Heme-copper/dioxygen adduct formation, properties, and reactivity.

Area of Science:

• Bioinorganic Chemistry
• Organometallic Chemistry
• Enzyme Mechanisms

Background:

• Heme-copper oxidases are crucial metalloenzymes involved in cellular respiration.
• Understanding dioxygen activation and O-O bond cleavage is vital in bioinorganic chemistry.
• Synthetic models provide insights into the complex mechanisms of these enzymes.

Purpose of the Study:

• To report recent developments in synthetic heme/copper/O2 chemistry.
• To explore potential relevance to heme-copper oxidase mechanisms and dioxygen activation.
• To characterize novel heme-copper-peroxo complexes and their coordination modes.

Main Methods:

• Generation of high-spin heme(Fe(III))-peroxo-Cu(II) complexes.
• Detailed structural and electronic characterization of representative complexes.
• Investigation of coordination modes influenced by varying copper-ligand environments.

Main Results:

• Successful synthesis of O2 adducts, forming heme(Fe(III))-peroxo-Cu(II) species.
• Coordination of the peroxo bridge is dependent on copper ligands: micro-eta(2):eta(1) with N4 ligands and micro-eta(2):eta(2) with tridentate chelates.
• Observation of a transient heme(Fe(III))superoxo intermediate during complex formation.

Conclusions:

• Synthetic heme/copper/O2 chemistry offers valuable models for understanding heme-copper oxidases.
• The coordination environment around copper dictates the binding mode of the dioxygen-derived ligand.
• Ongoing research focuses on the reductive O-O bond cleavage in these model systems.