The Mössbauer parameters of Fe(II)-humates point to the formation of inner-sphere chelate type complexes, whereas those of Fe(II)-polyuronates (pectates and alginates) suggest outer-sphere complexes which is in accord with the EPR (electron paramagnetic resonance) studies of their 3d-transition metal complexes. The following ligands must be taken into consideration: carboxylate and phenolic or alcoholic hydroxyl groups, nitrogen atoms and in hydrated states water molecules, resulting in various Fe(II)-species with different coordinations. In the case of Fe(III)-fulvate, a polynuclear structure may be assumed.
ASJC Scopus subject areas
- Soil Science