LIGAND-FIELD STRENGTHS AND OXIDATION-STATES FROM MANGANESE L-EDGE SPECTROSCOPY

L2,3 X-ray absorption spectra have been recorded for Mn(II), Mn(III), and Mn(IV) samples with a variety of ligands. For high-spin Mn(II) complexes, a systematic variation in spectra is observed as the ligand field is increased. A dramatically different spectrum is observed for Mn(CN)6(4-), consistent with the presence of a low-spin complex. Progressing in oxidation state from Mn(II) to Mn(III) through Mn(IV) complexes, the primary peak position shifts first 1.5-2 eV and then 1-2 eV to higher energy, and the ratio of L3 to L2 intensity decreases. The spectra have been quantitatively simulated with an atomic multiplet program with an octahedral crystal field superimposed. The high resolution, strong sensitivity to chemical environment and amenability to quantitative spectral shape analysis indicate that L-edges of the first transition series metals are a potentially useful probe for bioinorganic studies.