Dioxygen binding models

Spin-pairing model of dioxygen binding and its application to various transition metal systems as well as hemoglobin cooperativity. R. S. Drago and B. B. Corden, Acc. Chem. Res., 1980, 13, 353-360 (39). 

Figure 4.13 Co(acacen), an early model compound exhibiting reversible dioxygen binding at low temperatures.

A thorough kinetic and thermodynamic analysis of this model system (small positive or negative enthalpies of formation are canceled by more negative entropies of formation) led Karlin s group to conclude that the stability of dioxygen binding is driven by favorable enthalpies, but unfavorable reaction entropies preclude observation of Cu2-02 at room temperatures.412... 

Takano, Y., Yamaguchi, K., Hybrid density functional study of ligand coordination effects on the magnetic couplings and the Dioxygen binding of the models of hemocyanin. Int. J. Quantum Chem. 2007, 107, 3103-3119. 

Jameson, G. B., Molinaro, F. S., Ibers, etal., Models for the active-site of oxygen-binding hemoproteins - dioxygen binding-properties and the structures of (2-methylimidazole)-meso-tetra (a,a,a,a-ortho-pivalamidophenyl)porphyrinatoiron(II)-ethanol and its dioxygen adduct. J. Am. Chem. Soc. 1980, 102, 3224-3237. 

An important precursor of such studies is the investigation of model compounds that are fully characterized. For instance, the end-on mode of dioxygen binding in dicopper complexes has been investigated by molecular mechanics 3961. The successful reproduction of the structures of such model compounds provides a sound basis for the modeling of similar sites in metalloenzymes13971. 

The first crystallographically characterized peroxo-containmg model for oxyHc was originally reported by Karlin, and resnlted from dioxygen binding to the tetraden-tate Cu center of [Cu (TMPA)]+, forming the purple... 

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