Ferroin
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3D model (
JSmol ) |
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ChemSpider | |
ECHA InfoCard
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100.035.145 |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C36H24FeN62+ | |
Molar mass | 596.27 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ferroin is the
Structure
Many salts of [Fe(o-phen)3]2+ have been characterized by
Preparation and reactions
Ferroin sulfate may be prepared by combining
- 3 phen + Fe2+ → [Fe(phen)3]2+
The main reaction is 1-electron oxidation. [Fe(phen)3]2+ → [Fe(phen)3]3+ + 1 e− Addition of sulfuric acid to an aqueous solution of [Fe(phen)3]2+ causes hydrolysis:
- [Fe(phen)3]2+ + 3 H2SO4 + 6 H2O → [Fe(OH2)6]2+ + 3 [phenH]HSO4−
Redox indicator
Phenanthroline Fe(II) (Redox indicator) | ||
E0= 1.06 V | ||
Reduced. | ↔ | Oxidized |
This
Ferroin is suitable as a redox indicator, as the color change is reversible, very pronounced and rapid, and the ferroin solution is stable up to 60 °C. It is the main indicator used in cerimetry.[4]
Nitroferroin, the complex of iron(II) with 5-nitro-1,10-phenanthroline, has transition potential of +1.25 volts. It is more stable than ferroin, but in sulfuric acid with Ce4+ ion it requires significant excess of the titrant. It is however useful for titration in perchloric acid or nitric acid solution, where cerium redox potential is higher.[4]
The redox potential of the iron-phenanthroline complex can be varied between +0.84 V and +1.10 V by adjusting the position and number of
Related complexes
References
- .
- .
- ISBN 978-0-7167-2508-4.
- ^ ISBN 978-0-08-046672-9.