Hi Professor Jones,

Everyone in our group was very impressed with how quickly you came up with the MOs for the 5-carbon pi system. I was wondering if you might have used node counting and symmetry to do it. Also, would the whole system look like this:

+ - + - +

+ - 0 + -

+ 0 - 0 +

+ + 0 - -

+++++

exactly right - here is how I do it:

for all odd systems:

1. bottom MO all +

2. left side + all the way up

3. right end alternates + ­ + ­ etc

4. next-to-bottom MO has only one node - always easy.

5. middle MO always + o ­ o + o ­ o + o ­ etc

6. note the symmetry of the "dots" - the pattern is always symmetrical.

remember to count nodes.