CAAC‐Based Thiele and Schlenk Hydrocarbons. Issue 17 (6th March 2020)

• Record Type: Journal Article
• Authors: Maiti, Avijit; Stubbe, Jessica; Neuman, Nicolás I.; Kalita, Pankaj; Duari, Prakash; Schulzke, Carola; Chandrasekhar, Vadapalli; Sarkar, Biprajit; Jana, Anukul
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 17(2020)
• Page Start: 6729
• Page End: 6734
• Publication Date: 2020-03-06
• Subjects: Carbenes -- dimerization -- conjugation -- radicals -- structure elucidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201915802
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Diradicals have been of tremendous interest for over a century ever since the first reports of p ‐ and m ‐phenylene‐bridged diphenylmethylradicals in 1904 by Thiele and 1915 by Schlenk. Reported here are the first examples of cyclic(alkyl)(amino)carbene (CAAC) analogues of Thiele's hydrocarbon, a Kekulé diradical, and Schlenk's hydrocarbon, a non‐Kekulé diradical, without using CAAC as a precursor. The CAAC analogue of Thiele's hydrocarbon has a singlet ground state, whereas the CAAC analogue of Schlenk's hydrocarbon contains two unpaired electrons. The latter forms a dimer, by an intermolecular double head‐to‐tail dimerization. This straightforward synthetic methodology is modular and can be extended for the generation of redox‐active organic compounds. Abstract : Doubly radical : The p ‐ and m ‐phenylene bridged bis‐pyrrolinium cations A provide access to cyclic(alkyl)(amino)carbene (CAAC) analogues of Thiele's hydrocarbon (B ), a Kekulé diradical, and to Schlenk's hydrocarbon (C ), a non‐Kekulé diradical, respectively. B has a singlet ground state. C has two unpaired electrons in the ground state and forms a dimer by an intermolecular double head‐to‐tail dimerization.