Triply bonded pancake π-dimers stabilized by tetravalent actinides

Barluzzi, Luciano, Ogilvie, Sean P., Dalton, Alan B., Kaden, Peter, Gericke, Robert, Mansikkamäki, Akseli, Giblin, Sean R. ORCID: https://orcid.org/0000-0003-1876-8619 and Layfield, Richard A. 2024. Triply bonded pancake π-dimers stabilized by tetravalent actinides. Journal of the American Chemical Society 146 (6) , 4234–4241. 10.1021/jacs.3c13914

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Abstract

Aromatic π-stacking is a weakly attractive, noncovalent interaction often found in biological macromolecules and synthetic supramolecular chemistry. The weak nondirectional nature of π-stacking can present challenges in the design of materials owing to their weak, nondirectional nature. However, when aromatic π-systems contain an unpaired electron, stronger attraction involving face-to-face π-orbital overlap is possible, resulting in covalent so-called “pancake” bonds. Two-electron, multicenter single pancake bonds are well known, whereas four-electron double pancake bonds are rare. Higher-order pancake bonds have been predicted, but experimental systems are unknown. Here, we show that six-electron triple pancake bonds can be synthesized by a 3-fold reduction of hexaazatrinaphthylene (HAN) and subsequent stacking of the [HAN]3– triradicals. Our analysis reveals a multicenter covalent triple pancake bond consisting of a σ-orbital and two equivalent π-orbitals. An electrostatic stabilizing role is established for the tetravalent thorium and uranium ions in these systems. We also show that the electronic absorption spectrum of the triple pancake bonds closely matches computational predictions, providing experimental verification of these unique interactions. The discovery of conductivity in thin films of triply bonded π-dimers presents new opportunities for the discovery of single-component molecular conductors and other spin-based molecular materials.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Chemical Society
ISSN:	0002-7863
Date of First Compliant Deposit:	2 February 2024
Date of Acceptance:	23 January 2024
Last Modified:	14 Feb 2024 15:15
URI:	https://orca.cardiff.ac.uk/id/eprint/166108

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