# Form of the MOs of butadiene [closed]

We know that in butadiene there are 4 MOs. This is the MO with one node:

My question is: Why, with one node, can't we have something like this ?

## closed as off-topic by Todd Minehardt, airhuff, Jon Custer, Klaus-Dieter Warzecha, M.A.R.Mar 17 '17 at 13:20

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• MO symmetries should reflect the symmetry of the molecule. This is not a symmetry element for butadiene. – Zhe Mar 17 '17 at 2:20

• The main reason you can't have an MO like that is, going back to the two ethenes example, the orbitals that overlap to form the MO have to be of the same symmetry (ie we couldn't form an MO from one orbital with $\pi*$ symmetry and another with $\pi$ symmetry). Also, we only form as many MOs for butadiene as we put in from the two ethenes, so we can only form 4 MOs total. – Tyberius Mar 16 '17 at 18:50