Table 3.

Summary of Mechanisms and Activation Parameters for Solution Reactions of (2-Y-DMBI)₂ with PCBM and TIPSp.

A	Y	ΔUdiss (ΔGdiss)[a] / kJ mol−1	ΔGET[b] / kJ mol −1	Mechanism	ΔH‡ / kJ mol−1	ΔS‡ / J mol−1 K−1	ΔG‡ (300) / kJ mol−1
PCBM	Cyc	+210 ([c])	+41	II	+29.9 ± 0.3	−71.2 ± 3.3	+51.2 ± 1.4
PCBM	Fc	+165 (+60)	+17	II	[c]	[c]	[c]
PCBM	Rc	+181 ([c])	+46	II	+45.4 ± 3.5	−95.4 ± 11.2	+74.0 ± 6.8
TIPSp	Cyc	+210 ([c])	+78	II	+64.2 ± 1.9	−44.6 ± 5.8	+77.6 ± 3.6
TIPSp	Fc	+165 (+60)	+54	I	[c]	[c]	[c]
TIPSp	Rc	+181 ([c])	+82	I	+118.1 ± 8.7	+27.8 ± 18.3	+109.8 ± 14.2
TIPSp	Rc	+181 ([c])	+82	II	+69.1 ± 2.7	−73.4 ± 15.1	+91.2 ± 7.2

^[a]ΔU_diss from DFT (Table 2) and ΔG_diss from ESR; related to ΔG‡ for mechanism I.

^[b]ΔG_ET (related to ΔG^‡ for mechanism II) estimated for D₂ + A → D₂^•+ + A^•– from electrochemical data in Table 2 and from values of E_1/2^0/− = −1.07 and −1.45 V for PCBM and TIPSp, respectively.

^[c]Not determined