Electrochemical and Resonance Raman Spectroscopic Studies of Water‐Oxidizing Ruthenium Terpyridyl–Bipyridyl Complexes. Issue 3 (28th December 2016)

• Record Type: Journal Article
• Authors: Keidel, Anke; López, Isidoro; Staffa, Jana; Kuhlmann, Uwe; Bozoglian, Fernando; Gimbert‐Suriñach, Carolina; Benet‐Buchholz, Jordi; Hildebrandt, Peter; Llobet, Antoni
• Is Part Of: ChemSusChem. Volume 10:Issue 3(2017)
• Page Start: 551
• Page End: 561
• Publication Date: 2016-12-28
• Subjects: oxidation -- peroxido ligands -- Raman spectroscopy -- ruthenium -- water splitting; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201601221
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: The irreversible conversion of single‐site water‐oxidation catalysts (WOC) into more rugged catalysts structurally related to [(trpy)(5, 5′‐X2 ‐bpy)Ru IV (μ‐O)Ru IV (trpy)(O)(H2 O)] 4+ (X=H, 1‐dn 4+ ; X=F, 2‐dn 4+ ; bpy=2, 2′‐bipyridine; trpy=2, 2′:6′, 2"‐terpyridine) represents a critical issue in the development of active and durable WOCs. In this work, the electrochemical and acid–base properties of1‐dn 4+ and2‐dn 4+ were evaluated. In situ resonance Raman spectroscopy was employed to characterize the species formed upon the stoichiometric oxidation of the single‐site catalysts and demonstrated the formation of high‐oxidation‐state mononuclear Ru=O and RuO−O complexes. Under turnover conditions, the dinuclear intermediates, 1‐dn 4+ and2‐dn 4+ as well as the previously proposed [Ru VI (trpy)(O)2 (H2 O)] 2+ complex (3 2+ ) are formed. Complex3 2+ is a pivotal intermediate that provides access to the formation of dinuclear species. Single‐crystal X‐ray diffraction analysis of the isolated complex [Ru IV (O)(trpy)(5, 5′‐F2 ‐bpy)] 2+ reveals a clear elongation of the Ru−N bond trans to the oxido ligand that documents the weakness of this bond, which promotes the release of the bpy ligand and the subsequent formation of3 2+ . Abstract : Double up : The conversion of single‐site water‐oxidation catalysts of type1 2+ into the more rugged dinuclear derivatives of type1‐dn 4+ is studied through time‐resolved resonance Raman spectroscopy. The key intermediates of the mononuclear and dinuclear water‐oxidation catalytic cycles are identified, and the strongly pH‐dependent electrochemistry of1‐dn 4+ is examined in detail.