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. Author manuscript; available in PMC: 2022 Jun 8.
Published in final edited form as: Chem Rev. 2021 Dec 20;122(1):1–49. doi: 10.1021/acs.chemrev.1c00521

Table 22.

PCET Thermochemistry of Oxidant/Base and Reductant/Acid Pairs in MeCNa

oxidant E ∘b base pKac E∘(V vs H2) BDFEeff
N(4-MeO-C6H4)3•+ 0.16 pyridine 12.53    0.93    73.4
N(4-MeO-C6H4)3•+ 0.16 2,6-Me2-pyridine 14.13    1.02    75.6
N(4-MeO-C6H4)3•+ 0.16 4-NH2-pyridine 17.62    1.23    80.4
N(4-MeO-C6H4)3•+ 0.16 acetate 23.51298    1.58    88.4
N(4-Me-C6H4)3•+ 0.38379 pyridine 12.53    1.15    78.5
N(4-Me-C6H4)3•+ 0.38379 2,6-Me2-pyridine 14.13    1.24    80.7
N(4-Br-C6H4)3•+ 0.67 pyridine 12.53    1.44    85.2
N(4-Br-C6H4)3•+ 0.67 2,6-Me2-pyridine 14.13    1.53    87.4
N(2,4-Br2-C6H4)3•+ 1.14 pyridine 12.53    1.91    96.0
Cp2Fe+ 0 pyridine 12.53    0.770    69.8
Cp2Fe+ 0 2,6-Me2-pyridine 14.13    0.864    71.9
[Fe(bpy)3]3+ 0.70379 pyridine 12.53    1.47    85.9
[Fe(bpy)3]3+ 0.70379 2,6-Me2-pyridine 14.13    1.56    88.1
*IrIII(dF(CF3)ppy)2(dtbbpy)d,e 0.95131,e 4-N(Me)2-pyridine 17.95    2.04    99.1
*IrIII(dF(CF3)ppy)2(dtbbpy)d,e 0.95131,e benzoate 21.51298    2.25  103.9
*IrIII(dF(CF3)ppy)2(bpy)d,e 1.04131,e 4-N(Me)2-pyridine 17.95    2.13  101.1
*IrIII(dF(CF3)ppy)2(bpy)d,e 1.04131,e benzoate 21.51298    2.34  106.0
reductant E ∘b acid pKac E∘(V vs H2) BDFEeff
*IrIII(ppy)3d,e −2.13123,e pTSAf   8.6298  −1.59  15.3
*IrIII((dF)ppy)3d,e −1.92123,e pTSAf   8.6298  −1.38  20.1
*IrIII(d(OMe)ppy)3d,e −2.28123,e NMe3H+ 17.61380  −1.21  24.1
*IrIII(d(OMe)ppy)3d,e −2.28123,e NEt3H+ 18.5380  −1.16  25.3
[Ru(bpy)3]+ −1.71381,g pTSAf   8.6298  −1.17  25.0
[Ru(bpy)3]+ −1.71381,g NMe3H+ 17.61380  −0.64  37.3
[Ru(bpy)3]+ −1.71381,g NEt3H+ 18.5380  −0.59  38.5
[Ru(bpy)3]+ −1.71381,g benzoic acid 21.51298  −0.41  42.6
[Ru(bpy)3]+ –1.71381,g acetic acid 23.51298  −0.29  45.3
Ir(ppy)2(dtbbpy)d −1.89133 2,6-Me2-pyridinium 14.13  −1.03  28.4
Ir(ppy)2(dtbbpy)d −1.89133 NMe3H+ 17.61380  −0.82  33.1
(C5Me5)2Fe −0.51288 pyridinium 12.53    0.26  58.0
Cp2Fe   0 pyridinium 12.53    0.770  69.8
Cp2Fe   0 acetic acid 23.51298    1.420  84.7
a

Potentials for 1e− reductions are in V vs Cp2Fe+/0. Values for E∘(V vs H2) are in V; −eE∘ is the average free energy for 12H2(g) addition. Uncited values of E∘(V vs H2) were calculated from other values in the row using Scheme 2 or eq 18. BDFEeff (effective BDFE; BDFEeff = 23.06E∘ox/red + 1.37pKa,HA/A− + CG; see ref 104 for more discussion) values were calculated in kcal mol−1 from E∘(V vs H2) using eq 18.

b

From ref 382 unless otherwise noted.

c

pKa of baseH+ from ref 383 unless otherwise noted.

d

ppy = 2-phenylpyridine; (dF)ppy = 2-(2,4-difluorophenyl)pyridine; dF(CF3)ppy = 2-(2′,4′-difluorophenyl)-5-(trifluoromethyl)pyridine; d(OMe)ppy = 4-methoxy-2-(4-methoxyphenyl)pyridine; dtbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine.

e

Asterisk (*) denotes that the active oxidant or reductant is the excited-state complex. As such, the given potential is the reported excited-state redox potential.

f

p-Toluenesulfonic acid.

g

Reference potential adjusted from SCE to Cp2Fe+/0 using ref 287.