{Cu2+-Co3+-Cu2+} and {Cu2+-Fe3+-Cu2+} Heterobimetallic Complexes and Their Catalytic Properties

We report on the heterobimetallic complexes {Cu+-Co3+-Cu+} (3), {Cu+-Fe3+-Cu+} (4), {Cu2+-Co3+-Cu2+} (5), and {Cu2+-Fe3+-Cu2+} (6) and show their catalytic applications in the oxidation of hindered phenols and the oxidative coupling of terminal alkynes. The former reaction produces C-C-coupled and dealkylated products, whereas the latter leads to the homo- and heterocoupling of terminal alkynes. The facile redox interconversion between Cu+ and Cu2+ for the secondary metal ions in these heterobimetallic complexes appears to be essential for the observed catalysis, and an important design aspect is better substrate accessibility and the use of molecular oxygen as the sole oxidant.