586-021-04319-z

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