TY - JOUR
T1 - Ruthenium Water Oxidation Catalysts based on Pentapyridyl Ligands
AU - Gil-Sepulcre, Marcos
AU - Böhler, Michael
AU - Schilling, Mauro
AU - Bozoglian, Fernando
AU - Bachmann, Cyril
AU - Scherrer, Dominik
AU - Fox, Thomas
AU - Spingler, Bernhard
AU - Gimbert-Suriñach, Carolina
AU - Alberto, Roger
AU - Bofill, Roger
AU - Sala, Xavier
AU - Luber, Sandra
AU - Richmond, Craig J.
AU - Llobet, Antoni
PY - 2017/11/23
Y1 - 2017/11/23
N2 - © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Ruthenium complexes containing the pentapyridyl ligand 6,6′′-(methoxy(pyridin-2-yl)methylene)di-2,2′-bipyridine (L-OMe) of general formula trans-[RuII(X)(L-OMe-κ-N5)]n+ (X=Cl, n=1, trans-1+; X=H2O, n=2, trans-22+) have been isolated and characterized in solution (by NMR and UV/Vis spectroscopy) and in the solid state by XRD. Both complexes undergo a series of substitution reactions at oxidation state RuII and RuIII when dissolved in aqueous triflic acid–trifluoroethanol solutions as monitored by UV/Vis spectroscopy, and the corresponding rate constants were determined. In particular, aqueous solutions of the RuIII-Cl complex trans-[RuIII(Cl)(L-OMe-κ-N5)]2+ (trans-12+) generates a family of Ru aquo complexes, namely trans-[RuIII(H2O)(L-OMe-κ-N5)]3+ (trans-23+), [RuIII(H2O)2(L-OMe-κ-N4)]3+ (trans-33+), and [RuIII(Cl)(H2O)(L-OMe-κ-N4)]2+ (trans-42+). Although complex trans-42+ is a powerful water oxidation catalyst, complex trans-23+ has only a moderate activity and trans-33+ shows no activity. A parallel study with related complexes containing the methyl-substituted ligand 6,6′′-(1-pyridin-2-yl)ethane-1,1-diyl)di-2,2′-bipyridine (L-Me) was carried out. The behavior of all of these catalysts has been rationalized based on substitution kinetics, oxygen evolution kinetics, electrochemical properties, and density functional theory calculations. The best catalyst, trans-42+, reaches turnover frequencies of 0.71 s−1 using CeIV as a sacrificial oxidant, with oxidative efficiencies above 95 %.
AB - © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Ruthenium complexes containing the pentapyridyl ligand 6,6′′-(methoxy(pyridin-2-yl)methylene)di-2,2′-bipyridine (L-OMe) of general formula trans-[RuII(X)(L-OMe-κ-N5)]n+ (X=Cl, n=1, trans-1+; X=H2O, n=2, trans-22+) have been isolated and characterized in solution (by NMR and UV/Vis spectroscopy) and in the solid state by XRD. Both complexes undergo a series of substitution reactions at oxidation state RuII and RuIII when dissolved in aqueous triflic acid–trifluoroethanol solutions as monitored by UV/Vis spectroscopy, and the corresponding rate constants were determined. In particular, aqueous solutions of the RuIII-Cl complex trans-[RuIII(Cl)(L-OMe-κ-N5)]2+ (trans-12+) generates a family of Ru aquo complexes, namely trans-[RuIII(H2O)(L-OMe-κ-N5)]3+ (trans-23+), [RuIII(H2O)2(L-OMe-κ-N4)]3+ (trans-33+), and [RuIII(Cl)(H2O)(L-OMe-κ-N4)]2+ (trans-42+). Although complex trans-42+ is a powerful water oxidation catalyst, complex trans-23+ has only a moderate activity and trans-33+ shows no activity. A parallel study with related complexes containing the methyl-substituted ligand 6,6′′-(1-pyridin-2-yl)ethane-1,1-diyl)di-2,2′-bipyridine (L-Me) was carried out. The behavior of all of these catalysts has been rationalized based on substitution kinetics, oxygen evolution kinetics, electrochemical properties, and density functional theory calculations. The best catalyst, trans-42+, reaches turnover frequencies of 0.71 s−1 using CeIV as a sacrificial oxidant, with oxidative efficiencies above 95 %.
KW - kinetics
KW - pentapyridyl ligand
KW - ruthenium complexes
KW - substitution reactions
KW - water oxidation catalysis
U2 - 10.1002/cssc.201701747
DO - 10.1002/cssc.201701747
M3 - Article
VL - 10
SP - 4517
EP - 4525
JO - ChemSusChem
JF - ChemSusChem
SN - 1864-5631
IS - 22
ER -