Dimerization of a Reactive Azaacene Diradical: Synthesis of a Covalent Azaacene Cage

Kathleen Fuchs; Samara Medina Rivero; Anna Weidlich; Frank Rominger; Noel Israel; Alexey A Popov; Andreas Dreuw; Jan Freudenberg; Juan Casado; Uwe H F Bunz

doi:10.1002/anie.202305712

Dimerization of a Reactive Azaacene Diradical: Synthesis of a Covalent Azaacene Cage

Angew Chem Int Ed Engl. 2023 Aug 7;62(32):e202305712. doi: 10.1002/anie.202305712. Epub 2023 Jul 3.

Authors

Affiliations

¹ Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
² Department of Physical Chemistry, University of Málaga, Andalucia-Tech Campus de Teatinos s/n, 29071, Málaga, Spain.
³ Department of Physics & Astronomy, University of Sheffield, S37RH, Sheffield, UK.
⁴ Interdisciplinary Center for Scientific Computing, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 205, 69120, Heidelberg, Germany.
⁵ Center of Spectroelectrochemistry, Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtzstraße 20, 01069, Dresden, Germany.

PMID: 37219544
DOI: 10.1002/anie.202305712

Abstract

Two series of regioisomeric dicyanomethylene substituted dithienodiazatetracenes with formal para- or ortho-quinodimethane subunits were synthesized and characterized. Whereas the para-isomers (p-n, diradical index y₀ =0.01) are stable and isolable, the ortho-isomer (y₀ =0.98) dimerizes into a covalent azaacene cage. Four elongated σ-CC bonds are formed and the former triisopropylsilyl(TIPS) -ethynylene groups transformed into cumulene units. The azaacene cage dimer (o-1)₂ was characterized by X-ray single crystal structure analysis and temperature-dependent infrared (IR), electron paramagnetic resonance (EPR, solid-state), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV/Vis) spectroscopies (solution) indicating reformation of o-1.

Keywords: Azaacene Cage; Cumulene; Cyclization; Diradical; σ-Dimerization.

Abstract

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