How to spawn a mob with dyed wool head

I can successfully summon a mob with equipment and a block head. However when I try to summon a mob with a dyed wool block head, using wool:14, it doesn’t work.

What is the correct way to summon a mob with dyed wool block head?

Note: I’m running 1.8

/summon Zombie ~ ~1 ~ {Equipment:[{},{},{},{},{id:wool,Damage:<Metadata>,Count:1}]}