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Resonance Raman studies of transition metal peroxo complexes: 5 —The oxygen carrier cobalt(II)‐salen and its μ‐peroxo complexes, [(L)(salen)Co] 2 O 2 ; L = DMSO, py, DMF, pyO and no L
Author(s) -
Hester R. E.,
Nour E. M.
Publication year - 1981
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250110202
Subject(s) - raman spectroscopy , chemistry , resonance (particle physics) , ligand (biochemistry) , cobalt , crystallography , transition metal , metal , oxygen , metal salen complexes , inorganic chemistry , catalysis , organic chemistry , biochemistry , physics , receptor , particle physics , optics
Resonance Raman spectra of the species [Co(salen)], [Co(salen)] 2 and [Co(salen)(py)] were obtained both from the solids and from CHCl 3 solutions. These spectra show a large number of bands in the 100–1750 cm −1 region which are assigned to vibrational modes of the salen ring. Oxygenated complexes having the general form μ‐peroxo‐[Co(salen)(L)] 2 O 2 , with ligand L being DMSO, py, DMF, pyO or no L and occupying the axial position trans to the dioxygen, gave resonance Raman spectra with many bands throughout the region 100–1750 cm −1 . The ν(CoO) and ν (OO) wavenumbers in these complexes have been assigned by means of oxygen‐18 substitution. Force constants for the OO and COO bonds in the DMF complex have the values 380 and 247 N m −1 , respectively. The effect of changing the ligand L on the observed wave numbers is interpreted in terms of both σ and π‐donor effects through the metal. Band intensity excitation profiles demonstrate that the O 2 2− → Co 3+ CT transition occurs at ˜370±10 nm for the complexes containing ligands L and at 580 nm for the complex with no L. Resonance function plots of Raman band intensities are interpreted in terms of the relative values of the OO bond orders which are shown to vary with the ligand L as follows: py>pyO>DMF>DMSO. This order is, however, at variance with that based on the ν (OO) wavenumbers.