Ferroin
Encyclopedia
Ferroin is the chemical compound
with the formula [Fe(o-phen)3]SO4, where o-phen is an abbreviation for 1,10-phenanthroline
, a bidentate ligand. The term "ferroin" is used loosely and includes salts of other anions such as chloride.
. The active ingredient is the [Fe(o-phen)3]2+ ion, which is a chromophore
that can be oxidized to the ferric derivative [Fe(o-phen)3]3+. The potential for this redox change is +1.06 volts in 1M H2SO4.
The iron is low spin and octahedral with D3 symmetry. The intense color of this ferrous complex arises from a metal-to-ligand charge-transfer transition.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula [Fe(o-phen)3]SO4, where o-phen is an abbreviation for 1,10-phenanthroline
Phenanthroline
Phenanthroline is a heterocyclic organic compound. As a bidentate ligand in coordination chemistry, it forms strong complexes with most metal ions...
, a bidentate ligand. The term "ferroin" is used loosely and includes salts of other anions such as chloride.
Redox indicator
This coordination compound is used as an indicator in analytical chemistryAnalytical chemistry
Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...
. The active ingredient is the [Fe(o-phen)3]2+ ion, which is a chromophore
Chromophore
A chromophore is the part of a molecule responsible for its color. The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls...
that can be oxidized to the ferric derivative [Fe(o-phen)3]3+. The potential for this redox change is +1.06 volts in 1M H2SO4.
Preparation
Ferroin sulfate may be prepared by combining phenanthroline to ferrous sulfate in water.- 3 phen + Fe2+ → [Fe(phen)3]2+
The iron is low spin and octahedral with D3 symmetry. The intense color of this ferrous complex arises from a metal-to-ligand charge-transfer transition.