Reinecke's salt

Reinecke's salt

IUPAC name Chromate(1-), diaminetetrakis- (thiocyanato-N)-, ammonium, (OC-6-11)-
Other names ammonium tetrathiocyanato- diamminechromate(III), Reinecke salt, ammonium reineckate
Identifiers
CAS number	13573-16-5
ChemSpider	21106473^Y
RTECS number	na
Jmol-3D images	Image 1
SMILES [NH4+].S=C=N/[Cr-3]([NH3+])([NH3+])(/N=C=S)(/N=C=S)/N=C=S.O
InChI InChI=1S/4CNS.Cr.3H3N.H2O/c42-1-3;;;;;/h;;;;;31H3;1H2/q4-1;+3;;;;/p+1^Y Key: GXUDINOISGOIAV-UHFFFAOYSA-O^Y InChI=1/4CNS.Cr.3H3N.H2O/c42-1-3;;;;;/h;;;;;31H3;1H2/q4-1;+3;;;;/p+1/rC4H6CrN6S4.H3N.H2O/c6-5(7,8-1-12,9-2-13,10-3-14)11-4-15;;/h6-7H3;1H3;1H2/q-1;;/p+1 Key: GXUDINOISGOIAV-JJHXSEQHAU
Properties
Molecular formula	C₄H₁₂N₇OCrS₄
Molar mass	354.42 g/mol
Appearance	dark red solid
Density	? g/cm³, ?
Melting point	270 °C
Boiling point	decomposes
Solubility in water	soluble in hot water
Structure
Coordination geometry	octahedral
Dipole moment	0 D
Hazards
R-phrases	20/21/22
S-phrases	36
Main hazards	toxic
Related compounds
Related compounds	[Co(NH₃)₆]Cl₃, KSCN, Chromium(III) chloride
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Reinecke's salt is a chemical compound with the formula NH₄[Cr(NCS)₄(NH₃)₂].H₂O. The dark-red crystalline compound is soluble in boiling water, acetone, and ethanol.

Structure

The chromium atom is surrounded by six nitrogen atoms in an octahedral geometry; the NH₃ ligands are mutually trans. The salt crystallizes with one molecule of water. It was first reported in 1863.^[1] According to Organic Syntheses, NH₄[Cr(NCS)₄(NH₃)₂] is prepared by treatment of molten NH₄SCN (ca. 145–150 °C) with (NH₄)₂Cr₂O₇.^[2]

Use

This salt was once widely used to precipitate primary and secondary amines as their ammonium salts. Included in the amines that effectively form crystalline precipitates are those derived from the amino acids, including proline and hydroxyproline. It also reacts with Hg²⁺ compounds, giving a red color or a red precipitate.

References

^ Reinecke, A. "Über Rhodanchromammonium-Verbindungen" Annalen der Chemie und Pharmacie, volume 126, pages 113-118 (1863). DOI: 10.1002/jlac.18631260116.
^ Dakin, H. D. (1943). "Reinecke Salt". Organic Syntheses. p. Collected Volume 2, p.555. http://www.orgsyn.org/orgsyn/pdfs/CV2P0555.pdf.