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Structural and resonance Raman studies of an oxygen-evolving catalyst. Crystal structure of [(bpy){sub 2}(H{sub 2}O)Ru{sup III}ORu{sup IV}(OH)(bpy){sub 2}](ClO{sub 4}){sub 4}

Journal Article · · Inorganic Chemistry
DOI:https://doi.org/10.1021/ic960348o· OSTI ID:471524
The oxidized form of the blue dimer water oxidation catalyst [(bpy){sub 2}(H{sub 2}O)Ru{sup III}ORu{sup IV}(OH)(bpy){sub 2}](ClO{sub 4}){sub 4} (bpy is 2,2{prime}-bipyridine) has been characterized structurally by X-ray crystallography. Comparisons with [(bpy){sub 2}(H{sub 2}O)Ru{sup III}-ORu{sup III}(OH{sub 2})(bpy){sub 2}](ClO{sub 4}){sub 4}{center_dot}2H{sub 2}O, [(bpy){sub 2}ClRu{sup III}ORu{sup IV}Cl(bpy){sub 2}](ClO{sub 4}){sub 3}{center_dot}H{sub 2}O, and [(tpy)(bpy)Os{sup III}OOs{sup IV}(bpy)-(tpy)]Na(ClO{sub 4}){sub 6}{center_dot}3H{sub 2}O (tpy is 2,2{prime}:6{prime},2{double_prime}-terpyridine) reveal that oxidation of Ru{sup III}-O-Ru{sup III} to Ru{sup III}-O-Ru{sup IV} results in significant structural changes at the {mu}-oxo bridge. There is an increase toward linearity along M-O-M, a decrease in the M-O bond distances at the bridge, and an increase in the H{sub 2}O-Ru-O bridge angle. These changes are discussed in the context of the structural requirements for O...O coupling and O{sub 2} evolution in higher oxidation states. Resonance Raman spectra of these and related complexes reveal that internal ligand vibrations as well as overtone and combination bands of an intense, symmetrical M-O-M stretch at 360-400 cm{sup {minus}1} contribute significantly to the Raman spectra. Additional M-O-M bands are identified near 800 cm{sup {minus}1} and, tentatively, near 130 cm{sup {minus}1}. It is not possible to assign bands to Ru-OH{sub 2} or Ru-OH stretches; bands at low energy appear to originate from modes that are highly mixed.
OSTI ID:
471524
Journal Information:
Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 20 Vol. 35; ISSN 0020-1669; ISSN INOCAJ
Country of Publication:
United States
Language:
English