Henry Rzepa's Blog

Whilst clusters of carbon atoms are well-known, my eye was caught by a recent article describing the detection of a cluster of boron atoms, B₄₀ to be specific.[1] My interest was in how the σ and π-electrons were partitioned. In a C₄₀, one can reliably predict that each carbon would contribute precisely one π-electron. But boron, being more electropositive, does not always play like that. Having one electron less per atom, one might imagine that a fullerene-like boron cluster would have no π-electrons. But the element has a propensity[2] to promote its σ-electrons into the π-manifold, leaving a σ-hole. So how many π-electrons does B₄₀ have? These sorts of clusters are difficult to build using regular structure editors, and so coordinates are essential. The starting point for a set of coordinates with which to compute a wavefunction was the supporting information. Here is the relevant page: The coordinates are certainly there (that is not always the case), but you have to know a few tricks to make them usable.

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References

1. H. Zhai, Y. Zhao, W. Li, Q. Chen, H. Bai, H. Hu, Z.A. Piazza, W. Tian, H. Lu, Y. Wu, Y. Mu, G. Wei, Z. Liu, J. Li, S. Li, and L. Wang, "Observation of an all-boron fullerene", Nature Chemistry, vol. 6, pp. 727-731, 2014. http://dx.doi.org/10.1038/nchem.1999
2. H.S. Rzepa, "The distortivity of π-electrons in conjugated boron rings", Physical Chemistry Chemical Physics, vol. 11, pp. 10042, 2009. http://dx.doi.org/10.1039/B911817A