Formate-driven catalysis and mechanism of an iridium-copper complex for selective aerobic oxidation of aromatic olefins in water.

A hetero-dinuclear Ir-Cu complex with two adjacent sites was employed as a catalyst for the aerobic oxidation of aromatic olefins driven by formate in water. An Ir-H intermediate, generated through formate dehydrogenation, was revealed to activate terminal aromatic olefins to afford an Ir-alkyl species, and the process was promoted by a hydrophobic [Ir-H]-[substrate aromatic ring] interaction in water. The Ir-alkyl species subsequently reacted with dioxygen to yield corresponding methyl ketones and was promoted by the presence of the Cu moiety under acidic conditions.

Hydrogen peroxide production from oxygen and formic acid by homogeneous Ir-Ni catalyst.

Hydrogen peroxide was directly produced from oxygen and formic acid, catalysed by a hetero-dinuclear Ir-Ni complex with two adjacent sites, at ambient temperature. Synergistic catalysis derived from the hetero-dinuclear Ir and Ni centres was demonstrated by comparing its activity to those of the component mononuclear Ir and Ni complexes. A reaction intermediate of Ir-hydrido was detected by UV-vis, ESI-TOF-MS, and 1H NMR spectroscopies.

Mechanistic Insight into Synergistic Catalysis of Olefin Hydrogenation by a Hetero-Dinuclear Ru-Co Complex with Adjacent Reaction Sites.

We have designed and synthesized a hetero-dinuclear Ru-Co complex with a dinucleating ligand inspired by hetero-dinuclear active sites of metalloenzymes. A synergistic effect between the adjacent Ru and Co sites has been confirmed in catalytic olefin hydrogenation by the complex, exhibiting a much higher turnover number than those of mononuclear Ru or Co complexes as the components. A Ru-hydrido species was detected by H NMR and electrospray ionization (ESI)-time-of-flight (TOF)-MS measurements as an intermediate to react with olefins, and Co-bound methanol was suggested to act as a proton source.