EPR of electron irradiated K4OsII(CN)6 in KCl single crystals

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Abstract
Electron irradiation of the diamagnetic OsII(CN)64− ion in a KCl host lattice at 77 °K produces three paramagnetic species. Annealing experiments reveal that these species decay into at least four other species. EPR studies indicate that each species can be assigned to a pentacoordinated OsI(CN)5 complex, with 5d7 low spin configuration arising from the trapping of an electron in a dz2 orbital, associated with a charge compensating vacancy located at different lattice sites. The EPR spectra show a strong quadrupolar interaction. The g values, the magnetic hyperfine interaction, and a minimum value for the quadrupolar interaction with the 189Os nucleus are presented and discussed. Ligand hyperfine structure with four equivalent and one nonequivalent nitrogens is measured and the ligand fs and fp spin densities are calculated and discussed. The relative contribution of 5d and 6p electrons to the electric field gradient is discussed and compared with Mössbauer spectroscopy results.