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This content will become publicly available on January 19, 2019

Title: The Role of Seven-Coordination in Ru-Catalyzed Water Oxidation

A family of Ru complexes based on the pentadentate ligand t5a 3– ((2,5-bis(6-carboxylatopyridin-2-yl)pyrrol-1-ide) and pyridine (py) that includes {Ru II(Ht5a-κ-N 2O)(py) 3} (1H II(κ-N 2O)), {Ru III(t5a-κ-N 3O 1.5)(py) 2} (2 III(κ-N 3O 1.5)), and {Ru IV(t5a-κ-N 3O 2)(py) 2}+ ({2 IV(κ-N3O 2)}+) has been prepared and thoroughly characterized. Complexes 1HII(κ-N 2O), 2 III(κ-N 3O 1.5), and {2 IV(κ-N 3O 2)}+ have been investigated in solution by spectroscopic methods (NMR, UV–vis) and in the solid state by single-crystal X-ray diffraction analysis and complemented by density functional theory (DFT) calculations. The redox properties of complex 2 III(κ-N 3O 1.5) have been studied by electrochemical methods (CV and DPV), showing its easy access to high oxidation states, thanks to the trianionic nature of the t5a 3– ligand. Under neutral to basic conditions complex {2 IV(κ-N3O 2)}+ undergoes aquation, generating {Ru IV(OH)(t5a-κ-N 2O)(py) 2} (2 IV(OH)(κ-N 2O)). Further oxidation of the complex forms {Ru V(O)(t5a-κ-N 2O)(py) 2} (2 V(O)(κ-N 2O)), which is a very efficient water oxidation catalyst, reaching a TOF MAX value of 9400 s –1 at pH 7.0, as measured via foot of the wave analysis. The key to fast kinetics for the catalytic oxidation of water to dioxygen by 2more » V(O)(κ-N 2O) is due not only to the easy access to high oxidation states but also to the intramolecular hydrogen bonding provided by the noncoordinated dangling carboxylate at the transition state, as corroborated by DFT calculations.« less
Authors:
ORCiD logo [1] ;  [2] ;  [3] ; ORCiD logo [3] ;  [3] ;  [4] ;  [5] ;  [3] ; ORCiD logo [6]
  1. The Barcelona Institute of Science and Technology (BIST), Tarragona (Spain). Inst. of Chemical Research of Catalonia (ICIQ); Univ. Rovira i Virgli, Tarragona (Spain)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Univ. de Nantes (France)
  4. The Barcelona Institute of Science and Technology (BIST), Tarragona (Spain). Inst. of Chemical Research of Catalonia (ICIQ)
  5. Univ. Autonoma de Barcelona (Spain)
  6. The Barcelona Institute of Science and Technology (BIST), Tarragona (Spain). Inst. of Chemical Research of Catalonia (ICIQ); Univ. Autonoma de Barcelona (Spain)
Publication Date:
Report Number(s):
BNL-203210-2018-JAAM
Journal ID: ISSN 2155-5435
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 8; Journal Issue: 3; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1425070