Transition Metal Complexes and the Activation of Dioxygen

Abstract

In order to address how diverse metalloprotein active sites, in particular those containing iron and copper, guide O₂binding and activation processes to perform diverse functions, studies of synthetic models of the active sites have been performed. These studies have led to deep, fundamental chemical insights into how O₂coordinates to mono- and multinuclear Fe and Cu centers and is reduced to superoxo, peroxo, hydroperoxo, and, after O-O bond scission, oxo species relevant to proposed intermediates in catalysis. Recent advances in understanding the various factors that influence the course of O₂activation by Fe and Cu complexes are surveyed, with an emphasis on evaluating the structure, bonding, and reactivity of intermediates involved. The discussion is guided by an overarching mechanistic paradigm, with differences in detail due to the involvement of disparate metal ions, nuclearities, geometries, and supporting ligands providing a rich tapestry of reaction pathways by which O₂is activated at Fe and Cu sites.

Copper–Oxygen Complexes Revisited: Structures, Spectroscopy, and Reactivity

“…121,122,227,228 Detailed evaluation of the bare [CuO] + ion supports a triplet ground state with the configuration (1 σ ) 2 (2 σ ) 2 (1 π x ) 2 (1 π y ) 2 (1 δ ) 4 (3 σ *) 2 (2 π x *) 1 (2 π y *) 1 (4 σ *) 0 [Figure 30 (left)], 57,220,222 which has been noted to be analogous to the 3 Σ g − ground state of dioxygen. 229 But rather than having biradical spin density equally distributed between the two atoms like in O 2 , in [CuO] + the singly occupied 2 π * orbitals have predominant oxygen p character, as reflected by the spin densities of 1.68 on O and 0.32 on Cu.…”

“…1–4 Such reactions are critically important in myriad processes, including metabolism, synthesis of useful organic compounds, and energy-related conversions. Metal ions play a privileged role as oxygenation and oxidation reagents and catalysts, largely through their ability to activate O 2 and to generate structurally intriguing metal–oxygen species that can have the ability to attack even the strongest C–H bonds.…”

“…The reader also is pointed to a number of more narrowly targeted but useful reviews or accounts on this subject that have appeared since 2004. 4,9,12,14,17–39 …”

Effect of Gender on Some Biochemical Parameters in Iraqi Cholelithiasis patients.

“…However under pathological conditions the loss of Cpferroxidase activity make it impossible for most(Fe 2+ ) to be oxidized to (Fe 3+ ): accordingly, the amount of ferric ion and transferrinbound Fe 3+ will decrease, while non-transferrinbound iron such as citrate -Fe 2+ , ascorbate -Fe 2+ and free Fe 2+ will increase, this will induce oxidative stress and free radical formation, and trigger a cascade of pathological events leading to cell death. It is also possible that the rate of spontaneous oxidization of Fe 2+ to Fe 3+ will increase so that more (Fe 3+ ) can be formed, as well as, generate a large amount of reactive oxygen species [33]. The resultsofthe present study were showedthat high significant increase (p<0.01) in Fe levels in male and female patients group when compared to male and female control group that may be because increasing the activity of XO as it is as well as Mo components of enzymes.…”

The role of molecular oxygen in the iron(iii)-promoted oxidative dehydrogenation of amines

“…At each stage of the process, electrons flow to the coordinated O 2 moiety, either from the ligand unit or from an external source. 37 In the system described here, we start with the iron(III) complex 1, would then react with EtO − to the final product, the Fe(II)-monoimine complex 2. However, this mechanism is not compatible with the experimental rate law (eqn (3)).…”