This is the molecular orbital diagram for nitric oxide:

![enter image description here][1]


  [1]: https://i.sstatic.net/5SgBp.png

Now, we know that nitric oxide can dimerize. However, why does nitric oxide dimerize as to form an N-N bond? Why not an O-O bond? Wouldn't the lone electron be more likely "possessed" by the oxygen since oxygen is more electronegative (if we were to step away from molecular orbital theory for a second).