X-ray and nuclear spectroscopies to reveal the element specific oxidation states and electronic spin states for nanoparticulated manganese cyanidoferrates and analogs.

In this publication, the potential non-gadolinium magnetic resonant imaging agent - the nanoparticulate K₂Mn[Fe(CN)₆], its comparison sample KFe[Co(CN)₆], as well as their reference samples were measured and analyzed with Mn, Co and Fe L-edge X-ray absorption spectroscopy (L XAS). From the information obtained, we conclude that K₂Mn[Fe (CN)₆] has a high spin (hs)-Mn(II) and a low spin (ls)-Fe(II), while KFe[Co(CN)₆] has a hs-Fe(II) and a ls-Co(III). In these Prussian blue (PB) analog structures, L XAS also concluded that the hs-Mn(II) in K₂Mn[Fe(CN)₆] or the hs-Fe(II) in KFe[Co(CN)₆] is bonding to the N in the [M(CN)₆]^4-/3- ions [where M = Fe(II) or Co(III)], while the ls-Fe(II) in K₂Mn[Fe(CN)₆] or the ls-Co(III) in KFe[Co(CN)₆] is bonding to the C in the [M(CN)₆]^4-/3- ion, suggesting the complexed metalloligand [Mn(II) or Fe(II)] occupy the N-bound site in PB. Then, nuclear resonant vibrational spectroscopy (NRVS) was used to confirm the results from the L XAS measurements: the Mn(II), Eu(III), Gd(III), Fe(II) cations complexed by [M(CN)₆]^n--metalloligand are all taking the N-bound site in the PB-like structures. Our NRVS studies also approve that iron in K₂Mn[Fe(CN)₆] compound has 2+ oxidation state and is surrounding by the C donor atoms in the [M(CN)₆]^n- ions.