Reversible Cleavage and Formation of the Dioxygen O-O Bond Within a Dicopper Complex

• Published in: Science (American Association for the Advancement of Science) 1996-03, Vol.271 (5254), p.1397-1400
• Main Authors: Halfen, Jason A., Mahapatra, Samiran, Wilkinson, Elizabeth C., Kaderli, Susan, Young, Victor G., Que, Lawrence, Zuberbühler, Andreas D., Tolman, William B.
• Format: Article
• Language: English
• Subjects: Adducts; Biological and medical sciences; Cell structures and functions; Chemical bonds; Chemical Phenomena; Chemistry, Physical; Chloroplast, photosynthetic membrane and photosynthesis; Copper - chemistry; Crystal structure; Crystallography, X-Ray; Enzymes; Fundamental and applied biological sciences. Psychology; Heterocyclic Compounds - chemistry; Inhalants; Kinetics; Manganese; Molecular and cellular biology; Organic chemistry; Organometallic Compounds - chemistry; Oxidation; Oxidation-Reduction; Oxidation-reduction reaction; Oxidation-reduction reactions; Oxygen - chemistry; Photosynthesis; Photosynthesis research; Raman scattering; Solvents; Spectrophotometry, Ultraviolet; Spectrum Analysis, Raman; Temperature; Tissue oxygenation; Wavelengths
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.271.5254.1397

A key step in dioxygen evolution during photosynthesis is the oxidative generation of the O-O bond from water by a manganese cluster consisting of M$_2$(μ-O)$_2$ units (where M is manganese). The reverse reaction, reductive cleavage of the dioxygen O-O bond, is performed at a variety of dicoipper and di-iron active sites in enzymes that catalyze important organic oxidations. Both processes can be envisioned to involve the interconversion of dimetal-dioxygen adducts, M$_2$(O$_2$), and isomers having M$_2$(μ-O)$_2$ cores. The viability of this notion has been demonstrated by the identification of an equilibrium between synthetic complexes having [Cu$_2$($\mu - \eta^2$: $\eta^2 -O_2$)]$^{2+}$ and [cu$_2$(μ-O)$_2$]$^{2+}$ cores through kinetic, spectroscopic, and crystallographic studies.