Aromaticity of multi annuli systems

In high school books, Huckel's rule is used for determining aromaticity. We were taught this example

Huckel's rule is limited to monocyclic systems. We were taught to find aromaticity by -

looking for a closed loop. The two loops that were pointed out have been drawn (in pink) in the diagram above.
Applying Huckel's rule to it i.e counting the number of $\pi$ electrons and then applying the 4n+2 formula for aromatic compounds and 4n for anti.

No explanation was provided as to why this concept works on the grounds of 'this is out of syllabus'.

I have multiple questions regarding this 'closed loop' concept

What is it really called?
How does this loop methodology work?
What would happen if the inner loop was aromatic and outer anti aromatic?
(the example has both loops anti)

Gaurang Tandon

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asked Feb 23, 2018 at 11:37

Avyansh Katiyar

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3

$\begingroup$ Well, you put charges backwards... $\endgroup$
– Mithoron
Feb 23, 2018 at 16:17
$\begingroup$ chemistry.stackexchange.com/questions/78732/… - pretty much same thing. $\endgroup$
– Mithoron
Feb 23, 2018 at 16:18
$\begingroup$ related chemistry.stackexchange.com/questions/37641/… chemistry.stackexchange.com/questions/51484/… $\endgroup$
– Mithoron
Feb 23, 2018 at 16:22
$\begingroup$ @avatar if you want to separate charges to make the inner and outer rings look aromatic, the negative charge should be on the inner ring. $\endgroup$
– Oscar Lanzi
Feb 24, 2018 at 14:31
$\begingroup$ @Oscar the rings are anti aromatic $\endgroup$
– Avyansh Katiyar
Feb 24, 2018 at 14:33

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