Study of Coordination Chemistry and Biochemicals Using Mössbauer Spectroscopy

Two Mössbauer parameters—chemical shift and quadrupole splitting—can provide information about the bonding between the metal atom and its ligands, structure of the metal ligand complex, and the oxidation state of the metal. The oxidation state in iron and tin inorganic compounds can be determined from the chemical shift. The magnitude of this parameter provides an estimate of the 4s contribution to bonding in iron compounds. The second parameter, quadrupole splitting, is related to the symmetry of the ligands about the metal ion in a complex. The results obtained with hemoglobin and its complexes illustrate the role of Mössbauer spectroscopy in the study of biochemicals. A scatter plot of quadrupole splitting vs. chemical shift shows the relationship of the biochemicals to the iron inorganic complexes. The measurements from Mössbauer spectroscopy are compared with those obtained from other structural techniques.