Consider the following reactions that generate major organic ionic species P, Q, R, and S: I. Cyclopentadiene + Na P (organic anion) II. 3-Bromocyclopropene + AgSbF ₆ Q (organic cation) III. Cyclooctatetraene + 2 K R (organic dianion) IV. 5-Bromo-1,3-cyclopentadiene + AgSbF ₆ S (organic cation) Which of the species P, Q, R, and S are aromatic?

Step-by-step solution

Let us analyze the organic ionic species formed in each reaction: Reaction I: Cyclopentadiene reacts with sodium metal to form the cyclopentadienyl anion (P). This anion is planar, completely conjugated, and has 6 -electrons. It follows Hückel's (4n+2) rule ( n=1 ) and is aromatic. Reaction II: 3-Bromocyclopropene reacts with AgSbF ₆ to undergo halide abstraction, forming the cyclopropenyl cation (Q). This cation is planar, completely conjugated, and has 2 -electrons. It follows Hückel's rule ( n=0 ) and is aromati