Stabilization of the daughter species following the Auger event in some cobalt(III) chelates in different matrices

Abstract

The emission Mossbauer spectra of [57Co(III)(phen)g](0104)3•2 20 and [57Co(III)(bpy)3](C104)3-3H20 dispersed in matrices of sucrose, polyethylene oxide), and the corresponding Fe(II) chelates were studied. The ratio of the Fe(II)/Fe(III) species stabilized varies from matrix to matrix. These observations have been interpreted on the basis of electron acceptor and donor centers.

57Fe Absorption and Emission Mössbauer Spectroscopy in Co (III) Acetylacetonate

“…The effectiveness of other mechanisms, which have been suggested to determine the fate of the decayed ions, cannot be definitively ruled out. However, in our opinion, there is no clear-cut proof for the Coulomb explosion mechanism [24] ; all of the results invoked in favor of this process can equally well be interpreted in terms of the self-irradiation model, which is favored from the systematics of the available data. On the other hand, the competing donor-acceptor model [25] which has been suggested on the basis of results depending on the concentration of electron traps, appears more acceptable and can, in particular, explain the contrasting redox behavior reported in the acetylacetonate complexes of Co(I1) and Co(1II).…”

Hot Atom Chemistry 1976

“…Collective excitation of the π electron system is suggested as a possible way for the dissipation of the excitation energy [79]. The relative proportions Fe(II) and Fe(III) species from cobalt complexes dispersed in various matrices has been accounted for by the specific properties of electron donor -and acceptor centers [103]. A preliminary note mentions the spectroscopy of 57 Co in the carbonic anhydrase enzyme [10].…”

Emission Mössbauer Studies on Cobalt Carbonyl Complexes Labelled with 57Co

“…The velocity scale refers to eFe and corresponds to normal absorption geometry. spectra are not necessarily higher than the starting valence state of cobalt but can be also lower, e.g., Fe + for Co 2+ [6] and Fe 2+ for Co 3+ [7], The majority of 57 Co emission Mössbauer studies deals with Co(II) compounds but there has been also considerable work on Co(III) chelates. To the best of our knowledge, there is only one attempt in the literature to investigate cobalt of starting valence lower than two.…”