Dioxygen Lewis structure

Molecular orbital theory predicts that O2 is paramagnetic, in agreement with experiment. Note that the Lewis structure of O2 does not indicate that it has two unpaired electrons, even through it does imply the presence of a double bond. In fact, the prediction/confirmation of paramagnetism in O2 was one of the early successes of molecular orbital theory. Also, the ions 0+ (dioxygen cation), Oj (superoxide anion), and 0 (peroxide anion) have bond orders 2V2, U/2, and 1, respectively. The experimental energy levels of the molecular orbital for the O2 molecule are shown in Fig. 3.3.3(b). 

Draw the Lewis structures of difluorine, F2, dioxygen, 02, and dinitrogen, N2. How many bonding pairs and how many nonbonding pairs of electrons are present in each structure ... 

Bonding in the dioxygen molecule, O2, is especially interesting. Its Lewis structure shows a double bond and complete pairing of elecfrons ... 

Relative rates of O2 uptake by tra/is-[Ir(X)(CO)(PPh2R)2] ( = Cl, Br, I R = Ph, Et, Me) in CHjCh follow the order R = Me > Et > Ph and X = I > Br > Cl > F. If dioxygen addition is considered as an acid-base reaction (metal complex = Lewis base), then factors which increase the electron density at the metal centre should (in the absence of unfevourable steric effects) enhance the addition of O2 (reaction 90). The results suggest that as the basicity of the phosphine ligand increases and the electronegatively of X decreases, the rate of O2 addition also increases. The X-ray crystal structure of [Ir(Cl)(C0)(02)(PPh2Et)2] reveals a side-on coordination with the O2 centre, CO and Cl moieties defining the equatorial plane, or a distorted octahedral iridium(III) system with... 

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