One‐Electron Reduction of 2‐Mono(2,6‐diisopropylphenylimino)acenaphthene‐1‐one (dpp‐mian)

• Published in: Chemistry : a European journal 2019-03, Vol.25 (15), p.3858-3866
• Main Authors: Lukoyanov, Anton N., Ulivanova, Elena A., Razborov, Danila A., Khrizanforova, Vera V., Budnikova, Yulia H., Makarov, Sergey G., Rumyantcev, Roman V., Ketkov, Sergey Y., Fedushkin, Igor L.
• Format: Article
• Language: English
• Subjects: Acenaphthene; Carbon; Chemistry; Electrochemistry; Electrolysis; Electrons; EPR spectroscopy; imino-ketone; Ligands; Oxidation; Potassium; redox chemistry; Reduction; Sodium; Tetrahydrofuran; Tin; Tin chloride; Valence; X-ray diffraction
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201805427

The electrochemical characteristics of 2‐mono(2,6‐diisopropylphenylimino)acenaphthene‐1‐one (dpp‐mian) have been investigated. One‐electron reduction of dpp‐mian involves the iminoketone fragment, which is revealed by the EPR spectrum obtained after the electrolysis of the dpp‐mian solution in tetrahydrofuran (THF). The reduction of dpp‐mian with one equivalent of metallic potassium leads to a similar EPR spectrum. The sodium complex [(dpp‐mian)Na(dme)]2 (1) produces an EPR signal with hyperfine coupling on the nitrogen atom of the iminoketone fragment of the dpp‐mian ligand. Dpp‐mian can also be reduced in a one‐electron process by SnCl2×(dioxane). In this case, complex (dpp‐mian)2SnCl2 (2) is formed, with the tin atom displaying an oxidation state of +4. Tin(II) chloride dihydrate, SnCl2×2(H2O), also reduces dpp‐mian, but the two ligands bound to tin in the product form a new carbon–carbon bond between the ketone moieties of the dpp‐mian monoanions to form complex (bis‐dpp‐mian)HSnCl3 (3). Metallic tin reduces dpp‐mian to form the (bis‐dpp‐mian)2Sn (4) species. Compounds 1–4 were characterized by X‐ray diffraction. Going it alone: One‐electron reduction of 2‐mono(2,6‐diisopropylphenylimino)acenaphthene‐1‐one) (dpp‐mian, see scheme) proceeds via an iminoketone fragment, which is revealed by the EPR spectrum obtained after electrolysis of the dpp‐mian solution in THF. The product of reduction of dpp‐mian with one equivalent of metallic potassium or sodium has similar EPR parameters. Metallic tin can be used to reduce dpp‐mian to form (bis‐dpp‐mian)2Sn, with doubled dpp‐mian ligands. Oxidation of (bis‐dpp‐mian)2Sn leads to breaking of the interligand C−C bond and formation of dpp‐mian. The reduction of (bis‐dpp‐mian)2Sn also breaks the interligand C−C bond and results in the formation of dpp‐mian dianionic complexes.