Diatomic molecules, correlation diagrams electronic states

Diatomic Molecules as Possible Diagnostic Reagents and the Use of Correlation Diagrams. Since the primary reactions of polyvalent atoms are expected to form reactive intermediates, the most general approach to characterizing these primary reactions is to pick substrates whose reactions are most likely to convey information about the electronic states of the reacting atom and the geometry of its attack on the substrate. 

If the electronic states of the primary reaction products from a recoiling atom and a diatomic molecule can be determined, then adiabatic correlation diagrams could be used to deduce the electronic state of the reacting recoil atom, or the symmetry of attack, or both. 

A useful principle in drawing orbital correlation diagrams is the noncrossing rule, which states that for MO correlation diagrams of many-electron diatomic molecules. 

Homonuclear diatomics of heavier elements tend to lie closer to the separated atom limit of the correlation diagram (Fig. 7.2). Based on the dashed line representing O2 in this figure, what neutral, homonuclear, diatomic molecule would be the first to have a filled 8 molecular orbital in its groimd state, and how many electrons does it have ... 

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