## Thursday, September 17, 2015

### Convex and Concave Encapsulation of Multiple Potassium Ions by Sumanenyl Anions

Spisak, S. N.; Wei, Z.; O’Neil, N. J.; Rogachev, A. Y.; Amaya, T.; Hirao, T.; Petrukhina, M. A. J. Am. Chem. Soc. 2015, 137, 9768-9771
Contributed by Steven Bachrach.
Reposted from Computational Organic Chemistry with permission

Spisak, et al. treated sumanene 1 with excess potassium in THF.1

They obtained an interesting structure, characterized by x-ray crystallography: a mixture of the dianion and trianion of 1 (well these are really conjugate di- and tribases of 1, but we’ll call them di- and trianions for simplicity’s sake). A fragment of the x-ray structure is shown in Figure 1, showing that there is one potassium cation on the concave face and six potassium ions on the convex face.
Figure 1. X-ray structure of 1 surrounded by six K+ ions on the convex face and one K+ on the concave face.

To help understand this structure, they performed RIJCOSX-PBE0/cc-pVTZ computations on the mono-, di-, and trianion of 1. The structure of 1 (which I optimized at ωB97X-D/6-311G(d)) and the trianion are displayed in Figure 2. The molecular electrostatic potential of the trianion shows highly negative regions in the 5-member ring regions, symmetrically distributed and prime for coordination with 6 cations.
 1 trianion of 1
Figure 2. Optimized structure of 1 and its trianion.

### References

(1) Spisak, S. N.; Wei, Z.; O’Neil, N. J.; Rogachev, A. Y.; Amaya, T.; Hirao, T.; Petrukhina, M. A. "Convex and Concave Encapsulation of Multiple Potassium Ions by Sumanenyl Anions," J. Am. Chem. Soc. 2015137, 9768-9771, DOI: 10.1021/jacs.5b06662.

### InChIs

1: InChI=1S/C21H12/c1-2-11-8-13-5-6-15-9-14-4-3-12-7-10(1)16-17(11)19(13)21(15)20(14)18(12)16/h1-6H,7-9H2
InChIKey=WOYKPMSXBVTRKZ-UHFFFAOYSA-N
Trianion of 1: InChI=1S/C21H9/c1-2-11-8-13-5-6-15-9-14-4-3-12-7-10(1)16-17(11)19(13)21(15)20(14)18(12)16/h1-5,7-8H,9H2/q-3
InChIKey=IHJVIPHOCKVJDZ-UHFFFAOYSA-N