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Article

The Acid-Base Through-the-Cage Interaction as an Example of an Inversion in a Cage Isomerism

Institute of Nuclear Chemistry and Technology, 16 Dorodna Street, 03-195 Warsaw, Poland
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Symmetry 2020, 12(8), 1291; https://doi.org/10.3390/sym12081291
Received: 19 June 2020 / Revised: 27 July 2020 / Accepted: 29 July 2020 / Published: 3 August 2020
(This article belongs to the Special Issue Symmetry in Acid-Base Chemistry)
We define a new inversion in a cage isomerism (ic): X@CYicY@CX, ( is the isomerism relation) as an isomerism in the three-component system of molecules X, Y, and a cage C, in which one of the molecules is located inside and the other outside the cage. The ic isomerism is similar to the endo-exo one, which occurs only if either the interior or exterior of C is empty. By contrast, ic occurs only if neither the interior nor the exterior of C is empty. We also discuss the other closely related types of isomerisms are also discussed. Calculations of the XH⋯NH3@C60 and NH3⋯[email protected]60ic isomers were performed at the ωB97XD/Def2TZVP level. The calculated energies demonstrated that the systems with the HX acid outside (X = F, Cl) and the NH3 base inside the cage, XH⋯NH3@C60, are more stable than their ic isomers, NH3[email protected]60, by about 4–8 kcal/mol. This is because NH3 is more stabilized inside the cage than HX (a matter of 6.5 kcal/mol). In the studied systems and subsystems, the HX molecules are Lewis acids and the NH3 molecule is always a Lewis base. The C60 molecule with HX inside or outside the cage is also an acid for the NH3 base positioned outside or inside the cage. On the other hand, the C60 cage is truly amphoteric because it is simultaneously an acid and a base. View Full-Text
Keywords: endohedral fullerenes; isomerism; acid-base interaction endohedral fullerenes; isomerism; acid-base interaction
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MDPI and ACS Style

Dobrowolski, J.C.; Ostrowski, S. The Acid-Base Through-the-Cage Interaction as an Example of an Inversion in a Cage Isomerism. Symmetry 2020, 12, 1291. https://doi.org/10.3390/sym12081291

AMA Style

Dobrowolski JC, Ostrowski S. The Acid-Base Through-the-Cage Interaction as an Example of an Inversion in a Cage Isomerism. Symmetry. 2020; 12(8):1291. https://doi.org/10.3390/sym12081291

Chicago/Turabian Style

Dobrowolski, Jan C., and Sławomir Ostrowski. 2020. "The Acid-Base Through-the-Cage Interaction as an Example of an Inversion in a Cage Isomerism" Symmetry 12, no. 8: 1291. https://doi.org/10.3390/sym12081291

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