Characterization of the Oxygen Binding Motif in a Ruthenium Water Oxidation Catalyst by Vibrational Spectroscopy. (17th February 2016)

• Record Type: Journal Article
• Authors: Duffy, Erin M.; Marsh, Brett M.; Voss, Jonathan M.; Garand, Etienne
• Is Part Of: Angewandte Chemie. Volume 128:Number 12(2016)
• Page Start: 4147
• Page End: 4150
• Publication Date: 2016-02-17
• Subjects: Homogene Katalyse -- Ion-Molekül-Reaktionen -- IR-Spektroskopie -- Laser-Spektroskopie -- Reaktive Intermediate; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201600350
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: For homogeneous mononuclear ruthenium water oxidation catalysts, the Ru–O2 complex plays a crucial role in the rate determining step of the catalytic cycle, but the exact nature of this complex is unclear. Herein, the infrared spectra of the [Ru(tpy)(bpy)(O2 )] 2+ complex (tpy=2, 2′:6′, 2′′‐terpyridine; bpy=2, 2′‐bipyridine) are presented. The complex [Ru(tpy)(bpy)(O2 )] 2+, formed by gas‐phase reaction of [Ru(tpy)(bpy)] 2+ with molecular O2, was isolated by using mass spectrometry and was directly probed by cryogenic ion IR predissociation spectroscopy. Well‐resolved spectral features enable a clear identification of the O−O stretch using 18 O2 substitution. The band frequency and intensity indicate that the O2 moiety binds to the Ru center in a side‐on, bidentate manner. Comparisons with DFT calculations highlight the shortcomings of the B3LYP functional in properly depicting the Ru–O2 interaction.