Table 2.

Solvent Dependence of PCET Thermochemistry^a

molecule	# of solvents	avg. E∘(V vs H2)	avg. − ΔG∘/nb	Δεc	table
TEMPOH	4	0.558 ± 0.048	65.0 ± 1.3	34.8	5
4-oxo-TEMPOHd	3	0.595 ± 0.053	64.6 ± 1.4	34.8	5
2,4,6-tBu3PhOH	6	1.003 ± 0.028	75.4 ± 0.8	77.9	6
4-MeO-2,6-tBu2PhOH	3	0.864 ± 0.025	72.0 ± 0.6	34.4	6
1,4-hydroquinone	3	0.656 ± 0.011	67.4 ± 0.2	72.6	7
2,6-dimethyl-1,4-hydroquinone	5	0.560 ± 0.012	65.1 ± 0.4	72.6	7
O2(g) + 2H2(g) → 2H2O	4	1.242 ± 0.013	81.0 ± 0.4e	43.5	11
DPPH-H	3	0.929 ± 0.012	73.5 ± 0.4	34.4	15
CO2(g) + H2(g) → CO(g) + H2O	4	−0.091 ± 0.016	50.3 ± 0.4	43.5	21
CO2(g) + 4H2(g) → CH4(g) + 2H2O	3	0.176 ± 0.007	56.4 ± 0.3	43.5	21

^aAverages and standard deviations were calculated for each molecule across the different solvent conditions listed in the tables below. Values for E^∘(V vs H₂) are in V; −eE^∘ is the average free energy for $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.{\text{H}}_{2(\text{g})}$ addition.

^bThese are averages of the average free energies to remove H^• from the substrate; denoted as BDFE, BDFE_avg, or −ΔG^∘/n in the tables (see Section 4).

^cRange of solvent dielectric constants for the values being averaged, with ε values taken from ref 72.

^dValue in hexane redetermined by equilibration with TEMPOH. See Supporting Information for full details.

^eThree solvents used to calculate the avg. of −ΔG^∘/n.