Rational (supra)molecular design and catalytic activity of cage-like Cu₄-based phenylsilsesquioxanes

An extended (i.e., 19 distinct species) family of cage-like Cu₄-phenylsilsesquioxanes allowed us to accentuate the general regularities behind their structural organization. Influencing factors, namely the (i) size of external alkali metal ions (from Li to Cs) and (ii) nature of bridging linkers (including the smallest possible ones, like a water molecule) on the self-assembly/supramolecular assembly of such Cu₄-building blocks have been thoroughly explored. A Cu₄K₄-based complex has been evaluated as a precatalyst in the oxidation of alkanes (cyclohexane, n-heptane, methylcyclohexane) and alcohols. The experimental evidence that radical species participate in the oxidation of alkanes is provided.