Molecular orbital theory dioxygen

As predicted by molecular orbital theory dioxygen has two unpaired electrons and some of its chemistry shows diradical characteristics in particular, it reacts readily with other radicals. Singlet oxygen is an excited state in which the two electrons in the p anti-bonding orbitals have paired spins. It produced in some chemical reactions and has different chemical reactivity. 

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). 

Most recent authors have discussed the bonding in dioxygen complexes in terms of molecular orbital theory. Thus Drago in his spin-pairing model for 77 complexes of cobalt proposes a M.O. diagram arising fi om the interaction of one jtg orbital of dioxy-... 

The explanation of the paramagnetism of dioxygen was one of the early triumphs of molecular orbital theory, since the property could not be explained in terms of earlier theories. 

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