I have read that quinone systems are conjucated but not anti-aromatic. I had read the related questions:
- Is the aromaticity broken in some resonance structures of para-nitro-aminobenzene?
- Is a quinone ring aromatic?.
In one of those answers, I read a point which said that it was non aromatic:
[...] and you must be able to draw double bonds - internal to the ring - from each ring carbon atom. [...]
I don't get what this means as I had never heard of such a thing in Hückel's rule. I did read elsewhere that the system must be completely conjugated which is true in this case but due to cross conjugation the electrons are not delocalised throughout the system? I don't get why cross conjugation affects the delocalisation of the electrons this much? What is the proper explanation for this?