Reinecke's salt

Reinecke's salt

Names
IUPAC names 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
3D model (JSmol)	Interactive image
ChemSpider	21106473
ECHA InfoCard	100.033.625
RTECS number	na
CompTox Dashboard (EPA)	DTXSID10894851
InChI InChI=1S/4CNS.Cr.3H3N.H2O/c4*2-1-3;;;;;/h;;;;;3*1H3;1H2/q4*-1;+3;;;;/p+1 Key: GXUDINOISGOIAV-UHFFFAOYSA-O InChI=1/4CNS.Cr.3H3N.H2O/c4*2-1-3;;;;;/h;;;;;3*1H3;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
SMILES [NH4+].S=C=N/[Cr-3]([NH3+])([NH3+])(/N=C=S)(/N=C=S)/N=C=S.O
Properties
Chemical 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
Occupational safety and health (OHS/OSH):
Main hazards	toxic
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 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. According to Organic Syntheses, NH₄[Cr(NCS)₄(NH₃)₂] is prepared by treatment of molten NH₄SCN (ca. 145–150 °C) with (NH₄)₂Cr₂O₇.

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.