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Updated: Nov 29, 2025
Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics
Published on: April 12, 2019
A broad view on the complexity involved in water oxidation catalysis based on Ru-bpn complexes
Abolfazl Ghaderian1, Alicja Franke, Marcos Gil-Sepulcre
1Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain. allobet@iciq.cat cgimbert@iciq.es.
Abstract:
A new Ru complex with the formula [Ru(bpn)(pic)2]Cl2 (where bpn is 2,2'-bi(1,10-phenanthroline) and pic stands for 4-picoline) (1Cl2) is synthesized to investigate the true nature of active species involved in the electrochemical and chemical water oxidation mediated by a class of N4 tetradentate equatorial ligands. Comprehensive electrochemical (by using cyclic voltammetry, differential pulse voltammetry, and controlled potential electrolysis), structural (X-ray diffraction analysis), spectroscopic (UV-vis, NMR, and resonance Raman), and kinetic studies are performed. 12+ undergoes a substitution reaction when it is chemically (by using NaIO4) or electrochemically oxidized to RuIII, in which picoline is replaced by an hydroxido ligand to produce [Ru(bpn)(pic)(OH)]2+ (22+). The former complex is in equilibrium with an oxo-bridged species {[Ru(bpn)(pic)]2(μ-O)}4+ (34+) which is the major form of the complex in the RuIII oxidation state. The dimer formation is the rate determining step of the overall oxidation process (kdimer = 1.35 M-1 s-1), which is in line with the electrochemical data at pH = 7 (kdimer = 1.4 M-1 s-1). 34+ can be reduced to [Ru(bpn)(pic)(OH2)]2+ (42+), showing a sort of square mechanism. All species generated in situ at pH 7 have been thoroughly characterized by NMR, mass spectrometry, UV-Vis and electrochemical techniques. 12+ and 42+ are also characterized by single crystal X-ray diffraction analysis. Chemical oxidation of 12+ triggered by CeIV shows its capability to oxidize water to dioxygen.
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