Figure 1. Structure of cyclopropenyl anion (a), cyclopentadienyl anion (b) and cycloheptatrienyl anion (c) and phenyl carbanion (d)

From

Classification of Negative Charge Discriminate Hybridization with Aromatic and Anti-aromatic Behavior of Organic Compounds - Innovative Mnemonics

Arijit Das

World Journal of Chemical Education. 2021, 9(2), 57-63 doi:10.12691/wjce-9-2-4