A study of solid [{l{underscore}brace}Cu(MePY2){r{underscore}brace}{sub 2}O{sub 2}]{sup 2+} using resonance Raman and X-ray absorption spectroscopies: An intermediate Cu{sub 2}O{sub 2} core structure or a solid solution?
Solid [{l{underscore}brace}Cu(MePY2){r{underscore}brace}{sub 2}O{sub 2}]{sup 2+} is spectroscopically characterized using resonance Raman and X-ray absorption spectroscopy, for which the former technique probes the nature of the O-O bond and the latter defines the Cu-Cu interaction. In contrast to the crystal structure obtained for [{l{underscore}brace}Cu(MePY2){r{underscore}brace}{sub 2}O{sub 2}]{sup 2+}, which shows an intermediate Cu{sub 2}O{sub 2} core (Cu-Cu = 3.4 {angstrom} and O-O = 1.6 {angstrom}), resonance Raman peaks characteristic of both a side-on peroxide-bridged dicopper(II) core and bis-{mu}-oxo dicopper(III) core are observed. The bis-{mu}-oxo isomer is estimated to be present at approximately 5--20%. A good fit is obtained for EXAFS data for solid [{l{underscore}brace}Cu(MePY2){r{underscore}brace}{sub 2}O{sub 2}]{sup 2+} using an 80:20 ratio of Cu-Cu separations of 3.6 {angstrom} (characteristic of a side-on peroxide-bridged copper core) and 2.8 {angstrom} (associated with a bis-{mu}-oxo dicopper core). Analysis of the edge region places an upper limit on the amount of bis-{mu}-oxo isomer present in the solid at 40%. The factors governing the presence of bis-{mu}-oxo and/or side-on peroxide cores in solution for differing ligand systems are considered, and the contribution of the bite angle of the equatorial nitrogen atom donors is explored. The reactivity of [{l{underscore}brace}Cu(MePY2){r{underscore}brace}{sub 2}O{sub 2}]{sup 2+} in solution is correlated with the presence of the bis-{mu}-oxo core, using frontier molecular orbital theory.
- Research Organization:
- Stanford Univ., CA (US)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 20013123
- Journal Information:
- Journal of the American Chemical Society, Vol. 121, Issue 9; Other Information: PBD: 10 Mar 1999; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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