Cagelike Octacopper Methylsilsesquioxanes: Self-Assembly in the Focus of Alkaline Metal Ion Influence-Synthesis, Structure, and Catalytic Activity

Alexey N Bilyachenko; Ivan S Arteev; Victor N Khrustalev; Anna Y Zueva; Lidia S Shul'pina; Elena S Shubina; Nikolay S Ikonnikov; Georgiy B Shul'pin

doi:10.3390/molecules28031211

Cagelike Octacopper Methylsilsesquioxanes: Self-Assembly in the Focus of Alkaline Metal Ion Influence-Synthesis, Structure, and Catalytic Activity

Molecules. 2023 Jan 26;28(3):1211. doi: 10.3390/molecules28031211.

Authors

Alexey N Bilyachenko¹, Ivan S Arteev^{1

2}, Victor N Khrustalev^{3

4}, Anna Y Zueva^{1

3}, Lidia S Shul'pina¹, Elena S Shubina¹, Nikolay S Ikonnikov¹, Georgiy B Shul'pin^{5

6}

Affiliations

¹ A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str. 28, 119991 Moscow, Russia.
² Higher Chemical College, Mendeleev University of Chemical Technology of Russia, Miusskaya Sq. 9, 125047 Moscow, Russia.
³ Research Institute of Chemistry, Peoples' Friendship University of Russia (RUDN University), Miklukho-Maklay Str. 6, 117198 Moscow, Russia.
⁴ Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences (RAS), Leninsky Prospect 47, 119991 Moscow, Russia.
⁵ Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Ulitsa Kosygina 4, 119991 Moscow, Russia.
⁶ Chair of Chemistry and Physics, Plekhanov Russian University of Economics, Stremyannyi Pereulok, Dom 36, 117997 Moscow, Russia.

Abstract

A family of unusual octacopper cage methylsilsesquioxanes 1-4 were prepared and characterized. Features of their cagelike (prismatic) structure were established using X-ray diffraction studies. Effects of distortion of prismatic cages 1-4 due to variation of (i) additional alkaline metal ions (K, Rb, or Cs), (ii) combination of solvating ligands, and (iii) nature of encapsulating species were found. Opportunities for the design of supramolecular 1D extended structures were found. These opportunities are based on (i) formate linkers between copper centers (in the case of Cu₈K₂-based compound 2) or (ii) crown ether-like contacts between cesium ions and siloxane cycles (in the case of Cu₈Cs₂-based compound 4). Cu₈Cs₂-complex 4 was evaluated in the catalysis of alkanes and alcohols. Complex 4 exhibits high catalytic activity. The yield of cyclohexane oxidation products is 35%. The presence of nitric acid is necessary as a co-catalyst. The oxidation of alcohols with the participation of complex 4 as a catalyst and tert-butyl hydroperoxide as an oxidizer also proceeds in high yields of up to 98%.

Keywords: alkanes; alkyl hydroperoxide; cage-like compounds; metallasilsesquioxanes; molecular recognition; oxidative catalysis.

Grants and funding

This work (synthetic and catalytic studies) was supported by the Ministry of Science and Higher Education of the Russian Federation (Contract/agreement No. 075-00697-22-00) and was performed employing the equipment of Center for molecular composition studies of INEOS RAS. Funding for X-ray diffraction studies was provided by the Ministry of Education and Science of the Russian Federation (award no. 075-03-2020-223 (FSSF-2020-0017)). This work was also performed within the framework of the Program of Fundamental Research of the Russian Federation. Reg. No. 122040500068-0.