Cu6- And Cu8-Cage Sil- And Germsesquioxanes: Synthetic and Structural Features, Oxidative Rearrangements, and Catalytic Activity

This study reports intriguing features in the self-assembly of cage copper(II) silsesquioxanes in the presence of air. Despite the wide variation of solvates used, a series of prismatic hexanuclear Cu6 cages (1-5) were assembled under mild conditions. In turn, syntheses at higher temperatures are accompanied by side reactions, leading to the oxidation of solvates (methanol, 1-butanol, and tetrahydrofuran). The oxidized solvent derivatives then specifically participate in the formation of copper silsesquioxane cages, allowing the isolation of several unusual Cu8-based (6 and 7) and Cu6-based (8) complexes. When 1,4-dioxane was applied as a reaction medium, deep rearrangements occurred (with a total elimination of silsesquioxane ligands), causing the formation of mononuclear copper(II) compounds bearing oxidized dioxane fragments (9 and 11) or a formate-driven 1D coordination polymer (10). Finally, a "directed"self-assembly of sil- and germsesquioxanes from copper acetate (or formate) resulted in the corresponding acetate (or formate) containing Cu6 cages (12 and 13) that were isolated in high yields. The structures of all of the products 1-13 were established by single-crystal X-ray diffraction, mainly based on the use of synchrotron radiation. Moreover, the catalytic activity of compounds 12 and 13 was evaluated toward the mild homogeneous oxidation of C5-C8 cycloalkanes with hydrogen peroxide to form a mixture of the corresponding cyclic alcohols and ketones. ©

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  • 1 Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (RAS), Vavilov Strasse 28, Moscow, 119991, Russian Federation
  • 2 Peoples' Friendship University of Russia, Miklukho-Maklay Street 6, Moscow, 117198, Russian Federation
  • 3 Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences (SB RAS) Prosp. Akad., Lavrentieva 5, Novosibirsk, 630090, Russian Federation
  • 4 Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences (RAS), Leninsky Prospect 47, Moscow, 119991, Russian Federation
  • 5 National Research Center "kurchatov Institute", Akademika Kurchatova pl. 1, Moscow, 123182, Russian Federation
  • 6 Plekhanov Russian University of Economics, Stremyanny per. 36, Moscow, 117997, Russian Federation
  • 7 Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, Lisbon, 1049-001, Portugal
Ключевые слова
Catalyst activity; Catalytic oxidation; Coordination reactions; Ketones; Oxidation; Single crystals; Synchrotron radiation; Volatile fatty acids; 1D coordination polymer; Copper acetates; Homogeneous oxidation; Mononuclear copper; Oxidative rearrangements; Single crystal x-ray diffraction; Structural feature; Tetra-hydrofuran; Copper compounds
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