Abstract
A new Ru complex with the formula [Ru(bpn)(pic)(2)]Cl-2 (where bpn is 2,2 '-bi(1,10-phenanthroline) and pic stands for 4-picoline) (1Cl(2)) 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. 1(2+) undergoes a substitution reaction when it is chemically (by using NaIO4) or electrochemically oxidized to Ru-III, in which picoline is replaced by an hydroxido ligand to produce [Ru(bpn)(pic)(OH)](2+) (2(2+)). The former complex is in equilibrium with an oxo-bridged species {[Ru(bpn)(pic)](2)(mu-O)}(4+) (3(4+)) which is the major form of the complex in the Ru-III oxidation state. The dimer formation is the rate determining step of the overall oxidation process (k(dimer) = 1.35 M-1 s(-1)), which is in line with the electrochemical data at pH = 7 (k(dimer) = 1.4 M-1 s(-1)). 3(4+) can be reduced to [Ru(bpn)(pic)(OH2)](2+) (4(2+)), 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. 1(2+) and 4(2+) are also characterized by single crystal X-ray diffraction analysis. Chemical oxidation of 1(2+) triggered by Ce-IV shows its capability to oxidize water to dioxygen.
| Dokumententyp: | Zeitschriftenartikel |
|---|---|
| Fakultät: | Chemie und Pharmazie > Department Chemie |
| Themengebiete: | 500 Naturwissenschaften und Mathematik > 540 Chemie |
| ISSN: | 1477-9226 |
| Sprache: | Englisch |
| Dokumenten ID: | 90010 |
| Datum der Veröffentlichung auf Open Access LMU: | 25. Jan. 2022, 09:33 |
| Letzte Änderungen: | 25. Jan. 2022, 09:33 |
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