Table 1. Free Energies for Silyl Shifts from OFF to ON States (Schemes 1 and 2).

			S···S distancea
compound	ΔGrxnb	ΔGOFF →ON (ON→OFF)⧧c,d	ON	OFF	TS
1a	51.2	133.3 (82.1)	-	-	-
2a	–20.5	125.4 (145.9)	18.63	18.50	11.72
2b	1.0	116.8 (115.7)	13.57	13.54	9.51
2b*e	1.0	191.1e (190.0)e	13.57	13.54	13.54e
3a	–105.0	-	18.09	17.99	-
3b	–140.7	-	12.99	12.35	-

^aDistance between thiol end groups [Å].

^bReaction free energy [kJ/mol].

^cFree energy of activation relative to the OFF-state (normal print) [kJ/mol].

^dFree energy of activation relative to the ON-state (in italics) [kJ/mol].

^eRestricted S···S distance.