Oxygen center attachment, molecular

ATTACHMENT OF THE OXYGEN CENTER AROUND THE ACTIVE METAL DEVELOPMENT OF MOLECULAR CATALYSTS BASED ON THE M—O—M MOTIF... 

Molecular oxygen is transported throughout the body by attaching to the iron(ll) atom in the heme group of hemoglobin. The iron(ll) atom lies at the center of a square planar complex formed by nitrogen atoms. When the O, molecule attaches to the iron, the plane of the heme group becomes distorted. 

Fig. 14. Formation of metastable intermediate revealed in a classical molecular dynamics simulation of the decaniobate ion under basic conditions. Oxygen atoms are red, niobium atoms are green, and protons are white. The added hydroxide ion is represented by the yellow oxygen. Nbi is nucleophilically attacked by the hydroxide ion in (b), and the upper bond to the m3 and the bonds to the me oxygen atoms in the center of the ion are broken. The displaced niobium atom then proceeds to hydrate, with the waters represented by the blue oxygen atoms becoming progressively attached, and then hydrolyzing to release protons that can bind to other oxygen atoms on the decaniobate. Water molecules also hydrate the top Nb3 atoms as they become detached from the central m6 oxygen atoms after the Nb -m30 bond is ruptured.

In the most mechanisms proposed for the intradiol cleavage oxygenations, the direct attack of molecular oxygen upon a carbon atom attached with a phenolate O atom is favored (substrate activation process, A in Fig. 8). The alternative mechanism prefers the direct attack of O2 to the iron center (oxygen activation process, B in Fig. 8). 

---