# How does singlet oxygen work in pericyclics?

1. ### CrimpJiggler

149

and heres the diagram for the 1O2 dienophile:

Its the 1E+g the one I'm interested in. I see that its single electrons are in a couple of degenerate pi orbitals. I'm having trouble figuring out what the LUMO is here. Does it even matter that I have 2 LUMOs? I kinda suspect, that would make it much more reactive since unpaired electrons are pretty unstable. Is this oxygen singlet species technically a diradical?

Last edited: Oct 22, 2013
2. ### DrDu

4,164
The MO diagram for singlet oxygen from wikipedia is not quite correct insofar as it is not a pi_x or pi_y orbital which is doubly occupied in singlet oxygen but rather a ##\pi^*_\pm=\frac{1}{\sqrt{2}}(\pi^*_x\pm i\pi^*_y)## orbital.
So let's say that the ##\pi^*_+## is doubly occupied, then the ##\pi^*_-## is the LUMO.