Reinecke's salt

Reinecke's salt is an inorganic compound with the formula NH₄[Cr(NCS)₄(NH₃)₂·H₂O. The dark-red crystalline compound is soluble in boiling water, acetone, and ethanol.^[2] It can be classified as a metal isothiocyanate complex.

Reinecke's salt

Names
IUPAC name ammonium (OC-6-11)-diamminetetrakis(thiocyanato-N)chromate(1−)
Other names ammonium tetrathiocyanato- diamminechromate(III), Reinecke salt, ammonium reineckate
Identifiers
CAS Number	13573-16-5 Y
3D model (JSmol)	Interactive image
ChemSpider	21106473 Y
ECHA InfoCard	100.033.625
EC Number	237-003-3
PubChem CID	159682
UNII	JL96S212CS Y
CompTox Dashboard (EPA)	DTXSID10894851
InChI InChI=1S/4CNS.Cr.3H3N.H2O/c4*2-1-3;;;;;/h;;;;;3*1H3;1H2/q4*-1;+3;;;;/p+1 Y Key: GXUDINOISGOIAV-UHFFFAOYSA-O Y 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	1.49 g/cm3[1]
Melting point	270 °C (518 °F; 543 K)
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
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H312, H332, H410
Precautionary statements	P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P312, P304+P340, P312, P322, P330, P363, P391, P501
Related compounds
Related compounds	[Co(NH3)6]Cl3, KSCN, Chromium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Structure, preparation, reactions

The chromium atom is surrounded by six nitrogen atoms in an octahedral geometry. The NH₃ ligands are mutually trans and the Cr-NCS groups are linear. The salt crystallizes with one molecule of water.^[1]

It was first reported in 1863.^[3] NH₄[Cr(NCS)₄(NH₃)₂ is prepared by treatment of molten NH₄SCN (melting point around 145–150 °C (293–302 °F)) with (NH₄)₂Cr₂O₇.^[4]

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 Hg⁺² compounds, giving a red color or a red precipitate.