Table 1.

Summary of isomerization kinetics

macrocycle	T (°C)	ΔG‡expta,b	ΔG‡calcc
(S,R)-E(2,2)	69–84	27.0 ± 2.0	26.1*, 23.7
[(S,R)-E(2,2)]PtCl2	−10–6	20.3 ± 2.0	18.7*, 18.0
(S,R)-E(2,3)	120–135	31.0 ± 2.0	29.6*, 30.4
[(S,R)-E(2,3)]PtCl2	64–80	26.7 ± 1.9	26.4*, 24.7
(S,S)-E(3,3)	131	31.4 ± 0.1d	33.8d
[(S,S)-E(3,3)]PtCl2	125	30.0 ± 0.1e	29.7e
(S,R)-E(3,3)	128	31.0 ± 0.1f	32.7f
[(S,R)-E(3,3)]PtCl2	121	29.6 ± 0.1g	32.1g

The measured (ΔG^‡_expt) and calculated (ΔG^‡_calc) activation free energies of stiff stilbene E → Z isomerization in E(m,n) macrocycles and their platinum complexes [E(m,n)]PtCl₂ in kcal/mol.

^aat 298 K unless noted otherwise.

^bfree ligand in p-xylene-d₁₀; metal complex in DMF-d₇.

^cat 298 K unless specified otherwise, in vacuum at 1 atm; the two values for E(2,n), n = 2 or 3 correspond to the (S,R) and (S,S) diastereomers where * indicates the more stable diastereomer.

^dT = 131 °C.

^eT = 125 °C.

^fT = 128 °C.

^gT = 125 °C.