Table 3.

Catalytic systems, major products, maximum FEs, and mechanisms of Re complexes in electrochemical CO₂ reduction (n.a.=not available, prop.=proposal, comp.=computational investigation, exp.=experimental evidence).

Entry	Cat. system	Substitution	Major product	Max. FE (%)	Mechanism	Basis	Method	Ref.
1a		n=0, 1 X=H, MeCN, CO, HCO2, HCO3, CH3C(O), OMe, THF, OTf, PPh3, P(OEt)3, Cl, Br	CO/CO3 2− CO/H2O HCO2 − H2	98 [123] ca. 100[ 26 , 124 ] n.a. [125] 74 [126]	ETM	exp. comp.[ 60a , 63 , 127 ]	EPR, [128] IR‐SEC,[ 125 , 129 ] Raman [130] DFT	[26, 60a, 63, 122–131]
1b		R=vinyl, ethynyl, C6H4NH2, norbornenyl derivatives, CH2NHCOCH3/peptide resins, 4‐piperidinyl‐1,8‐naphthalimide, NHCSNH‐C6H4CF3, SMe, thiophene, 2,2′:5′,2′′‐terthiophene, 3′‐ethynyl 2,2′:5′,2′′‐terthiophene	CO/H2O	100 [98]	ETM	exp. [132]	IR‐SEC	[94a, 98, 132, 133]
1c		n=0, 1 R=Me, tBu, bisphenylethynyl, CH2NHCOCH3, tyrosyl derivative, CH2NEt2, CH2OH, CN, CO2H, CF3, NH2, NHMe, NMe2, OH, OMe, Si(Ph)4 X=H2O, Cl	CO/CO3 2−[134] CO/H2O HCO2H	100 [94f] 71 [135] 12 [136]	ETM	exp. comp. [130]	EPR, [130] IR‐SEC, [87a] Raman [130] DFT	[82, 94f, 130, 133a, 134–137]
1d		R1=H, C2H3 R2=Me, NHMe, NMe2, CF3	CO/CO3 2− CO/H2O	92 [138] 73 [94f]	n.a.	n.a.	n.a.	[ 94f , 137g , 138 ]
1e		X=O, S	CO/CO3 2‐	90	n.a.	n.a.	n.a.	[139]
1f		–	CO/H2O	89	ETM	exp. comp.	IR, UV/Vis‐SEC DFT	[140]
1g		R=C2H4OH	CO HCO2H	95 [141] 27 [141]	ETM (CO) ETH (HCO2H)	exp. comp.	IR, NMR, [95] UHPLC [141] DFT [95]	[ 95 , 141 ]
1h		R1=Ph, C6H4OH R2=Ph, phenyl‐2,6‐ diol, phenyl‐3,4,5‐triol	CO/CO3 2−	100	ETM	prop.	n.a.	[ 94f , 142 ]
1i		R=H, Me	CO	73	ETM	prop.	n.a.	[143]
2a		R1=H, NH2, 4‐piperidinyl‐ 1,8‐naphthalimide R2=H, NH2 R1∩R2=nanographene	CO/H2O	96 [144]	ETM	comp. [145]	DFT	[ 133a , 144 , 145 ]
2b		R=H, Me, Mes, 4‐MeOC6H4, 2,6‐(MeO)2C6H3, 3,5‐(MeO)2C6H3, 2,4,6‐(MeO)3C6H2, 3,4,5‐(MeO)3C6H2	CO/H2O	84 [146]	ETM	prop.	n.a.	[147]
2c		–	CO/CO3 2−	n.a.	ETM	prop.	n.a.	[148]
2d		R=H, tBu, CF3, NO2	CO	53	n.a.	n.a.	n.a.	[149]
3a		R1=Me, p‐C6H4R2, (m‐CF3)2C6H3 R2=CN, CF3, NO2 X=Cl, Br Y=CH, N	CO/H2O	92 [84]	ETM	prop. [84]	n.a.	[ 84 , 150 ]
3b		R1=tBu, pyrenyl R2=H, Me Y1=C, N Y2=CH, NH	CO/H2O	85 [151]	n.a.	n.a.	n.a.	[ 151 , 152 ]
4a		R1=C12H25, tolyl, C6H2(tBu)3, C3H6OH R2=H, NO2, OMe X=Cl, Br	CO/H2O	92	n.a.	n.a.	n.a.	[153]
4b		R=2,6‐(iPr)2C6H3, CH2C6H5, CH2C6F5	CO/H2O	99	ETM	exp.	IR‐SEC	[154]
5		R=H, Me, Ph	CO/H2O	61	ETM	comp.	DFT	[155]
6a		–	n.a.	n.a.	n.a.	n.a.	n.a.	[156]
6b		R=H, Me	CO	105±5	n.a.	n.a.	n.a.	[151]
7		L=pyrazole, 3,5‐dimethylpyrazole, indazole, 3‐(2‐pyridyl)pyrazole	CO	89	ETM	prop	n.a.	[157]
8		L=CO, Cl L∩L=bpy, phen n=0, 1 R=H, Ph, tolyl,C6H4Br, C6H4‐[M]	CO/H2O	94	ETM	prop.	n.a.	[158]