ironII110phenanthroline

Iron(II) 1,10-phenanthroline, often abbreviated as Fe(phen)3(2+), is a coordination complex consisting of an iron(II) ion coordinated to three bidentate 1,10-phenanthroline ligands. 1,10-phenanthroline is a heterocyclic organic compound with a planar structure containing two fused pyridine rings. This tridentate coordination to the central iron ion forms a stable octahedral complex.

The complex is well-known for its intense red color, which arises from metal-to-ligand charge transfer (MLCT) transitions. This characteristic color has led to its application as a spectrophotometric reagent for the determination of iron. The intensity of the color is directly proportional to the concentration of the iron complex, allowing for quantitative analysis.

Fe(phen)3(2+) exhibits notable electrochemical properties and can undergo redox reactions. It is also a relatively robust complex, stable under various conditions. Historically, this complex has played a role in analytical chemistry and continues to be studied for its photochemical and photophysical properties. Its synthesis typically involves reacting an iron(II) salt with 1,10-phenanthroline in a suitable solvent, often under anaerobic conditions to prevent oxidation of the iron(II) ion.