title: Role of the secondary coordination sphere in metal-mediated dioxygen activation.
abstract: Alfred Werner proposed nearly 100 years ago that the secondary coordination sphere has a role in determining the physical properties of transition-metal complexes. We now know that the secondary coordination sphere impacts nearly all aspects of transition-metal chemistry, including the reactivity and selectivity in metal-mediated processes. These features are highlighted in the binding and activation of dioxygen by transition-metal complexes. There are clear connections between control of the secondary coordination sphere and the ability of metal complexes to (1) reversibly bind dioxygen or (2) bind and activate dioxygen to form highly reactive metal-oxo complexes. In this Forum Article, several biological and synthetic examples are presented and discussed in terms of structure-function relationships. Particular emphasis is given to systems with defined noncovalent interactions, such as intramolecular H-bonds involving dioxygen-derived ligands. To further illustrate these effects, the homolytic cleavage of C-H bonds by metal-oxo complexes with basic oxo ligands is described.
authors.affiliation: Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025, USA.
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Shook
authors.forename: A S
authors.initials: AS
authors.lastname: Borovik
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D043844:Crown Ethers / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008667:Metalloproteins / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D043844:Crown Ethers; D008667:Metalloproteins; D009942:Organometallic Compounds; D028561:Transition Elements; C015762:18-crown-6; D010100:Oxygen