Question

Which of the following structures qualify as being aromatic, according to Huckel's rule?

Answer 1

Huckel's rule: If the planar cyclic conjugated molecule possess 4n+2 π electrons, where n is a positive integer, then the molecule is aromatic. Observe the following molecules: Aromatic according to Huckles rule Planar ring and contains 10π electrons. 4n+2-10 Thus follows huckel's rule. Hence, it is aromatic molecule. Planar ring and contains 6π electrons in the ring. 4n+2-6 Thus, follows huckel's rule of aromaticity. Hence, the molecule is aromatic

Not aromatic according to Huckles rule Heptalene is a non planar molcule. so, it is not- aromatic compound. 2- 18-annulene dianion contains 20π electrons. 4n+2-20 n-4.5 is not an integer. so, t is not aromatic. 2K It contains sp3 carbon atom and there is no contineous delocalization of π electrons. Thus, it is not aromatic.

It contains sp3 carbon atom and there is no contineous delocalization of π electrons throuh all the atoms. Thus, it is not aromatic ring. It contains 3 delocalised electrons (2 from the bond and one from the radical) So it is not aromatic compound according to Huckel rule.