Iron (II) iodide

Crystal structure
__ Fe 2+      __ I -
General
Surname	Iron (II) iodide
other names	Iron diiodide Iron iodide (ambiguous)
Ratio formula	FeI 2
Brief description	red-purple solid
External identifiers / databases
CAS number 7783-86-0 13492-45-0 (tetrahydrate) EC number 232-031-2 ECHA InfoCard 100.029.119 PubChem 422512 ChemSpider 74200 Wikidata Q3786756
properties
Molar mass	309.65 g mol −1
Physical state	firmly
density	5.32 g cm −3 (25 ° C) 2.87 g cm −3 (tetrahydrate)
Melting point	587 ° C (decomposition)
solubility	soluble in water soluble in acetone
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 302 + 312 + 332-315-319-335-360 P: 201-280-301 + 312 + 330-302 + 352 + 312-304 + 340 + 312-308 + 313
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Iron (II) iodide is an inorganic chemical compound of iron from the group of iodides .

Extraction and presentation

Iron (II) iodide can be obtained by reacting iron with iodine at 500 ° C.

${\displaystyle \mathrm {Fe+I_{2}\longrightarrow FeI_{2}} }$

Alternatively, the synthesis can be carried out by reacting freshly reduced iron with concentrated hydriodic acid under a nitrogen atmosphere in methanol . The hexamethanol solvate initially obtained is then thermally decomposed to anhydrous iodide:

${\displaystyle {\ce {Fe + 2 HI ->[MeOH][] FeI2 * 6 MeOH + H2}}}$

${\displaystyle {\ce {FeI2 * 6 MeOH ->[T][] FeI2 + 6 MeOH}}}$

Extremely finely divided iron (II) iodide is obtained by thermal decomposition of tetracarbonyldiiodido iron (II) Fe (CO) ₄ I ₂ .

properties

Iron (II) iodide is a hygroscopic red-violet to black solid that is soluble in water, ethanol and diethyl ether . Oxidation occurs rapidly in solution and in moist air . It becomes whitish in the air. The solution in water is colorless. It has a trigonal crystal structure of the cadmium (II) hydroxide type with the space group P 3 m 1 (space group no.164) (a = 404 pm, c = 675 pm). The tetrahydrate is a black solid that is soluble in ethanol and water and decomposes at 90-98 ° C.

use

Iron (II) iodide is used as an active ingredient in homeopathic medicines. In the scope it is known as Ferrum iodatum . The ascribed effect especially against glandular diseases has not been scientifically confirmed.

The tetrahydrate is used as a catalyst and for the production of alkali iodides.

Individual evidence

1. ↑ ^{a b c d e f g} Data sheet Iron (II) iodide, anhydrous, beads, −10 mesh, ≥99.99% trace metals basis from Sigma-Aldrich , accessed on May 23, 2020 ( PDF ).
2. ^ ^{A b c} Dale L. Perry: Handbook of Inorganic Compounds, Second Edition . Taylor & Francis, 2011, ISBN 1-4398-1462-7 , pp. 483 ( limited preview in Google Book search).
3. ↑ ^{a b} Roger Blachnik (Ed.): Pocket book for chemists and physicists . Volume III: Elements, Inorganic Compounds and Materials, Minerals . founded by Jean d'Ans, Ellen Lax. 4th, revised and revised edition. Springer, Berlin 1998, ISBN 3-540-60035-3 , pp. 454 ( limited preview in Google Book search).
4. ↑ ^{a b c} Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1645.
5. ↑ G. Winter: Iron (II) halides . In: Aaron Wold and John K. Ruff (Eds.): Inorganic Syntheses . tape 14 . McGraw-Hill Book Company, Inc., 1973, ISBN   07-071320-0  ( defective ) , p. 101-104 (English).
6. ^ Karl-Heinz Lautenschläger: Pocket book of chemistry . Harri Deutsch Verlag, 2007, ISBN 978-3-8171-1760-4 , pp. 410 ( limited preview in Google Book search).
7. ↑ Markus Wiesenauer: Homeopathy for chronic complaints in Große GU Kompasse , pp. 91, 106 & 152, Gräfe and Unzer Verlag GmbH, 2012