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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Catherine S.P on April 19, 2011, 05:03:56 AM

Title: Energy diagrams of pi molecular orbitals
Post by: Catherine S.P on April 19, 2011, 05:03:56 AM

Qu. What does the energy diagram showing the six pi-molecular orbitals look like?
Im confused as to how you draw this, do you:

Draw 6 pi orbitals? But then are all the pi orbitals the same and I also dont understand how they interact with each other;

Draw sigma orbitals to make up the pi orbitals? In this instance do you need 2 sigma orbitals to make up each pi molecular orbital and in each case do the sigma orbitals interact in exactly the same way for each pi orbital?

Also, how would you draw 6 of these on the same energy diagram, do each of the pi orbitals have slightly higher energy so you can draw them slightly above the previous pi-molecular orbital?! (But I thought they were all degenrate?!)

Title: Re: Energy diagrams of pi molecular orbitals
Post by: Honclbrif on April 19, 2011, 08:53:34 AM

I'm assuming you mean a conjugated system with 6 pi-orbitals.

Remember, sigma and pi-orbitals are molecular orbitals which are distinguished by their geometry. What type of atomic orbitals make a pi-orbital? How must these orbitals be arranged for them to overlap correctly? How many of these atomic orbitals do you need to make 6 pi-orbitals?