A small family of nonanuclear Cu5Cs4-based phenylsilsesquioxanes 1–2 were prepared by a convenient self-assembly approach and characterized by X-ray diffraction studies. The compounds 1 and 2 show some unprecedented structural features such as the presence of a [Ph14Si14O28]14– silsesquioxane ligand and a CuII 5CsI 4 nuclearity in which the metal cations occupy unusual positions within the cluster. Copper ions are “wrapped” into a silsesquioxane matrix, while cesium ions are located in external positions. This resulted in cesium-involved aggregation of coordination polymer structures. Both compounds 1 and 2 realize specific metallocene (cesium–phenyl) linkage between neighboring cages. Compound 2 is evaluated as a catalyst in the Baeyer–Villiger (B-V) oxidation of cyclohexanone and tandem cyclohexane oxidation/B-V oxidation of cyclohexanone with m-chloroperoxybenzoic acid (mCPBA) as an oxidant, in an aqueous acetonitrile medium, and HNO3 as the promoter. A quantitative yield of ε-caprolactone was achieved under conventional heating at 50 °C for 4 h or MW irradiation for 30 min (for cyclohexanone as substrate); 17 and 19% yields of lactone upon MW irradiation at 80 °C for 30 min and heating at 50 °C for 4 h, respectively (for cyclohexane as a substrate), were achieved. Complex 2 was evaluated as a catalyst for the oxidation of alkanes to alkyl hydroperoxides and alcohols to ketones with peroxides at 60 °C in acetonitrile. The maximum yield of cyclohexane oxidation products was 30%. Complex 2 exhibits high activity in the oxidation of alcohols.

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%.

Ten copper-based cage silsesquioxanes were prepared via convenient self-assembly synthesis employing halides of different quaternary ammonium cations, namely, Me4NBr, Et4NBr, PhMe3NCl, BzMe3NCl, and BzEt3NCl. This approach led to cages of similar Cu4M2 nuclearity (M = Rb, K, or Na). Sandwich-like structures of all compounds were established by single-crystal X-ray diffraction studies using synchrotron radiation. In all products, anionic cages are based on two cyclic silsesquioxane [Ph6Si6O12] ligands, coordinating to a central hexagonal CuII 4M2 motif with a 2M6-1 topology. The complexes include two charge balancers, namely, quaternary N-cations located at the external (crown ether-like) positions to cage fragments. Selected compounds were tested as homogeneous multicopper(II) catalysts in a series of model reactions, such as the mild oxidation and carboxylation of alkanes, including inert gaseous C2–C4 saturated hydrocarbons. This study extends the types of synthetic approaches and family of ionic metallasilsesquioxanes with promising structural features and catalytic properties.