Table 9.

Selected Reduction Potentials of Various Copper(ligand) Complexes and Enzyme Active Sites and Their Reported Geometries

copper complex	Ln	Cu(l) geometry	E1/2 (CuII/CuI) vs Fc+/0 (V)e	E1/2 (CuII/CuI) vs NHE (V)e
Cu(aq)	–	–		0.15 (H2O)1197
four-coordinate complexes
(MeCN)4Cu	4N	tetrahedral1198		1.18 (MeCN)1199
(Phen)2Cu	4N	distorted square planar1200		0.17 (H2O)1197
(2,9-Me2phen)2Cu	4N	distorted tetrahedral1201	0.19 (DMF)1202	0.82 (DMF)g
				0.60 (H2O)1097
(TMPA)(MeCN)Cu	4N	distorted tetrahedral1203	−0.41 (CH3CN)1002	0.22 (CH3CN)g
				0.02 (DMF)g
			−0.61 (DMF)771	−0.15 (H2O)1204
(TEPA)Cu	4N	distorted tetrahedral1254	−0.11 (DMF)1205	0.68 (DMF)g
(PMAS)Cu	2N, 2S	trigonal pyramidal1205	−0.16 (DMF)1205	0.47 (DMF)g
three-coordinate complexes
(MePY2)Cu	3N	distorted Tc	−0.31c (DMF)509	0.32 (DMF)g
(AN)Cu	3N	distorted T1206	−0.07 (MeCN)f	0.56 (MeCN)g
(MeAN)Cu	3N	distorted T1206	−0.20 (DMF)1207	0.43 (DMF)g
(L5)(MeIm)Cu	3N	b	−0.28 (DMF)633	0.35 (DMF)g
two-coordinate Cu(I) complexes
(Lδ)Cu	2N	linear,633d	0.33 (DMF)633	0.96 (DMF)g
(Im)2Cu	2N	probably linearb	−0.10 (H2O)1208	0.53 (H2O)b
(Py)2Cu	2N	probably linearb	−0.18 (H2O)1208	0.45 (H2O)g
copper enzymes
azurin	2N, 1S	trigonal planar1209		0.31 (H2O)1210
rusticyanin	2N, 1S	trigonal planar1211		0.68 (H2O)1212
T1 site, fungal laccase	2N, 1S	trigonal planar1213		0.76–0.79 (H2O)1214
CuH, (PHMcc)	3N	distorted T1215		0.27 (H2O)1216
CuB, CcO, bovine	3N	distorted T842		0.28–0.35 (H2O)876,877
CuB calculated potentialsa
CuB “relaxed” (calc)	3N	distorted Y902d		0.49 (calc)902
CuB “active” (calc)	3N	distorted Y902d		0.93 (calc)902

^aA “proton coupled” reduction potential is reported.

^bLCu^I X-ray structure not determined.

^cData not available for MePY2, geometry based on X- ray crystal structure for the (BnPY2)Cu derivative.

^dComputational structure.

^eDMF = dimethylformamide.

^fMeasured for this review.

^gAn estimated value for E_1/2 vs NHE by adding 0.63 V to the observed E_1/2 potentials reported vs Fc/Fc.⁺¹²¹⁷