1D–3D Coordination Polymers Based on M ₄ Cu ₄ -Phenylsilsesquioxane (M = K, Rb, Cs) Cages: Synthesis, Structure, and Catalytic Activity

The present study describes a convenient approach to cage-like coppersilsesquioxanes’ extended structures using large alkaline metal (K, Rb, Cs) ions as “supramolecular facilitators”. Extended family (nine examples) of Cu4-based phenylsilsesquioxane cages feature the same molecular architecture but differ principally in their supramolecular derivatives. The single-crystal X-ray diffraction analysis (SCXRD) revealed the intercage interactions due to both various alkaline metal-involved joints with solvate “linkers” (ethanol, water, acetonitrile, and acetone) and contacts between alkaline metal ions and phenyl rings of cyclic phenylsiloxanes, responsible for the generation of 1D, 2D, and 3D coordination polymers. Compound 1 was assessed as a precatalyst in the tandem oxidation of cyclohexane to ε-caprolactone. Using mCPBA as the oxidant under microwave irradiation at 80 °C for 30 min, the reaction achieved a yield of up to 31.8% of ε-caprolactone, with a high selectivity, evidencing the potential of this complex as a selective precatalyst for this one-pot process from a readily available petrochemical feedstock to a valuable industrial monomer.