Table 1.

Activation parameters for enantiomerization of [n]helicenes (n=4–9).

[n]Helicene	ΔH ≠ [kcal mol−1]	ΔS ≠ [cal K−1 mol−1]	ΔG ≠ [kcal mol−1] at 298 K[a,b]	t 1/2 [min] at 298 K
4	–	–	(4.0)	–
5	22.9	−4.1	24.1 (24.4)	1.74×103[c]
6	33.8	−5.3	35.4 (36.9)	3.40×1011[d]
7	40.4	−2.8	41.2 (42.0)	6.10×1015[e]
8	40.9	−3.4	41.9 (42.7)	1.99×1016[e]
9	41.6	−5.0	43.1 (44.2)	1.51×1017[e]

[a] ΔG ^≠ in parenthesis are calculated values using DFT, see ref. [38]. [b] All the experimental activation parameters are calculated by re‐plotting (ln(k _e/T) against 1/T) using the equation ln(k _e/T)=ln(κk _B/h)+ΔS ^≠/R−(ΔH ^≠/R)(1/T) with κ=0.5, see ref. [39]. [c] See ref. [36]. [d] See ref. [30]. [e] See ref. [37].